Chemistry and application of organic isocyanates,IX. Conversion of tolylene-2,4-diisocyanate into urethane derivatives by means of heptane-1,4,7-triol

Investigations on the conversion of tolylene-2,4-diisocyanate (2,4-TDI or TDI) with heptane-1,4,7-triol 1,4,7-HPT or HPT) at 55–85°C and various molar ratios of starting materials are described. By means of mass spectroscopic analysis and gel permeation chromatography, molecular weights of six oligomers and their percent contents in the products have been estimated. Moreover, a scheme of the formation of all prepared isocyanate prepolymers has been proposed. It has been shown, that apart from oligomers having the structures resulting from the reaction of 1,4,7-HPT with the isocyanate group in the position “4”, reaction products contained oligomers, which confirmed the reactivity of isocyanate group in the position “2”, too.     

Theoretical reactivity of tolylene-2,4-diisocyanate and tolylene-2,6-diisocyanate,and structures of oligomers contained in the products of conversion of tolylene-2,4-diisocyanate into urethane and biuret derivatives

By the methods of quantum chemistry it is possible to calculate a number of theoretical quantities dependant on the structure of chemical compounds. In this paper quantum chemical calculations have been done in order to explain quantitatively the differences in the reactivity of isocyanate groups in tolylene diisocyanates and for the account of directions of oligomer formation with definite structures. These quantities have been connected in a simple way with the chemical reactivity of the molecules. The results of calculations made with the INDO semiempirical method are in a very good correlation with results of experimental investigations.     

Urethanes. I. Organometallic catalysis of the reaction of alcohols with isocyanates

The catalysis of the reaction of n-butyl alcohol with isocyanates, using organometallic derivatives of lead, tin, and mercury, has been investigated. The rate of the reaction was measured by following the disappearance of the isocyanate absorption in the infrared. Phenyl, n-butyl, and cyclohexyl isocyanate were chosen to represent typical aromatic primary and secondary aliphatic isocyanates. Within the same series of catalysts, R_nMOAc, the catalytic effect decreases in the order RHg > R₃Sn > R₃Pb; and in all cases R = aryl > R = alkyl. The electronic effects of substituents on the aryl moiety are not pronounced. Changes in X of R_nMX greatly affect the catalytic activity. The mechanism of organometallic catalysis of the alcohol-isocyanate reaction occurs via a template-type mechanism whereby the catalyst acts to complex both reactants in a catalyst phase allowing the reaction to occur with greater facility.     

Chemistry and application of organic isocyanates IV. Conversion of hexamethylene diisocyanate into biuret derivatives by means of Na2SO4 · 10 H2O

The attempts of hexamethylene diisocyanate (HDI) conversion by means of Na₂SO₄ · 10 H₂O at 120°C to 160°C at different molar ratios of reactions of reactants have been described. It has been shown that in this process apart form N,N′,N″-tris(6-isocyanatohexyl)biuret there are also formed biuret derivatives of higher molecular weight. Due to the application of mass spectrometry analyses and gel permeation chromatography the scheme of formation of prepolymers having the biuret structure of molecular weight up to 1300 has been proposed.     

新时期高分子化学的发展及应用探析

高分子是化学科学的重要组成部分,人类最开始主要是利用和接触天然高分子材料,但是随着社会的进步和经济水平的提高,化学的研究进入了一个崭新的阶段。新时期的高分子化学技术广泛应用于人们生活各个方面。基于此,主要研究新时期高分子化学的发展及应用。     

Chemistry and application of organic isocyanates V. Conversion of 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane into urea and biuret derivatives by means of Na2SO4 · 10H2O

Under different conditions of reaction the conversion of 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane into urea and biuret derivatives was carried out applying water as the converting agent. It has been proved that reaction products are heterogeneous, since four oligomers are contained in the mixtures. The influence of the reaction conditions on the concentration of the components was investigated. The results of physico-chemical measurements of the obtained products in dependence on the temperature of synthesis and applied molar ratio of the reagents have been interpreted.     

