The synthesis of aliphatic bifunctional thioureas have been attempted using several nucleophilic displacement reactions. The first method involved treatment of an aliphatic diamine with ammonium thiocyanate, under two different sets of reaction conditions. The first set of reaction conditions utilized water as the solvent, while second employed acetone as the solvent. Both of the reactions utilizing l,2-ethylenediamine and ammonium thiocyanate did not afford the desired bis(thioureas). In particular, the crystalline solid obtained from the reaction carried out in water was 57.8 ± 0.05 % thiocyanate by mass. The second nucleophilic addition method involved the treatment of both 1,2-ethylenediamine and 1,6-hexanediamine diamine with silicon tetraisothiocyanate in anhydrous benzene. The product from the reaction of l,6-hexanediamine with silicon tetraisothiocyanate in anhydrous benzene was found to be 40.3 ± 2.07 % thiocyanate by mass. The third set of reaction conditions involved treatment of 1,6hexanediamine with silver thiocyanate in concentrated ammonium hydroxide. As a result of the presence characteristic thiocyanate IR absorbance peak at 2100 cm-1 in the product, it was found to contain thiocyanate ions. It was concluded that the product was composed of mainly the 1,6 hexanediamine thiocyanate salts. The final set of reaction conditions involved treatment of 1,6hexanediamine with silver thiocyanate and thiourea, in concentrated ammonium hydroxide. Upon analysis of the resulting reaction mixtures, it was determined that each fraction contained no thiocyanate anion or starting thiourea. Further work needs to be carried out in order to determine the products.
McEwen IV '91, Donald G., "Synthesis of Aliphatic Bis(Thioureas)" (1991). Honors Projects. Paper 26.