Log in

Relevant bibliographies by topics / Brønsted acid/base / Journal articles

To see the other types of publications on this topic, follow the link: Brønsted acid/base.

Journal articles on the topic 'Brønsted acid/base'

Author: Grafiati

Published: 4 June 2021

Last updated: 11 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Brønsted acid/base.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Tan, Choon-Hong, Bo Teng, and Wei Lim. "Recent Advances in Enantioselective Brønsted Base Organocatalytic Reactions." Synlett 28, no. 11 (May 23, 2017): 1272–77. http://dx.doi.org/10.1055/s-0036-1588847.

Full text

Abstract:

Enantioselective Brønsted base catalyzed reactions have established themselves as powerful tools for the construction of optically pure compounds. Most strategies aim at improving these reactions involve the modification of substrates to decrease the pK a of the acidic proton. Typically, an electron-withdrawing group such as an ester or a fluorine is placed at the α-carbon, where the proton is also residing. The activation of less active proton, thus, becomes a major challenge in this field of research. In order to overcome this pK a barrier, some new innovative approaches have been demonstrated in recent years. The implementation of dual activation modes and the development of organocatalytic Brønsted superbases are selected to be discussed in this minireview.1 Introduction2 Dual Activation Using Lewis Acid and Brønsted Base3 Dual Activation Using Iminium Catalyst and Brønsted Base4 Chiral Brønsted Superbase5 Chiral Ion-Pair Brønsted Base6 Summary and Outlook

APA, Harvard, Vancouver, ISO, and other styles

2

Shen, Juan, and Choon-Hong Tan. "Brønsted-acid and Brønsted-base catalyzed Diels–Alder reactions." Organic & Biomolecular Chemistry 6, no. 18 (2008): 3229. http://dx.doi.org/10.1039/b809505c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Nuthakki, Bharathi, Tamar L. Greaves, Irena Krodkiewska, Asoka Weerawardena, M. Iko Burgar, Roger J. Mulder, and Calum J. Drummond. "Protic Ionic Liquids and Ionicity." Australian Journal of Chemistry 60, no. 1 (2007): 21. http://dx.doi.org/10.1071/ch06363.

Full text

Abstract:

Protic ionic liquids (PILs) are a subset of ionic liquids formed by the equimolar mixing of a Brønsted acid and a Brønsted base. PILs have been categorized as poor ionic liquids. However, the issue of assessing the ionicity of PILs is still a matter of debate. In this work we studied some physicochemical properties of three chosen PILs, namely, ethanolammonium acetate (EOAA), 2-methylbutylammonium formate (2MBAF), and pentylammonium formate (PeAF), at the initial equimolar (stoichiometric) acid/base ratio and in the presence of excess acid and base. DSC phase-transition studies along with NMR, IR, and Raman spectroscopy were performed on the chosen PILs. The results are discussed in terms of the degree of ionization (extent of proton transfer from the Brønsted acid to Brønsted base), and the possibility of the formation of polar 1:1 complexes and larger aggregates in the neat stoichiometric PILs.

APA, Harvard, Vancouver, ISO, and other styles

4

Handa, Sachin, Sri S. Subramanium, Aaron A. Ruch, Joseph M. Tanski, and LeGrande M. Slaughter. "Ligand- and Brønsted acid/base-switchable reaction pathways in gold(i)-catalyzed cycloisomerizations of allenoic acids." Organic & Biomolecular Chemistry 13, no. 13 (2015): 3936–49. http://dx.doi.org/10.1039/c4ob02640c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Shelly, Kevin P., K. Nagarajan, and Ross Stewart. "Arylphosphonic acids. II. General acid and general base catalysis of acetone enolization." Canadian Journal of Chemistry 65, no. 8 (August 1, 1987): 1734–38. http://dx.doi.org/10.1139/v87-291.

