ALGORITHM FOR COMPUTER PERCEPTION OF TOPOLOGICAL SYMMETRY

For the exhaustive and irredundant generation of candidate structures in ESESOC (Expert System for the Elucidation of the Structures of Organic Compounds), a new algorithm for computer perception of topological equivalence classes of the nodes (non-hydrog

UNUSUAL VOLTAMMETRIC BEHAVIOR OF AN ELECTROCHEMICALLY SYNTHESIZED CONDUCTING PLATINUM CLUSTER COMPOUND K-1.64[PT(C2O4)(2)]

The compound K-1.64[Pt(C2O4)(2)] was electrochemically synthesized on a glassy carbon electrode using both single-potential step and cyclic voltammetry techniques; voltammetric behaviour of the working electrode was changed dramatically with deposition of

简易非水电位测定参比电极——Pt/(Ⅰ_3~-+Ⅰ~-)电极的制备

本文以微孔细陶作为电极内充液的支撑材料,制备了简易参比电极一Pt/(I_3~-+I~-)电极。初步考察了Pt/(I_3~-+I~-)电极在水溶液及多种有育机溶剂中的稳定性,并与Ag/AgCl、甘汞电极进行比较。实验结果表明,Pt/(I_3~-+I~-)电毁不仅在介电常数较大的有机溶剂中有稳定电位,在某些介电常数较小的有机溶剂中也有稳定电位。在水溶液中其电位稳定性不亚于Ag/AgCl、甘汞电极,可用怍测水溶液 pH 值的参比电极。Pt/(I_3~-+I~-)电捉还具育结构简单容易制备等院点。

Heterogeneous asymmetric hydrogenation of ethyl pyruvate on chirally modified Pt/Al2O3 catalyst with fixed-bed reactor

The enantioselective hydrogenation of ethyl pyruvate on the cinchonidine modified Pt/Al2O3 catalyst was investigated using a high-pressure reaction system with a fixed-bed reactor for the purpose to produce the,chiral product without separating the catalyst from the reaction system. The reaction was also investigated in a batch reactor for comparison. About 60% e. e. and 90% e. e. were obtained with the fixed-bed reactor and the batch reactor respectively, demonstrating the possibility for the heterogeneous asymmetric hydrogenation in the fixed-bed reactor. Some adsorbed chiral modifier, cinchonidine, can be slowly removed from the surface of Pt/Al2O3 under the continuous flow reaction, as a result, the e, e, values drops with the reaction time in the fixed-bed reactor. The enantio-selectivity is higher in the fixed-bed reactor, but lower in the batch reactor when ethanol was used as solvent than that when acetic acid as solvent. CO was used as molecular probe to characterize the adsorption of cinchonidine an the catalyst surface by IR spectroscopy, A red shift observed in IR spectra of coadsorbed CO with cinchonidine suggests that the cinchonidine adsorption is mainly through the pi -interaction with platinum surface and donating electron to the platinum surface.