Desymmetric hydrogenation of a meso-cyclic acid anhydride toward biotin synthesis

Catalytic reactivity in the hydrogenation of a cyclic anhydride to a biotin synthetic intermediate has been investigated on the basis of Lyons’ original method using Wilkinson Ru complex, revealing the high performance of DPPF and XANTPHOS diphosphines possessing wide bite angles. The results have shown a new trail for design of the corresponding asymmetric catalysts, and the potential utility of (S,S)-Et-FerroTANE and (S,S)-(R,R)-Ph-TRAP has been demonstrated.     

Ni-Sn-Cr/AC催化剂上乙酸甲酯气相羰基化合成醋酐反应的研究

以活性炭为载体,采用浸渍法制备Ni-Sn-Cr/AC催化剂,在连续流动固定床反应器上研究其对乙酸甲酯气相羰基化合成醋酐反应的催化性能。分别考察了Ni、Sn、Cr三种金属组分的负载量对催化活性的影响,进一步考察了反应压力、反应温度、反应时间对反应的影响。实验结果表明,在Ni9%-Sn12%-Cr6%/AC催化剂上,当反应温度205℃,压力5.5MPa,催化剂焙烧温度600℃,催化剂焙烧时间为4h的条件下,乙酸甲酯的转化率为38.8%,醋酐的选择性为81.1%。采用X射线衍射和元素分析技术分别对反应前和不同反应时间后的催化剂进行了表征。分析结果表明,Ni⁰是催化剂的主要活性中心,随着反应时间的延长,活性组分镍的流失现象比较严重,同时催化剂上出现积炭及载体骨架遭到破坏,是导致催化剂失活的主要原因。     

Strontium chloride-catalyzed one-pot synthesis of 2, 3-dihydroquinazolin-4(1H)-ones in protic media

A wide range of mono-and disubstituted 2,3-dihydroquinazolin-4(1H)-ones were obtained in high yields by condensation of isatoic anhydride,aldehydes with ammonium salts or primary amines in the presence of strontium chloride in aqueous ethanol under reflux.     

Silica-bonded N-propylsulfamic acid as a recyclable catalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones

2,3-Dihydroquinazolin-4(1H)-one derivatives are synthesized via a one-pot,three component reaction of isatoic anhydride and an aromatic aldehyde with ammonium acetate or primary amine catalyzed by silica-bonded N-propylsulfamic acid(SBNPSA) in refluxing ethanol.     

Reaction of Primary Alkylamines,Heterocumulenes, and Isatoic Anhydride,Catalyzed by Magnetic Fe3O4 Nanoparticles in H2O

An efficient protocol for the one‐pot reaction of isatoic anhydride (=1,2‐dihydro‐4H‐3,1‐benzoxazine‐2,4‐dione), primary alkylamines, and heterocumulenes (isothiocyanates and isocyanates) in H₂O catalyzed by magnetically recoverable Fe₃O₄ nanoparticles is described.     

Banana fiber/chemically functionalized polypropylene composites with in-situ fiber/matrix interfacial adhesion by Palsule process

Chemically functionalized maleic anhydride (MAH)-grafted polypropylene matrix has been used (in place of polypropylene as matrix with compatibilizer) to process banana fiber/chemically functionalized polypropylene (BF/CFPP) composites, without using any compatibilizer and without any fiber modification by Palsule process. Fiber/matrix interfacial adhesion generated, in-situ, due to interactions between BF and the MAH of the CFPP matrix has been established by Fourier transform infrared spectroscopy and scanning electron microscopy. Mechanical properties of the BF/CFPP composites developed by Palsule process with in-situ fiber/matrix interfacial adhesion in this study have been found to be higher than those of the matrix and it increases with increasing amounts of fibers in composites, and are better than properties of literature reported BF/polypropylene composites processed with compatibilizers. Measured modulus of BF/CFPP composites compares well with values predicted by rule of mixtures, Hrisch model, Halpin-Tsai equations and its modified Nielsen version, and with Palsule equation. The feasibility of developing natural fiber/MAH grafted polyolefin composites by Palsule process without using any compatibilizer and without any fiber treatment is demonstrated.     

Kinetics of the thermal decomposition of dinitramide

The kinetic regularities of the thermal decomposition of dinitramide in aqueous solutions of HNO₃, in anhydrous acetic acid, and in several other organic solvents were studied. The rate of the decomposition of dinitramide in aqueous HNO₃ is determined by the decomposition of mixed anhydride of dinitramide and nitric acid (N₄O₆) formed in the solution in the reversible reaction. The decomposition of the anhydride is a reason for an increase in the decomposition rates of dinitramide in solutions of HNO₃ as compared to those in solutions in H₂SO₄ and the self-acceleration of the process in concentrated aqueous solutions of dinitramide. The increase in the decomposition rate of nondissociated dinitramide compared to the decomposition rate of the N(NO₂)₂ ⁻ anion is explained by a decrease in the order of the N−NO₂ bond. The increase in the rate constant of the decomposition of the protonated form of dinitramide compared to the corresponding value for neutral molecules is due to the dehydration mechanism of the reaction. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 41–47, January, 1998.     

稀土催化邻苯二甲酸酐与环氧丙烷交替共聚

研究了用稀土络合催化剂Ｎｄ（ａｃａｃ）３－Ａｌ（ｉ－Ｂｕ）３催化邻苯二甲酸酐（ＰＡ）和环氧丙烷（ＰＯ）开环交替共聚（ａｃａｃ＝乙酰丙酮）．考察了共聚合反应特征，用红外光谱、核磁共振表征了共聚物的结构。共聚反应的动力学研究表明共聚与单体浓度呈一级关系，与催化剂浓度呈一级关系，表现活化能为１．２８７×１０￣５Ｊ／ｍｏｌ。     

Chemistry of naphthazarin derivatives. 11. Trisubstituted hydroquinone derivatives in the preparative synthesis of naphthazarins

The Friedel—Crafts acylation of trimethylhydroquinone, 3,5-diethyl-2-hydroxyhydroquinone, and 3,5-diethyl-1,2,4-trimethoxybenzene with dichloromaleic or citraconic anhydride in an AlCl₃—NaCl melt is accompanied by o-C-dealkylation to afford functionally substituted naphthazarins.     

Studies on the Crystallization Behavior of Polypropylene Solid Phase Grafted Maleic Anhydride

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