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1
Priest, Andrew. "Waste minimisation for bromination chemistry." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325651.
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Recsei, Carl. "Catalytic bromination for organic synthesis." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11625.
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On the instigation of Dr. C.S.P. McErlean I have investigated an enduring problem in synthetic organic chemistry: the lack of general methodologies for enantioselective halogenation. This omission in our otherwise broad capacity for introducing p-block elements asymetrically hampers the synthesis of naturally-occuring organohalogens, a large and growing class of known natural products possessing broad biological activity. We used rational design to envisage a chiral, nucleophilic catalyst with secondary binding sites upon catalyst. We synthesised a family of triazole-bearing BINOL-derived phosphoramidites and addressed issues related to the stability of these novel ligands. We showed that our catalytic system could be used to access the principle brominated substructures found in natural products. Our catalysts promoted rapid, chemoselective and diastereoselective bromocyclisation reactions, although enantioselectivity proved to be an enduring challenge. The delivery of a chloronium ion was also shown to be possible. Our success prompted us to embark on the synthesis of the snyderane natural products. We began with a one-step total synthesis of 3β-bromo-8-epicaparrapi oxide. Following this we synthesised the snyderols – the parent natural products of this family of sesquiterpenes. Our snyderol synthesis also required only a single step. We then targeted luzofuran, a recently isolated snyderane which had not previously been made. We synthesised luzofuran in a racemic fashion in two steps. We then completed a four-step asymmetric total synthesis, includeding the first report of a successful Noyori reduction of an allyl aryl ketone. An alternative reagent system based on the use of phosphine oxides as strong halogen bond acceptors was explored as a means to promote electrophilic halogenation reactions of prochiral biarylmethanes – substructures of interest in medicinal chemistry. We demonstrated that bifunctional catalysts were uniquely capable reagents in performing these reactions as compared to monovalent systems. The difficulty entailed in controlling the steric environment around the monovalent, reactive halonium equivalent meant that enantioselectivity was an enduring challenge.
3
Ferguson, Douglas. "Selectivity of aryl and benzylic bromination." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340755.
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4
Gunbas, Duygu Deniz. "Functionalization Of Saturated Hydrocarbons: High Temperature Bromination." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607307/index.pdf.
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ABSTRACT
FUNCTIONALIZATION OF SATURATED HYDROCARBONS:
HIGH TEMPERATURE BROMINATION
Gü<br>nbaS, Duygu Deniz
M.S., Department of Chemistry
Supervisor: Prof. Dr. Metin Balci
June 2006, 174 pages
Although saturated hydrocarbons are readily available and extremely cheap starting materials, they can not be used in synthetic chemistry without prior activation. Efficient functionalization of alkanes leading to the production of useful organic chemicals in an industrial scale is of considerable interest for the chemical and pharmaceutical industries and remains a long-term challenge for chemists. In this respect, halogenations of hydrocarbons which leads to a variety of useful synthetic intermediates is an open avenue which deserves special attention.
It is also noteworthy to mention that efficient methods for selective functionalization of saturated bicyclic hydrocarbons still remains elusive, albeit a number of methods employing various reagents have been developed for the C&<br>#8211<br>H bond activation of open chain and monocyclic alkanes.
Herein, we will investigate the high temperature bromination reactions as a method for functionalization of saturated bicyclic hydrocarbons such as octahydropentalene (1), octahydro-1H-indene (2) and 1a,2,7,7a-tetrahydro-1H-cyclopropa[b]naphthalene (3). The scope and the limitations of the reaction will reveal the regio-and stereoselectivity. Furthermore, formation mechanism of the products will be discussed and the chemistry of these compounds will be extended for further functionalization
5
He, P. "Solids as catalysts for regioselective bromination reactions." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637254.
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An introduction to a range of inorganic solids as heterogeneous catalysts in aromatic bromination reactions is given in Chapter 1. These solids involve silica, alumina, zeolites, clays, and heteropolyacids. Aromatic bromination over these solids is discussed. Regioselectivity towards the <I>para</I>-isomer of various alkylbenzenes is the main theme but the advantages and disadvantages of each brominating system are also discussed. In Chapter 2 the bromination of phenyl acetate (PA) is tested using zeolites, clays and AlCl<SUB>3</SUB> as catalysts. Zeolite NaY was found to be the most efficient catalyst for the <I>para-</I>selective bromination of PA in the presence of dichloromethane. Use of NaY zeolite allows the bromination of PA to give almost exclusively the <I>para</I>-isomer in quantitative yield. Additionally, the effect of the counterions, activation temperature of the zeolite, and solvent on the reaction were also investigated. In Chapter 3 the bromination of PA <I>via</I> a solvent-free process has been investigated. Additives (<I>i.e.</I> acetate anhydride, NaHCO<SUB>3</SUB> and NaOCOCH<SUB>3</SUB>) as HBr scavengers can markedly increase the selectivity for <I>para</I>-isomer. In particular, a mixture of zinc acetate and bromine is shown to be an efficient reagent for <I>para</I>-selective bromination. In Chapter 4 the separation of 4-bromophenyl acetate (4-BPA) is studied. 4-BPA can readily be separated in pure form from industrial distillation residues by selective sorption into ZSM-5 from a cyclohexane solution of the residues and subsequent desorption with acetone. Additionally, the effect of the zeolite parameters, solvent, and temperature on selective adsorption of 4-BPA, as well as re-generation of the used zeolite, have been investigated. In Chapter 5 transbromination of bromo-substituted phenols and phenyl acetates has been discussed using large-pore zeolites and AlCl<SUB>3</SUB> as catalysts. The reactions involve intermolecular transbromination. HZSM-5 zeolite shows shape selectivity for the <I>para</I>-isomer.
6
Cailleau, Thaïs. "Towards the catalytic asymmetric bromination of alkenes." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9132.
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This thesis relates our efforts towards the development of a general method for the catalytic asymmetric bromination of alkenes. Previous work within the group had reported the synthesis and the use of 2,6-di-[(4R,5R)-4,5-diphenyl-4,5-dihydro-1H-imidazol-2yl]-iodobenzene to catalyse the bromolactonisation of (±)-2-cyclopentene-1-acetic acid with some asymmetric induction observed. The reaction was initially postulated to proceed via formation of a hypervalent N-I(III)-Br bond in the catalyst, which by placing the electrophilic bromine in a chiral environment would allow for its selective delivery to the alkene substrate. Initial work aimed to acquire a better understanding of that reaction system and some mechanistic studies were undertaken. A different outcome to the one expected is reported and it was concluded that during the bromolactonisation reaction, no hypervalent iodine species was forming in situ and that instead a potential kinetic resolution via α-salt formation and diastereoselective halolactonisation mechanism was operating. These findings necessitated a redesign of the catalyst and the synthesis of various bis-amidine analogues is described. An unexpected rearrangement is also unveiled and its mechanism discussed. The new catalysts were screened in our asymmetric brominating system, using different alkene substrates, and the results are reported and discussed. Subsequent studies focused on elaborating a general method for the asymmetric dibromination of alkenes, where Br+ would be delivered by a stoichiometric chiral promoter. Screening of various alkene substrates to identify a suitable candidate is reported and discussed. The asymmetric dibromination of the chosen alkene is described and further investigations in order to elucidate the reasons for the lack of enantioselectivity observed are reported. Finally, attempts to synthesise Ts-DPEN following a similar route as previously developed within the group for the synthesis of DPEN is reported as a side chapter. Various attempts at the final benzoyl cleavage are described and discussed.
7
Thapa, Rajesh. "Regioselectivity in Free Radical Bromination of Unsymmetrical Dimethylated Pyridines." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1263340046.
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Ozer, Melek Sermin. "Functionalization Of Saturated Bicyclic Hydrocarbons: High Temperature Bromination." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612938/index.pdf.
