The Effect of 1,2- and trans-1,4-Units on Ketonization of Polybutadienes by Nitrous Oxide

Abstract

Earlier it was shown that the oxygenation of double bonds in polydienes by nitrous oxide (N 2 O) via the 1,3-dipolar cycloaddition mechanism (the so-called ketonization reaction) provides a synthetic route for obtaining a new type of carbonyl functionalized polymers and oligomers−unsaturated polyketones.Here, the ketonization of polybutadiene with a relatively high content of trans-1,4-units and 1,2-units at 160−230 °C and elevated pressure was studied. Oxygenated polymer products containing from 0.3 to 8.8 wt % oxygen in the form of carbonyl, mainly ketone, groups and having M n from 34000 to 860 g/mol, respectively, have been obtained. The conversion of ca. 10% of double bonds in the parent polybutadiene during the reaction transforms it into carbonyl functionalized liquid rubber. A comparison of the obtained results with those for ketonization of cis-1,4-polybutadiene has revealed the effect of cis/trans isomerism of 1,4-units and the content of 1,2-units on the reaction mechanism and the characteristics of the resulting polymer products.