The first accelerator used in an anaerobic adhesive was tributylamine [45]. Saccharin was also found to be an effective accelerator [46] and the combination of saccharin and N, N-dimethyl-p-toluidine was particularly effective if properly stabilized [47]. A large number of patents have been issued on various accelerators and combinations thereof. N-Aminorhodanine (XLIX) [48], 1-acetyl-2-phenylhydrazine (VI) [49,50], benzenesulfo — nylhydrazide (L) [51], dibenzenesulfonamide (X) [52], and similar compounds have been disclosed.
The use of saccharin has been of particular interest and a number of compounds have been prepared that have a similar chemical structure and reactivity. The reaction of sulfuryldiisocyanate (LI) with acetic acid gives a disulfonamide that is an effective accelerator [53]. Similar reactions of p-toluenesulfonyl isocyanate (LII) and chlorosulfonyl isocyanate (LIII) can be used to prepare many different compounds which are active accelerators [54,55]. These methods allow the preparation of accelerators with improved solubility.