- 17 - 
Also in 1933 Geor^i and Telk (34) stuc'ied the extraction and crystal- 
lization of rcterone .arid sngfested a. method involving-- the wt^s of carlicn 
tetrac^-loride. They 3U,?sested n edifications to- the ether extraction meth- 
ods of both Roark (lOO) ar.d Pr.oolhaas (78.) but; considered that ev.->n v/ith 
the modifications thep.e nethods did not gi-"-e satisfactoiy results. One 
change introduced in'P-oark's metncd involved drying the root in a vacuum 
at 75° C. for 6 hours. They stated that the drying did not, chanf;e the 
amount of extractives ohtained, but believed that the presence of mcisture 
interfered with the crystallization of the rotenbne. The. method surcrssted 
by these authors for estimatinf? rotenone uning carbon tetrachloride is 
briefly as follows: 
Fifty grams of the finely-ground root is treated for 72 
hours (three active 8-hcur periods) in a Soxhlet with, carbon 
tetrachloride. The extract is concentrated until the solution 
begins to tnicken, and is allov/ed to cool and reeded if 
necessary. .The flask is allcwad to stand in the cold cabinet 
for 24 hcJirs. The crude solvate is filtered on a tared Gooch 
crucible and washed with 10 tp 15 cc. of ice-cold carbon 
tetrachloride. After standing in the air for 24 hours it 
is v;eit.hed. The filtrate from, the first crystallization 
is concentrated, cooled, and seeded. It is alDowed to stand 
in the cold cabinet overnight ar.d any additional crystalline 
material treated as i.iath the first crop. The total crystalline 
r -material is. treated with toiling alcohol, the solution cooled, 
and the separated: rotenone drieii at 100'-^ C. and weighed. ^ 
correction is rpade for the solubility of rotenone in alconol. 
The purity of the recrystallized. product is criecked by melting- 
point determinat-io'n. ' ' ~ 
These investigators tried acetcn'? and chloroform for ertraction followed 
by crj'-stallization from carbon tetracriloride . .The separatior^ „oi carbon 
tetrachloride-insoluble resinous material in the acetone extr.^cts inter- 
fered with the separation of the rotenone, and the use of f.iis solvent was 
not recommended. Chloroform proved satisfactory and extracted the rotenone 
in less time than did carton tetrachloride, but anV- saving of. time over 
direct treatnent with carbon tetrachloride seemed d.oubtful. The rotenone 
values obtained by the chloroform and carbon tetrachlbride methods were in 
close agreement. The- values by tha modified othe.r methods' were in general 
lower and were irregular. 
C-eorgi (30) in 1933 stated that carton tetrachloride had been 
substituted for ether in the estimation of rotenone. 
Spoon and Eov/aan ( 116 ) in 1933 described the method used by them 
for determining rotenone in derris root. This v;as essentially the method 
of Eoark with some modifications, such as longer crystallization and deter- 
mination of the melting point of the separated rotenone. The latter step 
was designed, not as a means of calculating the purity of the material as 
in the method of i^oolhaas , but as a checK on its identity and approximate 
purity. 
A procedure proposed by Takei, L'iya.jima, and Ono ( 118 ) ir 1933 was 
a close approach to a truly chemical method for rotenone. Since the method 
