459 
OH COOH 
Citrodiamide (symmetric?) Ct rar 
The motherliquor of the citramide (see below) was acidified 
with nitric acid and precipitated with alcohol. The citrodiamide 
is gained as a white crystalline powder’). Usually the 
compound is mixed with its ammoniumsalt. 
OH COOCH, 
NE 
Citric acid trimethylester . COOCH,.CH,.C.CH,.COOCH,. 
‘One part of citric acid was dissolved in one part of methyl 
alcohol and the solution saturated with HCl-gas. On cooling 
the ester crystallized and was purified by recrystallizing from 
methylalecohol. Purity controlled by melting-point. 
OH CONH, 
Citramide COON an cae 
Citric trimethylester was dissolved in 5 parts of strong ammonia 
(spec. grav. 0.88); soon the citramide precipitated and was 
recrystallized from water’). 
Diethylester of monoamide-citric acid 
OH CONH, 
Ne Bea be 
COOC,H,.CH,C.C.H,COOC,H 
preparation described on page 437; purity controlled by 
melting-point. 
5 
The action of these substituted citrates was compared with the 
action of other organic compounds, having none or only one car- 
boxyl group, but one or more hydroxylgroups. 
We choose for comparison : 
CH OH 
Me ee 
monoethylester of tartaric acid COOC,H, .CH . CH . COOH 
preparation of Merck. 
woamylalcohol CH, . 
CH, . CH, . CHOH 
x 
3 
CH 
') When no erystals of this substance are obtainable, it may last months before 
erystallization begins. 
*) BEHRMANN und Hormann, Berl. Ber. 17, p. 2684. 
