The present work contributed to a new developed production method for enhancing the quality of isoamylene (IA) by adding a small amount of tertiary amyl alcohol (TAA) to the catalyst of strong acid cation exchange res...The present work contributed to a new developed production method for enhancing the quality of isoamylene (IA) by adding a small amount of tertiary amyl alcohol (TAA) to the catalyst of strong acid cation exchange resin.TAA improved the selectivity of 2-methyl-2-butene (2M2B) at a high conversion level for the isomerization of IA.Compared with the other results from the current IA units,the conversion of 2-methyl-1-butene (2M1B),the mass ratio of 2M2B to 2M1B and the selectivity of 2M2B were increased from 0.5474,7.32 and 0.6864 to 0.72,12 and 0.95,respectively,while the dimers content in the products decreased from 4.38% to below 1.0%.Optimized conditions for IA isomerization consisted of temperature between 28 and 33°C and system pressure of 0.5 MPa,weight hourly space velocity of 8.0 h-1 with TAA mass fraction of 0.7%-0.9% in raw material.The results in lab supported bases for the developed process in industrial application which was later proved to be successful.In addition,a possible mechanism of the isomerization process was speculated to propose a key step of water formation in the TAA-added isomerization process and a verified experiment was conducted to support this speculation.展开更多
A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino a...A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%（molar fraction）, an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc.展开更多
We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanos...We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanosilylation of racemic ketones is developed using our bifunctional cyanating reagent,Me_(2)(CH_(2)Cl)SiCN,giving C^(α)-tetrasubstituted silyl cyanohydrins withtwovicinal stereocenters inupto>20:1 diastereomeric ratio(dr)and 90-98% enantiomeric excess(ee)values,which can undergo various diversification reactions bymanipulating the chloromethyl group.A highly selective kinetic resolution of acyclicα-branched ketones is also developed that allows facile access to acyclic α-alkyl,allyl,and propargyl ketones with good recovery and excellent ee values.The synthetic value of this protocol is further demonstrated by the formal synthesis of the anti-obesity agent,taranabant(MK-0364).The activation of Jacobsen’s privileged catalyst(salen)AlCl by a suitable phosphorane plays a crucial role in the reaction.X-ray crystallographic analysis of single crystals of phosphorane-(salen)AlCl complexes and theoretical calculations help provide a working model.The present transformation opens a new path for the catalytic stereoselective synthesis of stereochemically complex tertiary alcohols featuring two stereocenters(adjacent or not)from racemic ketones.展开更多
Exceedingly fast preparation of trifluoromethyl tertiary alcohols has been accomplished from methyl ketones and trifluoromethyl ketones under solvent free conditions by cross Aldol reaction. The reaction was achieved ...Exceedingly fast preparation of trifluoromethyl tertiary alcohols has been accomplished from methyl ketones and trifluoromethyl ketones under solvent free conditions by cross Aldol reaction. The reaction was achieved in the presence of common inorganic base by grinding method at ambient temperature to give b-trifluoromethyl-b-hydroxyl ketones in high yields（up to 95%）.展开更多
以脂肪醇、环氧乙烷、氯化亚砜和亚硫酸钾等为原料,依次通过阴离子聚合、氯代、磺化等反应合成了脂肪醇聚氧乙烯醚磺酸盐（AESO）。通过IR,13 C NMR,ESI-MS等手段对产物进行了结构表征。利用单因素法对各步反应的工艺条件进行了优化。...以脂肪醇、环氧乙烷、氯化亚砜和亚硫酸钾等为原料,依次通过阴离子聚合、氯代、磺化等反应合成了脂肪醇聚氧乙烯醚磺酸盐（AESO）。通过IR,13 C NMR,ESI-MS等手段对产物进行了结构表征。利用单因素法对各步反应的工艺条件进行了优化。各步反应的最佳条件为：阴离子聚合反应中,采用环氧乙烷间断式进样法,n（脂肪醇）∶n（环氧乙烷）=1∶4,催化剂氢氧化钠的用量为脂肪醇质量的0.1%,反应温度为115~125℃,反应压力为0.4 MPa,收率为44.2%;氯代反应中,以吡啶为催化剂,氯化亚砜为氯代剂,n（脂肪醇聚氧乙烯醚）∶n（氯化亚砜）∶n（吡啶）=1∶1.6∶0.8,70℃反应10h,收率为92.4%;磺化反应中,以水为溶剂,正己醇为稀释剂,质量均为氯代物质量的20%,亚硫酸钾为磺化剂,n（亚硫酸钾）∶n（氯代物）=1.5∶1,反应压力为1.0 MPa,155℃反应6h,经两相滴定法测得收率为91.3%。展开更多
文摘The present work contributed to a new developed production method for enhancing the quality of isoamylene (IA) by adding a small amount of tertiary amyl alcohol (TAA) to the catalyst of strong acid cation exchange resin.TAA improved the selectivity of 2-methyl-2-butene (2M2B) at a high conversion level for the isomerization of IA.Compared with the other results from the current IA units,the conversion of 2-methyl-1-butene (2M1B),the mass ratio of 2M2B to 2M1B and the selectivity of 2M2B were increased from 0.5474,7.32 and 0.6864 to 0.72,12 and 0.95,respectively,while the dimers content in the products decreased from 4.38% to below 1.0%.Optimized conditions for IA isomerization consisted of temperature between 28 and 33°C and system pressure of 0.5 MPa,weight hourly space velocity of 8.0 h-1 with TAA mass fraction of 0.7%-0.9% in raw material.The results in lab supported bases for the developed process in industrial application which was later proved to be successful.In addition,a possible mechanism of the isomerization process was speculated to propose a key step of water formation in the TAA-added isomerization process and a verified experiment was conducted to support this speculation.
