Process for the selective ortho-alkylation of phenolic compounds

In a process for the selective orthoalkylation of a phenolic compound having at least one orthopositioned hydrogen atom and having the general formula ##STR2## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 represent hydrogen atoms or aliphatic hydrocarbon radicals, by catalytically reacting the phenolic compound with a saturated aliphatic alcohol having from 1 to 4 carbon atoms, in the vapor phase, the improvement which comprises carrying out the reaction at at a temperature of from 300.degree. C. to 500.degree. C. with a molar ratio of phenolic compound to alcohol ranging from 1:1 to 1:15 in the presence of a catalyst consisting of manganese oxide, silicon oxide and one or more oxides selected from the group consisting of magnesium oxide, calcium oxide, strontium oxide and barium oxide, said manganese and silicon contained in the mixed oxide catalyst being present in such a proportion as to provide an atomic ratio of manganese to silicon ranging from 100:0.01 to 100:20 and said one or more oxides selected from the group consisting of magnesium oxide, calcium oxide, strontium oxide and barium oxide being present in such an amount as to provide an atomic ratio of magnesium to additive metals ranging from 100:0.01 to 100:30.