The synthesis of anti-radiation active organic phosphorus compounds is an important field in search of radioprotectors.In order to develop new protectors of low toxicity and high potency, more than thirty phosphorus c...The synthesis of anti-radiation active organic phosphorus compounds is an important field in search of radioprotectors.In order to develop new protectors of low toxicity and high potency, more than thirty phosphorus compounds such as dialkylphosphorocyanidates(1), tetraalkylmonothiopyrophosphates(2), N-substituted dialkylphosphoramidates(3) and aminoalkylthiophosphates (4)have been designed and synthesized.展开更多
A novel environmentally benign process for the synthesis of methyl N-phenyl carbamate (MPC) from methanol and phenylurea was studied. Effect of solvent and catalyst on the reaction behavior was investigated. The IR s...A novel environmentally benign process for the synthesis of methyl N-phenyl carbamate (MPC) from methanol and phenylurea was studied. Effect of solvent and catalyst on the reaction behavior was investigated. The IR spectra of methanol and phenylurea dissolved in different solvents were also recorded. Compared with use of methanol as both a reactant and a solvent, phenylurea conversion and selectivity to MPC increased by using toluene, benzene or anisole as a solvent, while phenylurea conversion decreased slightly by using n-octane as a solvent. The phenylurea conversion declined nearly 50% when dimethyl sulfoxide (DMSO) was used as a reaction media, and MPC selec- tivity decreased as well. The catalytic reaction tests showed that a basic catalyst enhanced the selectivity to MPC while an acidic catalyst promoted the formation of methyl carbamate and aniline. Moderate degree of basicity showed the best catalytic performance in the cases studied.展开更多
A sequential one-pot synthesis of N-sulfonylcyclothioureas from N-monosulfonyl diamines, CS2 and chloroace- tic acid at room temperature in water is described. In the absence of highly toxic thiophosgene and organic s...A sequential one-pot synthesis of N-sulfonylcyclothioureas from N-monosulfonyl diamines, CS2 and chloroace- tic acid at room temperature in water is described. In the absence of highly toxic thiophosgene and organic solvents, this method is environmentally benign. Simple reaction conditions, easy purification of the products, good yields and thioglycolic acid as the useful byproduct are also important attributes of this methodology. The plausible mechanism including tandem reactions is proposed.展开更多
A new route was described to synthesize Arg-Gly-Asp-X（RGDX,X=amino acid） tetrapeptide.To better understand the method,the tetrapeptide Arg-Gly-Asp-CySS（RGDCySS） was chosen as a model target for X.First,GDCySS was ...A new route was described to synthesize Arg-Gly-Asp-X（RGDX,X=amino acid） tetrapeptide.To better understand the method,the tetrapeptide Arg-Gly-Asp-CySS（RGDCySS） was chosen as a model target for X.First,GDCySS was obtained in four steps,comprising the chloroacetylation of L-aspartic acid（ClCH2COAsp）,synthesis of chloroacetyl L-aspartic acid anhydride[ClCH2COAsp（CO）2O],formation of ClCH2COAsp-CySS and ammonolysis of ClCH2COAsp-CySS.Second,preparation of Arg-NCA,which was coupled with GDCySS to synthesize RGDCySS by the NCA method（Leuchs＇ anhydrides method,NCA：N-carboxy-a-amino acid anhydride）.The purity of the product was analyzed by the high performance liquid chromatography（HPLC）.Molecular weights of the peptide products were confirmed by mass spectroscopy.In the developed approach,less protected amino acids were used compared to conventional solid-phase synthesis.The new route offers advantages of low cost,simplicity and rapid synthesis with a reasonable yield of 63.0％（calculated according to arginine content）.展开更多
The growth of crystals of the high T c oxide superconductors has been hampe red by the complexities of the materials and their phase diagrams.The most common crys tal growth technique adopted for these oxides is the ...The growth of crystals of the high T c oxide superconductors has been hampe red by the complexities of the materials and their phase diagrams.The most common crys tal growth technique adopted for these oxides is the “flux”method,where the st arting materials are solved in a melt,which is usually formed by excess CuO and BaO or a KCl/NaCl mixture.The crystals are produced by slow cooling of the heate d solvent.This method,however,suffers from several disadvantages: (1) the crystals are contaminated with the crucible material, (2) the crystals are difficult to remove from the crucible, (3) the crystals contain flux inclusions.展开更多
文摘The synthesis of anti-radiation active organic phosphorus compounds is an important field in search of radioprotectors.In order to develop new protectors of low toxicity and high potency, more than thirty phosphorus compounds such as dialkylphosphorocyanidates(1), tetraalkylmonothiopyrophosphates(2), N-substituted dialkylphosphoramidates(3) and aminoalkylthiophosphates (4)have been designed and synthesized.
