Process for the preparation of dialkyl carbonates

In a process for the preparation of a carbonate by contacting a glycol carbonate of a 1,2-diol with 2 to 4 carbon atoms with an alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, allyl alcohol, cyclohexanol, ethylhexanol, benzyl alcohol and methyl-glycol to form the corresponding carbonate of said alcohol at a temperature between 50.degree. and 250.degree. C. in the presence of a catalyst, the improvement wherein a thallium compound is employed as catalyst which thallium compound is selected from the group consisting of thallium-I oxide, thallium-III oxide, thallium-I hydroxide, thallium-I carbonate, thallium-I acetate, thallium-III acetate, thallium-I bromide, thallium-I chloride, thallium-III chloride, thallium-I fluoride, thallium-I formate, thallium-I nitrate, thallium-I cyanate, thallium-I stearate, thallium-I naphthenate, thallium benzoate, thallium cyclohexylphosphonate, thallium-I hexahydrobenzoate, cyclopentadienylthallium, thallium methylate and thallium ethylate.