Phelps and Osborne — Esterification of Benzoic Acid. 47 



In the work given in Table III the arrangement of flasks 

 described above was made use of; and the ester was recovered 

 as stated above except in case of experiments (13) and (IT), 

 where the mass of impure ester was shaken in the separating 

 funnel with ice before neutralizing with sodium carbonate in 

 solution, and the strongly acid wash water was neutralized 

 with sodium carbonate before extracting with ether. In the 

 experiments of series A ethyl alcohol made as free from water 

 as possible was used, and in those of series B alcohol 88 # 8 per 

 cent pure. It was observed that ethyl ether could be detected 

 by its characteristic odor in the distillate, and the amount 

 seemed to be proportional to the quantity of sulphuric acid 

 used. From the results recorded it is evident here, also, 

 that the esterification goes on slowly. For, though a larger 

 amount of alcohol is used in experiment (5), 13*4 per cent less 

 of ester is obtained than in (4), where the time was more than 

 three times as long. Too great concentration of the mineral 

 acid is not desirable, and this becomes obvious when experi- 

 ments (8) and (9) are compared with (12) and (13), or when 

 (15) and (16) are compared with (17). For some reason, with 

 the absolute alcohol the greater concentration of the sulphuric 

 acid has diminished the yield 6 per cent from the theoretical 

 yield obtained under the other conditions, and witli alcohol of 

 88*8 per cent purity 8 per cent less of the ester is obtained. 

 In experiments (13) and (17) the mass of sulphuric acid was 

 removed by shaking first with ice before neutralizing with 

 sodium carbonate. It is interesting to note that in a given time, 

 as is seen in experiments (5) and (7), that with a smaller 

 amount of alcohol and twice as much sulphuric acid the ester 

 produced is 11 per cent greater; in experiments (7), (8), and (9) 

 it. is interesting to see that with the same proportions of all 

 reagents the increase of time is alone enough to completely 

 esterify all of the benzoic acid. In comparing (11) and (14) it 

 is seen that the vacuum fractionation seems to have been 

 advantageous. From the experiments of series B, where a 

 larger amount of 88*8 per cent alcohol was used with 2 grm. 

 of sulphuric acid, the yield is almost 6 per cent poorer than in 

 the cases where, with other conditions remaining the same, it 

 was theoretical, and 8 per cent poorer where the larger masses 

 of sulphuric acid were used. 



Although the impure ester was always treated with an excess 

 of sodium carbonate and the shaking vigorous and prolonged 

 for some minutes to neutralize all acidic substances, it was 

 sometimes found that the ester held a small amount of benzoic 

 acid. This showed itself as a residue in the flask from which 

 the ester was distilled under diminished pressure. It was 

 identified by the melting point, 121°, after recrystallizing from 



