78-84-2Relevant articles and documents
Marine natural products: highly functionalized steroids (12β-hydroxy-24-norcholesta-1,4,22-trien-3-one and 12β-acetoxy-24-norcholesta-1,4,22-trien-3-one) from sea raspberry, Gersemia rubiformis
Kingston, John F.,Fallis, Alex G.
, p. 820 - 824 (1982)
Two new C26 steroid Δ1,4-dien-3-ones 5 and 6 wit 12β oxygen functions have been isolated from the soft coral Gersemia rubiformis and their structures elucidated from their spectral data and chemical transformations.
Catalytic dehydration of 2,3-butanediol over P/HZSM-5: Effect of catalyst, reaction temperature and reactant configuration on rearrangement products
Zhao, Jinbo,Yu, Dinghua,Zhang, Wengui,Hu, Yi,Jiang, Ting,Fu, Jie,Huang, He
, p. 16988 - 16995 (2016)
As a type of important bio-based vicinal diol, 2,3-butanediol could be transformed into methyl ethyl ketone and 2-methyl propanal through a pinacol rearrangement mechanism under acid catalysis conditions. In this paper, a series of P/HZSM-5 (Si/Al = 360) samples with various phosphate contents were prepared and tested via the catalytic transformation of 2,3-butanediol, with particular focus on the effect of phosphate content on the ratio of methyl ethyl ketone to 2-methyl propanal. The catalyst structures were studied using several physico-chemical methods such as XRD, N2 sorption, NH3-TPD and FT-IR. At 180 °C, the ratio of methyl ethyl ketone to 2-methyl propanal increased from 5.1 to 37.5 when the content of phosphate increased from 0.5 to 8.0. When the reaction temperature increased from 180 °C to 300 °C over 4% P2O5/HZSM-5, the ratio of methyl ethyl ketone to 2-methyl propanal decreased from 15.6 to 2.5. The configuration of 2,3-butanediol would affect the conversion but not the selectivity. The characterization results demonstrated that the phosphate modification of HZSM-5 could not only reduce the strong and medium acid sites but also produce new weak acid sites. Strong acid sites and high reaction temperatures could promote the formation of 2-methyl propanal through methyl migration via carboniums. Based on these results, a possible surface reaction model was proposed.
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Hersh,Nelson
, p. 1631 (1936)
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Generation of Simple Enols in Aqueous Solution from Alkali Metal Enolates. Some Chemistry of Isobutyraldehyde Enol
Chiang, Y.,Kresge, A. J.,Walsh, P. A.
, p. 6314 - 6320 (1986)
The enol isomer of isobutyraldehyde was generated in aqueous solution by reaction of its lithium and potassium enolates with water and of the trimethylsilyl enol ether with fluoride ion, and rates of ketonization of the enol were measured in HCl, DCl (in D2O), and NaOH solutions and in CNCH2CO2H, HCO2H, CH3CO2H, CH2ClPO3H-, and H2PO4- buffers.Rates of enolization of isobutyraldehyde were also determined, by iodine scavenging, in HClO4 and NaOH solutions.The reaction rates in HCl and NaOH give two independent estimates of the keto-enol equilibrium constant for isobutyraldehyde in aqueous solution at 25 deg C, which are in good agreement with each other and whose average is KE = (1.37 +/- 0.09)*1E-4, pKE = 3.86 +/- 0.03.The ketonization rates in NaOH solution also provide an estimate of the acidity constant of isobutyraldehyde enol ionazing as an oxygen acid, KaE = (2.37 +/- 0.14)*1E-12 M, pKaE = 11.63 +/- 0.03, which, when combined with KE, gives the acidity constant of the keto form of isobutyraldehyde ionizing as a carbon acid, KaK = (3.23 +/- 0.29)*1E-16 M, pKaK = 15.49 +/- 0.04.The ketonization reaction in buffer solutions shows both general-acid and general-base catalysis, consistent with two parallel reaction paths involving rate-determing β-carbon protonation of both enol and enolate ion.Analysis of the data in terms of this scheme shows enolate to be 1E8 times more reactive than enol.Arguments are advanced to the effect that all of the present data are consistent with stepwise reaction mechanisms and do not require a concerted reaction path.
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Strohmeier,Weigelt
, p. C17 (1975)
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Kinetics of oxidation of L-valine by a copper(III) periodate complex in alkaline medium
Sharanabasamma,Angadi, Mahantesh A.,Salunke, Manjalee S.,Tuwar, Suresh M.