Full text

Abstract:

We have measured the rate constants for the enolization of acetone catalyzed by 29 arylphosphonate dianions (ArPO32−) and by 20 arylphosphonic acids (ArPO3H2). An excellent Brønsted correlation is found for the former reaction, with most ortho substituted compounds falling on the line drawn for the meta and para compounds (β = 0.72). The largest deviation is found for o-iodo, whose small positive deviation is ascribed to a polarizability effect in the transition state. The arylphosphonic acids give a fairly good Brønsted plot (α = 0.37) but here the ortho substituents tend to react slightly faster than would be expected on the basis of their equilibrium acid strengths. Catalysis by the monoanion ArPO3H− is difficult to detect; such ions appear to be acting as general acids, not general bases, and do not appear to act as bifunctional catalysts; it is shown that protonating acetone is 3.4 × 104 times as effective as deprotonating ArPO3H−. The Brønsted coefficients (β) for the rate-controlling steps for the enolization of acetone by the principal routes are shown to be inversely related to the magnitude of the rate constants.

APA, Harvard, Vancouver, ISO, and other styles

6

Sodeoka, Mikiko, and Yoshitaka Hamashima. "Acid-base catalysis using chiral palladium complexes." Pure and Applied Chemistry 78, no. 2 (January 1, 2006): 477–94. http://dx.doi.org/10.1351/pac200678020477.

Full text

Abstract:

Chiral Pd aqua and µ-hydroxo complexes were found to act as mild Brønsted acids and bases, and chiral Pd enolates were generated from these complexes even under acidic conditions. Highly enantioselective Michael addition, Mannich-type reaction, fluorination, and conjugate addition of amines have been developed based on the acid-base character of these Pd complexes.

APA, Harvard, Vancouver, ISO, and other styles

7

Chhabra, Tripti, Ashish Bahuguna, Sandeep Singh Dhankhar, C. M. Nagaraja, and Venkata Krishnan. "Sulfonated graphitic carbon nitride as a highly selective and efficient heterogeneous catalyst for the conversion of biomass-derived saccharides to 5-hydroxymethylfurfural in green solvents." Green Chemistry 21, no. 21 (2019): 6012–26. http://dx.doi.org/10.1039/c9gc02120e.

Full text

Abstract:

Sulfonated graphitic carbon nitride having both Brønsted base and Brønsted acid sites is used as a heterogeneous catalyst for the selective conversion of different biomass-derived saccharides to 5-hydroxymethylfurfural in green solvents.

APA, Harvard, Vancouver, ISO, and other styles

8

Ingleson, Michael, and Valerio Fasano. "Recent Advances in Water-Tolerance in Frustrated Lewis Pair Chemistry." Synthesis 50, no. 09 (March 29, 2018): 1783–95. http://dx.doi.org/10.1055/s-0037-1609843.

Full text

Abstract:

A water-tolerant frustrated Lewis pair (FLP) combines a sterically encumbered Lewis acid and Lewis base that in synergy are able to activate small molecules even in the presence of water. The main challenge introduced by water comes from its reversible coordination to the Lewis acid which causes a marked increase in the Brønsted acidity of water. Indeed, the oxophilic Lewis acids typically used in FLP chemistry form water adducts whose acidity can be comparable to that of strong Brønsted acids such as HCl, thus they can protonate the Lewis base component of the FLP. Irreversible proton transfer quenches the reactivity of both the Lewis acid and the Lewis base, precluding small molecule activation. This short review discusses the efforts to overcome water-intolerance in FLP systems, a topic that in less than five years has seen significant progress.1 Introduction2 Water-Tolerance (or Alcohol-Tolerance) in Carbonyl Reductions3 Water-Tolerance with Stronger Bases4 Water-Tolerant Non-Boron-Based Lewis Acids in FLP Chemistry5 Conclusions

APA, Harvard, Vancouver, ISO, and other styles

9

Wei, Wei, Rongjie Lu, Haojie Xie, Yifan Zhang, Xue Bai, Li Gu, Rui Da, and Xiaoya Liu. "Selective adsorption and separation of dyes from an aqueous solution on organic–inorganic hybrid cyclomatrix polyphosphazene submicro-spheres." Journal of Materials Chemistry A 3, no. 8 (2015): 4314–22. http://dx.doi.org/10.1039/c4ta06444e.

Full text

Abstract:

Poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) submicro-spheres were easily prepared, which exhibited a selective adsorption and separation of dyes that can be classified as Lewis acids and/or Brønsted acids by acid–base interactions.

