Process for preparing glycol esters from olefinically unsaturated compounds

Claim 1

In a process for the production of monobasic carboxylic acid diesters of C2-C5 vicinal glycols by the oxidation with molecular oxygen of a C2-C5 olefinically unsaturated compound in the presence of a monobasic carboxylic acid and a variable valence metal cation selected from at least one member of the group consisting of tellurium, antimony, vanadium, gallium, arsenic, selenium and silver and at least one of bromine, chlorine, a bromine-containing compound yielding bromide ions during reaction or a chlorine-containing compound yielding chloride ions during reaction, said oxidation being conducted within an oxidation zone in the presence of a liquid phase reaction medium comprising the carboxylic acid, wherein oxygen and the olefinically unsaturated compound are introduced to the oxidation zone and are contacted with the liquid phase reaction medium therewithin and wherein a vapor stream comprising unreacted oxygen and unreacted olefinically unsaturated compound is withdrawn from the oxidation zone and recycled at least in part to the oxidation zone, the improvement which comprises: maintaining at least 55 mole percent of a third component in the vapor stream recycled to the oxidation zone, said third component being selected from at least one member of the group consisting of ethAne, propane, and carbon dioxide and concurrently maintaining the oxygen partial pressure in the vapor stream recycled to the oxidation zone at a level of at least 5 p.s.i.a. and not greater than R where: where R is the oxygen partial pressure in psia P is the total pressure of the recycled vapor stream y1 is the mole fraction of ethane in the recycled vapor stream y2 is the mole fraction of nitrogen in the recycled vapor stream y3 is the mole fraction of carbon dioxide in the recycled vapor stream y4 is the mole fraction of methane in the recycled vapor stream y5 is the mole fraction of propane in the recycled vapor stream