May, 1947 CH3MgI
COMMUNICATIONS TO THE EDITOR
1233
H+ PBrl + C1*OZ+ CHIC1*02Hw CHaC140Br
1
Cu2(C~&
CH3C140CN
HzO
CHaC"OC02H
EtOH
+CH,C'400Et H
The ester, after purification by distillation, was furnished by Dr. Anderson. The mixture of subjected t o thermal decomposition between 110 once-crystallized tuberculostearic acid (m. p. and 130'. Traces of carbon dioxide were removed 10.3-1 1.7') with approximately an equal amount from the carbon monoxide formed, and the car- of the synthetic Z-acid melted a t 11.0-12.4', bon monoxide was burned to carbon dioxide, while a similar mixture with the d-acid melted a t absorbed in 1 N sodium hydroxide, and pre- 19.4-20.1'. A mixture of the two synthetic acids cipitated as barium carbonate. The radioactivity melted a t 21.0-25.S'. Melting points were deterof the a-carbon atom in the pyruvate was 3180 mined also for the amides and the tribromoanilides counts/min./mg. C (12.9 disintegrations per of our 1-acid and tuberculostearic acid, singly and count). There was no detectable activity in the as mixtures. The respective values were 75.1carbon monoxide formed in 90y0 yield, or in the $6.3') 71.5-75.6' and 72.5-76.3' for the amides, trace of carbon dioxide formed. I t is found in the and 94.0-95.3', 94.5-95.4' and 93.9-95.5' for the acid obtained by hydrolysis of the pyrolytic resi- tribromoanilides. It thus appears to be estabdue. Without further kinetic studies, i t is diE- lished that tuberculostearic acid is the levorotacult to suggest a detailed mechanism, but i t is tory isomer of 10-methyloctadecanoic acid. clear that the evolved carbon monxide comes 75c; 82 yo from the carboxyl group of the a-keto-ester. RADIATION LABORATORY AKD M. CALVIN DEPARTMENT OF CHEMISTRY R. M. LEMMOS UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA RECEIVED APRIL22, 1947
C8H17CHOHCH3+ CsH17CHBrCH3+ $8.50" -31.3" -8.56' +32.1°
CH3 +0.31"
CH3 -7.04" 4-7.12"
-0.36'
THE SYNTHESIS OF TUBERCULOSTEARIC ACID
Sir: Tuberculostearic acid is one of the branchedchain acids isolated by Anderson1 and co-workers from acid-fast bacteria. From oxidation experiments Spielman2 concluded that the acid was 10methyloctadecanoic acid and prepared the dlform of this acid for comparison. The synthetic acid melted at 20-21'; the natural acid a t 1011'. The amides and tribromoanilides of the two acids had closely similar melting points. The natural acid was reported as optically inactive, but Spielman suggested that i t might nevertheless be an active form having a faint rotation and a lower melting point than the corresponding dlform. I n order to test this suggestion we have again synthesized dl-10-methyloctadecanoic acid by another method and have also synthesized pure d- and ' 1-10-methyloctadecanoic acids. These acids were purified by repeated crystallization : dl-form, m. p. 25.4-26.1'; d- and 1-forms, m. p. 13.0-13.5", [ a ]ca. ~ 0.05'. These data strongly indicate that tuberculostearic acid is one of the active isomers of 10-methyloctadecanoic acid. This conclusion was tested further by means of mixture melting point experiments using our active acids and their derivatives and samples of tuberculostearic acid and its derivatives kindly (1) Anderson and Chargaff, J . Bioi. Ckcm., 85, 77, (1929). (2) Spielman, ibid., 106, 87 (1034).
CsHi7yHCHzCOOH
92%
847,
+ CaHiiCHCHCOOCzHj + I
I
CH, - 2 . 3 4 " $2.33"
CHI -5.04' +5.02"
CH3 -4.06"
CH3 4-5.17" -5.16" 86 O1 CaHi7CH(CH2)zCO(CHz)sCOOCzH6---$ $4.08"
I
CHs
f0.22" -0. E o
86 7, CsHi7CH(CHz)sCOOCzHj +CsH17CH(CHz)8COOH I I CH3 +0.14" CH3 +0.09" -0.15" --o.05°
The scheme of synthesis is outlined in the accompanying chart. The first rotation value, [ a ] D , in each instance refers to the isomer derived from (+)-2-decanol. Configurational inversion and slight racemization occurred in the formation of the 8-bromodecanes and the dibutyl 2-decylmalonates: Rigorous purification by fractional crystallization of the less soluble active 2-decylmalonic acids, however, assured the antipodal puriky of all succeeding compounds in both series. FURMAN CHEMICAL LABORATORY F R A ~ X L IS.NPROUT VANDERBILTUNIVERSITY JAMES CASON SASHVILLE 4, TENNESSEE A . TI'. ISCERSOLL RECEIVED APRIL 5 , 1947