APA, Harvard, Vancouver, ISO, and other styles

10

Catalán, Javier, and José Palomar. "Gas-phase protolysis between a neutral Brønsted acid and a neutral Brønsted base?" Chemical Physics Letters 293, no. 5-6 (September 1998): 511–14. http://dx.doi.org/10.1016/s0009-2614(98)00833-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Pezacki, John Paul. "Normal acid/base behaviour in proton transfer reactions to alkoxy substituted carbenes: estimates for intrinsic barriers to reaction and pKa values." Canadian Journal of Chemistry 77, no. 7 (July 1, 1999): 1230–40. http://dx.doi.org/10.1139/v99-087.

Full text

Abstract:

Theoretical Eigen curves can be drawn through Brønsted data for dimethoxycarbene (1), phenyltrimethyl-siloxycarbene (3a), 4-methylphenyl(trimethylsiloxy)carbene (3b), 4-methoxyphenyl(trimethylsiloxy)carbene (3c), and β-naphthyl(trimethylsiloxy)carbene (3d). The Brønsted plots for these data are clearly curved with α values near 1 when proton transfer is thermodynamically unfavourable and α values near 0 when proton transfer is thermodynamically favourable, suggesting that these carbenes behave as "normal" Brønsted bases. Estimates of the intrinsic barriers (ΔG0‡) for proton transfer reactions and of the pKa values for the conjugate acids of the carbenes, extracted from these theoretical curves, have been made. The magnitudes of the intrinsic barriers (ΔG0‡) for these proton transfer reactions determined by Eigen and Marcus theories are all 1-5 kcal mol-1, suggesting that these reactions are intrinsically fast. Small intrinsic barriers also imply "normal" acid/base behaviour. Extrapolated pKa values are also the first estimates for the pKa values of the conjugate acids of carbenes 1 and 3a-3d. Key words: carbenes, proton transfer reactions, carbocations, Marcus theory, Brønsted plots.

APA, Harvard, Vancouver, ISO, and other styles

12

Lathem, A. Paige, and Zachariah M. Heiden. "Quantification of Lewis acid induced Brønsted acidity of protogenic Lewis bases." Dalton Transactions 46, no. 18 (2017): 5976–85. http://dx.doi.org/10.1039/c7dt00777a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Nalbandian, Christopher J., Eric M. Miller, Sean T. Toenjes, and Jeffery L. Gustafson. "A conjugate Lewis base-Brønsted acid catalyst for the sulfenylation of nitrogen containing heterocycles under mild conditions." Chemical Communications 53, no. 9 (2017): 1494–97. http://dx.doi.org/10.1039/c6cc09998j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Zhang, Lei, Ling He, Cheng-Bin Hong, Song Qin, and Guo-Hong Tao. "Brønsted acidity of bio-protic ionic liquids: the acidic scale of [AA]X amino acid ionic liquids." Green Chemistry 17, no. 12 (2015): 5154–63. http://dx.doi.org/10.1039/c5gc01913c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Otsuka, Rikuto, Kazuo Maruhashi, and Tomohiko Ohwada. "Latent Brønsted Base Solvent-Assisted Amide Formation from Amines and Acid Chlorides." Synthesis 50, no. 10 (March 20, 2018): 2041–57. http://dx.doi.org/10.1055/s-0037-1609342.

Full text

Abstract:

Weakly basic amines, including even neutral amines such as nitroaniline and aminocarboxylic acids, react with acid chlorides very efficiently in N,N-dimethylacetamide (DMAC), without addition of a base, to give the corresponding amides in high yields. The role of DMAC and related solvents as latent Brønsted bases was studied in these amidation reactions. Less basic amines, such as aromatic amines, reacted with benzoyl chloride faster than more basic aliphatic amines.

APA, Harvard, Vancouver, ISO, and other styles

16

Rajendran, Chandran, Govindaswamy Satishkumar, Charlotte Lang, and Eric M. Gaigneaux. "Alumina grafted SBA-15 sustainable bifunctional catalysts for direct cross-coupling of benzylic alcohols to diarylmethanes." Catalysis Science & Technology 10, no. 8 (2020): 2583–92. http://dx.doi.org/10.1039/d0cy00471e.

Full text

Abstract:

AlSBA-15 catalysts possessing Brønsted acid and Lewis acid–base bifunctionalities catalyze the direct arylation of benzyl alcohols to diarylmethanes with an 85% product yield through C–O bond activation.

