Phelps and Eddy — Hydrobromic Acid. 289 



chloric acid, which might be taken even in large amount, is 

 a more efficient catalyzer in the production of ethyl benzoate. 



It has been noted in previous papers on esterification and in 

 this paper also, that an increase up to a certain limit in the 

 amount of catalyzer present under given conditions has been 

 helpful in every case studied. The increase in the amount 

 of catalyzer beyond that limit is decidedly harmful, judging 

 from the amount of ester formed. This would appear to be 

 due to the fact that the catalyzers used, hydrochloric acid, zinc 

 chloride, hydrobromic acid, zinc bromide, and sulphuric acid, 

 have a strong affinity for water. It is also a fact, that each of 

 the catalytic agents used reacts with alcohol of themselves to 

 produce water, ethyl chloride being formed with hydrochloric 

 acid, ethyl bromide with hydrobromic acid, and, ethyl ether 

 with sulphuric acid. Consequently when they are present in 

 large amounts together with a high-boiling point ester, abso- 

 lute alcohol is not able to effect dehydration as completely as 

 is necessary for complete esteriiication. 



Hence it would seem, that to esterify a given organic acid 

 under most advantageous conditions for complete esterih'cation 

 it is necessary to determine experimentally the proper propor- 

 tions of alcohol, the time of action, the most efficient catalyzers, 

 and the most suitable temperature at which reagents and cata- 

 lyzers interact. It has been shown that concentration of mineral 

 acids as catalyzers does not control the esterification at the 

 temperatures studied, and, further, that the best conditions of 

 temperature for the formation either of ethyl chloride or of 

 ethyl bromide are not ideal ones for esterification. When 

 further experimental data upon this question are at hand it is 

 hoped that the real function of catalyzers in esterification will 

 be made known. 