基金the National Natural Science Foundation of China(Nos.20472026 and 20525206)Chang Jiang Scholar Program of the Ministry of Education, China.
文摘A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%（molar fraction）, an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc.
基金supported by the National Natural Science Foundation of China(grant no.21725203)the Ministry of Education(PCSIRT)The Fundamental Research Funds for the Central Universities is highly appreciated.
文摘We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanosilylation of racemic ketones is developed using our bifunctional cyanating reagent,Me_(2)(CH_(2)Cl)SiCN,giving C^(α)-tetrasubstituted silyl cyanohydrins withtwovicinal stereocenters inupto>20:1 diastereomeric ratio(dr)and 90-98% enantiomeric excess(ee)values,which can undergo various diversification reactions bymanipulating the chloromethyl group.A highly selective kinetic resolution of acyclicα-branched ketones is also developed that allows facile access to acyclic α-alkyl,allyl,and propargyl ketones with good recovery and excellent ee values.The synthetic value of this protocol is further demonstrated by the formal synthesis of the anti-obesity agent,taranabant(MK-0364).The activation of Jacobsen’s privileged catalyst(salen)AlCl by a suitable phosphorane plays a crucial role in the reaction.X-ray crystallographic analysis of single crystals of phosphorane-(salen)AlCl complexes and theoretical calculations help provide a working model.The present transformation opens a new path for the catalytic stereoselective synthesis of stereochemically complex tertiary alcohols featuring two stereocenters(adjacent or not)from racemic ketones.
基金financial support from the National Natural Science Foundation of China(No.21262031)Bioactive Product Engineering Research Center for Gansu Distinctive PlantsState Key Laboratory of Applied Organic Chemistry,Lanzhou University
文摘Exceedingly fast preparation of trifluoromethyl tertiary alcohols has been accomplished from methyl ketones and trifluoromethyl ketones under solvent free conditions by cross Aldol reaction. The reaction was achieved in the presence of common inorganic base by grinding method at ambient temperature to give b-trifluoromethyl-b-hydroxyl ketones in high yields（up to 95%）.
文摘以脂肪醇、环氧乙烷、氯化亚砜和亚硫酸钾等为原料,依次通过阴离子聚合、氯代、磺化等反应合成了脂肪醇聚氧乙烯醚磺酸盐（AESO）。通过IR,13 C NMR,ESI-MS等手段对产物进行了结构表征。利用单因素法对各步反应的工艺条件进行了优化。各步反应的最佳条件为：阴离子聚合反应中,采用环氧乙烷间断式进样法,n（脂肪醇）∶n（环氧乙烷）=1∶4,催化剂氢氧化钠的用量为脂肪醇质量的0.1%,反应温度为115~125℃,反应压力为0.4 MPa,收率为44.2%;氯代反应中,以吡啶为催化剂,氯化亚砜为氯代剂,n（脂肪醇聚氧乙烯醚）∶n（氯化亚砜）∶n（吡啶）=1∶1.6∶0.8,70℃反应10h,收率为92.4%;磺化反应中,以水为溶剂,正己醇为稀释剂,质量均为氯代物质量的20%,亚硫酸钾为磺化剂,n（亚硫酸钾）∶n（氯代物）=1.5∶1,反应压力为1.0 MPa,155℃反应6h,经两相滴定法测得收率为91.3%。