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ABSTRACT
FUNCTIONALIZATION OF SATURATED BICYCLIC HYDROCARBONS:
HIGH TEMPERATURE BROMINATION
Ö<br>zer, Melek Sermin
M.Sc., Department of Chemistry
Supervisor: Prof. Dr. Metin Balci
January 2011, 139 pages
Although hydrocarbons are readily available and extremely cheap starting materials, they cannot be used in synthetic chemistry without prior activation. The selective functionalization of saturated hydrocarbons under mild conditions is of both biochemical and industrial importance.
Initially, saturated hydrocarbons such as octahydro-1H-indene 80, octahydro-1H-4,7-methanoindene 81 and bicyclo[4.2.0]octan-7-one 82 were synthesized as starting materials. Then high temperature bromination reactions of these saturated hydrocarbons as a method for C-H bond activation have been investigated and the synthetic application of the formed intermediates has been searched. Furthermore, the role of the alkyl substituents in tricyclic systems and the effect of carbonyl group in bicyclo[4.2.0] octan-7-one 82 have been studied and the mechanism for the formation of the products have been discussed. Finally, whole products were conscientiously purified and characterized.
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Aborways, Marwa M. "Oxidative bromination and ring expansion in organic chemistry." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/30280/.
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This thesis is composed of two independent research projects. The first major project discussed is electrophilic halogenation using inorganic halides in the presence of oxidant. This includes the conversion of tertiary propargyl alcohols in to α,α-dihaloketones. In addition, the oxidative bromination of a range of alkylbenzene derivatives using the inexpensive oxidant Oxone and sodium bromide is described with up to 4 C-H bonds being functionalised in this process. The second part of this thesis focuses on using silacyclobutanes in our aim to access new siliconcontaining chemical space. Silacyclobutanes are useful in organic synthesis because of their exciting reactivity based on their high Lewis acidity and ring strain. We describe our efforts at developing catalytic conditions for the Pd-mediated dimerisation of silacyclobutanes, as well as our preliminary results on the nickel-catalysed enantioselective ring expansion of benzosilacyclobutane with aldehydes. After Tamao-Fleming oxidation, this reaction produces extremely useful chiral benzylic alcohols.
10
Allott, Philip Hugh. "The thermochemistry of bromination of phenols and anilines." Thesis, Royal Holloway, University of London, 1986. http://repository.royalholloway.ac.uk/items/45ee4bfb-9be1-4500-9d03-2b883899c5cb/1/.
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A method has been developed for bromination of aromatic compounds in aqueous solution in an isoperibol calorimeter. The enthalpies of bromination of phenol to 2,4,6-tribromophenol and of aniline, 2-bromo-aniline, 4-bromoaniline and 2,4-dibromoaniline to 2,4,6-tribromo-aniline were measured using this method. These values were used to derive the standard enthalpies of formation of 2,4,6-tribromophenol, 2-bromoaniline, 4-bromoaniline, 2,4-dibromoaniline and 2,4,6-tribromo-aniline. The enthalpies of combustion of 2,4,6-tribromophenol and 2,4,6-tribromoaniline were measured using a rotating-bomb calorimeter. These values were used to derive the standard enthalpies of formation of 2,4,6-tribromophenol and 2,4,6-tribromoaniline. The discrepancy between these latter standard enthalpies of formation and those found using the solution calorimetric method is discussed, and possible sources of systematic error indicated. The solution calorimetric method was adapted for the thermometric titration of phenols in aqueous solution with an aqueous solution of bromine. The sequential nature of bromination of five compounds -phenol, 2-bromophenol, 2-methylphenol, 3-methylphenol and 2-hydroxy-benzoic acid - was investigated using this technique. The reasons for this sequentiality are discussed. abstract continued overleaf A complete data-processing system has been designed for the solution calorimeter. A microcomputer is used for data acquisition from the AC bridge of the calorimeter through an analogue-to-digital interface. The bridge voltage readings, once uploaded to a minicomputer, are processed to yield the corrected temperature change. Enthalpies of reaction can then be calculated and statistical analyses performed. The problems encountered in developing the system are discussed, especially with regard to the calculation of the corrected temperature change from the noisy temperature data. A least-squares cubic spline is used for curve-fitting and calculation of the first derivative of temperature versus time.
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Dudley, Kathryn E. "An Expedited, Regiospecific para-Bromination of Activated Aryls." TopSCHOLAR®, 2017. http://digitalcommons.wku.edu/theses/1917.
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Electrophilic Aromatic Substitution (EAS) is one of the most frequently used aryl substitution methods. Aside from the fact that most EAS reactions require an acid and an oxidizer to proceed, the reactions involving activated aryls typically produce a mixture of ortho- and para- products as well as an ortho-/para- disubstituted product. Regiospecificity in aromatic substitution is key in the production of many compounds in a variety of disciplines. Since EAS is one of the most often used substitution methods, it is extremely important to develop an efficient method for regiospecific substitutions. Previous research developed a method of ortho-substitution by using hydrocarbon media, a less hazardous, greener medium, which was modified to develop a method of p-iodination (bromination), but with extensive time periods. The research presented here not only reveals an expedient, rapid method for regiospecific p-bromination, but also does so without the need for an acid or an oxidizer. The conditions for p-bromination involve the use of acetone (sometimes with cyclohexane) and NBS resulting in GC yields of p-brominated product approaching 100% in a cost and time efficient manner without the concerns of hazardous materials or byproducts like Br2 or HBr. The reaction mechanism is briefly examined as well.
12
Cansell, Gemma. "Towards a general catalytic asymmetric bromination reaction of alkenes." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414026.
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Ross, Joanne Claire. "Supported zinc bromide and its use in aromatic bromination." Thesis, University of York, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298653.
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Jalali, Elnaz. "Regiospecific P-Bromination of Activated Aromatic Systems – Greener Approach." TopSCHOLAR®, 2017. http://digitalcommons.wku.edu/theses/1950.
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The halogenated derivatives of heterocyclic compounds (haloarenes) are highly utilized in many fields of chemistry, including drug discovery, medicinal, and material chemistry. There are a variety of ways to functionalize an aromatic system and introduce halogen substituent into the ring. However, electrophilic aromatic substitution (EAS) has been the focus of growing attention, particularly for electronrich substrates.
Electrophilic aromatic bromination protocols are one of the most important electrophilic aromatic substitution reactions. However, preparation of bromoarenes classically recommends the use of highly oxidative agents along with utilizing various metal catalysts in a halogenated solvent. The corrosive and toxic nature of these reagents and need of harsh conditions for these protocols make their utility less desirable in current practice. Furthermore, lack of regioselectivity for most substituted aromatics is the other distinguished drawback, since most products contain ortho/para directors which afford a mixture of isomers.
The innovation of our procedure for the bromination of various substituted aromatic compounds is twofold in that highly regiospecific para-bromination of activated aryls by treatment with NBS has been accomplished. Although various reaction mediums, such as cyclohexane, acetone, and acetonitrile has been used in this procedure, the significant high yields of the product formation along with the very short reaction times using acetonitrile make this approach more attractive. That this regiospecific p-substitution takes place under such mild conditions leads us to question whether it is EAS.
15
Boys, Sarah K. "Tyrosine derivatives and their anti-cancer applications." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6243.
