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Journal articles on the topic 'Catalyseur solide acide'

Author: Grafiati

Published: 4 June 2021

Last updated: 12 February 2022

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1

Carà, Piera Demma, Mario Pagliaro, Ahmed Elmekawy, David R. Brown, Peter Verschuren, N. Raveendran Shiju, and Gadi Rothenberg. "Hemicellulose hydrolysis catalysed by solid acids." Catalysis Science & Technology 3, no. 8 (2013): 2057. http://dx.doi.org/10.1039/c3cy20838a.

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2

Jahangiri, Hessam, Amin Osatiashtiani, Miloud Ouadi, Andreas Hornung, Adam F. Lee, and Karen Wilson. "Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours." Catalysts 9, no. 10 (October 11, 2019): 841. http://dx.doi.org/10.3390/catal9100841.

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Pyrolysis bio-oils contain significant amounts of carboxylic acids which limit their utility as biofuels. Ketonisation of carboxylic acids within biomass pyrolysis vapours is a potential route to upgrade the energy content and stability of the resulting bio-oil condensate, but requires active, selective and coke-resistant solid acid catalysts. Here we explore the vapour phase ketonisation of acetic acid over Ga-doped HZSM-5. Weak Lewis acid sites were identified as the active species responsible for acetic acid ketonisation to acetone at 350 °C and 400 °C. Turnover frequencies were proportional to Ga loading, reaching ~6 min−1 at 400 °C for 10Ga/HZSM-5. Selectivity to the desired acetone product correlated with the weak:strong acid site ratio, being favoured over weak Lewis acid sites and reaching 30% for 10Ga/HZSM-5. Strong Brønsted acidity promoted competing unselective reactions and carbon laydown. 10Ga/HZSM-5 exhibited good stability for over 5 h on-stream acetic acid ketonisation.

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3

Osatiashtiani, Amin, Lee J. Durndell, Jinesh C. Manayil, Adam F. Lee, and Karen Wilson. "Influence of alkyl chain length on sulfated zirconia catalysed batch and continuous esterification of carboxylic acids by light alcohols." Green Chemistry 18, no. 20 (2016): 5529–35. http://dx.doi.org/10.1039/c6gc01089j.

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4

Potter, Matthew E., Lindsay-Marie Armstrong, and Robert Raja. "Combining catalysis and computational fluid dynamics towards improved process design for ethanol dehydration." Catalysis Science & Technology 8, no. 23 (2018): 6163–72. http://dx.doi.org/10.1039/c8cy01564c.

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5

Potter, Matthew E., Danni Sun, and Robert Raja. "The curious effects of integrating bimetallic active centres within nanoporous architectures for acid-catalysed transformations." Catalysis Science & Technology 6, no. 8 (2016): 2616–22. http://dx.doi.org/10.1039/c5cy02061a.

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6

Rodenas, Y., R. Mariscal, J. L. G. Fierro, D. Martín Alonso, J. A. Dumesic, and M. López Granados. "Improving the production of maleic acid from biomass: TS-1 catalysed aqueous phase oxidation of furfural in the presence of γ-valerolactone." Green Chemistry 20, no. 12 (2018): 2845–56. http://dx.doi.org/10.1039/c8gc00857d.

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7

Bruno, Sofia M., Ana C. Gomes, Tânia S. M. Oliveira, Margarida M. Antunes, André D. Lopes, Anabela A. Valente, Isabel S. Gonçalves, and Martyn Pillinger. "Catalytic alcoholysis of epoxides using metal-free cucurbituril-based solids." Organic & Biomolecular Chemistry 14, no. 16 (2016): 3873–77. http://dx.doi.org/10.1039/c6ob00512h.

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8

Reche, Mariano Tapia, Amin Osatiashtiani, Lee J. Durndell, Mark A. Isaacs, Ângela Silva, Adam F. Lee, and Karen Wilson. "Niobic acid nanoparticle catalysts for the aqueous phase transformation of glucose and fructose to 5-hydroxymethylfurfural." Catalysis Science & Technology 6, no. 19 (2016): 7334–41. http://dx.doi.org/10.1039/c6cy01129b.

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The first catalytic application of a nanoparticulate niobia solid acid prepared from a high area peroxo niobic acid sol, and its SBA-15 supported analogue, is demonstrated for the heterogeneously catalysed aqueous phase conversion of glucose and fructose to 5-HMF.

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9

Kumar, Suresh, and Jagdish K. Makrandi. "A Facile Solvent Free Synthesis of 3-arylidenechroman-4-ones Using Grinding Technique." E-Journal of Chemistry 9, no. 3 (2012): 1251–56. http://dx.doi.org/10.1155/2012/324907.

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An efficient method for the synthesis of 3-arylidenechroman-4-ones has been developed under solvent free conditions using grinding technique. Grinding of variously substituted chroman-4-ones with aromatic aldehydes in presence of anhydrous barium hydroxide at room temperature give 3-arylidenechroman-4-ones in high yield (75-92%). Products are obtained by just acidification of the reaction mixture in ice cold water. Reaction in solid state, with enhanced rate, high selectivity and manipulative simplicity are the attractive features of this environmentally benign protocol. The chroman-4-one derivatives required for the reaction have been obtained by polyphosphoric acid (PPA) catalysed cyclisation of phenoxypropanoic acids under microwave irradiations.

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10

Hurst, G., I. Brangeli, M. Peeters, and S. Tedesco. "Solid residue and by-product yields from acid-catalysed conversion of poplar wood to levulinic acid." Chemical Papers 74, no. 5 (December 6, 2019): 1647–61. http://dx.doi.org/10.1007/s11696-019-01013-3.

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AbstractThis study examines the yields of solid residue and by-product from the microwave-assisted acid hydrolysis of lignocellulosic poplar wood for levulinic acid production. The aim of this study was to optimise levulinic acid production via response surface methodology (RSM) and also investigate the effect of reaction conditions on other products such as furfural, solid residue, formic acid and acetic acid yields. A maximum theoretical levulinic acid yield of 62.1% (21.0 wt %) was predicted when reaction conditions were 188 °C, 126 min and 1.93 M sulphuric acid, with a corresponding solid residue yield of 59.2 wt %. Furfural from the hydrolysis of hemicellulose was found to have significantly degraded at the optimum levulinic acid yield conditions. The investigation of formic acid yields revealed lower formic acid yields than stoichiometrically expected, indicating the organic acid reactions under microwave-assisted hydrolysis of lignocellulose. The solid residue yields were found to increase significantly with increasing reaction time and temperature. The solid residue yields under all conditions exceeded that of levulinic acid and, therefore, should be considered a significant product alongside the high-value compounds. The solid residue was further examined using IR spectra, elemental analysis and XRF for potential applications. The overall results show that poplar wood has great potential to produce renewable chemicals, but also highlight all by-products must be considered during optimization.

