8
F. B. SHORLAND
double bonds are separated by single methylenic groups giving the
structure
—CH=CH · CH 2 · CH=CH—
e. Aoetyhnic Acids. Acetylenic acids are not commonly found, but
have been isolated from the seed oils of a few species. Tariric (octadec6-ynoic) acid is present in the seed oils of several species of Picramnia.
[cf. Hilditch (3)] Erythrogenic (octadec-17-ene-9,ll-diynoic) acid
(42) has been found in the seed oil of Onguekoa gore Engler (= Ongokea klaineana Pierre). Ximenynic or santalbic (octadec-frans-ll-en-9ynoic) acid occurs in the seed fats of several Ximenia and Santalum
species (43-45).
3. Branched-CJmin Fatty Acids
Although the naturally occurring fatty acids are generally straightchain compounds, the presence of branched-chain fatty acids is more
widespread than was earlier believed. It has long been known that
considerable amounts of isovaleric acid are present in the depot fats of
the dolphin and porpoise, but it is only recently that branched-chain
fatty acids have been found in animal fats, notably those of ruminants,
as well as in vegetable fats. The branched-chain fatty acids isolated from
ruminant fats consist of the odd series of
(+)-anteiso[CH 8 CH 2 CH(CHo) n COOH]
CH 3
acids from C 13 to C 17 , inclusive, and the odd and even series of
-CH 3
CH . (CH 2 ) n COOH | acids
CH 3
from C13 to Ci 8 inclusive. Acids with more than one methyl side chain
have also been reported in ruminant fats (46-48). In wool grease, the
range of (-)-)-anteiso* acids extends from C 9 to C 3 i (odd series only),
and iso acids from Ci 0 to C 28 , only the even series being represented
(49). The branched-chain fatty acids of tubercle bacilli and certain
other acid-fast bacteria include tuberculostearic acid, phthioic acid, and
mycolic acid. The first of these is known to be D-( — )-10-methylstearic
acid (50, 51) the second is a mixture containing a,/?-unsaturated
branched-chain acids from which has been isolated mycolipenic acid
(-f-)-2,4,6-trimethyltetracos-2-enoic acid (52) and mycoceranic acid
(—)-2,4,6-trimethyloctacosanoic acid (53). The mycolic acids are
* The term anteiso was introduced by A. W. Weitkamp [/. Am. Chem. Soc. 67,
447 (1945)] to indicate compounds with the methyl side-chain in the antepenultimate position.
F. B. SHORLAND
double bonds are separated by single methylenic groups giving the
structure
—CH=CH · CH 2 · CH=CH—
e. Aoetyhnic Acids. Acetylenic acids are not commonly found, but
have been isolated from the seed oils of a few species. Tariric (octadec6-ynoic) acid is present in the seed oils of several species of Picramnia.
[cf. Hilditch (3)] Erythrogenic (octadec-17-ene-9,ll-diynoic) acid
(42) has been found in the seed oil of Onguekoa gore Engler (= Ongokea klaineana Pierre). Ximenynic or santalbic (octadec-frans-ll-en-9ynoic) acid occurs in the seed fats of several Ximenia and Santalum
species (43-45).
3. Branched-CJmin Fatty Acids
Although the naturally occurring fatty acids are generally straightchain compounds, the presence of branched-chain fatty acids is more
widespread than was earlier believed. It has long been known that
considerable amounts of isovaleric acid are present in the depot fats of
the dolphin and porpoise, but it is only recently that branched-chain
fatty acids have been found in animal fats, notably those of ruminants,
as well as in vegetable fats. The branched-chain fatty acids isolated from
ruminant fats consist of the odd series of
(+)-anteiso[CH 8 CH 2 CH(CHo) n COOH]
CH 3
acids from C 13 to C 17 , inclusive, and the odd and even series of
-CH 3
CH . (CH 2 ) n COOH | acids
CH 3
from C13 to Ci 8 inclusive. Acids with more than one methyl side chain
have also been reported in ruminant fats (46-48). In wool grease, the
range of (-)-)-anteiso* acids extends from C 9 to C 3 i (odd series only),
and iso acids from Ci 0 to C 28 , only the even series being represented
(49). The branched-chain fatty acids of tubercle bacilli and certain
other acid-fast bacteria include tuberculostearic acid, phthioic acid, and
mycolic acid. The first of these is known to be D-( — )-10-methylstearic
acid (50, 51) the second is a mixture containing a,/?-unsaturated
branched-chain acids from which has been isolated mycolipenic acid
(-f-)-2,4,6-trimethyltetracos-2-enoic acid (52) and mycoceranic acid
(—)-2,4,6-trimethyloctacosanoic acid (53). The mycolic acids are
* The term anteiso was introduced by A. W. Weitkamp [/. Am. Chem. Soc. 67,
447 (1945)] to indicate compounds with the methyl side-chain in the antepenultimate position.