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The incorporation of a propargyl group to a natural product target allows for a streamlined approach to the investigation of structure activity relationships (SARs) and target identification in forward chemical genetics programmes using a ‘click’-based approach. To this end, an efficient synthesis of O-propargylated tyrosine derivatives was designed, and these have been used in the construction of peptide motifs both (a) derived from phage display libraries and (b) found in natural products. The L-tyrosine derivative Y* (compound I, X=H, R=H) was incorporated into a peptide sequence, PTTIYY, which is known to prevent the inhibition of p53 by the AG-2 protein. Y* has been included as both the terminal and the internal tyrosine in the peptide sequence. ELISA assays were carried out to determine how the binding of PTTIYY* and PTTIY*Y to AG-2 compared to that of the un-marked PTTIYY sequence. The results of these assays allowed new conclusions to be drawn regarding the important binding features of the peptide and possible sites for further optimisation of the AG-2 binding properties of this peptide through ‘click’ functionalisation of the modified tyrosine. The binding of the peptides incorporating Y* was also assessed using MCF-7 breast cancer cell lysate, known to contain the AG-2 protein. These results confirmed those seen for the purified AG-2 ELISA. The related bromo-D-tyrosine derivative (compound I, X=Br, R=Me) has been prepared and employed towards the synthesis of a bisebromoamide derivative. Bisebromoamide is a newly discovered polypeptide, and a promising anti-cancer agent. The bisebromoamide derivative contains a thiazole unit (Tzl), two N-methylated amino acids, and an oxopropyl pyrrolidine (Opp) moiety, which is unique to bisebromoamide in natural products. The activity of this bisebromoamide derivative will be investigated via ‘click’-based affinity chromatography using a new supported linker recently developed within the Hulme group.
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Hakim, Mas Rosemal. "Stereoelectronic effects in brominations of cyclopropylarenes and 9-alkylanthracenes." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54185.
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The free radical bromination of several cyclopropylarenes has been studied. The abstraction of a cyclopropyl hydrogen by bromine atom, which to date has been an unrecognized process, is demonstrated in this study. Specifically, when a cyclopropyl group is attached to the 9-position of an anthracene, an unprecedented hydrogen abstraction product, the corresponding cyclopropyl bromide, is obtained. This is believed to be due to stereoelectronic effects. Molecular mechanics calculations and X-ray crystallography have been used to demonstrate that 9-cycIopropylanthracene, unlike other cyclopropylarenes, is effectively locked in a conformation which places the a-cyclopropyl C-H bond in alignment with the p-orbitals of the aromatic system. This proper alignment activates the a-cyclopropyl hydrogen for abstraction by bromine atom. The relative reactivities of several 9-alkylanthracenes towards bromine atom are established, namely: 9-methyI- > 9-cyclopropyI- > 9-ethyl- >> 9-isopropylanthracene. Semi-empirical molecular orbital theory and molecular mechanics calculations have been utilized to demonstrate that the relative reactivities are not a function of bond dissociation energies but rather a function of the size of the dihedral angle between the a C-H bonds and the plane of the central ring of the various 9-alkylanthracenes in their lowest energy conformations. The absolute rate constants for the abstraction of hydrogen by bromine atom from 9-methyl-, 9-cyclopropyl-, and 9·ethylanthracene are estimated to be 1.1 x 10⁸ M⁻¹ sec⁻¹, 3.8 x 10⁷ M⁻¹ sec⁻¹ and 7.2 x 10⁶ M⁻¹ sec⁻¹ respectively. The value for the primary hydrogen/deuterium isotope effect for the abstraction of hydrogen by bromine atom from 9-cyclopropylanthracene is determined to be 2.6. All of the above observations lend support to the importance of stereoelectronic effects in the free radical bromination of the cyclopropylarenes and 9-alkylanthracenes.<br>Ph. D.
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Degirmenci, Volkan. "Methane Activation Via Bromination Over Sulfated Zirconia/sba-15 Catalysts." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12609021/index.pdf.
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Methane activation with bromine followed by the condensation of the methyl bromide into higher hydrocarbons or oxygenates is a novel route. However, the selective production of monobrominated methane (CH3Br) at high conversions is a crucial prerequisite. A reaction model was developed according to the kinetic data available in the literature and thoroughly studied to investigate the optimum reactor conditions for selective methane bromination in gas phase. It was concluded that at high methane (><br>90%) conversions dibromomethane synthesis was favored at high selectivity (~90%) under the following conditions: T=330 °<br>C, Br:CH4 = 3. Sulfated zirconia included SBA-15 catalysts were prepared and characterized for the catalytic methane activation via bromination. The SBA-15 sol-gel preparation technique was followed and the zirconium was added during the preparation in the form of ZrOCl2·<br>8H2O with 5-30 mol % ZrO2 with respect to the SiO2 content simultaneously with the silicon source (TEOS). The catalysts were sulfated in 0.25 M H2SO4 solution. The zirconium contents of the catalysts were determined by elemental analysis and 15 wt. % Zr was determined as the highest amount. XRD analysis showed the crystalline zirconia peaks only for high zirconia loadings (><br>25 mol % ZrO2) indicating the good distribution of Zr in silica framework at lower loadings. BET surface areas of the sulfated catalysts are in the range of 313-246 m2/g. The porous structures of the catalysts were determined by TEM
pictures, which revealed that the increase in Zr content decreased the long range order of pore structure of SBA-15 in agreement with XRD results. The acidities of the catalysts were determined by 1H MAS NMR experiments. Brø<br>nsted acidity was identified by a sharp 1H MAS NMR line at 10.6 ppm. The highest acidity was observed at 5.2 wt. % Zr loading according to 1H MAS NMR experiments. 29Si MAS NMR analysis showed the formation of Si-O-X linkages (X=H, Zr). Further characterization of Brø<br>nsted acidity was performed by FT-IR spectroscopy of adsorbed CO at 82 K. The analysis
revealed that the Brø<br>nsted acidity of sulfated catalysts were similar to the acid strength of the conventional sulfated zirconia. In TPD experiments, the basic molecule isopropylamine (IPAm) was adsorbed and decomposition
temperature of IPAm was monitored. The temperature decreased from 340 °<br>C to 310 °<br>C in sulfated catalysts, indicating the acidic character of these samples.
Catalytic methane bromination reaction tests were performed in a quartz tubular reactor. The results showed that 69% methane conversion was attainable over SZr(25)SBA-15 catalyst at 340 °<br>C. The liquid 1H NMR measurements of the products revealed that ><br>99% methyl bromide selectivity
was achieved.
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Redmond, Joanna. "The development of a catalytic asymmetric bromination reaction of alkenes." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/8835.
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This thesis describes our investigations into the development of a general method for the catalytic, asymmetric bromination of alkenes. The bromination catalysts employed in the research are ortho-substituted iodobenzenes, which are hypothesised to deliver Br+ to the alkene substrate via a hypervalent I(III)-Br bond. Initially, endeavours to achieve a large scale preparation of our asymmetric bromination catalyst, 2,6-di-[(4R,5R)-4,5-diphenyl-4,5-dihydro-1H-imidazol-2-yl]iodobenzene, or R-IBAM, are detailed. In order to facilitate this, a large quantity of enantiopure 1,2-diphenylethylene diamine was required to form the chiral amidine moieties of our R-IBAM catalyst. Thus, the development of two novel methods for the synthesis and resolution of 1,2-diphenylethylene diamine are described and the subsequent application of each route to a large scale preparation of the enantiopure diamine. The subsequent novel and optimised preparation of our catalyst to produce 25 g of R-IBAM is detailed. The following studies into the catalytic asymmetric bromination of alkenes include the screening of the various reaction conditions, stoichiometric addition of N-bromosuccinimide to the catalysts and the synthesis and screening of a range of R-IBAM derivatives and analogues. An improved understanding of the catalytic cycle and the possible mechanisms of loss of enantioexcess in our brominated product is detailed. The final section of the thesis describes research into the exchange of Br+ between enantiopure bromonium ions and alkenes. The generation of an enantiopure bromonium ion in the absence of alkene was achieved via the rearrangement of enantiopure bromohydrin, (2S)-1-bromo-1-phenylpropan-2-ol. The intermediate bromonium ion was trapped by chloride to produce the enantiopure bromochlorinated product. This, to the best of our knowledge, represents the first example of the generation and trapping of an enantiopure bromonium ion. Our subsequent investigations into Br+ transfer from the bromonium ion to added alkene are described.
