Thermal behaviour of some terpenoids

The terpenoids acetyl sitosterol, lupeol, acetyl diosgenin and stigmasterol were studied. Comparison of the thermogravimetric curves and the activatio n energies of the terpenoids suggested the following sequence of thermal st ability: acetyl sitosterol < acetyl diosgenin < lupeol < stigmasterol. The DSC curves allowed determination of the melting points and the degrees of p urity. Comparison of the TG and DSC curves revealed the presence of phase t ransitions without mass loss that were attributed to rearrangements in the terpenoid molecules.