64 E. E. TURNER AND F. H. H. WILSON. 



contained not more than eight per cent, of water and less 

 than 025 per cent, of acetic acid). 



The above figures show that both glacial acetic acid and 

 dilute acetic acid give less methyl acetate than acid of a 

 moderate dilution. 



Having established the fact that, with a large excess of 

 acetic acid, dimethyl oxalate may be converted into methyl 

 acetate, it was important to find to what extent a reduc- 

 tion of the excess could be carried. An experiment using 

 one molecular proportion of dimethyl oxalate with two 

 molecular proportions of acetic acid and two molecular 

 proportions of water showed that an excess can be dis- 

 pensed with entirely, since on this occasion over eighty 

 per cent, of the desired conversion was effected. 



It is thus evident that the investigation requires extend- 

 ing in order to determine, among other obvious factors: 



(1) The optimum concentration of acetic acid for the 



conversion. 



(2) The correlation between this concentration and the 



existence of definite hydrates of acetic acid. 



(3) The extent to which the method is capable of extens- 



ion for the preparation of methyl esters generally. 



At this stage, it is sufficient to point out that pure acetic 

 acid is practically undissociated, and dilute acetic acid 

 dissociated to a measurable degree, and that a definite 

 hydrate, 2 H 4 2 , H 2 is known and corresponds to the 

 77 per cent, acid giving the best yield of ester. It should 

 further be pointed out that the formation of methyl acetate 

 "does not depend on its withdrawal from the system in 

 which it is produced, but is the result of the equilibrium 

 expressed by the equation : 



Me0 2 O.C0 2 Me + 2 Me. C0 2 H, aq. 



= H0 2 0. CO,H, aq. + 2 Me. C0 2 Me. 



It is therefore hoped that subsequent experiments may 

 throw some light on the mechanism of ester formation 

 generally. 



