The synthesis of β-lactams via a one-pot Reformatsky reaction of imines promoted by Zn/Cp2TiCl2 (cat.)

In the presence of Zn/Cp₂TiCl₂ (cat.) α-bromoacetates, γ-bromocrotonates or α-bromomethylacrylates react with imines in one-pot to form β-lactams, 3-vinyl-β-lactams or α-methylene-γ-lactams, respectively, at room temperature without the need for pretreatment of the solvent and Zn.     

双线性材料模型机械自紧厚壁圆筒的弹塑性分析

考虑了实际材料的应变硬化和Ｂａｕｓｃｈｉｎｇｅｒ效应，利用合理的简化假设、通过弹塑性分析，得到了计算机械自紧厚壁圆筒的应力、位移、过盈量与自紧度、残余胀大量和冲头推力等机械自紧技术的关键计算公式。本文的理论计算结果与实验值相符合。     

Mn/ZSM-5 participation in the degradation of cellulose under phosphoric acid media

The degradation reactions of cellulose under a combination of heterogeneous Fenton-like reagent with catalyst Mn/ZSM-5 and phosphoric acid media have been investigated. Phosphoric acid solution was selected as the reactive medium for the degradation of cellulose due to its good ability to destroy inter- and intra-molecular hydrogen bond so as to promote cellulose activation. The Fenton-like system, composing of H₂O₂ and Mn/ZSM-5 in combination with phosphoric acid, can effectively depolymerize cellulose to soluble sugars and partly degraded cellulose with much lower degree of polymerization. Small molecular products, 5-hydroxymethyl furfural and levulinic acid were extracted from the reaction solution. The performance of the catalyst Mn/ZSM-5 and the effect of reaction factors on the molar yield of 5-hydroxymethyl furfural were investigated. A three-step degradation scheme reflecting the main pathways of cellulose degradation in the reaction is proposed.