Mathematical Simulation of the Synthesis of cis-1,4-Polybutadiene on a Cobalt-Containing Catalyst in the Presence of Ethylene

Based on an analysis of experimental results and published data, the main elementary steps of the anionic coordination polymerization of butadiene rubber on a cobalt-containing catalyst in the presence of ethylene were found, and a mathematical model of the periodic process at an optimum water content was developed. The molecular-weight characteristics of the process depending on ethylene concentration were studied with the use of this model.     

Cyclo- and carbomagnesiation of 1,2-dienes catalyzed by Zr complexes

Cyclo- and carbomagnesiation of 1,2-dienes with EtMgR′ (R′=Et, Br) in the presence of Cp₂ZrCl₂ catalyst lead to alkylidenemagnesiocyclopentanes. Deuterolysis provides insights into the reaction pathways.     

Novel organomagnesium reagents in synthesis. Catalytic cyclomagnesiation of allenes in the synthesis of N-, O-, and Si-substituted 1Z,5Z-dienes

An efficient method for the synthesis of valuable N-, O-, and Si-containing 1Z,5Z-diene compounds was developed. The method comprises Cp₂TiCl₂-catalyzed homo- and cross-cyclomagnesiation of 1,2-dienes by Grignard reagents (RMgR′) to give 2,5-dialkylidenemagnesacyclopentanes in up to 96% yield. This approach was successfully used in the synthesis of 5Z,9Z-dienoic acids, precursors of acetogenins and insect pheromones.     

A difference-scheme with error O(τ2 + ¦h¦2) for a Navier-Stokes system

A system of quasilinear equations of parabolic type which approximates a nonstationary Navier-Stokes problem is considered in this article. Triple layered implicit difference schemes with a linear operator on the upper layer are constructed for this system. Rapidly converging iterative methods can be applied to find a solution on the upper layer. It is proved that the proposed scheme has error O( ²+¦h¦²).Translated from Matematicheskie Zametki, Vol. 12, No. 1, pp. 59–66, July, 1972.     

Raising the Coefficient of Turbulent Diffusion in the Reaction Zone as Means To Improve Technical and Economical Parameters of Polymer Production

Use of a new type of apparatus, high-output small-size tubular turbulent reactors of mainly dif- fuser-confuser design, in very fast processes, including polymerization, is considered. The turbulent diffusion coefficient D _t and its distribution over the apparatus volume were calculated as functions of the confuser divergence angle . The calculations were confirmed by experimental data. New reactor designs for a number of processes of large-tonnage polymer production were proposed and put into practice.