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11

Abdel-Latif, Ehab, Gerd Kaupp, and Mohamed A. Metwally. "Brand New Quantitative Solid-state Synthesis of N-pyrazolyl Azomethines." Journal of Chemical Research 2005, no. 3 (March 2005): 187–89. http://dx.doi.org/10.3184/0308234054213735.

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Fifteen preparatively useful azomethines 3 and 5 have been quantitatively (100% yield at 100% conversion) obtained as hydrates by ball-milling together 4-aminoantipyrine 1 and 3-amino-4,6-dimethylpyrazolopyridine 4 with solid benzaldehydes 2 without passing through liquid phases. Unlike (acid catalysed) azomethine syntheses in solution, the solid–solid condensations proceed “waste free” in the absence of any auxiliaries or microwave irradiation. The product yields are quantitative in all cases and the products do not require purifying workup.

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12

Khosravi, Kaveh, Mojgan Zendehdel, Shirin Naserifar, Fatemeh Tavakoli, Kobra Khalaji, and Atefeh Asgari. "Heteropoly acid/NaY zeolite as a reusable solid catalyst for highly efficient synthesis of gem-dihydroperoxides and 1,2,4,5-tetraoxanes." Journal of Chemical Research 40, no. 12 (December 2016): 744–49. http://dx.doi.org/10.3184/174751916x14792244600532.

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gem-Dihydroperoxides and 1,2,4,5-tetraoxanes were synthesised from aldehydes and ketones catalysed by heteropoly acid/NaY zeolite (HPA/NaY) as a new, effective and reusable solid catalyst using 30% aqueous hydrogen peroxide at room temperature. The reactions proceeded with high rates and excellent yields.

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13

Wali, Anil, and S. Muthukumaru Pillai. "Cyclodehydration of Some 1,n-Diols Catalysed by Sulfated Zirconia." Journal of Chemical Research 23, no. 5 (May 1999): 326–27. http://dx.doi.org/10.1177/174751989902300515.

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14

Gowri Krishnan, Shamala, Fei Ling Pua, Kumaran Palanisamy, and Sharifah Nabihah. "Preparation of Oil Palm EFB Derived Solid Acid Catalyst for Esterification Reaction: Effect of Calcination Temperature." Key Engineering Materials 701 (July 2016): 117–21. http://dx.doi.org/10.4028/www.scientific.net/kem.701.117.

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Oil palm empty fruit bunch (EFB) is one of the palm biomass produced in abundance after oil extraction in Malaysia. This study was focused to utilize this waste biomass as a beneficial raw materials. EFB was used to prepare new solid acid catalyst for biodiesel production. EFB was converted into solid catalyst via direct impregnation method and it was used to catalyse esterification of oleic acid. Transition metal sulfide salt, Fe2(SO4)3 was impregnated on EFB fibres. Effect of different calcination temperature was studied on the properties of catalyst. The result shows that Fe2(SO4)3 based solid acid catalyst which calcined at 500°C exhibited the highest catalytic activity with 93.90% esterification rate was achieved. The morphology and surface chemistry and function group determination for the solid acid catalyst were characterized by SEM-EDX and FTIR.

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15

Zhang, Yu Li, Xiang Ying Hao, Cui Zhang, and De Yun Ma. "Application of SO₄^2-/ Al-Fe-Activated Solid Acid Catalyst Prepared by Cross-Linking Method." Applied Mechanics and Materials 448-453 (October 2013): 2929–32. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.2929.

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SO42-/ Al-Fe-activated solid acid catalyst has been prepared using cross-linking method, and characterized by FTIR spectra, TG-DTA, XRD analysis. The catalyst is able to effectively catalyse the hydration of turpentine to α-terpineol, with the conversion up to 40% after > 4 uses.

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16

Bondock, Samir, Ehab Abdel Latif, and Johann Lex. "Solvent-free Photooxygenation of 5-methoxyoxazoles: Stereoselective Synthesis of α-amino-α-hydroxy Carboxylic Acid Derivatives." Journal of Chemical Research 2005, no. 7 (July 2005): 422–26. http://dx.doi.org/10.3184/030823405774309168.

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A solvent-free photooxygenation of 5-methoxyoxazoles 1a–j embedded in porphrin-loaded polystyrene beads as solid support is described and applied for the synthesis of 3H-1,2,4-dioxazole derivatives 2a–j. Acid catalysed hydrolysis of 3H-1,2,4-dioxazole derivatives gave α-amino-α-hydroxy carboxylic acid derivatives 3a–j. The structural elucidation of the new compounds were carried on the basis of spectral and X-ray analyses.

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17

Grigg, Ronald, Jeremy P. Major, Fionna M. Martin, and Mark Whittaker. "Solution and solid-phase synthesis of hydroxamic acids via palladium catalysed cascade reactions." Tetrahedron Letters 40, no. 43 (October 1999): 7709–11. http://dx.doi.org/10.1016/s0040-4039(99)01574-9.

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18

Chuah, G. K., S. H. Liu, S. Jaenicke, and L. J. Harrison. "Cyclisation of Citronellal to Isopulegol Catalysed by Hydrous Zirconia and Other Solid Acids." Journal of Catalysis 200, no. 2 (June 2001): 352–59. http://dx.doi.org/10.1006/jcat.2001.3208.

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19

Jeeru, Lakshmana Rao, V. Saikumar Reddy R., Sayantan Pradhan, Gautam Kundu, and Narayan C. Pradhan. "Kinetics of solid acids catalysed nitration of toluene: Change in selectivity by triphase (liquid-liquid-solid) catalysis." Asia-Pacific Journal of Chemical Engineering 13, no. 1 (December 3, 2017): e2158. http://dx.doi.org/10.1002/apj.2158.

