Phelps and Eddy — Hydrobromic Acid. 285 



pared with (23), but even with the largest amount, as in 

 i r Table II. the yield of ester is greater than when no zinc 

 :: : mide was used under conditions otherwise similar as in (5) 

 and G >f Table I. The temperature exerts a decided influence 

 here, again, in the presence of different amounts of zinc bro- 

 mide, as is seen in experiment 2), 3) and (5 ) when compared 

 with each other, and the same is seen when experiment (15) is 

 compared with (16), also when (17)" is compared with (18). 

 The same effect of temperature is not seen when zinc bromide, 

 as second catalyzer, is present in such large amounts as found 

 in experiments (19 . (20 and 21) when compared with each 

 other, alsc in 22 , 23 and 24 when they are compared with 

 each other. The rate of flow of the alcohol seems to have a 

 similar influence in presence of the second catalyzer that it had 

 in the presence of hydrobromic acid alone. Experiments (2) 

 and (6) show that, as do also (16) and (17). 



In Table III are given results which show the action of 

 hydrochloric acid either alone as catalyzer, or with zinc chlor- 

 ide, i£ second catalyzer in esterifying at different tempera- 

 tures benzoic acid. It is clear from an inspection of results 

 that raising the temperature retards the esterification of benzoic 

 acid by means of hydrochloric acid and zinc chloride, as it does 

 the esterification of benzoic acid by means of hydrobromic acid 

 and zinc bromide. In the work for the former paper the influ- 

 ence of temperatures as high as 125° was studied. No marked 

 effects at this temperature appeared. Attention was called 

 there to the difference in esterification produced by varying 

 the amount of the catalyzer, the amount of alcohol, and the 

 time of action. 



Table in. 





Ben- 





Alcohol 



Time of 



Benzoic ester 





Boic 



acid 

 grm- 





with HC1 



Tr'^pera- action 



toure * v 



hrs. min. 





__^ 





ZnCl a 

 grm. 



The: iv 

 grm. 



Found 

 grm. per ct. 





cm 3 perct. 



1 



5 







200 1-25 



100°-I10° 1 40 



61-48 



37-96 61*74 



- 



50 



.. 



200 1-25 



125°-150° 2 20 



61-48 



24-65 40-09 





1 



10 



200 I-2S 



100°-110° 2 10 



61*48 



58-33 94-88 



- 



50 



10 



200 1-25 



125°-150° 2 .. 



61-48 



50*56 82-24 



In all the experiments of Table III, in (4) and (24) of Table 

 II aud in 1 of Table I. the alcoholic distillate was collected in 

 four portions and the amount of mineral acid was determined 

 in each portion by titrating the diluted distillates with stand- 

 :- ; -odium hydroxide solution in the presence of phe- 

 n : lphthalein as an indicator. The amount of mineral acid 

 left in the flask from which the alcohol, charged with 

 hydrochloric or hydrobromic acid, was distilled, was similarly 



