ANALYTICAL CHEMISTRY
1622 known, but in regular use the method has been found to give solvent contents repeatable usually within l%, absolute. ACKNOWLEDGMENT
Permission of the management of The Texas Co. to release the information embodied herein is gratefully acknowledged. An espression of thanks is also due N.A . Lapham and P. C. Brite of Port Arthur Works Laboratories for their valuable assistance in conducting this study, and to Rennie Pomatti of The Texas Co. Beacon Laboratories for his suggestion of the use of dielectric measurements for this analysis. LITERATURE CITED
(3) Freymann, M., and Freymann, R., Bull. soc. sci. Bretagne, 21, 19-27 (1946). (4) Hodgman, C. D., ed., “Handbook of Chemistry and Physics,” 33rd ed., p. 782, Cleveland, Ohio, Chemical Rubber Publishing CO., 1951. ( 5 ) Knoke, S., 2. Elektrochem., 43, 749-51 (1937). (6) Perumova, E. D., Trudy Gosudarst. O p ~ t Zavoda . Sintet. Kuuchuka, Litera B I V (Synthetic Rubber), 1935, 199-213. (7j Rzhekhin, V., and Pogokina, N., Maslobolno-Zhirozoe D e b , 15, NO. 1. 16-18 (1939). (8) Schaafsma, A., I I e congr. mondial petrole 2, Sec. 2, Phys., Chiin., Rafiinage, 879-82 (1937). (9) Seidell, a,,“Solubilities of Organic Compounds,” 3rd e d . , Vol. 11, p. 298, Ne% York, D. Van Kostrand Go., 1941. (10) Trioen, RI., Rev. intern. brass. et malt., 1948, 85-93. RECEIVED for review October 5, 1951. Accepted June 14, 1952. Presented
Asada, T., and Abe, XI., Oyo Butsuri, 12, 64-6 (1943;. ( 2 ) Fox, J. J., Oil and Coloto. Trudes J . . 91, 993-5 (1937). (1)
a t the X I I t h International Congress of Pure and .4pplied Chemistry, N e w T o r k , K . T., September 10 t o 13, 1951.
Estimation of Mixed Phenyl and Ethyl Mercuric Compounds DOROTHY POLLEY AND V. L. IIILLER Western Washington Experiment Station, Pnyallzcp, Wash.
’
Y an investigation of fungicides it became desirable to find a -method of determining ethyl mercuric and phenyl mercuric
compounds in formulations which contained one or both materials. The reaction of diphenylthiocarbazone (dithizone) with several organic mercurials (4)and two analytical procedures using this reaction have been reported (1. 2 ) . In an earlier publication ( 2 ) the nuthors described a direct determination of phenyl mercuric or ethyl mercuric compounds using the dithizone procedure. It is believed that the following equation given by Webb (4)for the reaction under somewhat different conditions represents the chemistry of the color formation.
+
+
+
C2HSHgCI (DzS)H OH- -C (DzS)HgC,Hj HLO (DzS)H represents diphenylthiocarbazone
+ CI-
Iii the method described, better precision was obtained with the sodium acetate-acetic acid buffer ( 2 ) , rather than in the neutral or alkaline pH range as indicated by Webb’s equation. Because the phenyl and ethyl derivatives form the dithizonates under like conditions, a modification is necessary to determine one in the presence of the other. With the method herein reported, a solution containing both the ethyl and the phenyl compounds ma>- be analyzed for each component. The procedure is based on the rapid decomposition of phenyl mercuric compounds to inorganic mercury (3),and the relative stability of ethyl mercuric compounds in hydrochloric acid. By shaking in 12 AT hydrochloric acid, as little as 7 micrograms of ethyl mercuric phosphate can be determined in the presence of 3600 micrograms of phenyl mercuric acetate. Conversely, a sample containing 200 micrograms of ethyl mercuric phosphate and 19 micrograms of phenyl mercuric acetate can be analrzed.
