研究了在L-组氨酸类手性咪唑离子液体催化下,乙醛酸乙酯与异丁醛的羟醛缩合反应。系统考察了反应时间、催化剂用量及催化剂重复使用等因素对反应的影响,优化了反应条件。以43.1%的收率得到光学效率值为45%的(R)-3,3-二甲基-2-羟基-4-氧...研究了在L-组氨酸类手性咪唑离子液体催化下,乙醛酸乙酯与异丁醛的羟醛缩合反应。系统考察了反应时间、催化剂用量及催化剂重复使用等因素对反应的影响,优化了反应条件。以43.1%的收率得到光学效率值为45%的(R)-3,3-二甲基-2-羟基-4-氧代丁酸乙酯,其缩合产物及催化剂结构由1 H NMR确定。展开更多
It is one of the most attractive types of asymmetric synthesis that chiral commpounts are generated under the influence of chiral catalysts. In recent years catalytic asymmetric Michael addition by chiral metal comple...It is one of the most attractive types of asymmetric synthesis that chiral commpounts are generated under the influence of chiral catalysts. In recent years catalytic asymmetric Michael addition by chiral metal complexes has been recognized as an efficient method for obtaining asymmetric products. In this work we reported that using potassium thiazolidine -2-thione-4-carboxylate [(R)-TTCA·K] as the chiral catalyst, the addition reaction of cyclohexanone with acrylonitrile was carried out and optically active (S)-(+)-2-cyanoethyl cyclohexanone 1 ([α] 20 D=+2.8°, e.e. 19%) and hydrolysis product of 1, (S)-(-)-2-oxocyclohexanepropionic acid 2 ([α] 20 D=-2.95°, e.e. 19%), were obtained. Enantiomeric excess of compound 1 was determined by resolution of (R,S)-2-oxocyclohexanepropionic acid with (-)-quinine. Compounds 1 and 2 were easily racemized at a long time for laying aside and in the presence of dil H 2SO 4 or dil base. When (S)-(+)-2-cyanoethyl cyclohexanone reacts with ethylene glycol in the presence of toluene sulfonic acid as the catalyst the racemic 2-ethylendioxy cyclohexyl propionitrile was obtained. The mechanism of the reaction of cyclohexanone with acrylonitrile would be a complicated catalysis process.展开更多
Trimethylolundecane is synthesized from lauric aldehyde and formaldehyde,using sodium hydroxide as catalyst.The structure of synthesized product,trimethylolundecane,is characterized with 13C Nuclear Magnetic Resonance...Trimethylolundecane is synthesized from lauric aldehyde and formaldehyde,using sodium hydroxide as catalyst.The structure of synthesized product,trimethylolundecane,is characterized with 13C Nuclear Magnetic Resonance(NMR).The effects of reactant ratio,catalyst amount,reaction time and reaction temperature on the yield of trimethylolundecane are investigated.The synthetic conditions are optimized as follow:molar ratio of formaldehyde to lauric aldehyde is 6.5,molar ratio of sodium hydroxide to acetaldehyde is 1.25,the first step of reaction temperature is 45℃ with reaction time 240 min,and the second step of reaction temperature is 55℃ with reaction time 90 min.The optimized processes result in the yield of 86.12% for trimethylolundecane.展开更多
文摘研究了在L-组氨酸类手性咪唑离子液体催化下,乙醛酸乙酯与异丁醛的羟醛缩合反应。系统考察了反应时间、催化剂用量及催化剂重复使用等因素对反应的影响,优化了反应条件。以43.1%的收率得到光学效率值为45%的(R)-3,3-二甲基-2-羟基-4-氧代丁酸乙酯,其缩合产物及催化剂结构由1 H NMR确定。
文摘It is one of the most attractive types of asymmetric synthesis that chiral commpounts are generated under the influence of chiral catalysts. In recent years catalytic asymmetric Michael addition by chiral metal complexes has been recognized as an efficient method for obtaining asymmetric products. In this work we reported that using potassium thiazolidine -2-thione-4-carboxylate [(R)-TTCA·K] as the chiral catalyst, the addition reaction of cyclohexanone with acrylonitrile was carried out and optically active (S)-(+)-2-cyanoethyl cyclohexanone 1 ([α] 20 D=+2.8°, e.e. 19%) and hydrolysis product of 1, (S)-(-)-2-oxocyclohexanepropionic acid 2 ([α] 20 D=-2.95°, e.e. 19%), were obtained. Enantiomeric excess of compound 1 was determined by resolution of (R,S)-2-oxocyclohexanepropionic acid with (-)-quinine. Compounds 1 and 2 were easily racemized at a long time for laying aside and in the presence of dil H 2SO 4 or dil base. When (S)-(+)-2-cyanoethyl cyclohexanone reacts with ethylene glycol in the presence of toluene sulfonic acid as the catalyst the racemic 2-ethylendioxy cyclohexyl propionitrile was obtained. The mechanism of the reaction of cyclohexanone with acrylonitrile would be a complicated catalysis process.
文摘Trimethylolundecane is synthesized from lauric aldehyde and formaldehyde,using sodium hydroxide as catalyst.The structure of synthesized product,trimethylolundecane,is characterized with 13C Nuclear Magnetic Resonance(NMR).The effects of reactant ratio,catalyst amount,reaction time and reaction temperature on the yield of trimethylolundecane are investigated.The synthetic conditions are optimized as follow:molar ratio of formaldehyde to lauric aldehyde is 6.5,molar ratio of sodium hydroxide to acetaldehyde is 1.25,the first step of reaction temperature is 45℃ with reaction time 240 min,and the second step of reaction temperature is 55℃ with reaction time 90 min.The optimized processes result in the yield of 86.12% for trimethylolundecane.
