期刊文献+
共找到4篇文章
< 1 >
每页显示 20 50 100
Uncatalyzed Condensation Reactions between Aromatic Aldehydes and Thiobarbituric Acid in Water
1
作者 Bing Qin YANG Jun LU Min TIAN 《Chinese Chemical Letters》 SCIE CAS CSCD 2003年第12期1239-1241,共3页
A series of 5-arylidene thiobarbituric acids were prepared from aromatic aldehydes and thiobarbituric acid in water without catalyst conditions in good yields. The structures were characterized by elemental analysis,... A series of 5-arylidene thiobarbituric acids were prepared from aromatic aldehydes and thiobarbituric acid in water without catalyst conditions in good yields. The structures were characterized by elemental analysis, IR and 1H NMR spectra. 展开更多
关键词 Arylidene thiobarbituric acid uncatalyzed reaction environmentally benign synthesis.
下载PDF
Kinetic Determination of Uric Acid in Human Serum by Using the Uncatalyzed BZ Reaction in Non-equilibrium Steady State
2
作者 Ren,Jie Yang,Wu +1 位作者 Niu,Xiuli Gao,Jinzhang 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2012年第2期288-292,共5页
A novel kinetic method for determination of uric acid in human serum by means of an uncatalyzed BZ system consisting of potassium bromate and p-hydroxybenzaldehyde (p-HBA) in sulfuric acid medium was proposed, in wh... A novel kinetic method for determination of uric acid in human serum by means of an uncatalyzed BZ system consisting of potassium bromate and p-hydroxybenzaldehyde (p-HBA) in sulfuric acid medium was proposed, in which the analyte perturbation to the system was recorded close to the bifurcation point. The potential change was directly proportional to the logarithm of concentration of uric acid in the range of 3.73 × 10 8--7.48 × 10-4 mol.L-1 (r=0.9983) with a detection limit of 7.45 × 10-9mol.L-I and a recovery from 98.9% to 101.1%. A comparison between the proposed technique and other methods indicated that results obtained were in agreement with those in clinical detection. In addition, the possible mechanism of action of uric acid on the uncatalyzed BZ reaction was also discussed briefly. 展开更多
关键词 non-equilibrium steady state uric acid uncatalyzed BZ reaction
原文传递
An efficient and mild protocol for the synthesis of unsymmetrical ureas in the absence of catalyst and additives 被引量:2
3
作者 Rahman Hosseinzadeh Yaghoub Sarrafi Nora Aghili 《Chinese Chemical Letters》 SCIE CAS CSCD 2010年第10期1171-1174,共4页
A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in... A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in refluxing dioxane and does not require any catalyst or additives. 展开更多
关键词 Unsymmetrical ureas PHENYLUREA AMINES uncatalyzed reaction
下载PDF
Aminolysis of 1-(1-Hydroxybenzotriazolyl)-2,4-dinitrobenzene and 2-(1-Hydroxybenzotriazolyl)-5-nitropyridine
4
作者 Sherine N. Khattab Mohamed A. H. Kharaba +2 位作者 Amal El-Hawary Ayman El-Faham Ezzat A. Hamed 《Open Journal of Physical Chemistry》 2012年第3期156-168,共13页
The reaction 1-(1-hydroxybenzotriazolyl)-2,4-dinitrobenzene 1 and 2-(1-hydroxybenzotriazolyl)-5-nitro-pyridine 2 with amines undergoes amination followed by elimination of the 1-hydroxyl benzotriazolyl anion. The kine... The reaction 1-(1-hydroxybenzotriazolyl)-2,4-dinitrobenzene 1 and 2-(1-hydroxybenzotriazolyl)-5-nitro-pyridine 2 with amines undergoes amination followed by elimination of the 1-hydroxyl benzotriazolyl anion. The kinetic data for the reaction of 1 and 2 with Mo, CHA and An in MeOH and AN proceeded by uncatalysed mechanism in which the rate limiting step is the leaving group departure, whereas the reaction with Mo in toluene proceeded by uncatalysed mechanism in which the formation of the zwitterionic intermediate is the rate determining step. While the reactions of 1 with CHA and An and the reaction of 2 with CHA in toluene proceeded by SB mechanism in which the rate determining step is the proton transfer process. The reactions of 1 and 2 with Mo in the three solvents and with CHA and An in MeOH and AN is greatly depended on the stability of the zwitterionic intermediate. The effect of ring activation is due to the ground state stabilization and the more efficient delocalization of the negative charge with a nitro group than with a ring-nitrogen in the transition state. The low activation enthalpies ΔH# and the highly negative activation entropies ΔS# are due to the intramolecular hydrogen bonding with the ammonio hydrogen present in the transition state. 展开更多
关键词 NUCLEOPHILIC Aromatic Substitution Reactions Kinetic Measurements 1-Hydroxybenzotriazole Solvent Effect MORPHOLINE CYCLOHEXYLAMINE and ANILINE uncatalyzed and Specific Base Catalyzed Mechanisms
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部