Abstract: A process for preparing silyl maleates, fumarates, succinates and phthalates comprising reacting an olefinic containing maleates, fumarates, succinates or phthalates with hydrogenotrichlorosilane in the presence of the platinum catalyst and then reacting the product thereof with methanol wherein the methanol is added slowly over a period of at least 6 hours to the intermediate product such that it is introduced beneath and into the liquid layer of intermediate product where most of the HCl that is formed by the reaction is removed by azeotroping it out with the methanol and water along with the HCl dissolved therein and removing the azeotrope as it being formed.