Ring opening metathesis polymerization (ROMP) of five‐ to eight‐membered cyclic olefins: Computational, thermodynamic, and experimental approach

Abstract

Ring opening metathesis polymerization (ROMP) of a series of low-strain cyclic olefins and their hydroxyl derivatives using second generation Hoveyda-Grubbs catalyst has been investigated. Additionally, density functional theory (DFT) calculations were performed to evaluate the ring strain energies of the cyclic olefins and their hydroxyl derivatives, coupled with kinetic studies for the ROMP reactions. It was found that among different ring size monomers, Cy8 having a relatively moderate ring strain energy in comparison with the other cyclic olefins, exhibited the highest monomer conversion. The effect of temperature (0, 10, 15, and 25 8C) and monomer concentration (1 M; 2.5 M and 5 M for Cy5; and 1 M and 5 M for Cy7) for the cyclic olefins Cy5 and Cy7 were investigated. In general, the experimental results for the kinetic ROMP studies obtained using complex HG2 correlate really well with the DFT calculations determined for the ring strain energies of the cyclic olefins. For comparison, DFT calculations predicted the following trend for the ring strain energies Cy8 > Cy5 > Cy7 > Cy6, and the polymerizations carried out experimentally followed the same trend in terms of monomer conversion, with the exception of Cy5 and Cy7 at lower concentrations, which followed this trend Cy8 > Cy7 > Cy5 > Cy6.

Ring opening metathesis polymerization (ROMP) and thio‐bromo “click” chemistry approach toward the preparation of flame‐retardant polymers

“…30%). We had thought that this may be due to lower ring strain, but calculations (similar to recent results) showed that monomer 13 had a ring strain energy of 13.8 kcal/mol while monosubstituted 6 has 11.8 kcal/mol (Table S3, Supporting Information). Interestingly though, 13 could be successfully polymerized under more typical ROMP conditions (strict oxygen‐free conditions in CH 2 Cl 2 with [ 13 ] = 0.6 M) and higher initiator loading ([ 13 ]:[ 7 ] = 50:1) to provide polymer 14 as a gummy solid by precipitation into methanol in 75% yield.…”

Recent developments in entropy‐driven ring‐opening metathesis polymerization: Mechanistic considerations, unique functionality, and sequence control

“…For large, strainless macrocycles the influence of olefin stereochemistry does not originate from differential ring strain. Instead, a slight enthalpic benefit is associated with ring‐opening of cis ‐olefinic macrocycles due to alleviation of steric repulsion between nearby bulky groups on the same side of the double bond . As the monomers are ring‐opened and cycloreversion of the metallocyclobutane occurs, new olefins are produced in the polymer backbone with stereochemistry defined by the approach of the monomer relative to the catalyst‐bound alkylidene.…”

Data Envelopment Analysis and Decision Maker Models: An Innovative Approach for Optimization of Reaction Variables of Graft Copolymerization of Poly(butyl acrylate) to Tamarind Seed Xyloglucan

“…The ranking methodology proposed herein first normalized all the data set to make distinction between the DEA efficient units. The data set (both input and output) normalization was done with the help of Equation (5). By doing this the "maximin" weight of each DEA efficient unit was protected from any effect of scaling transformations of inputs and output.…”