Comment on the reply by M. D. Judd and M. I. Pope

Journal of Thermal Analysis and Calorimetry -     

Nucleosides and nucleotides. 3. Polycondensation of thymidine-3'-phosphate by the triester method

Condensation of a mixture of 25 mole per cent of 5′-O-p-methoxy-trityl-thymidine3′-[(β-cyanoethyl)phosphate] and 75 mole per cent of thymidine 3′-[(β-cyanoethyl)phosphate] in pyridine yielded a mixture of oligonucleotides, the largest being the pentanucleotide. It was demonstrated that longer chains are not obtained due to the formation of a C-pyridinium-thymidine nucleotide. For avoiding this undesired side reaction, the condensation was carried out using sym.-collidine as solvent. The analogous side reaction was not observed, longer chains of oligonucleotide were not obtained, however.     

两种细菌的毛细管电泳分离及其与药物相互作用的研究

通过对大肠杆菌与金黄色葡萄球菌的毛细管电泳行为的研究,包括对细菌样品预处理、缓冲液、检测波长以及聚合物添加剂对分离度的改进等的考察,在优化的实验条件下,实现了大肠杆菌与金黄色葡萄球菌的快速分离,从而建立一种新的细菌辅助识别与定性的补充方法。将抗菌药物阿奇霉素与金黄色葡萄球菌混合培育,发现由于阿奇霉素抑制细菌表面蛋白合成,造成与金黄色葡萄球菌作用后,细菌表面电荷密度降低,表现为阿奇霉素对金黄色葡萄球菌的电泳淌度的影响,而且培育时间与金黄色葡萄球菌的淌度线性相关。     

Structure and acid-basic properties of the surface of titanium oxides modified by phosphorus and aluminum and prepared by the alkoxo method. 2. Study of the active surface of titanium oxides

The data of temperature-programmed desorption of ammonia from the surface of oxide systems and IR spectroscopy were used to demonstrate that the strength of the surface acid sites in titanium oxides prepared by the alkoxo method and modified by aluminum decreases with respect to that in nonmodified titanium oxide. Modification of titanium oxide with P³⁺ ions from ethriol phosphite almost completely suppresses the acid properties. Modified oxides are able to chemisorb water. XANES data suggest that modification of titanium oxide with phosphorus ions increases the electron density on the titanium atoms and, correspondingly, the basicity of the materials.     

Vinyl Polymerization by Metal Complexes. XXXII. Formation of Glycolchitosan-Copper(II) Complex and the Initiation of Vinyl Polymerization by Using the Complex

The formation of the water-soluble glycolchitosan-copper (II) complex was studied by ultraviolet and visible spectroscopy and by viscosity measurement. The structure of the polymer complex in question was found to change with pH value of the system. The glycolchitosan-copper (II) complex was active as a free-radical initiator for the polymerization of methyl methacrylate and acrylonitrile in the presence of carbon tetra- chloride. The maximum conversion was observed at neutral pH, and was influenced by the presence of neutral salts. Relation- ship between the activity of the polymer complex for initiating the polymerization and its structure was discussed.     

Reactivity and selectivity control by reactants and products. A general relationship between the selectivity and the position of the transition state.

Although the reactivity-selectivity principle and the frontier molecular orbital theory lead to opposed reactivity-selectivity relationships, they lead to an identical transition state position-selectivity relationship. The transition state position is generally reactant- and product-dependent. The RSP which neglects reactant effects and the FMO which neglects product effects can be considered as the two limits of the general rule.     

Polymerization of N-vinylcarbazole by chlorides and oxychlorides of some group V elements. II. Kinetics and mechanism of the polymerization initiated by arsenic trichloride

The polymerization of N-vinylcarbazole (NVC) initiated by AsCl₃ in benzene and nitrobenzene solvents was studied at 33°C. R_p is proportional to the first power of the initiator concentration. R_p varies in a first-order manner with NVC concentration up to a certain optimum concentration of the latter, after which it falls and ultimately levels off. The rate and the molecular weight are depressed by the addition of various amines, preformed poly-NVC, and water. HCl does not have any cocatalytic effect on the system. Rate and the molecular weight are increased in nitrobenzene. The degree of polymerization stays independent of the initiator and NVC concentration and also of increasing conversion. These results suggest a conventional cationic mechanism, and overrule the possibility of a cation radical initiation. A suitable kinetic scheme has been proposed in conformity with the findings.