1070-34-4Relevant articles and documents
A New Class of Linear Tetrapyrroles: Acetylenic 10,10a-Didehydro-10a-homobilirubins
Tu, Bin,Ghosh, Brahmananda,Lightner, David A.
, p. 8950 - 8963 (2003)
Novel bilirubin analogues with dipyrrinones conjoined to an acetylene rather than a methylene group were synthesized and examined spectroscopically. Despite the increased separation of the dipyrrinones forced by replacing a -CH2- by a -C≡C- unit, molecular dynamics calculations show that, like bilirubin, they may still engage in intramolecular hydrogen bonding to carboxylic acid groups when the propionic acid chains are slightly lengthened, e.g., butanoic acids. Unlike bilirubin, however, which is bent in the middle and has a ridge-tile shape, the acetylene orients the attached dipyrrinones along a linear path, and intramolecular hydrogen bonding preserves a twisted linear molecular shape. The extended planes of the dipyrrinones intersect along the -C≡C- axis at an angle of 136° for the conformation stabilized by intramolecular hydrogen bonding in the bis-butyric acid rubin (lb). With shorter acid chains (propionic), only one CO2H can engage an opposing dipyrrinone in intramolecular hydrogen bonding, and in this energy-minimum conformation of the linear pigment 1a, the intersection of the extended planes of the dipyrrinones has an angle of 171°. Spectroscopic evidence for such linearized and twisted structures was found in the pigments' NMR spectral data and their exciton UV-vis and induced circular dichroism spectra.
Novel sulfonated carbonaceous materials from p-toluenesulfonic acid/glucose as a high-performance solid-acid catalyst
Zhang, Baohua,Ren, Jiawen,Liu, Xiaohui,Guo, Yun,Guo, Yanglong,Lu, Guanzhong,Wang, Yanqin
, p. 629 - 632 (2010)
A novel carbon-based solid-acid catalyst was simply prepared for the first time by the thermal treatment of p-toluenesulfonic acid (TsOH) with d-glucose at 180 °C in a sealed autoclave and it was proved to have high acidity and to be a highly efficient solid-acid catalyst in the reactions such as esterification of succinic acid with ethanol. Crown Copyright
Towards a bio-based industry: Benign catalytic esterifications of succinic acid in the presence of water
Budarin, Vitaly,Luque, Rafael,Macquarrie, Duncan J.,Clark, James H.
, p. 6914 - 6919 (2007)
The biorefinery of the future will need to integrate bioconversion and appropriate low environmental impact chemical technologies (Green Chemistry) so as to produce a wide range of products from biomass in an economically effective and environmentally acceptable manner. The challenge for chemists is to develop chemistry that works with fermentation-derived dilute, aqueous mixtures of oxygenated chemicals (platform molecules) rather than the petroleum-derived non-aqueous, non-oxygenated feedstocks we have been working with for 50+ years and to avoid energy intensive and wasteful concentration and purification steps. Here we show that a new family of tuneable mesoporous carbonaceous catalysts derived from starch can be used to accomplish efficient chemistry in aqueous solution. Our new aqueous catalytic chemistry relies on the ability to adjust the surface properties including the hydrophobicity-hydrophilicity balance of mesoporous Starbons by carbonisation at different temperatures (250-750°C). Simple treatment of these materials with sulfuric acid then provides a series of porous solid acids that can function under a range of conditions including dilute aqueous solution. The reactions of succinic acid (platform molecule) in aqueous alcohol demonstrate the outstanding activities of these new catalysts.
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Fenton,Gostling
, p. 554 (1898)
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Pig liver esterase catalyzed hydrolyses of diesters. A new route to the syntheses of achiral half-esters
Ager,Prakash
, p. 739 - 742 (1995)
Pig liver esterase catalyzed hydrolyses of diesters of alkanes, aromatic and heterocyclic compounds gave high yields of the corresponding half-esters under mild reaction conditions.
Zeolite Y from kaolin clay of Kachchh, India: Synthesis, characterization and catalytic application
Gandhi, Dolly,Bandyopadhyay, Rajib,Soni, Bhavna
, (2021/11/23)
Kaolin clay obtained from Kachchh, Gujarat was used as alumina and silica source to synthesize zeolite Y by hydrothermal method. The synthesis route comprised of the following steps: sulfuric acid treatment at 110 ?°C (4 ?h) for impurity removal followed by calcination at 600 ?°C for 4 ?h, thermal activation of kaolin into metakaolin by NaOH fusion at 850 ?°C (8 ?h); aging of reaction mixtures at 50 ?°C (24 ?h); crystallization (24 ?h) followed by washing and drying. The synthesized zeolite Y was examined by multiple characterization techniques which revealed a pore volume of 0.22 ?cm3/g with pore size of 2.89 ?nm having essential surface area of 320 ?m2/g, indicating a porous material having majority of micropores and remaining mesopores. The zeolite exhibited good catalytic activity for succinic acid esterification using ethanol to produce monoethyl and diethyl succinate. The conversion of SA (72%) and yield (60%) of valuable diester indicated good conversion rate and selectivity at moderate reaction conditions. Detailed structural comparison with zeolite Y synthesized using standard chemical route is also carried out. This work demonstrated an effective way of preparing environmentally benign porous zeolite Y having high surface area and pore volume that can be useful for catalytic applications.
Electrochemical cross-coupling of biogenic di-acids for sustainable fuel production
Holzh?user, F. Joschka,Creusen, Guido,Moos, Gilles,Dahmen, Manuel,K?nig, Andrea,Artz, Jens,Palkovits, Stefan,Palkovits, Regina
, p. 2334 - 2344 (2019/05/21)
Direct electrocatalytic conversion of bio-derivable acids represents a promising technique for the production of value-added chemicals and tailor-made fuels from lignocellulosic biomass. In the present contribution, we report the electrochemical decarboxylation and cross-coupling of ethyl hydrogen succinate, methyl hydrogen methylsuccinate and methylhexanoic acid with isovaleric acid. The reactions were performed in aqueous solutions or methanol at ambient temperatures, following the principles of green chemistry. High conversions of the starting materials have been obtained with maximum yields between 42 and 61% towards the desired branched alkane products. Besides costly Pt electrodes also (RuxTi1-x)O2 on Ti electrodes exhibited a notable activity for cross-Kolbe electrolysis. As some of the products are insoluble in water, easy product isolation and reuse of the reaction solvent is enabled via phase separation. Several side products have been identified to evaluate the efficiency of the reaction and to elucidate the factors influencing the product selectivity. The yielded alkanes and esters were assessed with regard to their potential as fuels for internal combustion engines. While the longer alkanes constitute promising candidates for the compression-ignition engine, the smaller ester represents an interesting option for the spark-ignition engine.
