| It is an object of this paper to provide a commercially feasible and economical process for producing nitrosamine-free lactam disulfide which has an application as sulfur donor in rubber vulcanization. According to the structure design, lactams were selected as the starting materials for the preparation of lactam disulfides. Due to the ease of synthesis and availability four lactams were screened and two of four lactams,γ-velerolactam andω-heptanolactam, were prepared firstly conversing cyclopentanone and cycloheptanone with hydroxylamine hydrochloride into cyclopentanone oxime and cycloheptanone oxime, then implying the Beckmann rearrangement of oxime with 20% oleum, in 81% and 77.5% overall yield, respectively. An improved process for preparation of lactam disulfides was investigated. It was charactered that excess of caprolactam was implied as acid acceptor so as to expel the contamination of other kinds of acid acceptor. Especially for the caprolactam disulfide, the optimum reaction conditions through orthogonal experiments were obtained as follows: the temperature 60℃, the mole ratio of caprolactam: S2Cl2 5:1, the reaction time 2.5h, under the conditions the reaction of caprolactam and S2Cl2 was carry out in a solvent of carbon 11(a high boiling point petroleum) and caprolactam disulfide was obtained with easy workup in 89.2% yield, recrystallized from ethyl acetate with a 129~130℃melting point and with HPLC purity more than 99%. For the purpose of lower cost, the process for recycling caprolactam hydrochloride was designed. The purity of related compounds were determined by GC or HPLC, structures confirmed by IR, 1H NMR and GC-MS, LC-MS.By addition of BLD, CLD and DTDM as sulfur donor to NR and IIR, the curing behaviour and the properties of vulcanizate before and after aging were investigated. DTDM can be substituted by BLD and CLD to improve the scorch safety and reversion resistance.
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