New Catalysts for the Hydrogenation of Glucose to Sorbitol

Nickel catalysts supported on ZrO₂, TiO₂ and ZrO₂/TiO₂ mixtures performed more active, selective and stable than Ni/SiO₂ catalysts in the hydrogenation of glucose to sorbitol. This was shown by catalytic testing as well as by determination of Ni crystallite size before and after the test. The reason for the better performance was assumed to be metal‐support interaction in the Ni/ZrO₂, Ni/TiO₂ and Ni/ZrO₂/TiO₂ catalysts.     

Functional polymers for colloidal application. VI. Syntheses and dispersing ability of lipomodified naphthalenesulfonate formaldehyde condensates

Butyl-substituted naphthalenesulfonate formaldehyde condensates (C4NSF) with different molecular weights were synthesized. The structures were confirmed by NMR in terms of the appearance of the signal at δ = 3.3–4.0 ppm, and the molecular weights of the synthesized C4NSFs were compared by gel permeation chromatography (GPC). C4NSFs used as dispersants were compared to unmodified naphthalenesulfonate formaldehyde condensates (NSF) in their ability to disperse nonpolar particles (carbon black) and polar particles (TiO₂) in water. Their dispersing ability was evaluated by both a viscosity method and a microscopy method. For dispersing carbon black in water, it was found that using C4NSFs as dispersing agents results in a lower viscosity, a lower yield value by the viscosity method, and a more homogeneous dispersion of particles as determined by microscopy. These results indicate that the butyl group enhances the dispersing ability of C4NSF. The effect of the butyl group on the dispersing ability of C4NSF was interpreted by the results of the measured adsorption amount that was also enhanced by the existence of the butyl group. For dispersing TiO₂ in water, C4NSF results in a higher viscosity and a higher adsorption amount of the dispersed system than NSF. These phenomena were interpreted in terms of the hydrophobic interaction between the butyl groups and the bridging effect. © 1993 John Wiley & Sons, Inc.     

Interpenetrating polymer network from blocked isocyanates. I. Structure and properties of polyurethane-urea polyvinyl simultaneous interpenetrating networks

A series of polyurethane-urea/polyvinyl simultaneous interpenetrating polymer networks (SINs) were prepared starting from a mixture of isocyanate prepolymer blocked with N-(1-1′-dimethyl-3-cxobutyl) acrylamide oxime, chain extender, vinyl monomers, and catalysts. Their physical properties and morphology were investigated using differential scanning calorimetry, dynamic mechanical measurements, and small-angle X-ray scattering. The polyurethane-urea networks examined were two-phase in nature. The vinyl network was formed with diacetone acrylamide oxime, trimethylolpropane trimethacrylate, and N-vinyl-pyrrolidone. Calorimetric analyses revealed that the polyether soft segment phase separated within the SINs. At higher temperature, dynamic mechanical measurements demonstrated the presence of only one glass transition temperature (T_g) intermediate in temperature to the T_g of the vinyl network and the T_g of the urethane hard phase. This is indicative of chain entanglement (interpenetration) between the vinyl network and the polyurethane hard segments resulting in a two-phase morphology. Small-angle X-ray scattering analyses provided measurements of diffuse phase boundary thickness, phase mixing, and domain size distribution. Appreciable interfacial thickness was not observed and thus phase mixing occurred within the phases. Domain size distribution indicated that high network constraints hindered the development of domains and limited the phase segregation.     

Syntheses and reactions of photopolymers,I. New photosensitive azo monomers,photolysis, interfacial polycondensation,viscosity measurements,photodegradation

The synthesis of new, unsymmetrically functionalized azo compounds and their incorporation into polymers is described. Their photochemical decomposition and thermal stability was studied by UV spectroscopy and differential scanning calorimetry (DSC), respectively. Chemical degradation was followed by viscosity measurements.     