to wash down the sides of the funnel. The funnel i3 placed i c 9. Burrell shaker and set to shake gently for 15 minutes. Immediately after the shaking, 1 ml. of 20.0% hydroxylamine hydrochloride and 12 ml. of refrigerated redistilled water are added. The funnel is removed from the shaker, mixed by inverting, and 10 ml. of the dithizone reagent are added. The funnel is shaken vigorously for 1 minute. -411 except the last ’3 drops of the chloroform layer is drained into a second separator?. funnel which contains 20 ml. of 3 A: hydrochloric acid. The shaking is repeated, and the chloroform is transferred to a thire i funnel having 15 to 20 ml. of redistilled water and 5 ml. of pH 4.5 buffer ( 2 ) . Following the shaking and separation, the percentage transmittance is determined using an Evelyn photoelectric colorimeter set for 6 ml. with a 620 filter. The amount of ethyl mercuric compound present is found by comparing with a standard ethyl mercuric curve. This curve may be drawn from th? phenyl mercuric standard curve using the formula previously described, or from a series of ethyl mercuric standards carrieii through the regular procedure ( 2 ) . To find the amount of henyl mercuric compound present, the ethyl mercuric compounais first converted to equivalent phenyl mercuric by comparing the ethyl percentage transmittances witl? the standard phenyl mercuric curve. This value subtractea from the total micrograms calculated as phenyl mercuric give. the micrograms of the phenyl mercuric compound. DISCUSSION
I n this investigation ethyl mercuric phosphate, ethyl mercuric chloride, and phenyl mercuric acetate were used as representative of ethyl and phenyl mercuric compounds. Whitmore (5) states that the stability of the carbon-mercury linkage in organic mercury compounds varies widely in hydrochloric acid, Also. he lists the type equation for the reaction a3 follows: C6HSHgC1 f HCI + CsHc f HgClz
PROCEDURE
It wa3 noted in the previous article that ethyl and phenyl mercuric
The reagents are described in an earlier publication ( 2 ) . A 0.2- to 5.0-ml. aliquot of an aqueous solution of the sample is analyzed for the total of the ethyl mercuric and phenyl mercuric compounds by the dithizone procedure ( 2 ) . The total micrograms are found by comparison with the phenyl mercuric standard curve. The strength of the dithizone solution can be varied from 6 to 10 micrograms per ml. of chloroform to give a range of 1 to 100 micrograms of the ethyl mercuric plus phenrl . mercuric compounds. A second aliquot Containing sufficient ethyl mercuric compound to be within thk percentage 6ansmittance knge, but not ekceeding 1.4 ml., is measured into a 125-ml. cylindrical separatory funnel containing 2 ml. of 12 11’ hydrochloric acid. The funnel should be dry before addition of the acid. Care is taken to prevent any of the sample from touching the upper half of the funnel. Three milliliters more of 12 N hydrochloric acid are added. using the acid
Compounds can be identified qualitatively by their relative stability in 3 ,V hydrochloric acid (a). Taking this as a basis for separating the compounds quantitatively, various conditions n-ere investigated to determine how to decompose the phenyl mercury completely and leave the ethyl mercury intact. Ethyl and phenyl mercuric compounds were left standing overnight in 3 to 12 S hydrochloric acid. The acid n m then diluted with 1 ml. of hydroxylamine hydrochloride and sufficient water to give 18 ml. of 3.3 *V acid. The ethyl mercuric phosphate n-31 measured by the usual procedure ( 2 ) . Larger amounts of phenyl mercuric acetate were decomposed by the stronger acid (Table I). This advantage, however, was offset by the erratic and low value; of the ethyl mercuric phosphate alone in the 12 i\- acid. BJ- vary-
V O L U M E 2 4 , NO. 10, O C T O B E R 1 9 5 2
1623
ing the Irngth of time the samples stood in the acid, it n a s found that in a short time the 12 S acid still decomposed large amounts of the phenyl mercuric compound, but did not affect the ethyl mercuric (Table 11). From these trials the shaking for 15 minutes in 12 N hydrochloric acid was selected as the optimum condition for the separation. I n the presence of hydrochloric acid, phenyl mercuric compounds precipitate white curdy phenyl mercuric chloride. This may be taken as a rough estimate of the presence of considerable amounts of phenyl mercuric acetate. Gentle shaking of the separatory funiiels is believed to aid in dissolving the phenyl mercuric chlorides FO that hydrolysis takes place rapidly. In the more dilute hydrochloric acid solutions, the phenyl mercuric chloride does not appear to dissolve as readily and therefore does not hydrolyze. The cylindrical separatory funnel as specified because it fits better in the Burrell shaker. With this method small amounts of ethyl mercuric phosphate give consistent results in as much as 4000 niicrograms of phenyl mercury (Table 111). The phenyl derivative is completely decomposed, giving the mercuric ion ~vhichdoes not interfere. TKO drops of the dithizone solution are left in the funnels to be sure that none of the aqueous phase containing the mercury goes into rhe nest funnel. The mercury recovered from the 3 N acid in the first separatory funnel u-as within 3% of the amount calculated (Table IV). .In aliquot not greater than 1.4 ml. is designated because of dilution. When the concentrated acid is 11.7 S an increase of 0.1 nil. in the aliquot produces variable results. The over-all accuracy of the procedure for each component is 3% of the sum of the 2 parts unless this percentage is less than 2 micrograms. The accuraq- is better for sniall amounts of ethyl
Table I.
