The synthesis of p-toluenesulfonyl semicarbazide is carried out in two steps, using p-toluenesulfonyl chloride as the starting material, under catalytic and basic conditions. The specific steps are as follows:
(1) Using p-toluenesulfonyl chloride as the starting material, sodium sulphite as the reducing agent, and water as the solvent, the p-toluenesulfonyl chloride is reduced to p-toluenesulphite in the presence of an inorganic base, thereby yielding an aqueous solution of p-toluenesulphite;
(2) Add azodicarbonamide to the aqueous solution of p-toluenesulphonic acid salt obtained in step (1) and allow the reaction to proceed; stop the reaction when no further gas is released; the reaction temperature is 78–82 °C. After the reaction, cool, filter, wash and dry to obtain the target product, p-toluenesulphonyl semicarbazide.