有机科研用试剂的研发与应用

综述了科研用化学试剂研发平台已获得的研发产品糖衍生物、手性试剂、芳杂环、金属有机化合物、材料单体和其他有机合成中间体等高端试剂的研究简况与应用情况,概述了研发试剂的质量控制体系建设.阐明了该平台建立的意义,说明高端试剂研发平台的建立对我国多个领域科研工作起到有效的支撑作用.     

Catalysis of the reaction between isocyanates and protonic substrates. I. Metal salt–amine complexes as catalysts in the polyurea foaming process

Tertiary amines and metal [Cu(II), Zn(II)] salts exhibit a synergistic effect in the catalysis of the isocyanate water reaction. The amino complexes of zinc and copper salts display a very large versatility in defining the most suitable formulations for the polyurea foam production. The foaming process is indeed controlled by the nature and the composition of these new catalytic combinations; kinetics of foaming and textural characteristics of final foams are easily modified in that way.     

阻垢剂的合成及应用研究进展

阐述了阻垢剂的种类、性能及研究应用现状,其中聚环氧琥珀酸和聚天冬氨酸两大类新型绿色阻垢剂成为近几年国内外的研究热点.并指出今后的工作重点和发展方向.     

Flame-retarding materials—I. Syntheses and flame-retarding property of alkylphosphate-type polyols and corresponding polyurethanes

In this research, oligomeric polyalkyl phosphate-type polyols (P% = 14–17) were synthesized from ethylene glycol or 1,4-butanediol (PBE or PBB) by means of butyl phosphorodichloridate, which was prepared from phosphorus oxychloride and butanol. These polyols were then reacted with isocyanate to form the corresponding polyurethanes (PETD and PBTD). These polyols were characterized by FTIR, ¹H-NMR, and ³¹P-NMR, and the thermal stabililties were measured by thermogravimetry analysis. The degradation phenomena were traced by FTIR and interpreted in terms of the degradation and formation of bonds. The corresponding polyurethanes were also characterized by FTIR and ¹H-NMR, and their thermal stability was also studied by thermogravimetry analysis. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1635–1643, 1998     

Studies on 4-thiazolidinones. I. Cleavage of 3-Phenyl-2,4-thiazolidinediones with benzylamine and hydrazine

5-Arylidene-3-phenyl-2,4-thiazolidinediones 1a – h undergo ring cleavage with excess benzylamine to give an equimolar mixture of phenyl benzyl urea 5 and dibenzyl urea 6 . The intermediate in this type of reaction is isolated under controlled conditions and proved to be 1,5-dibenzyl-3-phenyl biuret 3 . Using hydrazine, each of 1d – g gives the corresponding biuret derivative 7a – d , respectively. The cleavage occurs at 1,2 as well as 4,5 bonds.     

Electrochemical test methods for evaluating organic coatings on metals: an update. Part I. Introduction and generalities regarding electrochemical testing of organic coatings

The status of evaluating organic coated metals utilizing electrochemical means was reviewed for the period of 1988–1994. The general improvements in the overall technology are presented in three sections. Part I covers the test cell configurations, changes in testing approaches and a brief survey of measurement equipment. Part II presents the test methods involving a single test parameter such as the panel potential relative to a reference electrode, electrochemical voltage and/or current noise, as well as the dc resistance of the coating on the metal substrate. Multiple test parameter measurements such as potentiodynamic curves and electrochemical impedance spectroscopy are covered in Part III. Although the majority of data were taken from the literature, some supplementary data are included from NSWCCD studies.     

物理化学多媒体课件的制作及在教学中的应用

《物理化学》作为工科院校冶金、化工等专业必修的一门基础理论课,多年来在教学中一直延续着传统的教学模式,根据学生的反馈意见,大多数学生认为：对其中一些抽象的概念难以理解,解题时无从下手。物理化学多媒体课件在教学中的应用则可以克服以上困难,将抽象的概念蕴含于一些简单明了的动画中,使学生一目了然,同时也促进了学生对《物理化学》这门课程本身的学习。激发了学生的学习兴趣。经过六个班次的教学实践,收到了良好的教学效果。