APA, Harvard, Vancouver, ISO, and other styles

17

Volla, Chandra M. R., Arindam Das, Iuliana Atodiresei, and Magnus Rueping. "Fluorine effects in organocatalysis – asymmetric Brønsted acid assisted Lewis base catalysis for the synthesis of trifluoromethylated heterocycles exploiting the negative hyperconjugation of the CF3-group." Chem. Commun. 50, no. 58 (2014): 7889–92. http://dx.doi.org/10.1039/c4cc03229b.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Zhao, Jun, Baining Lin, Yifan Zhu, Yonghua Zhou, and Hongyang Liu. "Phosphor-doped hexagonal boron nitride nanosheets as effective acid–base bifunctional catalysts for one-pot deacetalization–Knoevenagel cascade reactions." Catalysis Science & Technology 8, no. 22 (2018): 5900–5905. http://dx.doi.org/10.1039/c8cy01821a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Ponec, Robert. "Molecular Basis of LFER. Simple Model for the Estimation of Brønsted Exponent in Acid-Base Catalysis." Collection of Czechoslovak Chemical Communications 69, no. 12 (2004): 2121–33. http://dx.doi.org/10.1135/cccc20042121.

Full text

Abstract:

A simple model was proposed allowing to estimate the Brønsted exponents in acid-base catalysis on the basis of the pK values of the species participating in the proton transfer process. The approach was tested using the experimental data on the basically catalyzed halogenation of carbonyl compounds and on the proton removal from nitroalkanes. It has been shown that the model is able to reproduce the Brønsted exponents not only in the case of "ordinary" Brønsted plots with the slope within the expected range 0-1 but also for unusual plots with negative slopes. In addition, the proposed model opens the possibility of calculation of the activation energies of a given proton transfer reaction and also provides straightforward theoretical justification for the validity of the Hammond postulate in these reactions.

APA, Harvard, Vancouver, ISO, and other styles

20

Kim, Sung-Ki, Chul-Yong Park, Hee Choi, and Seoung-Hey Paik. "An Analysis of Chemistry Textbooks' and Teachers' Conceptions on Brønsted-Lowry Acid-Base." Journal of the Korean Chemical Society 61, no. 2 (April 20, 2017): 65–76. http://dx.doi.org/10.5012/jkcs.2017.61.2.65.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Nakamoto, Hirofumi, and Masayoshi Watanabe. "Brønsted acid–base ionic liquids for fuel cell electrolytes." Chem. Commun., no. 24 (2007): 2539–41. http://dx.doi.org/10.1039/b618953a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Subramanian, Hariharaputhiran, Craig P. Jasperse, and Mukund P. Sibi. "Characterization of Brønsted Acid–Base Complexes by 19F DOSY." Organic Letters 17, no. 6 (March 2, 2015): 1429–32. http://dx.doi.org/10.1021/acs.orglett.5b00297.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Casey, William H. "Enthalpy Changes for Brønsted Acid-Base Reactions on Silica." Journal of Colloid and Interface Science 163, no. 2 (March 1994): 407–19. http://dx.doi.org/10.1006/jcis.1994.1120.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Bao, Youmei, Naoya Kumagai, and Masakatsu Shibasaki. "Managing the retro-pathway in direct catalytic asymmetric aldol reactions of thioamides." Chemical Science 6, no. 11 (2015): 6124–32. http://dx.doi.org/10.1039/c5sc02218e.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Zhang, Lei, Fangyuan Zhou, Zhenjiang Li, Bo Liu, Rui Yan, Jie Li, Yongzhu Hu, Chan Zhang, Zikun Luo, and Kai Guo. "Tunable hydantoin and base binary organocatalysts in ring-opening polymerizations." Polymer Chemistry 11, no. 35 (2020): 5669–80. http://dx.doi.org/10.1039/d0py00812e.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Sakakura, Akira, Risa Yamashita, Takuro Ohkubo, Matsujiro Akakura, and Kazuaki Ishihara. "Intramolecular Dehydrative Condensation of Dicarboxylic Acids with Brønsted Base-Assisted Boronic Acid Catalysts." Australian Journal of Chemistry 64, no. 11 (2011): 1458. http://dx.doi.org/10.1071/ch11301.

