Theoretical study on the thermal decomposition of thiourea

Thiourea, under thermal condition, undergoes isomerization to carbamimidothioic acid intermediates which then decompose to two pairs of products via elementary reaction steps, including ammonia/isothiocyanic acid, and hydrogen sulfide/carbodiimide. Consistent with experimental results, theoretical studies from both MP2 and DFT calculations indicate that other two possible products, i.e., thiocyanic acid and cyanoamine, with much higher activation energies, are therefore difficult to form.