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20

Nascimento, Ana C., Carla S. R. Tecelão, José H. Gusmão, M. Manuela R. da Fonseca, and Suzana Ferreira-Dias. "Modelling lipase-catalysed transesterification of fats containingn-3 fatty acids monitored by their solid fat content." European Journal of Lipid Science and Technology 106, no. 9 (September 2004): 599–612. http://dx.doi.org/10.1002/ejlt.200401000.

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21

Choudary, Boyapati M., N. Sreenivasa Chowdari, and M. Lakshmi Kantam. "Friedel–Crafts sulfonylation of aromatics catalysed by solid acids: An eco-friendly route for sulfone synthesis." Journal of the Chemical Society, Perkin Transactions 1, no. 16 (2000): 2689–93. http://dx.doi.org/10.1039/b002931i.

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22

Hino, Makoto, and Kazushi Arata. "Acylation of toluene with acetic and benzoic acids catalysed by a solid superacid in a heterogeneous system." Journal of the Chemical Society, Chemical Communications, no. 3 (1985): 112. http://dx.doi.org/10.1039/c39850000112.

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23

Tanaka, Kan, Akira Miyazawa, Ai Hiate, Masashi Tashiro, Tatsunori Saisyo, Ryo Okabe, Kazufumi Kohno, and Takehiko Yamato. "An Acid Catalysed Intramolecular C–C Coupling Reaction of 8-halomethyl-16-methoxy[2.2]Metacyclophanes." Journal of Chemical Research 2005, no. 8 (August 2005): 495–97. http://dx.doi.org/10.3184/030823405774663228.

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The hydrolysis of 8-bromomethyl[2.2]metacyclophane 1a with a methoxy group at the 16-position was carried out in an 80% aqueous dioxane solution by refluxing in the presence of Nafion-H (a solid perfluorinated resin sulfonic acid) as a catalyst. The reaction yielded the corresponding 8-hydroxymethyl[2.2]metacyclophane 3 and the intramolecular C–C coupling product 2 with a spiro skeleton.

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24

Li, Tong-Shuang, Jian-Xin Wang, and Xue-Jing Zheng. "Simple synthesis of allobetulin, 28-oxyallobetulin and related biomarkers from betulin and betulinic acid catalysed by solid acids." Journal of the Chemical Society, Perkin Transactions 1, no. 23 (1998): 3957–66. http://dx.doi.org/10.1039/a806735j.

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25

Lima, Sérgio, Martyn Pillinger, and Anabela A. Valente. "Dehydration of d-xylose into furfural catalysed by solid acids derived from the layered zeolite Nu-6(1)." Catalysis Communications 9, no. 11-12 (June 2008): 2144–48. http://dx.doi.org/10.1016/j.catcom.2008.04.016.

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26

Mackay, Maureen F., Douglas J. Gale, and John F. K. Wilshire. "Structural studies of some 1-polymethyleneimino-2,4-dinitrobenzenesand related compounds; crystal structure of 1-(cis-2′,6′-dimethylpiperidin-1′-yl)-2,4-dinitrobenzene." Australian Journal of Chemistry 53, no. 8 (2000): 715. http://dx.doi.org/10.1071/ch00076.

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The ultraviolet and 1H n.m.r. spectra of some 1-polymethyleneimino-2,4-dinitrobenzenes and related compounds are discussed. The effect of trifluoroacetic acid on these spectra was also investigated; with 1-azetidinyl-2,4-dinitrobenzene, acid-catalysed ring opening was observed. The solid-state conformation of 1-(cis-2′,6′-dimethylpiperidin-1′-yl)-2,4-dinitrobenzene has been defined by single-crystal X-ray crystallography. Triclinic crystals belong to the space group P–1 with a 8.165(1), b 7.865(1), c 11.148(1) Å, α 95.23(1), β 106.00(1), γ 92.63(1)˚ and Z 2. The structure was refined to a final R of 0.048 for the 2222 observed data. In the crystal, the phenyl ring adopts a slight boat conformation, while the amino and o-nitro groups are significantly twisted from the mean plane of the ring.

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27

Stobiecki, Maciej, Maciej Buśko, Łukasz Marczak, Paweł Bednarek, Mariola Piślewska, and Przemysław Wojtaszek. "The complexity of oxidative cross-linking of phenylpropanoids — evidence from an in vitro model system." Functional Plant Biology 29, no. 7 (2002): 853. http://dx.doi.org/10.1071/pp01233.

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The development of an in vitro model system to study the process of dimerization of hydroxycinnamic acids is reported. Model compounds ferulic acid (FA) or methyl ferulate were reacted with H2O2 in the presence of horseradish peroxidase (HRP) or peroxidases from Lupinus albus L. apoplastic fluids. Following solid-phase extraction, the reaction products were analysed using gas chromatography-mass spectrometry. Major analytical and biochemical parameters of model reactions were determined and optimized. Six ferulic dimers were identified and quantified. With the use of this model system we found methyl ferulate to be a better substrate for lupin and horseradish peroxidases than FA. Use of various peroxidases did not influence the qualitative composition of reaction products although it affected the rate of substrate utilization and the quantitative output of reactions. Various isoforms of lupin apoplastic peroxidases revealed differentiated specificity towards hydroxycinnamic acids or their methyl esters. The potential of isoflavonoids (major phenolic components in white lupin cell walls) to influence peroxidase-catalysed formation of ferulic dehydrodimers was also tested. Genistein (5,7,4'-trihydroxyisoflavone) and genistin (genistein-7-O-β-glucoside) did not affect the qualitative composition of the reaction products. However, genistein inhibited the rate of ferulic substrate oxidation, while genistin showed the opposite effect, stimulating both utilization of ferulic substrate by HRP and subsequent polymerization and / or degradation of dehydrodimers formed. To our knowledge, this is the first indirect evidence that isoflavonoids might play a regulatory role in the oxidative formation of intermolecular cross-links in cell walls.

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28

Wijayati, Nanik, Harno Dwi Pranowo, Jumina Jumina, and Triyono Triyono. "SYNTHESIS OF TERPINEOL FROM α-PINENE CATALYZED BY TCA/Y-ZEOLITE." Indonesian Journal of Chemistry 11, no. 3 (December 20, 2011): 234–37. http://dx.doi.org/10.22146/ijc.21386.

