Dec., 1945
2241
SYNTHESIS OF ORGANIC COMPOUNDS OF GOLD
[CONTRIBUTION FROM THE WnTH INSTITUTE OF APPLIEDBIOCHEMISTRY, AND THE DEPARTMENT OF AGRICULTURAL AND BIOLOGICAL CHEMISTRY, THEPENNSYLVANIA STATE COLLEGE]
The Synthesis of Some Organic Compounds of Gold BY CHARLES W. D E N K OAND ~ ARTHUR K. ANDERSON Several organic gold compounds were desired by.us for a series of experiments on the physiological ef€ectsof gold compounds.* Two types of compounds, gold alkylxanthates ROCSSAu and aliphatic gold thio acids KCH(SAu)COOH, were synthesized by procedures based on the methods outlined by Zeise, Scala and Biilman.' The gold alkylxanthates were prepared thus ROH
+ Cs2 + KOH --+ ROCSSK AuCb ROCSSAU + ROCSS6SCOR __f
-
The aliphatic gold thio acids were prepared as indicated
-
NarCOS
GHrOCSSK RCH(X)COONa HCl NHdOH RCHCOONa + RCHCOOH I I SSCOCiHs SSCOCnHi HCl AuCli RCH(SH)COONH4__+ RCH(SH)COOH
RCH(X)COOH
+
NH&-COC~HI MOH
RCH (SAu)COOM +RCH (SAu)COOM MCI
Table I lists the gold compounds prepared, together with their formulas, melting points and gold content, the gold content being an index of purity. PROPERTIES OF
In preparing the gold alkylxanthate a 10% solution of auric chloride (as HCl.AuC18.4HsO) was added dropwise to a 25% solution of potassium ethylxanthate with constant stirring. A three-fold excess by weight of ROCSSK was used. If an excess of auric chloride is used or if the GHsOCSSK is added to auric cHoride there is more difficulty in obtaining a pure product. The oily gold alkylxanthate was filtered off, washed several times with water and ether leaving a ycllow powder with a slightly fruity odor. The product was kept iu amber bottles to prevent fading due to light. The compounds are insoluble in water and the common orgdnic solvents. Yields are practically quantitative (97.-9870 of theoretical). Aliphatic Gold Thio Acids.-The appropriate a-halogen acids were used to prepare n-thiol acids using the method of Biilman" as outlined in the previous series of reactions. Forty eight grams of a-bromobutyric acid yielded 16 g. of a-thiobutyric acid, b. p. 120-123' a t 18 nun. (53% theoretical yield). The acid had a somewhat unpleasant odor and solidified after standing in the refrigerator a few hours. To a 10% solution of a-thiobutyric acid was added dropwise with constant stirring, a 10% solution of auric chloride, forming a light yellow flocculent precipitate, a-gold thiobutyric acid. If an excess of auric chloride is added the precipitate becomes dark brown. The yellow precipitate was washed several times with water and dried. Yields are practically quantitative. or-Gold thiobutyric acid forms a soluble sodium salt and an insoluble calcium salt. The acid is soluble in absolute ethyl, n-propyl, ipropyl, n-butyl, i-butyl and 95y0 ethyl alcohol; insoluble in ether, carbon tetrachloride, petroleum ether and carbon disulfide. At loo",0.055 g. dissolved in 100 ml. of water. By a similar method starting with monochloroacetic acid, a-thioglycolic acid was prepared with some of its salts. The potassium, ammonium and sodium salts of gold thioglycolic acid are soluble in water whereas the calcium and strontium salts are insoluble.
TABLE I ORGANIC GOLDCOMPOUNDS
Compound
Formula
M. p., OC.
Found
Gold %
Calcd.
Gold alkylxanthates 1 Methyl 2 Ethyl 3 %-Propyl 4 ;-Propyl 5 n-Butyl 6 i-Btltyl
CH:OCSSAu GH~OCSSAU CIH~PCSSAU C:HIOCSSAu CiHpOCSSAu C~HBOCSSAU
160 ca. 165-168 165-167 163-165 162-164 162 cn.
64.45 61.64 59.16 59.42 57.78 66.89
64.81 61.94 59.29 69.29 56.92 56.92
Gold thio acids 1 Strontium gold thioglycolate 2 a-Gold thiobutyric acid
(CHtSAuCOO)&r CHKHnCH(SAt1)COOH
240-280 187-1S7
60.61 61.40
59.53 62.24
Experimental Gold Alkylxanthate&-These compounds were prepared according t o methods of Zeise' and Scala." Potassium alkylxanthates were prepared by dissolving potassium hydroxide in the appropriate alcohol and adding carbon disulfide. All have a characteristic odor and pale yellow color, decompose on heating, and ate very soluble in water. (1) P u e n t address: Charlw W. Dcnko, 1st Lt., Sn.C., Medical Nutrition Lah., Chicago, Ill. (2) Denko and Anderson, J . Lab. Clin. Mad., 99, 110s (1944). (3) (a) Zcise, An%. der Phorm.. 16, 178 (1835): (b) Scala, Gars. chim. dol., 17, 78 (1887): (e) Biilman, An*., are. a51 (1905): 148, 120 (10MIL
Summary 1. The following organic gold compounds have been prepared : gold alkylxanthates, methyl, ethyl , n-propyl, i-propyl, n-butyl, i-butyl; strontium gold thioglycolate and a-gold thiobutyric acid. . 2. Some reactions and physical properties of these gold compounds are noted. CHAGRIN FALLS,OHIO, STATE COLLEGE, PENNSYLVANIA RBCBSVED AUGUST 24.1945