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Rauert, Cassandra Brea. "Brominated flame retardant migration into indoor dust." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5287/.
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Brominated flame retardants (BFRs) are ubiquitous in indoor air and dust, leading to human exposure and resultant concerns about adverse impact on health. Despite elevated concentrations in dust, little is known about how BFRs transfer to dust from treated products. A test chamber was constructed to investigate pathways via which the polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) migrate from source materials to indoor dust. These were: (1) BFRs volatilise and subsequently partition to dust, (2) particles or fibres of the source abrade, transfering to dust directly (3) direct source-dust contact results in transfer. A HBCD treated textile curtain, and a PBDE TV casing were both tested. Partitioning post volatilisation was a less effective mechanism than abrasion. Direct source-dust contact resulted in effective and rapid transfer. A forensic microscopy investigation on ‘real world’ dust of elevated BFR content identified polymer particles containing BDE-209, likely originating from a BFR treated polymeric material indicating abrasion. An \(in\) \(vitro\) extraction test investigated the bioaccessibility of dust contaminated \(via\) pathways (1) and (2). Results indicate bioaccessibility may be less efficient from samples containing elevated concentrations of BFRs, and from dusts contaminated primarily via abrasion. More detailed research is essential to confirm these findings.
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Tucker, David John, and n/a. "An Investigation of the Chemical Constituents of Two Species of Marine Sponge." Griffith University. Division of Science and Technology, 1990. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050826.155059.
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An investigation of the dichioromethane extract of the sponge, Xestospongia testudinaria indicated that the extract was composed of approximately 40% sterols, 30% saturated fatty acids, 10% mono-unsaturated fatty acids and 20% poly-unsaturated acids. The sterol profile was found to vary between two collections of the sponge. In the first collection the major sterol was the C30 compound, xestosterol (4), which had not previously been reported to occur in this species. In the second collection there was a wider distribution of components with cholesterol (2a) being a major constituent and xestosterol being present in a much lower percentage than in the first collection. The poly-unsaturated acid fraction contained an extremely complex mixture. The novel brominated bisacetylenic C18 (47) and brominated C28 (65) acids were found to be the major components. Another six novel brominated acetylenic acids, which were very unstable, were also identified as well as an ester of 4 with 47. The method developed for the separation of the poly-unsaturated acids from the other classes of metabolites and for the isolation of the pure compounds is discussed and their structural elucidation, largely on the basis of NIMR spectroscopy is described. From the hexane extract of Carteriospongia foliascens, two novel bisalkylated norscalarane derivatives (114 and 116) and a bisalkylated scalarane derivative (130) have been isolated. By use of high field NMR and multipulse NMR techniques a complete assignment of the 111 and 13C NMR spectra of 130 has been achieved on 1.5mg of material. This represents the first report of a complete assignment of the 1J4 NMR spectrum of a scalarane derivative. The C-4 stereochemistry of 130 was determined by use of 1H NMR spectroscopic techniques, which gave results in agreement with the previously used 13C NMR method.
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Tucker, David John. "An Investigation of the Chemical Constituents of Two Species of Marine Sponge." Thesis, Griffith University, 1990. http://hdl.handle.net/10072/367459.
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An investigation of the dichioromethane extract of the sponge, Xestospongia testudinaria indicated that the extract was composed of approximately 40% sterols, 30% saturated fatty acids, 10% mono-unsaturated fatty acids and 20% poly-unsaturated acids. The sterol profile was found to vary between two collections of the sponge. In the first collection the major sterol was the C30 compound, xestosterol (4), which had not previously been reported to occur in this species. In the second collection there was a wider distribution of components with cholesterol (2a) being a major constituent and xestosterol being present in a much lower percentage than in the first collection. The poly-unsaturated acid fraction contained an extremely complex mixture. The novel brominated bisacetylenic C18 (47) and brominated C28 (65) acids were found to be the major components. Another six novel brominated acetylenic acids, which were very unstable, were also identified as well as an ester of 4 with 47. The method developed for the separation of the poly-unsaturated acids from the other classes of metabolites and for the isolation of the pure compounds is discussed and their structural elucidation, largely on the basis of NIMR spectroscopy is described. From the hexane extract of Carteriospongia foliascens, two novel bisalkylated norscalarane derivatives (114 and 116) and a bisalkylated scalarane derivative (130) have been isolated. By use of high field NMR and multipulse NMR techniques a complete assignment of the 111 and 13C NMR spectra of 130 has been achieved on 1.5mg of material. This represents the first report of a complete assignment of the 1J4 NMR spectrum of a scalarane derivative. The C-4 stereochemistry of 130 was determined by use of 1H NMR spectroscopic techniques, which gave results in agreement with the previously used 13C NMR method.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Division of Science and Technology<br>Full Text
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Ochonogor, Alfred Ezinna. "Thermal and catalytic pyrolysis of waste brominated plastics." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574522.
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The pyrolysis of brominated high impact polystyrene, brominated acrylonitrile butadiene styrene, television housing, integrated circuit tray and personal computer front panel plastics were performed respectively in a two stage reactor at a degradation temperature of 570 QC and heating rate of 20 QC. Four catalysts were used during the pyrolysis; waste fluid catalytic cracking catalyst (FCC), a natural zeolite catalyst, two Y -zeolite catalysts (CB V 400 and CBV720) in order to increase the value of the pyrolysis products. The pyrolysis products were analysed by various analytical techniques. The thermogravimetric analysis of brominated high impact polystyrene, brominated acrylonitrile-butadiene-styrene and television housing plastic showed a two stage degradation pattern while plastics from personal computer and integrated circuit tray showed a single step thermal degradation. On the TGA-FTIR the brominated high impact polystyrene, brominated acrylonitrile butadiene styrene and television housing plastic pyrolysed to form mono-substituted aromatics and aliphatic hydrocarbons, carbon dioxide and carbon monoxide. The pyrolysis investigation at 570QC showed that the oil yield was highest for the personal computer front panel plastic (85.37 wt %) and . '" ~ least for the television housing plastic (57.61 wt % oil). The natural zeolite catalyst increased the oil yield from all the plastics during pyrolysis. The gas yield was highest for the brominated acrylonitrile-butadiene-styrene (2.71 wt %) and least for the brominated high impact polystyrene (0.92 wt %). The solid residue yield for the personal computer plastic and the brominated high impact polystyrene were low but that for brominated acrylonitrile-butadiene-styrene, television housing plastic and integrated circuit tray plastic were much higher. Each of the pyrolysis oils contained mainly aromatic compounds. With the exception of the brominated high impact polystyrene all the other pyrolysis oils contained phenols and benzenebutanenitrile. The catalysts did not remove all of the bromine completely from the pyrolysis degradation products.
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Lawrence, Ruth. "N-oxides as organocatalysts for the Baeyer-Villiger oxidation and bromination reactions." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.723313.
