372 Phelps and Hubbard — Ester ification of Succinic Acid. 



experiments differed from others in respect to the proportions 

 of the reagents and to supplementary treatment. 



In the experiments of series A of the table the alcohol used 

 was 99*5 per cent pure and this was charged with dry gaseous 

 hydrochloric acid to the amount of 10 grams to the liter. The 

 succinic acid was the pure acid of commerce. 



In the experiments of series B, the alcohol used was made 

 more nearly absolute than that used in series A by heating 

 99*5 per cent alcohol for an hour over fresh calcium oxide with 

 a return condenser, and distilling to a protected receiver open 

 to the air through a calcium oxide tube. In experiments (12), 

 (13), (14), and (15) succinic acid prepared pure by hydrolysis 

 of the ester in the presence of nitric acid was used, in the 

 others, the acid of commerce. The alcohol was charged with 

 dry hydrochloric acid to the amount of 10 grams to the liter. 

 In (16) and (IT) the alcohol was charged with dry hydrochloric 

 acid to the amount of 80 grams to rhe liter, and in experiment 

 (18) the alcohol originally charged with 80 grams to the liter 

 was reinforced by passing into the sideneck flask a rapid cur- 

 rent of hydrochloric acid gas, dried by passing through concen- 

 trated sulphuric acid in a bead tower of thirty centimeters 

 length, simultaneously with the charged alcohol vapor. 



An inspection of the yields obtained in the experiments of 

 series B, in which the more nearly absolute alcohol was 

 employed with experiments otherwise nearly similar of series 

 A in which alcohol of 99*5 per cent purity was used, show per- 

 haps a trifling advantage in favor of the slightly stronger alcohol. 

 Thus (12) of B gave 1 per cent more yield than (6) of A 

 though in the latter 25 per cent more of the charged alcohol 

 was used under conditions otherwise closely similar ; (13) of B 

 gave about the same yield as (7) of A, though in the latter 25 

 per cent more of the charged alcohol was used ; but the yield 

 in (15) of B with an increase of 16'6 per cent in the amount 

 of charged alcohol and 12*5 per cent in the reaction time was 

 a trifle less than that of (8) of series A. 



Upon examining the yields of experiments in which equal 

 amounts of the alcohol similarly charged were brought into 

 action with a given amount of succinic acid, it appears, as is 

 natural, that the amount of succinic ester produced increased 

 with the time of reaction. This inference becomes evident in 

 a comparison of experiments (1) and (2), (6) and (7), (8) and (9), 

 (10) and (11), (12) and (13), and (14) and (15). 



It appears also that the proportion of similarly charged alco- 

 hol, for a given weight of succinic acid, affects the yield of 

 ester — very markedly at first, but that the effect of increasing 

 beyond a moderate limit the amount of alcohol passed through 

 the apparatus in a given time is not so important. This effect 