基金Project supported by the Science and Technology Ministry of China (No. 2001CCA02700).
文摘A novel environmentally benign process for the synthesis of methyl N-phenyl carbamate (MPC) from methanol and phenylurea was studied. Effect of solvent and catalyst on the reaction behavior was investigated. The IR spectra of methanol and phenylurea dissolved in different solvents were also recorded. Compared with use of methanol as both a reactant and a solvent, phenylurea conversion and selectivity to MPC increased by using toluene, benzene or anisole as a solvent, while phenylurea conversion decreased slightly by using n-octane as a solvent. The phenylurea conversion declined nearly 50% when dimethyl sulfoxide (DMSO) was used as a reaction media, and MPC selec- tivity decreased as well. The catalytic reaction tests showed that a basic catalyst enhanced the selectivity to MPC while an acidic catalyst promoted the formation of methyl carbamate and aniline. Moderate degree of basicity showed the best catalytic performance in the cases studied.
基金Project supported by the National Natural Science Foundation of China （No. 20802049）.
文摘A sequential one-pot synthesis of N-sulfonylcyclothioureas from N-monosulfonyl diamines, CS2 and chloroace- tic acid at room temperature in water is described. In the absence of highly toxic thiophosgene and organic solvents, this method is environmentally benign. Simple reaction conditions, easy purification of the products, good yields and thioglycolic acid as the useful byproduct are also important attributes of this methodology. The plausible mechanism including tandem reactions is proposed.
基金Supported by the National Natural Science Foundation of China（No.81271697）, the Science Foundation of Changchun City, China（No.09SF02）, the China Postdoctoral Science Foundation（No.20100481048）, the Specialized Research Fund for the Doctoral Program of Higher Education of China（No.20100061120077） and the Social Development Project of Science and Tech- nology Department of Jilin Province, China（Nos.20106031, 20120967, YYZX2012）.
文摘A new route was described to synthesize Arg-Gly-Asp-X（RGDX,X=amino acid） tetrapeptide.To better understand the method,the tetrapeptide Arg-Gly-Asp-CySS（RGDCySS） was chosen as a model target for X.First,GDCySS was obtained in four steps,comprising the chloroacetylation of L-aspartic acid（ClCH2COAsp）,synthesis of chloroacetyl L-aspartic acid anhydride[ClCH2COAsp（CO）2O],formation of ClCH2COAsp-CySS and ammonolysis of ClCH2COAsp-CySS.Second,preparation of Arg-NCA,which was coupled with GDCySS to synthesize RGDCySS by the NCA method（Leuchs＇ anhydrides method,NCA：N-carboxy-a-amino acid anhydride）.The purity of the product was analyzed by the high performance liquid chromatography（HPLC）.Molecular weights of the peptide products were confirmed by mass spectroscopy.In the developed approach,less protected amino acids were used compared to conventional solid-phase synthesis.The new route offers advantages of low cost,simplicity and rapid synthesis with a reasonable yield of 63.0％（calculated according to arginine content）.
文摘The growth of crystals of the high T c oxide superconductors has been hampe red by the complexities of the materials and their phase diagrams.The most common crys tal growth technique adopted for these oxides is the “flux”method,where the st arting materials are solved in a melt,which is usually formed by excess CuO and BaO or a KCl/NaCl mixture.The crystals are produced by slow cooling of the heate d solvent.This method,however,suffers from several disadvantages: (1) the crystals are contaminated with the crucible material, (2) the crystals are difficult to remove from the crucible, (3) the crystals contain flux inclusions.