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The hydration of a-pinene has been studied in the presence of TCA/Y-Zeolite catalyse. The catalyst was prepared by impregnating trichloroacetic acid (TCA) on support of Y-Zeolite. The TCA/Y-Zeolite catalyst converted a-pinene into hydrocarbons, while the TCA/Y-Zeolite catalyst was active and selective for producing alcohols, with a conversion of 66% and showed 55% selectivity for α-terpineol at 10 min. The reaction taken place in a solid-liquid mode and most of the α-terpineol is extracted out by the organic phase during the course of the reaction. TCA/Y-Zeolite was found as good catalyst for hydration of α-pinene to produce α-terpineol.

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29

Kumar, Dinesh, Damodara N. Kommi, Rajesh Chebolu, Sanjeev K. Garg, Raj Kumar, and Asit K. Chakraborti. "Selectivity control during the solid supported protic acids catalysed synthesis of 1,2-disubstituted benzimidazoles and mechanistic insight to rationalize selectivity." RSC Adv. 3, no. 1 (2013): 91–98. http://dx.doi.org/10.1039/c2ra21994h.

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30

Gianotti, Enrica, Maela Manzoli, Matthew E. Potter, Vasudev N. Shetti, Danni Sun, James Paterson, Thomas M. Mezza, Alan Levy, and Robert Raja. "Rationalising the role of solid-acid sites in the design of versatile single-site heterogeneous catalysts for targeted acid-catalysed transformations." Chem. Sci. 5, no. 5 (2014): 1810–19. http://dx.doi.org/10.1039/c3sc53088d.

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31

Li, Tong-Shuang, Hui-Yun Duan, Bao-Zhi Li, Brij B. Tewari, and Sheng-Hui Li. "Novel oxidative coupling of 2-naphthols to 1,1′-bi-2-naphthols catalysed by solid Lewis acids using atmospheric oxygen as oxidant." Journal of the Chemical Society, Perkin Transactions 1, no. 3 (1999): 291–94. http://dx.doi.org/10.1039/a808656g.

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32

Yadav, Ganapati D., and Ketan P. Pimparkar. "Insight into Friedel-Crafts acylation of 1,4-dimethoxybenzene to 2,5-dimethoxyacetophenone catalysed by solid acids—mechanism, kinetics and remedies for deactivation." Journal of Molecular Catalysis A: Chemical 264, no. 1-2 (March 2007): 179–91. http://dx.doi.org/10.1016/j.molcata.2006.07.075.

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33

Evtuguin, D. V., C. Pascoal Neto, and J. Rocha. "Lignin Degradation in Oxygen Delignification Catalysed by [PMo7V5O40]8- Polyanion. Part I. Study on Wood Lignin." Holzforschung 54, no. 4 (July 4, 2000): 381–89. http://dx.doi.org/10.1515/hf.2000.065.

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Summary The behaviour of lignin in wood delignification by oxygen in acidic media in the presence of the molybdovanadophosphate heteropolyanion [PMO7V5O40]8−as studied using wet chemistry methods, solid and liquid state 13C NMR spectroscopy. Lignin is oxidised by [PMO7V5O40]8− almost completely to carbon dioxide, with a minor yield of intermediate low-molecular weight aromatic products. The analysis of the reaction products shows that the lignin acidolysis and homolysis involving the oxygen participation in oxidation take place. The residual lignin in the wood residue is more “condensed” and richer in guaiacyl structural units than that in the initial wood. The analysis of “condensed” structures issued from permanganate oxidation of residual lignins suggests that these are formed predominantly by acid-catalysed reactions. The use of an organic solvent, such as ethanol, in the pulping solution favours the oxidative delignification, protecting the lignin against competing reactions (condensation).

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34

Hamer, P. D., D. E. Shallcross, A. Yabushita, M. Kawasaki, V. Marécal, and C. S. Boxe. "Investigating the photo-oxidative and heterogeneous chemical production of HCHO in the snowpack at the South Pole, Antarctica." Environmental Chemistry 11, no. 4 (2014): 459. http://dx.doi.org/10.1071/en13227.

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Environmental context Snowpacks present a surprisingly active environment for photochemistry, leading to sunlight-induced oxidation of deposited organic matter and the subsequent emission of a variety of photochemically active trace gases. We seek to address questions regarding the ultimate fate of organic matter deposited onto snow in the remote regions of the world. The work is relevant to atmospheric composition and climate change. Abstract We investigate snowpack fluxes of formaldehyde (HCHO) into the South Pole boundary layer using steady-state photochemical models. We study two chemical sources of HCHO within the snowpack. First, we study chemical production of HCHO from the processing of methyl hydroperoxide (CH3OOH): photolysis, reaction with the hydroxyl radical (OH•), and by an acid catalysed rearrangement. Assuming surface layer concentration effects for acidic solutes, we show that the acid catalysed production of HCHO within ice could contribute a non-negligible source to the snowpack HCHO budget. This novel source of HCHO complements existing explanations of HCHO fluxes based on physical emission of HCHO from snow. Secondly, we investigate HCHO production from the oxidation of organic matter (OM) by OH• within snow to explain observed fluxes of photochemical origin from the South Pole snowpack. This work shows that laboratory-derived photochemical production rates of HCHO and our standard model are inconsistent with field observations, which has implications for the distribution of OM relative to oxidants within ice particles. We resolve this inconsistency using new laboratory measurements of the molecular dynamics of the OH• photofragment from hydrogen peroxide (H2O2) and nitrate (NO3–) photolysis, which show that only OH produced in the outermost monolayers can contribute to gas phase and surface layer chemistry. Using these new measurements in conjunction with realistic treatments of ice grain size, H2O2 and NO3– distribution within ice grains, diffusion of gas species within solid ice, and observed OM particle size distributions yields snowpack HCHO photochemical production rates more consistent with observations.

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35

Štoček, Jakub Radek, and Martin Dračínský. "Tautomerism of Guanine Analogues." Biomolecules 10, no. 2 (January 22, 2020): 170. http://dx.doi.org/10.3390/biom10020170.