Full text

Abstract:

Bifunctional Brønsted base-assisted boronic acid catalysts, arylboronic acids bearing two sterically bulky (N,N-dialkylamino)methyl groups at the 2,6-positions, exhibit remarkable activities for the dehydrative intramolecular condensation of dicarboxylic acids. The steric bulkiness of the (N,N-dialkylamino)methyl groups of 1, which prevents the formation of less active species such as the N→B chelated species and triarylboroxines 3, is crucial for the high catalytic activity. This is the first successful method for the catalytic dehydrative self-condensation of di- and tetracarboxylic acids.

APA, Harvard, Vancouver, ISO, and other styles

27

Parvathalu, Nenavath, Sandip G. Agalave, Nirmala Mohanta, and Boopathy Gnanaprakasam. "Reversible chemoselective transetherification of vinylogous esters using Fe-catalyst under additive free conditions." Organic & Biomolecular Chemistry 17, no. 12 (2019): 3258–66. http://dx.doi.org/10.1039/c9ob00307j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Greaves, Tamar L., Krystal Ha, Benjamin W. Muir, Shaun C. Howard, Asoka Weerawardena, Nigel Kirby, and Calum J. Drummond. "Protic ionic liquids (PILs) nanostructure and physicochemical properties: development of high-throughput methodology for PIL creation and property screens." Physical Chemistry Chemical Physics 17, no. 4 (2015): 2357–65. http://dx.doi.org/10.1039/c4cp04241g.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Pratanpornlerd, W., and S. Bureekaew. "Zr-based metal-organic framework with dual BrØnsted acid-base functions." IOP Conference Series: Materials Science and Engineering 383 (July 2018): 012011. http://dx.doi.org/10.1088/1757-899x/383/1/012011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Deng, Wei-Hua, P. Naresh Kumar, Wen-Hua Li, Chiranjeevulu Kashi, Ming-Shui Yao, Guo-Dong Wu, and Gang Xu. "Superprotonic conductivity of Ti-based MOFs with Brønsted acid–base pairs." Inorganica Chimica Acta 502 (March 2020): 119317. http://dx.doi.org/10.1016/j.ica.2019.119317.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Sahu, Samrat, Avijit Roy, Mahadeb Gorai, Sudip Guria, and Modhu Sudan Maji. "C3-Alkenylation between Pyrroles and Aldehydes Mediated by a Brønsted Acid and a Brønsted Base." European Journal of Organic Chemistry 2019, no. 37 (September 9, 2019): 6396–400. http://dx.doi.org/10.1002/ejoc.201901228.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Yavuz, Erdem, Nikolay Cherkasov, and Volkan Degirmenci. "Acid and base catalysed reactions in one pot with site-isolated polyHIPE catalysts." RSC Advances 9, no. 15 (2019): 8175–83. http://dx.doi.org/10.1039/c9ra01053j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Tan, Choon-Hong, and Benjamin List. "Cluster Preface: Asymmetric Brønsted Base Catalysis." Synlett 28, no. 11 (June 20, 2017): 1270–71. http://dx.doi.org/10.1055/s-0036-1590548.

Full text

Abstract:

Choon-Hong Tan is a professor at the Division of Chemistry and Biological Chemistry, Nanyang Technological University, Singapore. He received his BSc (Hons) First Class from the National University of Singapore (NUS) and his Phd from the University of Cambridge. He underwent postdoctoral training at the Department of Chemistry and Chemical Biology, Harvard University and the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School. He began his independent career at the Department of Chemistry, National University of Singapore in 2003. Choon Hong has focused on the development of organocatalytic Brønsted base reactions that can be catalyzed with chiral guanidines. He has also demonstrated that pentanidiums (conjugated guanidiniums) are efficient phase-transfer catalysts. Recently, he described the use of chiral organic cations such as bisguanidiniums to modulate and activate anionic metallic salts. Benjamin List has been a director at the Max-Planck-Institut für Kohlenforschung since 2005. He obtained his Ph.D. in 1997 (Frankfurt). From 1997 until 1998 he conducted postdoctoral research at The Scripps Research Institute in La Jolla (USA) and became an assistant professor there in January 1999. In 2003 he joined the Max-Planck-Institut für Kohlenforschung. He has been an honorary professor at the University of Cologne since 2004. Ben List’s research focuses on organic synthesis and catalysis. He has contributed fundamental concepts to chemical synthesis including aminocatalysis, enamine catalysis, and asymmetric-counteranion-directed catalysis (ACDC). His latest work deals with chiral counteranions in asymmetric catalysis. This remarkably general strategy for asymmetric synthesis has recently found widespread use in organocatalysis, transition-metal catalysis, and Lewis acid catalysis.

