Practical, Economical, and Scalable Synthesis of Monoalkyl Oxalates.

The large-scale synthesis of several kinds of monoalyl oxalates, which are half-esters of dialkyl oxalates, under practical and environmentally friendly conditions is described by applying the selective monohydrolysis reaction of symmetric diesters that we reported previously. The most suitable conditions were examined for the kinds of base, equivalent, cosolvent, and reaction time for large-scale production of five kinds of monoalkyl oxalate, monomethyl oxalate, monoethyl oxalate, monopropyl oxalate, monoisopropyl oxalate, and monobutyl oxalate, which are among the most versatile building blocks, but the commercial availabilities are limited. The conditions are mild, simple, and environmentally benign, and the half-esters were produced in high yields, exhibiting high purities in only a few hours without requiring special equipment. Therefore, the synthetic advantage of this reaction is anticipated.