固体超强酸催化合成苯乙酸月桂醇酯

以固体超强酸SO42-/TiO2为催化剂,以苯乙酸和月桂醇为原料,直接合成苯乙酸月桂醇酯,研究探讨了原料摩尔比、反应时间、催化剂用量等工艺条件对苯乙酸月桂醇酯收率的影响。结果表明,最佳反应条件为:醇酸摩尔比3.0∶1,催化剂用量5%,反应时间3h,酯化率可达90.8%。     

Insight into the Mechanism of Phenylacetate Decarboxylase (PhdB), a Toluene-Producing Glycyl Radical Enzyme

We recently reported the discovery of phenylacetate decarboxylase (PhdB), representing one of only ten glycyl-radical-enzyme reaction types known, and a promising biotechnological tool for first-time biochemical synthesis of toluene from renewable resources. Here, we used experimental and computational data to evaluate the plausibility of three candidate PhdB mechanisms, involving either attack at the phenylacetate methylene carbon or carboxyl group [via H-atom abstraction from COOH or single-electron oxidation of COO⁻ (Kolbe-type decarboxylation)]. In vitro experimental data included assays with F-labeled phenylacetate, kinetic studies, and tests with site-directed PhdB mutants; computational data involved estimation of reaction energetics using density functional theory (DFT). The DFT results indicated that all three mechanisms are thermodynamically challenging (beyond the range of many known enzymes in terms of endergonicity or activation energy barrier), reflecting the formidable demands on PhdB for catalysis of this reaction. Evidence that PhdB was able to bind α,α-difluorophenylacetate but was unable to catalyze its decarboxylation supported the enzyme's abstraction of a methylene H atom. Diminished activity of H327A and Y691F mutants was consistent with proposed proton donor roles for His327 and Tyr691. Collectively, these and other data most strongly support PhdB attack at the methylene carbon.     

利可君合成工艺的改进

目的改进利可君合成工艺。方法以胱氨酸、苯乙酸乙酯和甲酸乙酯为原料,以还原铁粉为催化剂合成L-半胱氨酸盐酸盐,以石油醚为溶剂在超声条件下合成α-甲酰基苯乙酸乙酯,两者以乙醇为溶剂环合反应制备利可君。结果 L-半胱氨酸盐酸盐收率99.51%,c-甲酰基苯乙酸乙酯反应时间4h,收率92.6%,利可君合成总收率75.3%。结论以胱氨酸为原料降低了合成成本,超声条件下合成α-甲酰基苯乙酸乙酯缩短了生产周期,收率提高9.2%,利可君总收率比化统工艺提高了22.5%～27.2%,以乙醇为溶剂环合,生产更安全环保。     

微波辐射相转移催化合成丙酸苄酯

以三氧化二铝担载羧酸钾 ,以四丁基溴化铵 (TBAB)为相转移催化剂 ,采用微波辐射干反应技术 ,丙酸钾和氯苄直接酯化合成丙酸苄酯 ,最佳反应条件为 :羧酸钾 0 1mol,氯代烷 0 1 2mol,TBAB1 5mmol,微波功率 40 0W ,微波辐射时间 3 2min ,产率 92 %。利用上述条件合成了丁酸苄酯、苯乙酸苄酯、丙酸辛酯和丁酸辛酯 ,产率为 87%～ 90 %。     

Selective hydrogenation of ethyl phenylacetate to 2-phenylethanol: a convenient catalyst preparation method

A ruthenium-tin-alumina catalyst, prepared by a combination of kneading and impregnation methods, which we have named the combination method, was able to selectively hydrogenate ethyl phenylacetate to 2-phenylethanol; tin oxide was used as a chloride-free tin source. For this combination catalyst, the optimum atomic ratio for Ru: Sn was found to be 1 4. X-ray diffraction measurements showed the presence of tin particles. It appeared that the number of the tin particles had a large effect on the hydrogenation of C=O groups. However, the catalyst prepared with ruthenium oxide had a low activity, possibly owing to the ruthenium metal or ruthenium-tin alloy, which was formed and which obstructed the reaction.     

Consumer rejection threshold of ethyl phenylacetate and phenylacetic acid,compounds responsible for the sweet‐like off odour in wines made from sour rotten grapes

Backgrounds and Aims: This study aimed to determine a consumer rejection threshold (CRT) for ethyl phenylacetate (EPhA) and phenylacetic acid (PhAA) in wine. These compounds have recently been reported to be responsible for sweet‐like, honey off odours in wine made from sour rotten grapes. Methods and Results: Non‐expert wine consumers (n = 35) received pairs of samples comprising a control wine against a spiked wine with an ascending concentration of the target compounds and were asked to indicate which sample they preferred. Results estimated a conjoint CRT for EPhA and PhAA of 140 and 700 µg/L, respectively. Wines spiked with a EPhA and PhAA concentration around the CRT evoked intense ‘dried fruit’ aromas that led to a decrease of the general aroma quality; these wines are significantly rejected by consumers. Conclusions: The measured CRT provides an initial estimation of the risk concentration for EPhA and PhAA in red wine, as they represent a ‘taint’ for regular wine consumers. Significance of the Study: These data allow wine producers to predict if a given wine will be disliked by consumers or to help guide ‘blending away’ of such wines.     

苯乙酸乙酯的合成方法研究

提出了通过双酯化工艺提高苯乙酸酯化生产苯乙酸乙酯产率的生产方法     

新型固体超强酸催化合成苯乙酸乙酯

以稀土固体超强酸SO4^2-/ZrO2/La^3 为催化剂，苯乙酸和乙醇为原料合成苯乙酸乙酯，考察了影响反应的因素。如果表明：n(醇）：n(酸）＝3.5:1.0，催化剂用量为1.0g(苯乙酸为0.05mol的情况下）；反应时间为4.5h是最适宜的反应条件。酯化率达90.0%。     

利可君合成工艺的改进

目的改进利可君合成工艺。方法以胱氨酸、苯乙酸乙酯和甲酸乙酯为原料,以还原铁粉为催化剂合成L-半胱氨酸盐酸盐,以石油醚为溶剂在超声条件下合成α-甲酰基苯乙酸乙酯,两者以乙醇为溶剂环合反应制备利可君。结果L-半胱氨酸盐酸盐收率99．51％,α-甲酰基苯乙酸乙酯反应时间4h,收率92．6％,利可君合成总收率75．3％。结论以胱氨酸为原料降低了合成成本,超声条件下合成α-甲酰基苯乙酸乙酯缩短了生产周期,收率提高9．2％,利可君总收率比传统工艺提高了22．5％～27．2％,以乙醇为溶剂环合,生产更安全环保。     

高温高压水中乙酸苯酯无催化水解反应动力学

测定了乙酸苯酯在高温高压水中(压力15MPa,温度152-216℃)的水解反应动力学数据。结果表明在无任何外加催化剂的情况下,乙酸苯酯能够顺利进行水解反应。随温度升高,反应速率迅速增大,选择性从不足50％提高到80％以上。拟合得到反应活化能为67．77kJ/mol。