Abstract
The kinetics of the thermal decomposition of dimethyl‐N‐(2‐cyano‐2‐propyl)ketenimine, DKI, in benzene solution over the 61–92°C. range have been investigated by means of proton magnetic resonance spectroscopy for quantitative analysis of reaction mixtures. The NMR equipment used comprised a Varian Model 3311 spectrometer, operating at a fixed radio frequency of 56.445 Mcycles/sec. and equipped with the Model V‐K 3506 super‐high‐resolution field‐stabilizing unit and the Model V‐K 3507 slow‐sweep unit. The kinetic data obtained tally closely with those reported earlier for a nitrometric and ultraviolet spectrophotometric study of the thermal breakdown of 2,2'‐azobisisobutyronitrile, AZO, in the same solvent within the 60–80°C. range. Consequently the general mechanism assumed in interpreting the previous results for the AZO decomposition is confirmed. They also agree with all other comparable data available as well as expected. As a natural part of this study, it has been shown that NMR provides reliable and convenient methods of quantitative analysis of reaction mixtures when DKI or AZO is thermally decomposed. One variation of the analytical technique practiced involved comparison of the C^13^‐sidebands in the NMR spectrum of a major constituent of a mixture with the main spectrum from a minor constituent. This was especially valuable for settling the initial purity of the DKI decomposed and the extent to which side products such as isobutyronitrile, methacrylonitrile, and 2,3,5‐trimethyl‐2,3,5‐tricyanohexane were formed.