49 
these several esters. Solutions were prepared containing 10 cc. of the 
X 80 solution of each of these esters and 5 cc. of clear lipase. These 
were allowed to stand at 20 c C. for one and three hours, respectively, 
and were then titrated with X 50 sodium hydroxide. The following 
results were obtained: 
Cubic centimeters X 50 sodium hydrox- 
ide required. 
Per cent of hydrolysis. 
Time. 
8-iodopro- 
pionate. 
Acetate. 
Butyrate. 
0-iodopro- 
pionate. 
Acetate. Butyrate. 
1 hour 
1.3 
0.50 
1.6 
20.8 
8.0 
25.6 
3 hours 
2. 60 
. 65 
3.05 
41.6 
10.4 
48.8 
At the time that these observations were made on the ethyl 
/?-iodopropionate no ethyl propionate was at hand with which to com- 
pare it. It is evident, however, from these results and from what has 
gone before, that ethyl /3-iodopropionate is readily hydrolyzed by 
lipase and that the introduction of an iodine atom into the ft position 
in the molecule of ethyl propionate does not exert any retarding effect 
on the hydrolysis of the ester bv lipase, but if anything accelerates 
the hydrolysis somewhat. It still remains to be determined, however, 
whether any secondary decomposition of the /3-iodopropionic acid has 
occurred under these conditions, in which event two molecules of acid 
would result from the decomposition of one molecule of the ethyl 
y#-iodopropionate, thus: 
(1) , CHJ.CH 2 COOC 2 H 5 =CH 9 I.Cn o COOH-hC 0 H 5 OH, and 
(2) , GILA CH 2 COOH = CH 2 OHCH 2 COOH+ HI. 
It is obvious that were these changes to occur simultaneouslv the 
results with ethyl /5-iodopropionate given above would be too high by 
one-half. However, there is no great likelihood that the change rep- 
resented by equation (2) would take place with measurable rapidity at 
this great dilution/' 
Ethyl cyanacetate has also been compared with ethyl acetate in its 
conduct toward lipase, using X 20 solutions of the esters. At this 
dilution ethvl cvanacetate is slowlv hvdrolvzed even bv pure water. 
This change is a slow one, however, and in no way interferes with the 
study of its hydrolysis by lipase. In order to form some idea of the 
rapidity with which ethyl cyanacetate is hydrolyzed by lipase and 
with the view of comparing it with ethyl acetate in this respect two 
solutions were prepared, (1) containing 10 cc. X 20 ethyl cyanacetate 
and 5 cc. of clear lipase solution and (2) containing 10 cc. X 20 ethyl 
° See the work of Kastle and Reiser “On the Decomposition of the Salts of ATono- 
chloracetic and Monobromacetic Acids.” Am. Chem. Jour., XV, 471-493, 1893. 