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This thesis is concerned with exploring novel applications of N-oxides as organocatalysts. Specifically, aromatic N-oxides have been successfully implemented as catalysts within the Baeyer-Villiger oxidation of α,β-unsaturated ketones and electrophilic aromatic bromination reactions. Chapter 1 provides a review of the current applications of N-oxides, highlighting their use as organic oxidants, neutral ligands and in particular organocatalysts. These roles exploit several key features of the N-oxide, including the intrinsic weakness and polarity of the N→O bond, their Lewis basicity and ability to function as hydrogen bond acceptors. As organocatalysts, these species have predominantly been utilised as nucleophilic catalysts, however their potential to act as hydrogen bond catalysts represents an emerging area of interest. Chapter 2 describes the development of an organocatalysed Baeyer-Villiger oxidation, for which N-oxides and carboxylates have been identified as suitable catalysts. The optimised protocol, which employs DMAP as the pre-catalyst, was applied to a wide range of saturated and more specifically α,β-unsaturated ketones, with enhanced reaction rates and/or chemoselectivities achieved in the majority of cases. From extensive mechanistic studies, it is proposed that the N-oxide functions as a hydrogen bond acceptor; facilitating concerted proton transfer within the addition step. The unique role of the catalyst allowed for predictions to be made about the rate determining step of the oxidations performed. A series of by-products obtained from the over oxidation of (E)-4-phenyl-3-buten-2-one were characterised and the mechanistic pathway for their formation has been fully elucidated. Development of the reaction conditions for the selective formation of many of these species is also provided. Additionally, the novel reactions of 3-(4-methoxyphenyl)but-3-en-2-one are examined. Chapter 3 details investigations into the applicability of the novel, relatively bench stable formate ester, (formyloxy)(phenyl)methyl acetate, as a formylating reagent. A high yielding and operationally simple procedure for the synthesis of this formate ester from commercially available, inexpensive (E)-4-phenyl-3-buten-2-one is described in Chapter 2. A solvent and catalyst free protocol has been developed for the N-formylation of various amino species including primary and secondary (aliphatic and aromatic) amines and an amino acid ester as well as the O-formylation of alcohols. Demonstrating its synthetic utility, the developed methodology was applied to the one-pot synthesis of an isocyanide from the corresponding amine as well as the N-formylation of an unprotected amino acid under aqueous conditions. Chapter 4 outlines preliminary studies into the application of N-oxides as nucleophilic catalysts for electrophilic aromatic bromination reactions with elemental bromine. The development of novel methodology for the 4-picoline N-oxide catalysed regioselective monobromination of tert-butylbenzene is discussed, for which a reactive N-oxide bromine complex is thought to be generated in situ. Conditions have also been established for a KI promoted system, with IBr proposed as the catalytic species. Both methodologies allow for selective electrophilic aromatic bromination of toluene in the light without competitive benzylic bromination. Chapter 5 contains experimental procedures and compound characterisation data for Chapters 2-4 inclusive.
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Gumus, Selahaddin. "Secondary Electronic and Solvent Effects on Regiospecific P-Bromination of Aromatic Systems." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/3031.
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Bromoarenes are important aromatic building blocks that are commonly used to synthesize various functional compounds in pharmaceutical, agrochemical and related industries.1,2 This great demand for bromoarenes makes their preparation a widely studied area of synthetic organic chemistry. However, further understanding of the reactivity and regiochemistry of aromatic functionalization reactions is still necessary, as much about the secondary substitution and solvent effects remain unknown.
Resonance Theory is a widely used theoretical model to predict the regiospecifity and reactivity of the bromination of various aromatic compounds.3 The reactivity and regiospecificity of many substituted aromatic compounds is well explained using resonance theory.4 However, kinetic understanding of the p-bromination of halosubstituted aromatic compounds has not been investigated to the best of our knowledge.5,6In this thesis, the reactivity and regiospecifity of the p-bromination of activated secondary substituted aromatic compounds as well as media effects on the process will be discussed.
Synthesizing bromoarenes has been accomplished using many different experimental setups.7-11 N-bromosuccinimide is the most highly utilized electrophilic aromatic brominating agent. Many of the NBS- based aromatic bromination reactions have been reported using strong acids, strong bases, halogenated solvents, nonpolar solvents and polar solvents alike.12 The bromination reactions reported herein were performed using two different solvents, acetonitrile and acetone, to investigate the effects of solvent polarity on p-bromination. Although acetonitrile is one of the most commonly used solvents in the p-bromination of aromatic compounds, acetone has not been investigated.
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D'Silva, Kyle David. "Brominated organic micro-pollutants in food and environmental biota." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423582.
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Liu, Heping. "Substance flow analysis of brominated flame retardants in vehicles." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263644.
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Ålander, Lovisa. "Evaluation of lipid bromination : For the relative measurement of a chlorine gas biomarker." Thesis, Umeå universitet, Kemiska institutionen, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184523.
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McAllister, Linda. "Experimental and theoretical studies of the halogen bond and the electrophilic bromination reaction." Thesis, University of York, 2014. http://etheses.whiterose.ac.uk/6965/.
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The work presented in this thesis is an investigation into the halogen bond using both experimental and theoretical techniques. These studies have contributed toward the understanding of the interaction during a period when the definition of this interaction was being debated.1 The interactions investigated have a range of strengths; varying from the very weak interactions with rare gas atoms to the strong interactions with halonium ions acting as halogen-bond donors. The competition and cooperation between halogen and hydrogen bonds have been investigated including a situation where halogen bonding can be favoured over hydrogen bonding. Small-molecule analogues of orthogonal halogen and hydrogen bonding observed in biological systems have also been produced. The similarity between the two interactions has been highlighted by the fact that the Steiner-Limbach equation can model the bonding in both cases. New halogen-bonded liquid crystals between dihalogens and alkoxystilbazoles and alkoxyphenylpyridines have been synthesised and the complexes between elemental iodine and alkoxystilbazoles unexpectedly showed SmC phases with high stability. Attempts to synthesise equivalent liquid crystals with elemental bromine were unsuccessful, an electrophilic bromination reaction followed by elimination of HBr taking place instead. In order to understand this reaction further, the intermediates of the electrophilic bromination reaction for different substituted stilbenes was investigated computationally and the results showed that a carbocation intermediate is favoured if an electron-donating substituent is present. In contrast, stilbenes with two electron-withdrawing substituents favoured symmetric bromonium ion intermediates. Such halonium ion intermediates feature a halogen atom that carries a positive charge, which can interact with Lewis bases in a novel category of halogen bonding, which has properties similar to halogen bonding with traditional halogen-bond donors.
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Owen, Steven Robert. "Antimony oxide compounds for flame retardant ABS polymer." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/27210.
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Antimony trioxide (Sb2O3) is a common additive in flame retardant formulations and a study has been made to determine the effects of adding it alone, or with four commercial brominated materials (OBDPO, BTBPE, TBBA and PDBS80) to ABS polymer. The results focus upon mechanical, rheological, microscopical and flame retardant properties, and the effects of different Sb2O3 grades with average particle sizes ranging from 0.1 to 11.8 μm. The Sb2O3 was mainly studied up to 12 wt% loading in ABS, since this is considered to be the maximum level used in commercial flame retardant formulations.
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Lindström, Jonna. "Dietary intake estimations of brominated flame retardants for Swedish children." Thesis, Södertörn University College, School of Life Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-1829.