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Tautomerism of nucleic acid (NA) bases is a crucial factor for the maintenance and translation of genetic information in organisms. Only canonical tautomers of NA bases can form hydrogen-bonded complexes with their natural counterparts. On the other hand, rare tautomers of nucleobases have been proposed to be involved in processes catalysed by NA enzymes. Isocytosine, which can be considered as a structural fragment of guanine, is known to have two stable tautomers both in solution and solid states. The tautomer equilibrium of isocytosine contrasts with the remarkable stability of the canonical tautomer of guanine. This paper investigates the factors contributing to the stability of the canonical tautomer of guanine by a combination of NMR experiments and theoretical calculations. The electronic effects of substituents on the stability of the rare tautomers of isocytosine and guanine derivatives are studied by density functional theory (DFT) calculations. Selected derivatives are studied by variable-temperature NMR spectroscopy. Rare tautomers can be stabilised in solution by intermolecular hydrogen-bonding interactions with suitable partners. These intermolecular interactions give rise to characteristic signals in proton NMR spectra, which make it possible to undoubtedly confirm the presence of a rare tautomer.

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36

Tian, Jia, Hui Wang, Dan-Wei Zhang, Yi Liu, and Zhan-Ting Li. "Supramolecular organic frameworks (SOFs): homogeneous regular 2D and 3D pores in water." National Science Review 4, no. 3 (March 15, 2017): 426–36. http://dx.doi.org/10.1093/nsr/nwx030.

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Abstract Studies on periodic porosity and related properties and functions have been limited to insoluble solid-state materials. Self-assembly provides a straightforward and efficient strategy for the construction of soluble periodic porous supramolecular organic frameworks (SOFs) in water from rationally designed molecular building blocks. From rigid tri- and tetra-armed building blocks and cucurbitu[8]ril (CB[8]), a number of two-dimensional (2D) honeycomb, square and rhombic SOFs can be generated, which is driven by CB[8]-encapsulation-enhanced dimerization of two aromatic units on the periphery of the multi-armed molecules. By utilizing the same three-component host−guest motif as the driving force, three-dimensional (3D) diamondoid and cubic SOFs can be obtained from tetrahedral and [Ru(bipy)3]2+-derived octahedral monomers and CB[8]. All of the 2D and 3D periodic frameworks are soluble in water, and are able to maintain the periodicity as well as the pore sizes in the solid state. 3D SOFs are highly efficient homogeneous polycationic frameworks for reversible adsorption of anionic species including organic dyes, peptides, nucleic acids, drugs, dendrimers and Wells-Dawson-typed polyoxametallates (WD-POMs). WD-POM molecules adsorbed in the [Ru(bipy)3]2+-based SOF can catalyse the reduction of proton to H2 upon visible-light sensitization of [Ru(bipy)3]2+, which allows multiple electron transfer from [Ru(bipy)3]2+ to WD-POM. This review summarizes the design, formation and characterization of this new family of self-assembled frameworks, highlights their applications as homogeneous porous materials and finally outlines some future research directions.

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Mathews, Helena, C. Cohen, W. Wagoner, J. Kellogg, V. Dewey, and R. Bestwick. "180 GENETIC TRANSFORMATION OF RED RASPBERRY (RUBUS IDAEUS L.) WITH A GENE TO CONTROL ETHYLENE BIOSYNTHESIS." HortScience 29, no. 5 (May 1994): 454f—454. http://dx.doi.org/10.21273/hortsci.29.5.454f.

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We have developed efficient plant rageneration and transformation systems for red raspberry (Rubus idaeus L.). We have successfully introduced a gene for controlling biosynthesis of ethylene into raspberry for the first time. Leaf and petiole segments were co-cultivated with disarmed Agrobacterium strains EHA 101 or 105 containing plasmids pAG5420, pAG 1452 or pAG1552. The plasmids encoded gene sequences for S-adenosylmethionine hydrolase (SAM ase) driven by the fruit specific or wound and fruit specific tomato SE8 or E4 promoters. SAM ase catalyses the conversion of S-adenosylmethionine (SAM) to methylthioadenosine (MTA) and homoserine which can reenter the methionine recycling pathway. SAM is therefore not available for the synthesis of 1-am inocyclopropane carboxylic acid (ACC), the metabolic precursor for ethylene biosynthesis. Initial shoot regenerants were mostly chimeras containing transformed and non-transformed cells. Solid clones of pure transgenics were developed by repeated culture of leaf, petiole and nodal explants of primary regenerants on higher stringency selection medium. Transformants were screened on medium with kanamycin, geneticin or hygromycin depending on the selection marker gene NPTII or hpt. Genomic integration of transgenes were confirmed by Southern hybridization. Transgenic plants of cultivars Canby, Meeker and Chilliwack have been transplanted to the greenhouse for fruit set and further evaluation of transgenic traits.

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Kamwilaisak, Khanita, and Mallika Thabuot. "The Fixed Bed Reaction of Residual Natural Rubber for Oil Production by Pyrolysis Process." Advanced Materials Research 931-932 (May 2014): 225–30. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.225.

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The aim of this study is to use pyrolysis reaction to produce oil product as a fuel or chemical feedstock. The fixed bed reactor was used as a pyrolysis system. The pyrolysis reaction of residual para rubber was operated in the absence of catalyse. The operating conditions such as particle size (0.5 and 1.0 cm3) and pyrolysis temperature (500, 550 and 600 OC) were studied under N2 conditions and retention time 90 min. The result shows the para rubber size 1.0 cm3 can be produced liquid phase more than of para rubber size of 0.5 cm3. The optimised condition with the highest oil yield was at 550OC with rubber size of 1.0 cm3. The percentage of the product was 60% of liquid, 35% of gas and 5% of solid (char). Furthermore, the FTIR result can be presented the supported evidence that the transformation of aliphatic contents to be aromatic contents was increased with increased temperature. Also, GCMS analysis was used for the identification and quantification of the product. It was found 5 major products that can be used as a chemical feedstock. The maximum amount of component was 2-Benzenedicarboxylic acid, diisooctyl ester (Isooctyl phthalate) with 22.08%. This is a plasticizer with higher cost than fuel.

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Candy, Rachel M., Kyle R. Blight, and David E. Ralph. "Analysis of the Bacterial Sulphur System." Advanced Materials Research 825 (October 2013): 190–93. http://dx.doi.org/10.4028/www.scientific.net/amr.825.190.

