共查询到19条相似文献,搜索用时 46 毫秒
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以易制备和无气味的3-(二乙硫/苄硫基)亚甲基-2,4-戊二酮1作乙硫醇和苄硫醇替代试剂,进行了环保和无气味的β-羰基硫醚的合成研究。在甲醇介质中,氯化乙酰存在下,1发生分解反应,释放出乙硫醇或苄硫醇,然后与α,β-不饱和酮2进行硫杂迈克尔加成反应,高产率生成β-羰基硫醚,反应过程无恶臭气味。 相似文献
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本文研究了硫酸铝催化柠檬醛和1,2-丙二醇的缩醛化反应,考察醇酸用量比、催化剂用量、反应温度及时间对反应结果的影响。当柠檬醛和1,2-丙二醇用量均为0.10mol,A12(SO4)5.18H2O10g/mol,加入18ml环已烷,在94~102℃温度范围内回流分水2.5h,获得缩醛的产率可为85.5%,且使用该催化剂具有易分离、操作简单、产品质量好的特点。 相似文献
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以乙缩醛 ( 0 .75mol)和正丁硫醇 ( 0 .5mol)为原料 ,溴化镁 ( 73g)为一次性催化剂 ,在乙醚( 1 0 0mL)中 ,室温条件下反应 32h ,经红外光谱、色谱、质谱、元素分析以及核磁共振谱检测 ,确证了产物为乙醛正丁硫醇缩硫醛 ,粗产率为 68%。用硅胶作柱层析固定相 ,V(四氯化碳 )∶V(二氯甲烷 ) =1 0∶1作为展开剂和洗脱剂提纯产品 ,质量分数为 95%。 相似文献
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合成缩醛(酮)的催化剂研究进展 总被引:1,自引:1,他引:0
综述了固体超强酸、杂多酸、固载杂多酸、脱铝超稳沸石、树脂、分子筛、铌酸、漆酚衍生物、维生素C、碘、硫酸盐、氯化物、蒙脱土等40多种催化剂催化合成缩醛(酮)的方法和反应条件。评述了各类催化剂的催化性能、特点、能否重复使用等内容。结果表明:固体超强酸、固载杂多酸、HY型分子筛、脱铝超稳沸石、硫酸铜、高分子载体氯化物等几种环境友好催化剂是合成缩醛(酮)的优良催化剂。 相似文献
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SuryaKanta De 《Advanced Synthesis \u0026amp; Catalysis》2005,347(5):673-676
A variety of carbonyl compounds can be easily and rapidly converted to the corresponding cyclic and acylic dithioacetals in the presence of a catalytic amount of ruthenium chloride in acetonitrile at room temperature. Some of the major advantages of this protocol are high chemoselectivity, operational simplicity, very short reaction times, high yields, and also compatibility with other protecting groups. 相似文献
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Olivier Diebolt Clment Cruzeuil Christian Müller Dieter Vogt 《Advanced Synthesis \u0026amp; Catalysis》2012,354(4):670-677
Hydroformylation of terminal alkenes in alcohol solvents leads to the selective formation of the corresponding acetals. The Xantphos ligand gave the best results as well as acetal selectivities higher than 99% and linear/branched ratios of up to 52 were obtained. The scope of the reaction was studied. Acetals were found to be unreactive under hydroaminomethylation conditions. 相似文献
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Naoki Komatsu Azusa Taniguchi Shinobu Wada Hitomi Suzuki 《Advanced Synthesis \u0026amp; Catalysis》2001,343(5):473-480
S,S‐Acetals are smoothly deprotected with air in the presence of a catalytic amount of Bi(NO3)3⋅5 H2O (1–50 mol %) under ambient conditions to regenerate the original carbonyl compounds in good to excellent yield. This mild, simple, and environmentally benign system is successfully applied to the deprotection of S,O‐ and O,O‐acetals and is compatible with various functional groups. From the mechanistic study of the reaction, the catalytic cycle is considered to be composed of the following four steps: (1) the nitrososulfonium ion of the S,S‐acetal is formed by attack of nitrosonium ion (NO +) generated from Bi(NO3)3⋅5 H2O through the equilibrium with NO2, (2) the nitrososulfonium ion is hydrolyzed to afford the hemithioacetal and thionitrite, (3) the hemithioacetal collapses to the original carbonyl compound and thiol, which is oxidized by NO + to give disulfide and NO via thionitrite, and (4) the NO captures molecular oxygen from air to regenerate NO2. 相似文献
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Moran Zhang Yunxia Wang Yang Yang Xiangdong Hu 《Advanced Synthesis \u0026amp; Catalysis》2012,354(6):981-985
A mild and catalyzed alternative to the direct aldol reaction has been developed based on the gold‐catalyzed methoxy group transfer from dimethyl acetals to terminal alkynes. Due to the simultaneous activation of the acetals, this aldol approach is only functional for acetals but not aldehydes. A ligand effect from the gold complex has also been observed. 相似文献
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Bastien Doumche Alain Archelas Roland Furstoss 《Advanced Synthesis \u0026amp; Catalysis》2006,348(14):1948-1957
The hydrolytic kinetic resolution of five glycidaldehyde acetal derivatives was examined using the recombinant Aspergillus niger epoxide hydrolase as biocatalyst. This could successfully be performed, at room temperature, using solely demineralised water as solvent and following a two‐phase methodology allowing us to operate at a global substrate concentration as high as 200 g/L in the reactor. The observed E values were shown to be modest to excellent, depending on the structure of the acetal moiety, indicating that it is possible to achieve this resolution very efficiently just by choosing the right substituents. Both the unreacted (R)‐epoxide and the formed (S)‐diol could thus be obtained in good to excellent ee (ee>99 % for the epoxide). For the best substrates, the reaction could be performed within a few hours by using a biocatalyst over substrate molecular ratio of about 9 to 10×10−4 mol %. The turnover frequency (TOF) as well as the total turnover number (TON) of the enzyme proved to be excellent as compared to chemical catalysts – reaching respectively values in the order of 6×102 mol sub/mol enz/min and 6×104 mol sub/mol enz. The space‐time yield of the best (two‐phase) reactor could thus reach a value as high as 56 g/L/hour. As a demonstration experiment, a 50‐g scale resolution of glycidaldehyde 2,2‐dimethyltrimethylene acetal was performed. 相似文献