, p. 187 - 199 (2012)
The kinetics of oxidation of L-valine by a copper(III) periodate complex was studied spectrophotometrically. The inverse second-order dependency on [OH-] was due to the formation of the protonated diperiodatocuprate(III) complex ([Cu(H3IO6) 2]-) from [Cu(H2IO6) 2]3-. The retarding effect of initially added periodate suggests that the dissociation of copper(III) periodate complex occurs in a pre-equilibrium step in which it loses one periodate ligand. Among the various forms of copper(III) periodate complex occurring in alkaline solutions, the monoperiodatocuprate(III) appears to be the active form of copper(III) periodate complex. The observed second-order dependency of [L-valine] on the rate of reaction appears to result from formation of a complex with monoperiodatocuprate(III) followed by oxidation in a slow step. A suitable mechanism consistent with experimental results was proposed. The rate law was derived as: (Equation presented) The temperature effect on the rate of reaction was also studied. The activation parameters of the reaction Ea, ΔH#, ΔS#, ΔG#, and log 10 A are 49 ± 2 kJ·mol-1, 47.5 ± 2 kJ·mol-1, -49 ± 2 J·K -1·mol-1, 62 ± 3 kJ·mol-1 and 6.0 ± 0.1, respectively. Springer Science+Business Media, LLC 2012.
Detailed structure-function correlations of bacillus subtilis acetolactate synthase
Sommer, Bettina,Von Moeller, Holger,Haack, Martina,Qoura, Farah,Langner, Clemens,Bourenkov, Gleb,Garbe, Daniel,Loll, Bernhard,Brück, Thomas
, p. 110 - 118 (2015)
Isobutanol is deemed to be a next-generation biofuel and a renewable platform chemical.[1] Non-natural biosynthetic pathways for isobutanol production have been implemented in cell-based and in vitro systems with Bacillus subtilis acetolactate synthase (AlsS) as key biocatalyst.[2-6] AlsS catalyzes the condensation of two pyruvate molecules to acetolactate with thiamine diphosphate and Mg2+ as cofactors. AlsS also catalyzes the conversion of 2-ketoisovalerate into isobutyraldehyde, the immediate precursor of isobutanol. Our phylogenetic analysis suggests that the ALS enzyme family forms a distinct subgroup of ThDP-dependent enzymes. To unravel catalytically relevant structure-function relationships, we solved the AlsS crystal structure at 2.3 ? in the presence of ThDP, Mg2+ in a transition state with a 2-lactyl moiety bound to ThDP. We supplemented our structural data by point mutations in the active site to identify catalytically important residues.
ALDEHYDE GENERATION VIA ALKENE HYDROFORMYLATION
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Paragraph 0083; 0084, (2021/09/26)
Aldehyde generation includes providing a first input stream, a second input, and an alkene substrate to a reactor system. The first input stream includes a catalyst, a ligand, and an organic solvent. The second input stream includes a mixture of carbon monoxide (CO) and hydrogen gas (H2). The alkene substrate is in either gaseous form or liquid form, the liquid form of the alkene substrate being provided with the first input stream, the gaseous form of the alkene substrate being provided with the second input stream. The reactor system includes a first reactor and a second reactor, where the second reactor is gas permeable and positioned within the first reactor.
Chemo- And regioselective hydroformylation of alkenes with CO2/H2over a bifunctional catalyst
Hua, Kaimin,Liu, Xiaofang,Wei, Baiyin,Shao, Zilong,Deng, Yuchao,Zhong, Liangshu,Wang, Hui,Sun, Yuhan
supporting information, p. 8040 - 8046 (2021/11/01)
As is well known, CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Combining CO2 and H2 to prepare building blocks for high-value-added products is an attractive yet challenging topic in green chemistry. A general and selective rhodium-catalyzed hydroformylation of alkenes using CO2/H2 as a syngas surrogate is described here. With this protocol, the desired aldehydes can be obtained in up to 97% yield with 93/7 regioselectivity under mild reaction conditions (25 bar and 80 °C). The key to success is the use of a bifunctional Rh/PTA catalyst (PTA: 1,3,5-triaza-7-phosphaadamantane), which facilitates both CO2 hydrogenation and hydroformylation. Notably, monodentate PTA exhibited better activity and regioselectivity than common bidentate ligands, which might be ascribed to its built-in basic site and tris-chelated mode. Mechanistic studies indicate that the transformation proceeds through cascade steps, involving free HCOOH production through CO2 hydrogenation, fast release of CO, and rhodium-catalyzed conventional hydroformylation. Moreover, the unconventional hydroformylation pathway, in which HCOOAc acts as a direct C1 source, has also been proved to be feasible with superior regioselectivity to that of the CO pathway.
SYSTEMS AND METHODS FOR REGIOSELECTIVE CARBONYLATION OF 2,2-DISUBSTITUTED EPOXIDES FOR THE PRODUCTION OF ALPHA,ALPHA-DISUBSTITUTED BETA-LACTONES
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Paragraph 0082, (2021/01/29)
Provided are methods of producing carbonyl compounds (e.g., carbonyl containing compounds) and catalysts for producing carbonyl compounds. Also provided are methods of making polymers from carbonyl compounds and polymers formed from carbonyl compounds. A method may produce carbonyl compounds, such as, for example α,α-disubstituted carbonyl compounds (e.g., α,α-disubstituted β-lactones). The polymers may be produced from α,α-disubstituted β-lactones, which may be produced by a method described herein.