A NOVEL ACETYLENIC ESTER-VINYL ETHER REARRANGEMENT

A novel acetylenic ester-vinyl ether rearrrangement takes place when perfluoroacetylenicester is subject to hydrolysis with aqueous sodium hydroxide. The rearrangement is highlystereoselective and the Z-isomer predominates to the extent of above 94% in all cases. Thecrossover experiments showed that this rearrangement proceeds predominately intramolecu-larly. By using ~(18)O labeling technique and on the basis of mass spectral study, it wasshown that the rearrangement most likely roceeds through an intramolecular 1, 3 shiftof the methoxy group to the β-carbon atom. A novel mechanism involving a cage reactionin the organic phase of a two-phase system is proposed.     

Unconventional Hamilton-type variational principle in phase space and symplectic algorithm

By a novel approach proposed by Luo, the unconventional Hamilton-type variational principle in phase space for elastodynamics of multidegree-of-freedom system is established in this paper. It not only can fully characterize the initial-value problem of this dynamic, but also has a natural symplectic structure. Based on this variational principle, a symplectic algorithm which is called a symplectic time-subdomain method is proposed. A non-difference scheme is constructed by applying Lagrange interpolation polynomial to the time subdomain. Furthermore, it is also proved that the presented symplectic algorithm is an unconditionally stable one. From the results of the two numerical examples of different types, it can be seen that the accuracy and the computational efficiency of the new method excel obviously those of widely used Wilson-θ and Newmark-β methods. Therefore, this new algorithm is a highly efficient one with better computational performance.     

矩阵损失下带约束的回归系数非齐次线性估计的Minimax可容许性的特征

本文在矩阵损失下给出了带约束的回归系数线性估计在非齐次线性估计类中是Minimax可容许估计的充要条件。     

DV—Xa方法与电子光谱解析

本介绍了第一原理量子化学ＤＶ－Ｘａ方法在电子光谱的理论计算方面的应用。在三个例子中分别详细讨论了过渡金属原子簇的紫外－可见吸收谱Ｖ／ＵＶ、Ｘ－射线光电子能谱ＸＰＳ、和ＸＡＮＥＳ的计算,应用于ＭｏＳ４原子簇结构、Ｃｕ２Ｏ／Ｃｕ表面与２－氨基嘧啶相互作用模型、和ＭｏＳ２导带底部结构分析。根据在不同光谱分析的特点,采用相应的计算方案。电子光谱的解析除了在解释光谱现象外,能够进一步帮助了解分子或原子簇的结构。     

含氟炔酮和炔醛类化合物的质谱研究

本文报道18个含氟炔酮和炔醛类化合物的质谱及其解析结果。在含氟炔酮中,当全氟烷基联结于羰基碳或炔碳上时,质谱的断裂规律有所不同,观察到苯基或取代苯基或全氟烷基重排脱CO的碎片离子,在含氟炔醛中,出现脱CO和脱氟或部分氟碳烷基的碎片的离子(CF2C≡CH)[+]。另外亦出现脱氟或部分氟碳烷基的碎片离子(CF2C≡CCHO)[+],此碎片离子的相对丰度次序为:n-C3F7>C2F5>CF3。在化合物5～15中,有氟重排离子(M-R1R2+F)[+]出现。     

一种新型的重排——炔酯-烯醚重排

全氟炔酸酯,用氢氧化钠水溶液处理,发生一种特殊的炔酯-烯醚重排。此重排在有机化学中尚未见先例。第一个问题,重排究竟是分子内还是分子间的反应?我们研究了交叉反应,结果表明重排以分子内反应为主,但伴有少量分子间的反应。第二个问题,究竟氢氧离子是进攻羰基碳还是β碳?我们用~(18)O标记元素进行研究。质谱的数据表明~(18)是在羧酸基上。     

我国固体无机化学的研究进展

综合介绍了建国５０年来，尤其是近２０年来我国固体化学研究领域所取得的进展，阐述了该领域在合成方法上的更新以及不断向信息、能源、环保等应用领域提供的各种新材料。