DECOMPOSITION OF DIMETHYL OXALATE BY ACETIC ACID. 63 



THE DECOMPOSITION OP DIMETHYL OXALATE 

 BY AGE TIC AOID, 



By E. E. Turner, b.a., d.Sc, a.i.c, and P. H. H. Wilson. 



[Read before the Royal Society of N. S. Wales, July 6, 1921.'] 



The difficulty attending the preparation of pure methyl 

 acetate suggested the desirability of investigating the 

 action of acetic acid under various conditions upon dimethyl 

 oxalate, since the latter may be obtained in a state of 

 purity starting from commercial methyl alcohol, even when 

 this product contains ethyl alcohol, whilst methyl acetate 

 cannot be prepared without a preliminary purification of 

 the alcohol through dimethyl oxalate. 



It was thought probable that slightly diluted acetic acid 

 would react with dimethyl oxalate to give a sufficiently 

 large yield of methyl acetate to render the method useful 

 in the laboratory as a means of obtaining small quantities 

 of methyl acetate such as are frequently required for 

 physico-chemical work. In practice, the method is even 

 better than was anticipated; with sixty-five to seventy- 

 five per cent, acetic acid, dimethyl oxalate is very com- 

 pletely converted into methyl acetate. 



The results of a few initial experiments are given below: 



Percentage concentration Molecular proportions Percentage yield of 

 of acetic acid. of water. methyl acetate. 



100 



95 1 6 



80 4 40 



77 5 70 



70 7 83 



65 9 76 



58 12 64 



Method: One molecular proportion of dimethyl oxalate 

 heated under reflux with five molecular proportions of 

 glacial acetic acid and the appropriate quantity of water 

 for three hours; the prolucts fractionated twice, and the 

 methyl acetate formed analysed by the usual methods. (It 