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Heterogeneous bacterial sulphur systems are inherently complicated. However, developing an understanding of the influence of environmental factors such as pH,Iand PCO2is important for a number of fields. Examples of these include minimising acid mine drainage and maximising metal recovery from low-grade sulphide minerals. Measuring the effect of these factors on the extent and rate of sulphur (S) oxidation is complicated by the presence and nature of solid phase elemental S. The rate and extent of S oxidation can be determined indirectly via the reaction product, H2SO4, which was quantified using pH measurements in this study. The method was critically dependent on the quality of pH data but proved effective in providing rate constants for the catalysed S oxidation reaction and yield (biomass/substrate) estimates in the range pH > 1.5. IncreasingIover the range 0.176 0.367 mol L-1decreased bacterial cell yields but increased the rate of sulphur oxidation significantly. Partial pressures of CO2in the range of 0.039 1.18% v/v produced no significant effect on the rates of S oxidation or bacterial cell yields. Bacterial cell yields were not affected in the pH range 1.5 2.5, however the rate of S oxidation increased significantly from pH 2.0 2.5. In the range pH < 1.5 the batch cultures progressed and although no reliable rate data was recorded cell yields decreased from 7.43 to 2.05 (× 1012cells mol-1) at pH 1.5 to 1.0 respectively.

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Roldin, P., A. C. Eriksson, E. Z. Nordin, E. Hermansson, D. Mogensen, A. Rusanen, M. Boy, et al. "Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multi-layer model ADCHAM." Atmospheric Chemistry and Physics Discussions 14, no. 1 (January 10, 2014): 769–869. http://dx.doi.org/10.5194/acpd-14-769-2014.

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Abstract. We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: (1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), (2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and (3) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. These salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar like amorphous phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if low-volatility and viscous oligomerized SOA material accumulates in the particle surface layer upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass transfer limited uptake of condensable organic compounds onto wall deposited particles or directly onto the Teflon chamber walls of smog chambers can have profound influence on the observed SOA formation. During the early stage of the SOA formation the wall deposited particles and walls themselves serve as a SOA sink from the air to the walls. However, at the end of smog chamber experiments the semi-volatile SOA material may start to evaporate from the chamber walls. With these three model applications, we demonstrate that several poorly quantified processes, i.e. mass transport limitations within the particle phase, oligomerization, heterogeneous oxidation, organic salt formation, and chamber wall effects can have substantial influence on the SOA formation, lifetime, chemical and physical particle properties, and their evolution. In order to constrain the uncertainties related to these processes, future experiments are needed where as many of the influential variables as possible are varied. ADCHAM can be a valuable model tool in the design and analysis of such experiments.

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Roldin, P., A. C. Eriksson, E. Z. Nordin, E. Hermansson, D. Mogensen, A. Rusanen, M. Boy, et al. "Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM." Atmospheric Chemistry and Physics 14, no. 15 (August 11, 2014): 7953–93. http://dx.doi.org/10.5194/acp-14-7953-2014.

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Abstract. We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas-phase Master Chemical Mechanism version 3.2 (MCMv3.2), an aerosol dynamics and particle-phase chemistry module (which considers acid-catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion-limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study (1) the evaporation of liquid dioctyl phthalate (DOP) particles, (2) the slow and almost particle-size-independent evaporation of α-pinene ozonolysis secondary organic aerosol (SOA) particles, (3) the mass-transfer-limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), and (4) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. In the smog chamber experiments, these salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar-like amorphous-phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if the concentration of low-volatility and viscous oligomerized SOA material at the particle surface increases upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass-transfer-limited uptake of condensable organic compounds onto wall-deposited particles or directly onto the Teflon chamber walls of smog chambers can have a profound influence on the observed SOA formation. During the early stage of the SOA formation the wall-deposited particles and walls themselves serve as an SOA sink from the air to the walls. However, at the end of smog chamber experiments the semi-volatile SOA material may start to evaporate from the chamber walls. With these four model applications, we demonstrate that several poorly quantified processes (i.e. mass transport limitations within the particle phase, oligomerization, heterogeneous oxidation, organic salt formation, and chamber wall effects) can have a substantial influence on the SOA formation, lifetime, chemical and physical particle properties, and their evolution. In order to constrain the uncertainties related to these processes, future experiments are needed in which as many of the influential variables as possible are varied. ADCHAM can be a valuable model tool in the design and analysis of such experiments.

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Maru, Minaxi S., Parth Patel, Noor-ul H. Khan, and Ram S. Shukla. "Copper Hydrotalcite (Cu-HT) as an Efficient Catalyst for the Hydrogenation of CO2 to Formic Acid." Current Catalysis 9, no. 1 (September 10, 2020): 59–71. http://dx.doi.org/10.2174/2211544709999200413110411.

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: Hydrogenation of CO2 to energy-rich products over heterogeneous metal catalysts has gained much attention due to their commercial applications. Specifically, the first-row transition metal catalysts are very rarely reported and discussed for the production of formic acid from the hydrogenation of CO2. Herein, hydrotalcite supported copper metal has shown activity and efficiency to produce formic acid from the hydrogenation of CO2, without adding any additional base or promoter and was effectively recycled 4 times after separating by simple filtration without compromising the formic acid yield. Hydrotalcite supported copper-based catalyst (Cu-HT) was synthesized through the coprecipitation method and used as a heterogeneous catalyst for the hydrogenation of CO2. The precise copper metal content determined by ICP in Cu-HT is 0.00944 mmol. The catalyst afforded maximum TOF, 124 h-1 under the employed reaction conditions: 100 mg catalyst, 60 °C, 60 bar total pressure of CO2/H2 (1:1, p/p) with 60 mL of mixed methanol:water (5:1, v/v) solvent. Cu-HT catalyst was synthesised and thoroughly characterized by FT-IR, PXRD, SEM, TEM, XPS and BET surface area. The first-order kinetic dependence with respect to the catalyst amount, partial pressures of CO2, and of H2 was observed and a plausible reaction mechanism is suggested. Background: CO2 hydrogenation to energy-rich products over heterogeneous metal catalysts has gained much attention due to their commercial applications. Specifically, the first-row transition metal catalysts are very rarely reported and discussed for the production of formic acid from the hydrogenation of CO2. Objective: he aim is to investigate the heterogeneous catalyst systems, using solid soft base hydrotalcite supported Cu metal-based catalyst for effective and selective hydrogenation of CO2 to formic acid. Methods: The Cu –HT catalyst was synthesized and characterized by FT-IR, PXRD, SEM, TEM, XPS and BET surface area in which the precise copper content was 0.00944 mmol. The Cu-HT catalysed hydrogenation of CO2 was carried out in the autoclave. Results: The Cu-HT catalyst afforded maximum TOF of 124 h-1 under the employed reaction conditions: 100 mg catalyst, 60 °C, 60 bar total pressure of CO2/H2 (1:1, p/p) with 60 mL of mixed methanol: water (5:1, v/v) solvent, without adding any additional base or promoter and was recycled 4 times by simple filtration without compromising the formic acid yield. Formation of formic acid was observed to depend on the amount of the catalyst, partial pressures of CO2 and H2, total pressure, temperature and time. Conclusion: Cu-HT based heterogeneous catalyst was found to be efficient for selective hydrogenation of CO2 to formic acid and was effectively recycled four times after elegantly separating by simple filtration.

