Telechelic cis‐1,4‐oligoisoprenes through the selective oxidolysis of epoxidized monomer units and polyisoprenic monomer units in cis‐1,4‐polyisoprenes

Abstract

Telechelic cis-1,4-oligoisoprenes were prepared by the selective cleavage of weak epoxidized units (E) in epoxidized cis-1,4-polyisoprenes (EPIs) and by the random cleavage of isoprenic units (I) in cis-1,4-polyisoprene (PI). In both cases, cleavage by periodic acid (H 5 IO 6 ) in tetrahydrofuran led to aldehydic and ketonic chain ends. Through variations in the E/(I ϩ E) molar percentage (E%) in the cleavage of EPI and through variations in the H 5 IO 6 /I molar percentage (PA%) in the cleavage of PI, a polydispersity index near 2 and a number-average molecular weight of 2 -20 ϫ 10 3 were obtained. The correlation of the degree of scission with E% and PA%, combined with kinetic, led to the proposal of a two-step mechanism for the H 5 IO 6 cleavage of double bonds.

Use of hydroxytelechelic cis-1,4-polyisoprene (HTPI) in the synthesis of polyurethanes (PUs). Part 1. Influence of molecular weight and chemical modification of HTPI on the mechanical and thermal properties of PUs

“…Strongly involved in the obtaining of telechelic polyisoprenes through an original degradation of high molecular weight cis-1,4-polyisoprene with controlled microstructures and functionalities [23,24], our laboratory investigated their reaction with TDI for the elaboration of new polyurethanes. Focusing on a comparative mechanical and thermal study, polyurethanes based on commercial hydroxytelechelic polybutadiene (PBHT R20 LM w ) and hydrogenated hydroxytelechelic polyisoprene (EPOL w ) were also synthesized.…”

Liquid Rubbers as Toughening Agents

“…The NMR spectrum showed the presence of aldehyde and ketone moieties, residual oxiranes, and secondary furanic and cyclic structures [41]. Gillier-Ritoit et al [42] investigated the chain degradation of polyisoprene and epoxidized polyisoprene using H 5 IO 6 in an organic solvent. The degraded polyisoprene gave H-NMR characteristics similar to those of degraded epoxidized polyisoprene with aldehyde and ketone terminal ends, but the reaction is slower than in case of epoxidized polyisoprene.…”

Degradation of non-vulcanized natural rubber renewable resource for fine chemicals used in polymer synthesis

“…Numerous publications, as for example [21,[25][26][27][28][29][30][31][32][33][34][35][41][42][43][44][45][46][47][48][49][50][51][52][53][54] , are devoted to oxidative methods of degradation natural rubber. The widely used approach is degradation through the epoxidation reaction of isoprene units of the rubber polymer chain.…”

“…The main reaction product isolated is oligomeric isoprene terminated by carbonyl groups. Its structure is confirmed by 1 H-NMR, Certainly, all the researchers noted that they did not reach a complete epoxidation of the polyisoprene and the resulting products contained isoprene units, epoxidized isoprene units and carbonyl terminal groups [25][26][27][28]42] . However, Phinyocheep et al [26] suggest that the degradation of the epoxidized natural rubber (ENR) by periodic acid does not take place by the cleavage of the epoxy-containing isoprene fragments, but via C=C of the isoprene unit through the formation of the intermediate vis-diols.…”

“…Gillier-Ritoit et al [27] degraded poly(cis-1,4-isoprene) (PI) using two agents to obtain the carbonyl terminated oligomers: periodic acid (1 step process) and m-chloroperbenzoic acid (MCPBA) + periodic acid (2 step process). The authors consider that in both the cases the first stage of the process is epoxidation.…”