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<p>The dietary intake of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) have been estimated for Swedish children. A dietary survey performed in 2003, including 4, 8-9 and 11-12 year olds, and concentrations in individual food items were combined. The food included in the study was mainly of animal origin, consisting of fish and shellfish, dairy products, meat products, eggs, animal and vegetable fats and fats from miscellaneous food products. The medium-bound intake of PBDEs (9 congeners) were estimated to 23.0 ng/day, 30.9 ng/day and 27.7 ng/day for 4, 8-9 and 11-12 years olds respectively. The corresponding estimations for HBCD were 7.94 ng/day 10.7 ng/day and 9.46 ng/day for 4, 8-9 and 11-12 years olds respectively. These results show a higher daily intake for 8-9 year olds compared with the other age groups. However, when estimating the daily intake per kg bw, the intake decreases with age. BDE-47 contributed the most to the total intake of PBDEs, with approximately 40%. The food group contributing the most to the intake of PBDEs and HBCD was fish and shellfish, of which non-Baltic fatty fish was the largest contributor. There were no considerable differences between boys and girls in any of the aspects examined. The result from this study show a lower intake of PBDEs and HBCD in Swedish children compared with children in other studies made in Europe and the United States.</p><br><p>Bromerade flamskyddsmedel används för att skydda brännbara material från att fatta eld, till exempel skyddas textilier och plaster i bland annat elektronik, fordon och möbler. Två typer av bromerade flamskyddsmedel är polybromerade difenyletrar (PBDE) och hexabromocyklododekan (HBCD). Dessa är additiva flamskyddsmedel och blandas i materialet som ska skyddas men binder inte in i produkten och kan därför lätt läcka ut i miljön, vilket också har skett. Halter har påträffats i miljön och i biota långt från plaster där ämnena produceras eller används.</p><p>PBDE och HBCD har visats ha hormonstörande och neurotoxiska effekter i studier på råtta och mus. Thyroxinnivåerna sjunker vid exponering av PBDE och HBCD, vilket skulle kunna leda till sköldkörtelproblem och störd utveckling av bland annat hjärnan om exponering sker perinatalt. De neurotoxiska effekterna inkluderar inlärnings- och minnessvårigheter och ett förändrat beteende med hyper- och hypoaktivitet som följd.</p><p>Human exponering för PBDE och HBCD sker främst via födan och speciellt via animaliska produkter då dessa ämnen är lipofila, bioackumulerande och ofta biomagnifierande vilket gör att de påträffas i högre koncentrationer högre upp i trofinivåerna. Studier från bland annat Sverige och Finland visar att fisk och skaldjur är den största källan till intag av PBDE.</p><p>De flesta intagsberäkningar av PBDE och HBCD baseras på livsmedelskonsumtionen hos vuxna och visar följaktligen endast hur intaget ser ut för den delen av populationen. För barn, som är en av de känsligaste grupperna i populationen, finns inte många studier att tillgå, varken från Sverige eller andra delar av världen. I den här studien har därför intaget av PBDE (summan av 9 kongener) och HBCD beräknats för barn i Sverige.</p><p>I en rikstäckande kostundersökning utförd 2003 deltog barn i åldrarna 4, 8-9 och 11-12 år. De fick i en matdagbok ange sin konsumtion under fyra på varandra följande dagar. Data från denna undersökning kombinerades sedan med haltdata från olika livsmedel för att räkna ut intaget av PBDE och HBCD på individbasis. Undersökningen innefattade främst animaliska livsmedel och innehöll därför fisk och skaldjur, mejeriprodukter, köttprodukter, ägg, animaliskt och vegetabiliskt fett och fett från övriga livsmedel.</p><p>Resultaten visar att födointaget av PBDE var 23,0 ng/dag, 30,9 ng/dag och 27,7 ng/dag för 4, 8-9 respektive 11-12 åringar. Intaget av HBCD beräknades till 7,94 ng/dag, 10,7 ng/dag och 9,46 ng/dag för 4, 8-9 respektive 11-12 åringar. Detta visar att 8-9 åringar har det högsta dagliga intaget av PBDE och HBCD. När intaget beräknas på kroppsvikt däremot, har de yngsta barnen det högsta intaget som sedan sjunker med åldern. Fisk och skaldjur var den största källan till intaget av PBDE och HBCD, trots att konsumtionen av dessa livsmedel var relativt lågt. Det fanns ingen större skillnad mellan pojkar och flickor, varken i intag av PBDE eller av HBCD. Jämfört med de få studier som gjorts i andra länder, är det tydligt att svenska barn har ett lägre intag av PBDE och HBCD.</p><p>Undersökningen tyder också på att intaget av PBDE och HBCD hos svenska barn, utifrån de kunskaper vi har idag, inte utgör någon risk med avseende på de effekter av PBDE och HBCD som påträffats i toxikologiska studier. Däremot är barn i ett känsligt skede i livet och upprepad exponering samt exponering för flera miljögifter samtidigt skulle kunna påverka deras utveckling negativt.</p>
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Rattfelt, Nyholm Jenny. "Persistency, bioaccumulation and toxicity assessment of selected brominated flame retardants." Doctoral thesis, Umeå : Department of Chemistry, Umeå University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-22528.
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Thom, Darren James. "The cure chemistry of brominated butyl rubber, a model compound approach." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0015/MQ54486.pdf.
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Soboyejo, N. O. "Disperse dyes derived from brominated 1,4-amino- or hydroxy-substituted anthraquinones." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371497.
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Kuang, Jiangmeng. "Brominated flame retardants in indoor environments, with a focus on kitchens." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7769/.
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Paired kitchen-living room dust samples from 30 UK houses were collected for the analysis of BFRs, including PBDEs, HBCDDs and PBEB, EH-TBB, BTBPE, BEH-TEBP, DBDPE. Ninety-six plastic kitchen utensils were collected, screened for Br concentration by X-ray fluorescence spectrometer, with 30 of these samples analysed for BFR concentrations. A simulated cooking experiment was conducted to evaluate BFR exposure. Temporal and geographical differences in concentrations of BFRs in indoor dust samples were investigated via comparing BFR concentrations in UK samples in 2006-07 and 2015 and comparing 116 indoor house dust samples collected between 2014-15 from 6 countries (Finland, Greece, Spain, Jordan, US and Mexico) respectively. Concentrations of BDE-209 in living room dust were significantly lower and those of DBDPE significantly higher (p < 0.05) compared to concentrations in 2006-07 in UK dust. All target BFRs were present at higher concentrations in living rooms than kitchens. Considerable BFR transfer from kitchen utensils to cooking oils was observed and estimated exposure via cooking was 60 ng/day. US dust showed the highest Penta-BDE concentrations, followed by Mexico. Jordanian dust samples contained the highest concentrations of Octa-BDE. US and Mexican samples were found to display a similar composition to that found in the FireMaster® 550 formulation (EH-TBB:BEH-TEBP=4:1).
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POMA, GIULIA. "Evaluation of bioaccumulation processes of brominated flame retardants in biotic matrices." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50902.
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The global reduction in the use of PBDEs and HBCD as flame retardants has opened the way for the introduction of “Novel” BFRs (NBFRs) in place of the banned formulations, indicating those BFRs that are new in the market or newly/recently observed in the environment in respect to PBDEs and HBCD. Consequently, consumption and production of these NBFRs will keep rising, and increasing environmental levels of these chemicals are expected in the near future. Important representatives of this group are decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), and pentabromoethylbenzene (PBEB).
In Italy, previous studies have shown that some BFRs (PBDEs) were measured at high concentrations in the Varese province due to the presence of a great number of textile and plastic industries, and particularly in the sediments of Lake Maggiore, where those facilities wastewaters are finally collected mainly through two lake tributaries (Bardello and Boesio). For these reasons, the present thesis has the aim to evaluate the presence, and the potential bioaccumulation and biomagnification processes of six different classes of BFRs (PBDEs, HBCD, DBDPE, BTBPE, HBB and PBEB) in the Lake Maggiore ecosystem, with particular regard to zebra mussels (Dreissena polymorpha), zooplankton, one littoral fish species (common roach - Rutilus rutilus), and two different pelagic species (twaite shad – Alosa agone and European whitefish – Coregonus lavaretus). Finally, the study has also considered the BFR contamination in the lake sediments with the aim of characterizing in detail the possible presence of temporal trends and/or identifying potential sources of contamination. Moreover, it is plausible that the BFR uptake by benthic organisms, followed by fish predation, might be a significant source of bioaccumulation.
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Stastny, Angela. "Stoichiometric Delivery of Halogens to Substrates and a Study of Selective Bromination of Olefins by a Pt(IV) Complex." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523629125459729.
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Lanoix, Stéphanie. "Development of Radical Cascade via Gold(I) Photocatalysis and Application towards One-Pot Bromination/Carbocyclization." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32062.
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Radical chemistry is a crucial tool to organic chemists. Recent trends in the field have been directed towards the development of photocatalysts capable of generating a radical through a renewable source like sunlight using a single electron transfer mechanism. The use of Au2dppm2Cl2, having a stronger reducing potential, allows an expansion of the reactivity to those achieved by iridium and ruthenium catalysts.1 The focus of this thesis is axed on the development of Au2dppm2Cl2 as an efficient photoredox catalyst for a tandem one-pot catalysis and its application in a dual catalytic system.
