Preparation of sodium salts ofN-sulfonic acids by sulfomethylation of nitro oligomers obtained from waste rubbers

Abstract

The sulfomethylation of nitro oligomers obtained from waste rubbers (NO-GWR) with sodium hydroxymethane sulfonate was studied in aqueous–alkali solutions from 50 to 80°C for reaction times of 3.5–5.5 h with weight ratios of 1.0:0.3–0.6. The initial NO-GWR was produced by the oxidation/destructive nitration of waste rubbers with nitric acid in a heterogeneous medium. The influence of the reaction conditions on the yields and functional compositions of the sodium salts of two types of N-sulfonic acids was investigated. Some of the nitro groups transformed into sulfaminate groups at 80°C or lower. One type of N-sulfonic acid was isolated from its sodium salt by ion exchange. The oligosulfo derivatives were characterized by elemental and thermal analyses, IR and 1H-NMR spectroscopy, and the number-average molecular weight. The sodium salts of the N-sulfonic acids obtained from NO-GWR possessed functional compositions similar to those of sodium salts from butadiene–styrene nitro oligomers prepared from butadiene–styrene latexes. Therefore, NO-GWR obtained from available raw materials can be used as the initial derivative for the preparation of salts of N-sulfonic acids instead of the nitro oligomers used now from elastomers. The salts can be used in galvanic coating techniques as brighteners. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1002–1013, 2005