Analysis of α-Olefin Sulfonic Acids by NMR Spectroscopy

Abstract

The structural analysis of α–olefin sulfonic acids (AOS acid) was carried out by means of NMR method. It was indicated that AOS acid was a mixtures of alkene sulfonic acid, 1,3–alkane sultone, 1,4–alkane sultone and unchanged olefin from its NMR spectrum, those of 1,3–hexadecane sultone as well as 1,4–hexadecane sultone and the results reported in the previous paper. However, the two signals, absorbed at 5.06 and 3.43 ppm, were not able to assign. And the signal of olefinic protons of Δ1–alkene sulfonic acid could not be found in NMR spectrum of AOS acid. In the NMR spectrum of product which was obtained by the acidic hydrolysis in NMR sample tube, two signals of 5.06 and 3.43 ppm were obviously disappeared. In the NMR spectrum of basic hydrolysis product, it was found that new signal was appeared at 6.1~6.8 ppm based on double bond methin proton of Δ1–alkene sulfonic acid. Those results clearly indicate that those unknown peaks are due to the precuser of Δ1–alkene sulfonic acid. And these unknown peaks were assigned to methin proton (–O–CH–) and methylene proton (–CH2–SO2–) of 1, 2–alkane disultone, from this result and previous paper of Mori13) and Markgraf15). As assignments for all signals of AOS acid were finished, quantitative analyses of the sultones, alkene sulfonic acid and 1, 2–alkane di–sultone in AOS acid were carried out. Using the peak area of methin proton signal of alkene sulfonic acid (A), methin proton signal of 1,2–alkane di–sultone (B) and methylene proton signal of sultone (C) (See Fig. 8), the each component was determined by the following equation. Alkene sulfonic acid (mol %) = 100 A/(A + B + 2 C) As an examples of the application of this method, AOS acids, reacted under the various conditions of sulfonation, were determined by NMR method, and coefficient of variation was found to be 1.2%. © 1973, The Chemical Society of Japan. All rights reserved.