The use of Au2dppm2Cl2 in a dual catalysis for the synthesis of β-amino acids was undertaken. The problems encountered over the course of the investigation showed an insufficient oxidation potential of the photoredox catalyst in addition to the facile homolytic cleavage of the C-halogen bond under UV light. However, this shows great promise for the achievement of beta amino acids using solely organocatalysis.
The development of a tandem one-pot radical cyclization for the synthesis of fused- carbocycles, which are frequently encountered scaffolds in diterpenoid natural products, is reported. The initial experiments were conducted on a model substrate, enabling the verification of the proposed hypothesis. The success of this methodology was then applied to various substrates affording the desired fused 5 membered rings in good yields. These reactions show tremendous potential in the field of total synthesis for the rapid access of complex molecular structures. (1) Revol, G.; McCallum, T.; Morin, M.; Gagosz, F.; Barriault, L. Angew. Chem. Int. Ed. 2013, 52, 13342.
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Söderström, Gunilla. "On the combustion and photolytic degradation products of some brominated flame retardants." Doctoral thesis, Umeå University, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-107.
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<p>Many modern products, especially electronic goods, are protected by brominated flame retardants (BFR). Some of the most common flame retardants are polybrominated diphenylethers (PBDE), tetrabromobisphenol-A (TBBP-A) and hexabromocyclododecane (HBCD). These compounds have been found in environmental samples and shown to have physiological effects on experimental animals. This thesis considers end-of-life aspects of brominated flame retardants. When spread in the environment, these compounds may be degraded into other forms. For example, if sludge contaminated with PBDE is used as an agricultural fertilizer, the PBDE could be degraded by sunlight to species of PBDE with lower degree of bromination and, to some extent, also form polybrominated dibenzofurans (PBDF). In addition, PBDF and polybrominated dibenzo-p-dioxins (PBDD) are formed during combustion of brominated flame retardants. When waste products with brominated flame retardants are co-combusted with household waste or other chlorinated fuel, polybrominated- chlorinated dibenzo-p-dioxins (PBCDD) and polybrominated- chlorinated dibenzofurans (PBCDF)will be formed. The bromin/chlorine composition of dioxins and furans is dependent on the bromine/chlorine ratio in the fuel, but the types of brominated flame retardants that are being combusted is less important. In the studies reported here, bromine levels higher than "normal" for household waste has been used. The results show that there is a pronounced increase in total dioxin levels in fluegas when when bromine is present, implying that waste containing brominated flame retardants should only be incinerated at combustion plants with effecient air pollution control devices.</p>
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Barnes, Otho. "LEACHING POTENTIAL OF METALS AND BROMINATED FLAME RETARDANTS IN OBSOLETE NOTEBOOK COMPUTERS." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06242009-160001/.
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Due to the increasing use of electronic components and the accelerated rate in which these components become obsolete, there has been a dramatic increase of discarded electronic waste (E-waste). E-waste includes obsolete electronic products such as computers, scanners, cellular phones, etc. These electronic components are manufactured using a variety of hazardous materials. As these components are discarded, the toxic and hazardous substances may become mobile and could impact human health and the environment. The toxic substances of concern contained in E-waste include heavy metals and brominated flame retardants (BFRs). This study attempts to identify the leaching potential of BFRs and metals.
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Söderström, Gunilla. "On the combustion and photolytic degradation products of some brominated flame retardants /." Umeå : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-107.
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Viberg, Henrik. "Neonatal Developmental Neurotoxicity of Brominated Flame Retardants, the Polybrominated Diphenyl Ethers (PBDEs)." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4576.
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Thuresson, Kaj. "Occupational exposure to brominated flame retardants : With emphasis on polybrominated diphenyl ethers." Doctoral thesis, Stockholm : Department of Environmental Chemistry, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-318.
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O'Neill, Andrew. "Investigations in molecular structure : from scattering to molecular complexes of brominated compounds." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1709/.
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The main focuses of this research were to examine the capabilities of solution techniques to attempt to monitor the nucleation process in crystallisation, and to investigate structural outcomes of crystallisation processes, with reference to polymorphism and intermolecular interactions. To achieve this, work on the investigation of nucleation and early-stage crystallisation was carried out at the Department of Pharmaceutical Sciences at the University of Strathclyde and also at the central synchrotron facility of Station 2.1 at the SRS Daresbury. Small angle X-ray scattering (SAXS) was carried out on solutions of methyl-4-hydroxybenzoate (pMHB) and 2-bromobenzoic acid. These studies were carried out after developing solution methods to enable us to determine the point at which crystals emerged from solution. This was achieved using Focussed Beam Reflectance Measurements. Structural studies were also carried out on pMHB to examine its polymorphic behaviour and crystal structures were solved at various temperatures from 100K to 300K. The crystal structure of methyl-2,5- dibromobenzoate was also solved at 100K after discovering it sublimes at room temperature. This structure could only be solved from a twinned crystal and indicated the appearance of interesting halogen interactions occurring. Structural studies have also been carried out using the bromanilic acid molecule as a focus to generate a number of co-crystal complexes to examine their halogen bonding capability and to determine any structural significances in their formation. Co-crystal complexes of bromanilic acid and a variety of molecules were made in 1:1 and 1:2 ratios to see if any additional halogen interactions could be observed or induced, in addition to the expected hydrogen-binding interactions. The co-crystals included a range of picolines and lutidines as well as bromo-substituted pyridines to attempt to induce halogen interactions. This generated a number of new compounds whose structures were determined using single crystal X-ray diffraction and the interactions were monitored to observed whether any defined patterns with regards to the tendency of bromanilic acid co-crystallisations to produce predictable patterns of intermolecular interactions could be determined.
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Smykalla, Lars, Pavel Shukrynau, Marcus Korb, Heinrich Lang, and Michael Hietschold. "Surface-confined 2D polymerization of a brominated copper-tetraphenylporphyrin on Au(111)." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-165144.
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A coupling-limited approach for the Ullmann reaction-like on-surface synthesis of a two-dimensional covalent organic network starting from a halogenated metallo-porphyrin is demonstrated. Copper-octabromo-tetraphenylporphyrin molecules can diffuse and self-assemble when adsorbed on the inert Au(111) surface. Splitting-off of bromine atoms bonded at the macrocyclic core of the porphyrin starts at room temperature after the deposition and is monitored by X-ray photoelectron spectroscopy for different annealing steps. Direct coupling between the reactive carbon sites of the molecules is, however, hindered by the molecular shape. This leads initially to an ordered non-covalently interconnected supramolecular structure. Further heating to 300 °C and an additional hydrogen dissociation step is required to link the molecular macrocycles via a phenyl group and form large ordered polymeric networks. This approach leads to a close-packed covalently bonded network of overall good quality. The structures are characterized using scanning tunneling microscopy. Different kinds of lattice defects and, furthermore, the impact of polymerization on the HOMO–LUMO gap are discussed. Density functional theory calculations corroborate the interpretations and give further insight into the adsorption of the debrominated molecule on the surface and the geometry and coupling reaction of the polymeric structure<br>Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Smith, Maureen McBride. "Modeling trihalomethane formation in bromide-containing surface water undergoing conventional treatment." CSUSB ScholarWorks, 1993. https://scholarworks.lib.csusb.edu/etd-project/638.
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Turner, Isabelle. "The study of ß-cyclodextrin interactions with sugars using inhibition kinetics and the bromination of pyrimidine derivatives." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0001/MQ43636.pdf.
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Julander, Anneli. "Exposure to brominated flame retardants in electronics recycling : air and human plasma levels /." Örebro : Örebro universitetsbibliotek, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-91.
