Deterrninat ion of Hexachlorocyclohexane in Impregnated Cloth JEROME GOLDENSON
AI\D
SAMUEL SASS
Chemical Warfare Service Technical C o m m a n d , Edgewnod .4rsencc/, Iff1
Hexachlorocyclohexane (666) has been found to be a powerful iii$ecticide and miticide, and is being tested in connection with a study of miticides for impregnating cloth. The object of the work reported here was to devise a method for determining 666 applicable to cloth impregnated with the insecticide and sufficiently rapid and simple to be performed by personnel with limited training. The procedure etolied consists in extraction of an average sample of cloth by acetone in a Soxhlet apparatus, dehydrochlorination of the extracted 666 with 0.3 S sodium hydroxide, and titration of the liberated chloride.
T
HE chemical, physical, and insecticidal properties of the mixture of hexachlorocyclohexanes called 666 have been summarized by Slade ( 5 ) . Crude 666 is an amorphous solid consisting mainly of four spatial isomers, designated as alpha (melting point 157.5-158' C.), beta (melting point 309"), gamma (melting point 112.5"), and delta (melting point 138-139'). T h e gamma isomer, called Gammexane, xhich is present to the extent of 10 to 12% in the crude material, is almost entirely responsible for the insecticidal action ( 5 ) . I n connection \T-ith the study of insecticides for impregnation in cloth being conducted a t Edgewood Arsenal, it was decided to investigate the value of 666 \?-hen incorporated in cloth. .41though it is believed that 666 may be too toxic to man for use in clothing, it has potential value in cloth for control of pests in stored products. To facilitate this investigation, a chemical analytical method applicahle to cloth impregnated TI-ith the conipound was needed. The method descrihed in this paper, involving extraction of the 666 by acetone, followed by alkaline dehydrochlorination ivith 0.3 -V sodium hydroxide, n-as found satisfactory for the puiyoie.
If only small amounts of 666 are known to be present, one of the more sensitive methods for estimation of chloride should be used for greater accuracy (1, 3, 4,6). Chlorinated Paraffin Used as Binder. Cut the cloth sample into 1-cm. squares and mix. Place a tveighed portion of cloth containing not more than 150 mg. of 666 in the thimble of a Soxhlet extraction apparatus, and add to the thimble about 10 ml. more of acetone than is required to fill the thimble portion of the extractor. Extract for 2 hours, and remove the flask of the extractor while most of the acetone is in the thimble portion of the apparatus. Carefully evaporate the extract contained in the flask to a volume of 10 t o 11 ml. Add 15 ml. of approximately 0.3 S sodium hvdroxide solution and attach the flask t o a reflux condenser. Reflux foi 2 hours, cool, and estimate the chlorides contained in the flask by the Volhard titration method. Run a blank under the same conditions on cloth containing the sanie amount of chlorinated paraffin as in the sample. Correct the sample titration for the blank titration and calculate as in thp preceding paragraph. EXPERIMENT.&L
666 is stable in concentrated nitric acid, from vhich it can be recrystallized ( b ) . It is n l ~ ostable at high temperatures but in the presence of alkalies, such as dry lime or lime water, it loses hydrorhloric acid a t ordinary temperatures, giving a mixture of the isomers of trichlorohenzene. The beta isomer of 666 is the most resistant to alkaline dehydrochlorination. Tests xere first carried out to determine d i e t h e r the follon-ing
REAGENTS AND 3lATERIALS
St'andard solutions of sodium hydroxide, sulfuric acid, silver nitrate, and potassium thiocyanat,e. rlcetone, C.P. Crude 666 receiyed from Hooker Cheniical Co. containing 73.3270 chlorine or 100.245 as CsHbCls. This material was used as received, since all impregnations w r e done n i t h the compound in this condition. Undyed cotton herringbone txill cloth. Binding agents, such as chlorinated paraffin (C. 8.Army Spccification K O .4-503-127B) and polyvinyl alcohol. Emulsifying agents, such as Sacconol XR, Span 80, and T m e n 80.
Table I. :iample Taken
hlkaline S o l n t i ~ i n Used
Jf 0.
PROCEDURE
145 145
T h e detailed alkaline deli>drorhlorination procedure.< irliich \\-ere found to yield optimum results are as follonx:
162 159 150
Interfering Binders Such as Chlorinated Paraffin Absent from Cloth. Cut the cloth sample into 1-em. squares and mix to make the sample more homogeneous. Place a weighed portion of the clot'h containing not more thah 150 mg. of 666 in the paper thimble of a Soxhlet extraction apparatus and add 15 ml. of 0.3 LY sodium hydroxide solution to the flask. .kid to the thimble about' 10 ml. more of acetone than is required to fill the thimble portion of the extractor. Extract and reflux for 2 hours, remove the flask from the apparatus, cool, and estimate the chlorides in the solution contained in the flask by the T'olhard titration method. Calculate the 666 content as follon-s:
S;
Alkaline DehJ-clrochlorinationof 666
182 151 149 155 167 171 155 154
666 = (nil. of AigSOi\(normality of AgXO,, (!1.695) __ -ample n eight 320
0 . 1 .$' S a O H (40 m l . ) 0 . 1 S K a O H (35 nil ) T alcohol (10 ml.), 0 . 5 S alcoholic KOH ( 2 5 nil.) 0 . 1 S S a H C O s (50 nil ) alcohol (10 ml.) 0 . 1 N Ka.OOCCH8 (50 nil.) alcohol (10 nil.) 0 . 1 S S a O H (35 inl.) alcohol (10 ml.) 0 . 1 -Y SazCOs (50 1111 ) T alcohol (10 m l . ) TYater 110 nil.) Dvridine (15 .. nil.) 0 . 5 S S a H C O J (15 mi.) + alcohol (10 nil.) 0 . 5 S S a . O O C C H 8 ( 1 5 nil ) alcohol (10 nil.) 0 . 4 5 S a A r O ? (15 n i l ) alcohol (10 1;il ) 0 . 3 S S a O H ( 1 5 1111 ) + alcohol (10 nil.) 0 . 3 .V S a O H (15 i i ~ 1 . j aretone (10 ml.)
+
+
+
+
+
+
666 F o u n d By Vullinrd Iqeflux By acid-base estimation of titrarion chlorides Time CI ifours 7% 13 3 1 44.7
1
84.3 98.2
8i 5
1
1
,..
75.0
1
9.3
7
9:
..
2
88.1
86 3
2
90.1
82 1
2
... ...
i o .8
2
....
7
...
b3.i
2
, 2
86 6
14 5
97.95
S i 1
...
97.3
V O L U M E 19, NO. 5, M A Y 1 9 4 7 Table I f .
dlkaline Deh\droc.hloriiiatioii of 666 i n Presence of Chlorinated Paraffin
('hlorinared p:11 ;If-
ti66
61)
32 1
lteflux .\Ik:iiiiir > i i i i i r i o i : l i e d 'l'iiile
666 Found R y \.