APA, Harvard, Vancouver, ISO, and other styles

34

Cicač-Hudi, Mario, Christoph M. Feil, Nicholas Birchall, Martin Nieger, and Dietrich Gudat. "Proton transfer vs. oligophosphine formation by P–C/P–H σ-bond metathesis: decoding the competing Brønsted and Lewis type reactivities of imidazolio-phosphines." Dalton Transactions 49, no. 47 (2020): 17401–13. http://dx.doi.org/10.1039/d0dt03633a.

Full text

Abstract:

Cationic imidazolio-phosphines show two-sided reactivity towards bases, undergoing either Brønsted-type proton transfer to imidazolio-phosphides or autocatalytic Lewis acid/base reaction cascades to yield P-free imidazolium ions and oligophosphines.

APA, Harvard, Vancouver, ISO, and other styles

35

Lin, Jingjing, and Carsten Korte. "Influence of the acid–base stoichiometry and residual water on the transport mechanism in a highly-Brønsted-acidic proton-conducting ionic liquid." RSC Advances 10, no. 69 (2020): 42596–604. http://dx.doi.org/10.1039/d0ra08969a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Areán, C. O. "Probing Brønsted Acidity of Protonic Zeolites with Variable-Temperature Infrared Spectroscopy." Ukrainian Journal of Physics 63, no. 6 (July 12, 2018): 538. http://dx.doi.org/10.15407/ujpe63.6.538.

Full text

Abstract:

Most industrial applications of zeolites as solid-acid catalysts rely on their high Brønsted acidity, which affects both catalytic activity and selectivity, and hence the convenience to find an accurate experimental technique for measuring the acid strength. The enthalpy change, ΔH0, involved in the hydrogen bonding interaction between a weak base (such as carbon monoxide) and the Brønsted acid [Si(OH)Al] hydroxyl groups should correlate directly with the zeolite acid strength. However, on account of simplicity, the bathochromic shift of the O–H stretching frequency, Δv(OH), is usually measured by IR spectroscopy at a (fixed) low temperature in-stead of ΔH0 and correlated with the acid strength for ranking the zeolite acidity. Herein, the use of variable-temperature IR spectroscopy to determine simultaneously ΔH0 and Δv(OH) is demonstrated, followed by a review of recent experimental results showing that the practice of ranking the acid strength by the corresponding O–H frequency shift probed by a weak base could be misleading; and that can be so much the case of zeolites showing a wide range of structure types.

APA, Harvard, Vancouver, ISO, and other styles

37

McClelland, Robert A., and Poule E. Sørensen. "Kinetics of the equilibration of 3-hydroxyphthalide and o-formylbenzoic acid. Hemiacetal breakdown with a carboxylic acid leaving group." Canadian Journal of Chemistry 64, no. 6 (June 1, 1986): 1196–200. http://dx.doi.org/10.1139/v86-198.

Full text

Abstract:

A temperature-jump relaxation study is reported for the equilibration: 3-hydroxyphthalide (SH) [Formula: see text]o-formylbenzoate (R−) [Formula: see text]o-formylbenzoic acid (RH). A kinetic analysis is carried out in which SH and R− interconvert with catalysis in the ring opening direction by water and by added general bases. Excellent Brønsted plots based upon a series of oxyacid buffer catalysts are obtained. These have slopes β for the base-catalyzed ring opening of 0.81 and α for the reverse acid-catalyzed ring closing of 0.19. A mechanism where S−, the conjugate base of SH, is a discrete intermediate can be ruled out on the basis of the Brønsted values and the magnitudes of the rate constants. The lifetime of S− is estimated to lie in the range 10−11–10−15 s. Two mechanisms can be proposed. A fully concerted mechanism "enforced" by lifetimes less than 10−13 s involves direct interconversion of SH and R− with no intermediate. A preassociated mechanism "enforced" by lifetimes in the 10−11–10−12 s range requires, in the ring closing direction, that an acid catalyst be hydrogen bonded to the carbonyl in R−.