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Christiansson, Anna. "Synthesis of highly brominated diphenyl ethers and aspects on photolysis and indoor spreading." Doctoral thesis, Stockholm : Department of Environmental Chemistry, Stockholm university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7519.
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Egloff, Caroline. "Effects of Four New Brominated Flame Retardants on Hepatic Messenger RNA Expression, In Vitro Toxicity and In Ovo Toxicity in the Domestic Chicken (Gallus gallus)." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19969.
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Brominated flame retardants (BFR) such as hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), bis(2-ethylhexyl)tetrabromophthalate (BEHTBP), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenylethane (DBDPE) are contaminants of environmental concern. These BFRs are replacement alternatives for some of the major production BFRs, which have been restricted from the marketplace due to their adverse health effects. Their presence in environmental matrices, including wild birds, suggests they should be tested for possible toxic effects. BFR alternatives have been detected in the eggs of colonial fish-eating birds, suggesting maternal transfer during ovogenesis and the potential for these chemicals to bioaccumulate through the food chain. However, information regarding the toxicity of HCDBCO, BEHTBP, BTBPE and DBDPE exposure in birds is lacking. This thesis consisted of a combined in vitro/in ovo approach to determine: 1) the concentration-dependent effects of these four BFR alternatives in chicken embryonic hepatocytes (CEH), and 2) the dose-dependent effects of HCDBCO and BTBPE in chicken embryos following injection into the air cell of eggs prior to incubation. Changes in the mRNA expression levels of genes previously found to be responsive to other BFRs were assessed in CEH and liver tissue, in addition to examining overt toxicity (i.e. cytotoxicity, pipping success). None of the BFRs tested were cytotoxic up to 60 µM HCDBCO, 60 µM BEHTBP, 1.4 µM BTBPE or 0.2 µM DBDPE in CEH. Injection doses up to 50 µg/g egg HCDBCO and 10 µg/g egg BTBPE had no effect on embryonic pipping success. The accumulation of HCDBCO and BTBPE was variable in liver and did not follow a linear uptake pattern with respect to injection dose, due in part to difficulties with the solubility of these chemicals in the dimethyl sulfoxide (DMSO) vehicle. In, CEH, HCDBCO caused a decrease in CYP1A4/5 mRNA at all concentrations tested, while CYP2H1 and CYP3A37 were induced only at 10 µM. In contrast, only TTR mRNA was down-regulated in hepatic tissue at all injection concentrations of HCDBCO. The highest concentration of BTBPE induced CYP1A4/5 mRNA to 115- and 18-fold in CEH, and 6.5- and 1.8-fold in liver tissue. In vitro and in ovo exposure to BTBPE caused a concentration-dependent decrease in DIO3 mRNA, while CYP3A37 was down-regulated 2-fold at 10 µg/g in liver tissue. In CEH, DBDPE induced CYP1A4/5 mRNA to a maximum of 29- and 59-fold at 0.2 µM, and increases in DIO1 mRNA and decreases in CYP3A37 mRNA were also observed. None of the gene targets were responsive to BEHTBP exposure in CEH. This is the first study to report on the toxicological and molecular effects of HCDBCO, BEHTBP, BTBPE and DBDPE in an avian species. Using this combined in vitro/in ovo approach has permitted the characterization of these four BFR alternatives by defining possible mechanisms of biological action in a model avian species, the chicken.
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Arévalos, Villalba Cibeli May. "ESTUDO DA CINÉTICA DA REAÇÃO QUÍMICA TRADICIONAL E ELETROQUÍMICA DE TETRABROMAÇÃO DO P-XILENO E DO 2,5-DICIANO-PXILENO." Universidade Estadual de Ponta Grossa, 2018. http://tede2.uepg.br/jspui/handle/prefix/2700.
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Previous issue date: 2018-04-13<br>O texto deste trabalho esta dividido em três capítulos. No Capítulo 1 tem-se a revisão bibliográfica onde é apresentada a aplicação dos compostos orgânicos bromados, a principal forma de síntese destes e as mudanças que vêm ocorrendo devido o uso de solventes prejudiciais à camada de ozônio. Serão descritos métodos alternativos de sínteses, sendo que o mais abordado é o método eletroquímico usado, portanto neste trabalho, por meio do qual é possível realizar a bromação de anéis aromáticos e bromação de aromáticos na posição benzílica. Também serão apresentadas as aplicações dos compostos sintetizados: α, α α’, α’-tetrabromo-pxileno e α, α, α’, α’-tetrabromo-2,5-diciano-p-xileno. No Capítulo 2 são apresentados os estudos experimentais e teóricos, onde se buscou uma explicação para as diferenças observadas na reação química tradicional de tetrabromação benzílica no 2,5-diciano-p-xileno em comparação ao p-xileno. Para isso se realizou para cada composto a reação de Wohl-Ziegler por 10 horas, recolhendo-se amostras em cada tempo determinado, estas amostras formam analisadas por Ressonância Magnética Nuclear de Hidrogênio (RMN de H1) e Cromatografia Gasosa acoplada a Espectrometria de Massas (CG-MS). Também foi realizado um estudo teórico de carga a partir de simulação computacional. O que se observa é que o composto contendo o substituinte nitrila apresenta uma reação de bromação mais lenta com a formação de quatro compostos intermediários, enquanto que para o composto sem substituinte a reação é mais rápida e apenas dois compostos intermediários são observados. No Capítulo 3 é descrito um método alternativo de síntese para a tetrabromação benzílica do 2,5-diciano-p-xileno e do p-xileno. A obtenção destes compostos ocorre usando-se reações eletroquímicas, onde não é necessário o uso de solventes de venda proibida (CCl4). Também se realizou um acompanhamento cinético, analisando-se as amostras coletadas por RMN de H1 e CG-MS, para fazer a comparação de síntese pelo método tradicional e eletroquímico. Sendo que a principal diferença observada é que no método eletroquímico as reações são mais lentas, também com este método é possível continuar adicionando bromos na posição benzílica ao composto p-xileno, obtendo-se este composto pentabromado e hexabromado.<br>The text of this paper is divided into three chapters. In Chapter 1 there is a bibliographic review where the application of brominated organic compounds is presented, the main form of synthesis of these and the changes that have been occurring due to the use of solvents harmful to the ozone layer. It will be described alternative methods of synthesis, and the most approached is the electrochemical method used, therefore in this work, through which it is possible to perform the bromination of aromatic rings and bromination of aromatics in the benzylic position. The applications of the synthesized compounds: α, α, α', α'-tetrabromo-p-xylene and α, α, α ', α'-tetrabromo-2,5-dicyano-p-xylene will also be presented. In Chapter 2 we present experimental and theoretical studies, where an explanation was sought for the differences observed in the traditional chemical reaction of benzylic tetrabromination in 2,5-dicyano-p-xylene compared to p-xylene. In order to do this, the reactions of Wohl-Ziegler were carried out for 10 hours. Samples were collected at each determined time. These samples were analyzed by Hydrogen Nuclear Magnetic Resonance (H1 NMR) and Gas Chromatography Coupled to Mass Spectrometry (CG-MS). A theoretical load study was also carried out from a computer simulation. What is observed is that the compound containing the nitrile substituent has a slower bromination reaction with the formation of four intermediate compounds, whereas for the compound without substituent the reaction is faster and only two intermediate compounds are observed. In Chapter 3 an alternative method of synthesis for the benzylic tetra-bromination of 2,5-dicyano-p-xylene and p-xylene is described. The production of these compounds occurs using electrochemical reactions, where it is not necessary to use solvents of prohibited sale (CCl4). Also, a kinetic monitoring was performed, analyzing the samples collected by H1 NMR and CG-MS, to make the comparison of synthesis by the traditional and electrochemical method. As the main difference observed is that in the electrochemical method the reactions are slower, also with this method it is possible to continue adding bromines in the benzylic position to the compound p-xylene, obtaining this compound pentabromado and hexabromado.