gave 11.5, 12.1% (calcd. for three methyls, 1O.if,'/0), thus four terminal methyls (three branches) are indicated. Infrared spectra6 first indicated a carbon-carbon double bond, and quantitative hydrogenation resulted in absorption of one equivalent of hydrogen for a molecular weight of 423. Ultraviolet absorption spectra showed X maximum a t 217 mp, log c 4.03, whereas pure synthetic 3-methyl-2-nonenoic acid showed X maximum a t 219 mp, log e 3.92. Thus, it seems definitely established that this substance, for which we propose the name Czs-phthienoic acid, is an ru,&unsaturated acid. For the hydrogenated acid, [ c ~ ] ~4~- D2.8*, eq. wt., 421.6, n Z 5 D 1.4565. Thus, the high molecular rotation of phthioic acid fractions, which has previously been inexplicable, may now be attributed to the presence of unsaturation near an asymmetric center. Thus, there must be a branching alkyl in the y- or &position, probably in the yposition. This type of structure also explains the large change in optical rotation in going from acid to ester, and failure of the acid to betray its unsaturation by addition of halogen.2 The ultraviolet absorption spectrum of the hydrogenated acid ((228-phthianoic acid) has been compared with that of numerous synthetic branched-chain acids, but the absorption band due to carboxyl is weak (log c about 2) and broad, and traces of impurities niay have a large effect. I t is felt that these data cannot yet be interpreted with certainty, but the presence of alkyls at the cy- and @-positions seems possible. Both the natural product and model synthetic acids arc being studied further.
corresponding probably to around 60% purity. From a larger batch of 210 j i per mg. the following data were obtained :
(1) Lipmann, Kaplan, Novelli, Tuttle, and Guirard, J . B i d . Chcm., lW, 869 (1847); 186,236 (1950). (SO It.ploxr wad Lipmann, J . Bid, Clem., 174. 37 (la48).
(8) This group was supported by research grants from the National Cancer Institute, the U. S. Public Health Service, and from the Nutrition Foundation.
rM/mg.
Pantothenic acida 0.71 Adenosine4 0 91 Adenine, from U. V. absorption a t 260 mp 099 Ribose 1 14 Reducing sugar, after acid hydrolysi5 1.03 Phosphoriii 2.15 Sulfur 1.31 Cystine equivalent (= half cystine, after acid hydrolysis) 0.89 Glutamic acid
molar ratio
%
1 1 28
15.4 24 4
145 1 ri 1 11 3 (1 I Xti 1 26 1
c1 7 4.2
10.8