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DEGUCHI, Hiroshi, Hiroyuki TAKEYA, Esteban C. GABAZZA, Junji NISHIOKA, and Koji SUZUKI. "Prothrombin kringle 1 domain interacts with factor Va during the assembly of prothrombinase complex." Biochemical Journal 321, no. 3 (February 1, 1997): 729–35. http://dx.doi.org/10.1042/bj3210729.

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The kringle 2 domain of prothrombin has been shown to interact with factor Va during the activation of prothrombin by the prothrombinase complex composed of factor Xa, factor Va, negatively charged phospholipids and Ca2+ ions. However, contradictory results have been reported about the role of the kringle 1 domain of prothrombin during the assembly of the prothrombinase complex. In an attempt to clarify the role of the kringle 1 domain of prothrombin, its effect on the activation of prothrombin by the prothrombinase complex and its direct binding to human factor Va were assessed. Comparative evaluation with the effects caused by other prothrombin structural components [a fragment 1 (γ-carboxyglutamic acid and kringle 1 domains), a kringle 2 domain and a catalytic protease domain] was also performed. In the presence of factor Va, each kringle 1 and kringle 2 fragment significantly inhibited the factor Xa-catalysed prothrombin activation in the absence of phospholipids. However, in the absence of both factor Va and phospholipids, kringle 2 fragment, but not kringle 1 fragment, inhibited prothrombin activation. Evaluation of the molecular interaction of the kringle domains with factor Va in assays with solid-phase phospholipid vesicles showed that each kringle 1 and kringle 2 fragment inhibited the prothrombinase complex activity. Assessment of the direct binding of prothrombin and each kringle domain of prothrombin with factor Va by fluorescence polarization showed that prothrombin, kringle 1 and kringle 2 fragments bind directly to factor Va with dissociation constants of 1.9ŷ0.1, 2.3ŷ0.1 and 2.0ŷ0.4 ƁM (meansŷS.D.) respectively. These findings suggest that both kringle 1 and 2 domains of prothrombin interact with factor Va during the assembly of the prothrombinase complex.

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Aschmann, Sara M., Janet Arey, and Roger Atkinson. "Reaction of OH radicals with 5-hydroxy-2-pentanone: formation yield of 4-oxopentanal and its OH radical reaction rate constant." Environmental Chemistry 10, no. 3 (2013): 145. http://dx.doi.org/10.1071/en12146.

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Environmental context Alkanes, major constituents of vehicle exhausts, are emitted to the atmosphere where they react, chiefly by gas-phase reactions with the hydroxyl radical, to form products which can also react further. In laboratory experiments, we studied the further reactions of a model first-generation alkane reaction product. Understanding alkane reaction chains is important because the toxicity, secondary aerosol formation and other properties of vehicle emissions can change as new compounds are formed. Abstract 1,4-Hydroxycarbonyls are major products of the gas-phase reactions of alkanes with OH radicals, and in the atmosphere they will react with OH radicals or undergo acid-catalysed cyclisation with subsequent dehydration to form highly reactive dihydrofurans. 3-Oxobutanal (CH3C(O)CH2CHO) and 4-oxopentanal (CH3C(O)CH2CH2CHO) are first-generation products of the OH radical-initiated reaction of 5-hydroxy-2-pentanone (CH3C(O)CH2CH2CH2OH). The behaviours of 3-oxobutanal and 4-oxopentanal have been monitored during OH+5-hydroxy-2-pentanone reactions carried out in the presence of NO, using solid phase microextraction fibres coated with O-(2,3,4,5,6,-pentafluorobenzyl)hydroxyl amine (PFBHA) for on-fibre derivatisation of carbonyl compounds and an annular denuder coated with XAD resin and further coated with PFBHA. The time-concentration data for 4-oxopentanal during OH+5-hydroxy-2-pentanone reactions were independent of relative humidity (0–50%), and were consistent with a rate constant for OH+4-oxopentanal of (1.2±0.5)×10–11cm3 molecule–1s–1 at 296±2K, a factor of 2 lower than both literature rate constants for other aldehydes and that estimated using a structure-reactivity approach. The molar formation yield for 4-oxopentanal from OH+5-hydroxy-2-pentanone in the presence of NO was determined to be 17±5%, consistent with predictions based on a structure-reactivity relationship and current knowledge of the subsequent reaction mechanisms.

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Henderson, P. J. F., C. K. Hoyle, and A. Ward. "Expression, purification and properties of multidrug efflux proteins." Biochemical Society Transactions 28, no. 4 (August 1, 2000): 513–17. http://dx.doi.org/10.1042/bst0280513.

