A. Kh. Bulai

Kinetics of polysulphone synthesis: nuclear magnetic resonance spectroscopy and rheological investigation

Abstract Time-dependent changes in monomers, dimers, end reactive groups and central links occurring in the synthesis of polysulphone derived from dichlorodiphenylsulphone and the sodium salt of diphenylolpropane in dilute solution in dimethylsulphoxide were investigated by nuclear magnetic resonance spectroscopy. On this basis, a kinetic model of the reaction was designed and elementary reaction constants, which appeared to be dependent on the chain length, were determined. Simultaneously, the time-dependent change in the viscosity of the reaction medium in concentrated solutions was measured and the results obtained were analysed by the rheokinetic method. A correlation was found to exist between the rheokinetic constants and the rate constants in sufficiently high-molecular-weight products determined by nuclear magnetic resonance spectroscopy.

Synthesis of substituted pyridines by reaction of tetracyanoethylated ketones with hydrochloric and hydrobromic acids

Previously unknown derivatives of pyridine have been synthesized by reaction of tetracyanoethylated ketones with concentrated aqueous solutions of hydrochloric and hydrobromic acids. The unique course of the reaction of 4,4,5,5-tetracyano-2-pentanone with gaseous hydrogen chloride has been demonstrated.

13C NMR study of the structure of polyethylene-polyamines

The signals in the 13C NMR spectrum of a commercial sample of polyethylene-polyamine have been assigned and an additive scheme for calculating the chemical shifts proposed. The content in the technical product of all possible 18 structural fragments (linear and cyclic) has been determined from the spectrum. The number of primary, secondary and tertiary nitrogen atoms in the polyethylene-polyamine molecule has been calculated and the number average M determined.

1H and 13C NMR analysis of the synthesis of polyarylene sulphonoxides based on diphenylolpropane and dichlorodiphenylsulphone

the method of 1H and 13C NMR analysis has been used to investigate reaction mixtures formed in the synthesis of oligoarylene sulphonoxides from the sodium salt of diphenylolpropane and dichlorodiphenylsulphone. A quantitative study was carried out to determine the amount of different endgroups and of monomeric and “dimeric” products formed at some stages in the synthesis. Number-average molecular weights were determined for oligoarylene sulphonoxides in the reaction mixture.

Study of polyether thermoelastoplasts by the 1H and 13C NMR method

The degree of polycondensation and the nature of the end groups in a series of polyalkyleneoxylglycols (polyethylene, polytetramethylene and polypropyleneoxyglycols and also the copolymer of propyleneoxyglycol and tetrahydrofuran), used for synthesis of polyether elastoplasts (PETEP), have been determined by 13C NMR. For polyether thermoelastoplasts based on 1,4-butanediol, dimethyl terephthalate and polyalkyleneoxyglycols, an analysis of the composition was made. For PETEP based on ethylene glycol, dimethyl terephthate and polyalkyleneoxyglycols, both composition and chain structure was determined. It was shown that degradation of polyalkyleneoxyglycol does not occur in the synthesis of PETEP. The content of the components in PETEPS coincides with the composition of the original mixture and the monomer units were shown to be randomly distributed in them.

Synthesis of pyrrolopyrimidines from 2,5-diaryl-3,3,4,4-tetracyanopyrrolidines

Feasibility has been demonstrated for the synthesis of pyrrolo[1,2-a]pyrimidines by the reaction of 2,5-diaryl-3,3,4,4-tetracyanopyrrolidines I with β-dicarbonyl compounds, which was carried out by the rearrangement of I to give 2-(N-arylidenamino)-5-aryl-3,4-dicaynopyrroles II. A different pathway was found for the reaction of pyrroles II with β-diketones and ethyl acetoacetate. The existence of a latento-enaminonitrile fragment in these compounds permits their conversion to pyrrolo[2,3-d]pyrimidines.

A13C NMR study of structural isomers and compositional sequences in oligoesters based on propylene oxide and maleic anhydride

Abstract The nature and concentration of end groups was determined and an analysis of structural isomers and compositional sequences in oligoesters based on propylene oxide and maleic anhydride, containing short propylene oxide blocks, was made by means of the 13 C NMR method.

Synthesis and NMR 13C study of polycondensates based on asymmetrical monomers

The NMR13C method used to establish the structure of polycondensates (polyesters) based on asymmetrical monomers (β-hydroxyethyl esters of bisphenols) and symmetrical (dicarboxylic acid dichlorides) monomers. It was found that under conditions of non-equilibrium polycondensation, according to the structure of initial compounds and the method of introduction into the reaction zone, polymers may be obtained with varying directions of adding the units: “head to head”, “tail to tail”, “head to tail” and “tail to head”. By changing these factors polymer structure may be adjusted in the requisite direction.

Synthesis of polymer emulsifiers by spontaneous polymerization of 4-vinylpyridine in media of different polarities☆

Abstract Several cation-active polymer emulsifiers were synthesized by spontaneous polymerization of 4-vinylpyridine by the action of butyl bromide and nonyl bromide. Synthesis was carried out in acetone, nitrocyclohexane, nitromethane, methanol, water, a mixture of methanol with water and without solvent. The effect of medium polarity on the yield, composition, molecular weight and microstructure of polyemulsifier was elucidated. Results confirm that monomer associates are formed prior to polymerization both in aqueous and non-polar medium. Products are effective stabilizers of nonpolar hydrocarbon emulsions in water.

Synthesis of unsaturated polyesters from maleic anhydride and isobutylene oxide

Abstract Reaction mixtures originating in the synthesis of unsaturated polyesters from maleic anhydride and isobutylene oxide were analysed by 1 H and 13 C NMR. The contents of unreacted isobutylene oxide and of several side products in the reaction mixture, and the concentrations of isobutylene and maleic acid structural units in the oligoester chain were determined quantitatively at different stages of the process. Four reactions were found to proceed during the synthesis of the polyester: isomerization of isobutylene oxide to isobutyral, its condensation with isobutylene oxide to a cyclic acetal, homopolymerization and copolymerization of isobutylene oxide.