196 I. K. and M. A. Phelps — Use of Zinc Chloride. 



table where only one gram of zinc chloride was used, the rins- 

 ing with cold water before neutralizing with sodium carbonate 

 was omitted. In experiments (4) to (10) the 40 cmS of alcohol 

 heated with the succinic acid contained l - 25 per cent of hydro- 

 chloric acid gas, while absolute alcohol in amounts recorded in 

 the table distilled into this mixture heated at 100° to 110°. 

















Succinic ester 





s 



uccinie 





-A.lcoliol 



Reaction 





_ A _ 







acid 



ZnCl 2 



with HC1 



time 



Theory 



Found 



per 



No. 



grm. 



grm. 



cm 3 



per cent 



hr. 



min. 



grm. 



grm. 



cent 



(1) 



50 



10 



200 







2 



30 



73-7 



66-90 



90-8 



(2) 



50 



10 



200 



1-25 







50 



73-7 



71-25 



96-7 



(3) 



50 



1 



200 

 160 



1-25 

 



-- 



45 



73-7 



69-40 



94-2 



(4) 



50 



10 



40 

 160 



1-25 

 



4 



-- 



73-7 



69-70 



94-6 



(5) 



50 



10 



40 

 60 



1-25 

 



-- 



45 



73-7 



72-00 



97-7 



(6) 



50 



1 



40 

 60 



1-25 







-- 



20 



73-7 



53-15 



72-1 



(?) 



50 



1 



40 

 160 



1-25 

 



-- 



55 



73*7 



52-05 



70-6 



(8) 



50 



1 



40 

 160 



1-25 

 



1 



-- 



73-7 



70-30 



95-4 



(9) 



50 



1 



40 

 160 



1-25 

 



-- 



45 



73-7 



71-78 



97-4 



10) 



50 



1 



40 



1-25 





50 



73-7 



71-88 



97-5 



From an inspection of the results in the table, it is evident 

 that in presence of zinc chloride to the amount of ten grams 

 with the proportions of succinic acid and alcohol given in the 

 table, a fair yield of succinic ester is possible. Introducing 

 hydrochloric acid and shortening the time of the reaction tends 

 to increase the yield as shown by (2). Reducing the amount 

 of zinc chloride present gives satisfactory results, as is clear by 

 comparing (5) with (9) and (10). Although the amount of 

 alcohol present in (6) and (7) during the reaction is double that 

 theoretically required to esterify the acid present, it is not 

 sufficient for the esteritication under the conditions of the 

 experiments. The simplest conditions of all those given in 

 the experiments where a yield is satisfactory are those under 

 which (8), (9), and (10) were made. 



Hence, it is clear that in presence of zinc chloride diethyl 

 succinic ester is easily obtained in large amount closely approx- 

 imating that theoretically possible from a known amount of 

 succinic acid. This is most easily done by heating at a tem- 

 perature about 100° succinic acid with alcohol containing a 

 small amount of hydrochloric acid in presence of zinc chloride 

 in small quantity, while gaseous alcohol is driven into the 

 mixture. 