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A general strategy is described for the amplified expression, purification and characterization in Escherichia coli of multidrug efflux proteins from Staphylococcus aureus, Bacillus subtilis, Methanococcus janaschii and E. coli. They all catalyse drug/H+ antiport of substrates such as quinolones and ethidium and exemplify a family of putatively 12-helix membrane proteins. The gene for each protein was cloned downstream of the tac promoter in plasmid pTTQ18; an oligonucleotide encoding six histidine residues was added, in frame, to the C-terminus to facilitate purification. Growth conditions were optimized in 1–25-litre cultures of E. coli host strains to amplify the expression of each protein; the retention of activity was confirmed by assays of antibiotic resistance in vivo and/or assays of energized transport activity in vitro with synthetic substrates. Proteins were solubilized in dodecylmaltoside and purified to more than 90% homogeneity with Ni2+-nitrilo-triacetate-affinity column chromography, yielding 5–25 mg per 25 litres of original culture. All the transport proteins migrated anomalously in SDS/PAGE at apparent molecular masses below those predicted from the gene sequence; identity and integrity were therefore confirmed by N-terminal amino acid sequencing and Western blotting for the C-terminal hexahistidine tag. Examination of the secondary structure of detergent-solubilized proteins by CD or Fourier-transform infrared spectroscopy following purification indicated a high content of α-helix (more than 75%). Matrix-assisted laser desorption ionization MS confirmed the high degree of purity and the true molecular mass. The formation of three-dimensional crystals is being attempted but crystals have yet to be grown that diffract X-rays. The growth of two-dimensional protein arrays has been more successful, with diffraction of electrons at low resolution. Proteins have been fused to green fluorescent protein or maltose-binding protein to facilitate these structural analyses. In addition, ligands for efflux proteins labelled with 13C or 15N have been synthesized to implement solid-state NMR studies of the ligand-binding site.

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"Influence of Catalyst Preparation Conditions on Coconut Shell-derived Solid Acid Catalyst Performance for Transesterification." International Journal of Recent Technology and Engineering 8, no. 2S3 (August 10, 2019): 270–77. http://dx.doi.org/10.35940/ijrte.b1047.0782s319.

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The carbon-based solid acid catalyst is mostly synthesized through a series of incomplete carbonization and sulfonation process. This paper investigates the influence of catalyst preparation conditions on the catalyst performance in biodiesel conversion. Coconut-shell-derived solid acid catalyst was prepared through incomplete carbonization followed by sulfonation using concentrated sulphuric acid. The effect of catalyst preparation variables including carbonization temperature, carbonization time, sulfonation temperature and sulfonation time was evaluated using response surface methodology. The adequacy of the mathematical model represents the process was confirmed by using ANOVA analysis with R2 value of 0.9121 and p-value <0.0001. Optimal process conditions were obtained at carbonization temperature of 469.97 ºC, carbonization time of 3.37 h, sulfonation temperature of 99.14 ºC and sulfonation time of 7.11 h. At these conditions, the coconut shell-derived catalyst able to catalyse the transesterification reaction and achieved >80% FAME conversion. This study uncovers the potential of biomass valorisation into a useful end produc

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Xu, Gui-Zhuan, Chun Chang, Wei-Na Zhu, Bo Li, Xiao-Jian Ma, and Feng-Guang Du. "A comparative study on direct production of ethyl levulinate from glucose in ethanol media catalysed by different acid catalysts." Chemical Papers 67, no. 11 (January 1, 2013). http://dx.doi.org/10.2478/s11696-013-0410-0.

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AbstractDirect production of ethyl levulinate (EL) from glucose catalysed by a liquid acid catalyst (sulfuric acid) and a solid acid zeolite catalyst USY NKF-7 (USY) in ethanol media was investigated in this study. Effects of the initial glucose concentration (C G0), reaction temperature (T), amount of acid catalyst, and water addition on the yields of EL were compared, respectively. The results show that higher yield of EL can be obtained at lower C G0. Higher temperature and acid concentration can accelerate the reaction rate, but the formation rate of the by-products increases more quickly than that of EL. Water addition also can result in the decrease of the yield of EL. Although sulfuric acid is efficient in the production of EL, the USY is more efficient in converting glucose to 5-ethoxymethyl-2-furaldehyde. Moreover, the use of USY can limit the diethyl ether production, and it can be reused for multiple times.

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Mon, Marta, Rosaria Bruno, Sergio Sanz-Navarro, Cristina Negro, Jesús Ferrando-Soria, Lucia Bartella, Leonardo Di Donna, et al. "Hydrolase–like catalysis and structural resolution of natural products by a metal–organic framework." Nature Communications 11, no. 1 (June 17, 2020). http://dx.doi.org/10.1038/s41467-020-16699-3.

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Abstract The exact chemical structure of non–crystallising natural products is still one of the main challenges in Natural Sciences. Despite tremendous advances in total synthesis, the absolute structural determination of a myriad of natural products with very sensitive chemical functionalities remains undone. Here, we show that a metal–organic framework (MOF) with alcohol–containing arms and adsorbed water, enables selective hydrolysis of glycosyl bonds, supramolecular order with the so–formed chiral fragments and absolute determination of the organic structure by single–crystal X–ray crystallography in a single operation. This combined strategy based on a biomimetic, cheap, robust and multigram available solid catalyst opens the door to determine the absolute configuration of ketal compounds regardless degradation sensitiveness, and also to design extremely–mild metal–free solid–catalysed processes without formal acid protons.

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Boughachiche, F., K. Rachedi, H. Zerizer, R. Duran, S. Karama, M. Biaci, Z. Aknouche, S. Bouchina, and A. Boulahrouf. "Production of Protease on Wheat Bran by a Newly Isolated Streptomyces SP. Under Solid State Fermentation." Journal of Bio-Science, July 11, 2021, 33–48. http://dx.doi.org/10.3329/jbs.v29i0.54820.

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Proteases are a group of enzymes that catalyse the degradation of proteins resulting in the production of their amino acid constituents. In the present study newly isolated Streptomyces sp. was subjected to produce proteases through solid state fermentation while wheat bran was used as substrate. To produce proteases, a local strain Streptomyces sp. was isolated from a soil sample of Ezzemouls saltpan, located in Ain M'lila (East of Algeria). The phenotypic and phylogenetic studies of this strain showed that it represents probably a new species. The SSF production medium for Streptomyces sp. was optimized using Plackett and Burman statistical methods. The results showed a maximum activity on basal wheat bran medium supplemented with 1% fructose. The best SSF humidifying solution was pH 9.0 phosphate buffer at 50% moisture. Protease has an optimum at pH 7.0, which is a typical characteristic of neutral proteases. The optimum temperature was 60°C and proved stable up to 80°C. The results showed that the novel Streptomyces sp. isolate is a good producer of extracellular neutral protease on wheat bran, which can be beneficial for industries. J. Bio-Sci. 29(1): 33-48, 2021 (June)

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