APA, Harvard, Vancouver, ISO, and other styles

38

Uraguchi, Daisuke, Natsuko Kinoshita, Daisuke Nakashima, and Takashi Ooi. "Chiral ionic Brønsted acid–achiral Brønsted base synergistic catalysis for asymmetric sulfa-Michael addition to nitroolefins." Chemical Science 3, no. 11 (2012): 3161. http://dx.doi.org/10.1039/c2sc20698f.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Noda, Akihiro, Md Abu Bin Hasan Susan, Kenji Kudo, Shigenori Mitsushima, Kikuko Hayamizu, and Masayoshi Watanabe. "Brønsted Acid−Base Ionic Liquids as Proton-Conducting Nonaqueous Electrolytes." Journal of Physical Chemistry B 107, no. 17 (May 2003): 4024–33. http://dx.doi.org/10.1021/jp022347p.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Wakchaure, Vijay N, and Benjamin List. "A New Structural Motif for Bifunctional Brønsted Acid/Base Organocatalysis." Angewandte Chemie International Edition 49, no. 24 (May 7, 2010): 4136–39. http://dx.doi.org/10.1002/anie.201000637.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Denmark, Scott E., and Matthew T. Burk. "Enantioselective Bromocycloetherification by Lewis Base/Chiral Brønsted Acid Cooperative Catalysis." Organic Letters 14, no. 1 (December 6, 2011): 256–59. http://dx.doi.org/10.1021/ol203033k.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Kumar, Rajnish, and Ganesan Mani. "Exhibition of the Brønsted acid–base character of a Schiff base in palladium(ii) complex formation: lithium complexation, fluxional properties and catalysis of Suzuki reactions in water." Dalton Transactions 44, no. 15 (2015): 6896–908. http://dx.doi.org/10.1039/c5dt00438a.

Full text

Abstract:

The Brønsted acid–base character of bis(iminopyrrolylmethyl)amine was shown through the X-ray structures of palladium complexes. The bischelated palladium complex is fluxional as studied by the VT ¹H NMR method and effectively catalyzes Suzuki reactions in water.

APA, Harvard, Vancouver, ISO, and other styles

43

Domingo, Pedro L., Begoña Garcia, and Jose M. Leal. "Acid–base behaviour of the ferrocyanide ion in perchloric acid media potentiometric and spectrophotometric study." Canadian Journal of Chemistry 65, no. 3 (March 1, 1987): 583–89. http://dx.doi.org/10.1139/v87-102.

Full text

Abstract:

Ferrocyanide ion behaves as a tetravalent Brønsted base and can react with four protons, forming ferrocyanic acid. By potentiometric and spectrophotometric techniques it is shown that the first two protonation equilibria overlap, as do the third and fourth equilibria. The two techniques yield identical results when processed with the inclusion of non-ideality terms. The method of "separation of equilibria" is proposed to allow separate study of each of the overlapping equilibria. Values of pK1 = −2.54 ± 0.10, pK2 = −1.08 ± 0.03, pK3 = 2.65 ± 0.02, and pK4 = 4.19 ± 0.02 were obtained.

APA, Harvard, Vancouver, ISO, and other styles

44

Samoilichenko, Yuri, Veronica Kondratenko, Mariam Ezernitskaya, Konstantin Lyssenko, Alexander Peregudov, Victor Khrustalev, Victor Maleev, et al. "A mechanistic study of the Lewis acid–Brønsted base–Brønsted acid catalysed asymmetric Michael addition of diethyl malonate to cyclohexenone." Catalysis Science & Technology 7, no. 1 (2017): 90–101. http://dx.doi.org/10.1039/c6cy01697a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Czarnocki, Stefan, Louis Monsigny, Michał Sienkiewicz, Anna Kajetanowicz, and Karol Grela. "Ruthenium Olefin Metathesis Catalysts Featuring N-Heterocyclic Carbene Ligands Tagged with Isonicotinic and 4-(Dimethylamino)benzoic Acid Rests: Evaluation of a Modular Synthetic Strategy." Molecules 26, no. 17 (August 28, 2021): 5220. http://dx.doi.org/10.3390/molecules26175220.

