- 56 - 
V7ith another 10-15 cc. portion of hot CCI4. (This trcatncnt removes 
all the CHC1 3 fron the resins.) The CHCl 3 extract is usually complete- 
ly soluble in CCl*. If snail quantities of insoluble material are 
present, the purification procedure described later will eliminate 
then. However, if a large quantity of insoluble residue should remain 
when the extract is dissolved in the first portion of CCI4, it should 
be filtered off and thoroughly washed with further portions of hot 
solvent, after which the filtered solution plus washings should be 
treated as described above for the removal of CHCl . 
"Acid exactly 25 cc. of CC1. and heat gently to completely dis- 
solve the extract. Cool the flask in an ice bath for several minutes 
and seed with a few crystals of rotenone-carbon tetrachloride solvate 
if necessary. Stopper the flask and swirl until crystallization is 
apparent. If at this stage only a small quantity of crystalline mater- 
ial separates, add an accurately weighed quantity of pure rotcnone, 
estimated to bo suff icier t so that the find result, expressed as pure 
rotcnone, is at least 1 gram. Then warm to effect complete solution, 
and again induce crystallization. At the sane tine prepare a saturated 
solution of rotencne in CC1 4 for washing. Place the flasks containing 
the extract and the washing solution in an ice bath capable of main- 
taining a temperature of C. and allow to remain overnight. 
"After 17-18 hours in the ice bath, rapidly filter the extract 
through a weighed Go^ch crucible fitted with a disk of filter paper, 
removing the flask from tho ice "oath only long enough to pour each 
fraction of extract into the crucible. Rinse the residue of crystal- 
line material from the flask and wash under suction with sufficient of 
the ice-cold saturated solution (usually 10-12 cc.) to renovo the ex- 
cess mother liquor. Allow the crucible to remain under suction for 
about 5 minutes and then dry to constant weight at 40° C. , which usually 
requires about an hour. The weight obtained is the "crude rotenonc- 
c:.rbon tetrachloride solvate." 
"Break up the contents of the crucible with a spatula, mix 
thoroughly, and'weigh 1 gran into a 50 cc. Erlonneyor flask. Add 10 
cc. of alcohol that has previously been .saturated with rotcnone at room 
temperature, swirl the flask for a few ninutes, stopper tightly, and 
set aside for at least 4 hours, preferably overnight,, at the same tem- 
perature. Filter on a weighed &o"'ch crucible fitted with a disk of 
filter paper. Rinse tho crystalfi fron the flask and wash under suction 
with a solution of ethyl alcohol saturated with rotcnone at the temper- 
ature of recrystallizatioa $5-10 oc. will usually be required). Allow 
the crucible to remain under gj&etion for 3-5 minutes and then dry at 
105° C. to constant weight, Krhtch should be effected in 1 hour. 
"Multiply the weight, expressed in grans, by the weight of the 
crude rotenone-carbon totrpkchloride solvate, and to tho product add 
0.07 gran, which represents the correction for rotenone held in solu- 
tion in the 25 cc. of CC1. used in crystallization. If any pure ro- 
tenone has been added, «aS*j*aciS Its weight from the value obtained. 
LIBRARY 
STATE PLANT BOARD 