Effect of Acid Strength When Standing Overnight
Acid Used Sormality 3.5
6 0
9 12
2 hr.
y
0 1500 2000
Original CnHaHg, y 26
Found,
as CzHsHg, Av. y 27
0 2500 2900 3500 4000
Table I\’.
Original CzHaHg, y 35.2
Found, 8s CzHaHg, Av. y 35.5 35.2 35.4 36.1 35.2 36.5
26.4
26.4 26.3 27.0 26.8 27.5
RIercury from Deconiposition of Phenyl Mercuric Compounds
Phenyl AIercuric .kcetate. y 2647
Hg Recovered,
Hg Recovered,
Y
%
1596 1668
101 99
3650
2115 2106
97 87
4040
2450 2442 2383 2417 2442 2358
102 101 99 100
101 98
Table T-. .inalysis of 3Iixtures CsHaHgOAc, 1 per Mi. Calculated Found 3619 3685 3751 3650 2647 2719 2625 2703 2647 2596 681 650 146 151 147 150 21 21 19 22 19 21
(C&Hg)aPO4, Calculated 6.9 6 8 9.8 9.9 59 500 140 143 6.8 196 6.9
y
per AIL Found 8.7 7.8 10 2 10.5 60 825 145 139 7.2 198 7.2
30 >44 26
26 28 >48
-1
0
500 1000 0 125
Found, Original as CzHsHg, CzHsHg, Y Av. Y 26 26 30 >40 28
29 33 >47
Found, Found, Added Original as hdded Original as C ~ H ~ H KCzHaHg, , CzHsHg, CsHsHg, CzHbHy, CzHsHg, Y y Av. -1 Y I Av. y 0 26 26 3000 30 4000 >44 0 2000 3000
76
0 1000 2000
28
26 28 >44
LITERATURE CITED (1)
Gran, Gunnar, Saensk Papperstidn., 5 3 , 234 (1950).
(2) Miller, 1‘. L., Polley, Dorothy, and Gould, C. J., A x . 4 ~ . CHEM., 23, 1286 ( 1 9 5 1 ) .
1 3 ) Shiraeff, D. -4., A m . Dyestz6.f Reptr., 3 3 , 310 (1944). ( 4 ) Webb, J. L. A , ,
29 30 >39
30 min.
n
35 35 36 36
1 5 inin.
0 2600 3500 4000
26 26 26 27
10 n:in.
Y
mercuric conipounds in large amounts of phenyl mercuric compounds than for the reverse solutione, since the small amounts of 0 6 7 0 26 26 ethyl compound are actually measured and the small amounts of 3000 28 phenyl compound are determined by difference. Therefore, in 3500 >44 0 5 0 0 26 Variable a predominantly phenyl mercuric eolu3 t o 27 tion each compound will measure within 2 micrograms or 3% of its calculated Table 11. Effect of Standing Time in 6 Y, 9 .V,and 12 .VHCI amount, whichever is the larger (Table V). 6N 9 N 12 .v
600 1 hr.
Added CsHaHg, 0 50 260
10
-4dded CsHaHg Time 4 hr.
1\11. 17
Table 111. -4ccuracy of Procedure Added CeHsHg, 0 37 200 800 1700 3500
26 26 28 29
Bhatia, I. S.,Corwin, A. H., and Sharp, A. G., J . -4m. Chem. Soc., 7 2 , 9 1 (1950). ( 5 ) Whitmore, F. C., “Organic Compounds of Mercury,” iYew York. Chemical Catalog Co., 1921. RECEIVED for review April 26, 1952. Accepted June 16, 1952. Presented a t the Northr e s t Regional Meeting, AMERICAXCAEMICAL SOCIETY, Cor\.allis, Ore. June 20 and 21. 1952. Scientific Paper 1117, Washington Agricultural Experiment Stations, Pullman, Kash., Project 724
