Effect of organic solvents on the functionalization of liquid natural rubber by iron salt-mediated chloro-nitro reaction

This study presents the functionalization process and the effect of organic solvents on the iron salt-mediated chloro-nitro reaction. The product obtained from the reaction is the chloro-nitro compound of liquid natural rubber (Cl-N-LNR). LNR functionalization was achieved by NO2Cl radical formed from iron(III) nitrate nonahydrate and iron(III) chloride in various organic solvents including ethyl acetate (EtOAc), tetrahydrofuran (THF), and dioxane (DOX). Fourier-transform infrared spectroscopy (FT-IR) was used to evaluate the structure of the resulting Cl-N-LNR. The degree of functionalization with the nitro group is 13÷15% mol units of Cl-N-LNR and the efficiency of the chlorine-nitration reaction is 80÷90%. Depending on the type of solvent used for the reaction, the structures of the functionalized chains received are disparate. Notably, the Cl-N-LNR is made in a THF/DOX solvent mixture that exhibited superior properties compared to the other solvents.