Full text

Abstract:

A modular and flexible strategy towards the synthesis of N-heterocyclic carbene (NHC) ligands bearing Brønsted base tags has been proposed and then adopted in the preparation of two tagged NHC ligands bearing rests of isonicotinic and 4-(dimethylamino)benzoic acids. Such tagged NHC ligands represent an attractive starting point for the synthesis of olefin metathesis ruthenium catalysts tagged in non-dissociating ligands. The influence of the Brønsted basic tags on the activity of such obtained olefin metathesis catalysts has been studied.

APA, Harvard, Vancouver, ISO, and other styles

46

Bojanowski, Jan, and Anna Albrecht. "Doubly Decarboxylative Synthesis of 4-(Pyridylmethyl)chroman-2-ones and 2-(Pyridylmethyl)chroman-4-ones under Mild Reaction Conditions." Molecules 26, no. 15 (August 3, 2021): 4689. http://dx.doi.org/10.3390/molecules26154689.

Full text

Abstract:

The doubly decarboxylative Michael–type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has been confirmed by mechanistic studies. Moreover, attempts to develop an enantioselective variant of the cascade are also described.

APA, Harvard, Vancouver, ISO, and other styles

47

Schmidt-McCormack, Jennifer A., Jessyca A. Judge, Kellie Spahr, Ellen Yang, Raymond Pugh, Ashley Karlin, Atia Sattar, Barry C. Thompson, Anne Ruggles Gere, and Ginger V. Shultz. "Analysis of the role of a writing-to-learn assignment in student understanding of organic acid–base concepts." Chemistry Education Research and Practice 20, no. 2 (2019): 383–98. http://dx.doi.org/10.1039/c8rp00260f.

Full text

Abstract:

Acid–base chemistry is a foundational topic that is taught in courses across the chemistry curriculum. Students often have difficulty distinguishing between the different theories of acid–base chemistry—Brønsted–Lowry and Lewis acid–base chemistry—and applying these two definitions correctly in unfamiliar scenarios. To help students learn these definitions and be able to apply them, an acid–base Writing-to-Learn assignment was developed and evaluated. The Writing-to-Learn assignment involved a three-step process where students constructed an initial draft in response to a writing prompt, participated in peer review, and made revisions based on peer review feedback, before submitting a final draft. This process is informed by sociocultural theory applied to writing, which states that student learning of concepts increases through engagement with their peers’ work and receiving peer feedback on their own writing. To test the efficacy of the acid–base writing assignment, an external assessment, comprised of conceptual questions related to acid–base chemistry and students’ confidence when responding to them, was administered in two groups; a treatment group who completed the Writing-to-Learn assignment, and a comparison group who completed a separate assignment. Additionally, students who completed the Writing-to-Learn assignment were interviewed about their experiences. Regression analysis revealed that students in the treatment group had a greater increase in their conceptual understanding and confidence as compared to the students in the comparison group. The results demonstrate the students could successfully write about the Brønsted–Lowry and Lewis acid–base models separately, but were less successful with connecting these two concepts together in their writing. These results demonstrate the efficacy of Writing-to-Learn as an approach for promoting conceptual learning of acid–base chemistry.

APA, Harvard, Vancouver, ISO, and other styles

48

Devineau, Alice, Guillaume Pousse, Catherine Taillier, Jérôme Blanchet, Jacques Rouden, and Vincent Dalla. "One-Pot Hydroxy Group Activation/Carbon-Carbon Bond Forming Sequence Using a Brønsted Base/Brønsted Acid System." Advanced Synthesis & Catalysis 352, no. 17 (November 9, 2010): 2881–86. http://dx.doi.org/10.1002/adsc.201000602.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Basterretxea, Andere, Elena Gabirondo, Ana Sanchez-Sanchez, Agustin Etxeberria, Olivier Coulembier, David Mecerreyes, and Haritz Sardon. "Synthesis and characterization of poly (ε-caprolactam-co-lactide) polyesteramides using Brønsted acid or Brønsted base organocatalyst." European Polymer Journal 95 (October 2017): 650–59. http://dx.doi.org/10.1016/j.eurpolymj.2017.05.023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Qumruddeen, Arun Yadav, Ruchir Kant, and Chandra Bhushan Tripathi. "Lewis Base/Brønsted Acid Cocatalysis for Thiocyanation of Amides and Thioamides." Journal of Organic Chemistry 85, no. 4 (January 10, 2020): 2814–22. http://dx.doi.org/10.1021/acs.joc.9b03275.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!