Xug. 20, 10%
DEXTROPIMARINAL IN COMMERCIAL GUMROSIN
4087
u.s. DEPARTMENT O F AGRICULTURE'] The Occurrence of Dextropimarinal and Isodextropimarinal in Commercial Gum Rosin [COXTRIBUTION FROM THE NAVAL STORES STATION,
BY EDWARD z ? l C c . ROBERTS AND
KAY
v. LAWREXCE
RECEIVED DECEMBER 5 , 1955 It is shown here that dextropimarinal, an aldehyde present in P . silnestris, but not previously reported t o be ill 1'. pelustris or I-'. elliotti, is present in commercial gum rosin derived from the latter sources. Previous reports on the aldehyde coniponents of various rosins and resinous extracts leave the reported occurrence of isodextropirnarinal in doubt. However, it is demonstrated here that isodextropiinarinal is present in gum rosin, 3s previous authors have indicated.
Harris and Sanderson2isolated an aldehyde from
P. palustris and P. elliotti (P. caribaea) which was thought to be identical with cryptopinone, a carbonyl compound isolated from P. silvestris by Sorensen and B r ~ u n . The ~ former authors isolated isodextropimaric acid from the oxidation product of the aldehyde, concluded that the aldehyde was isodextropimarinal, and confirmed the previous supposition that this aldehyde and cryptopinone were identical by a comparison of their 2,4-dinitrophenylhydrazones. Later, in collaboration with B a r t ~ n Sorensen ,~ and Bruun proved cryptopinone to be dextropimarinal on the basis of a comparison of the 2,4-dinitrophenylhydrazone of the isolated aldehyde with authentic samples of the derivatives of both isodextropiinarinal and dextropimarinal, synthesized from the corresponding acids. Inasmuch as the two acids are well characterized, the aldehyde syntheses were straightforward, and the comparisons clearcut, there can be little doubt that cryptopinone is indeed dextropimarinal. Considering the fact that the occurrence of isodextropimarinal is thrown into some doubt and that dextropimarinal has not been reported in *Imerican naval-stores pine, the present investigation was undertaken. The presence of both dextropimarinal and isodexti2pimarinal in commercial samples of gum rosin (cn. 90% P. eZZiotti and 10% P.palustris) has been demonstrated by the isolation of the corresponding acids from mixtures of resinates obtained by the oxidation of the carbonyl fraction of gum rosin, using chromium trioxide under conditions sufficiently mild that only aldehydes would be expected to yield acids. In both cases the fractions in question were isolated using carbonyl reagents. That aldehydes were present in the carbonyl fractions was demonstrated by positive Tollens tests, chromium trioxide oxidation, and the fact that the infrared absorption spectrum showed two niaxima characteristic of aldehydes. (2695, 1'733 cm.-') .5 Dextropimarinal was shown to be present in the carbonyls isolated from rosin using Girard P rea(1) One of the laboratories of t h e Southern Utilization Research Branch, Agricultural Research Service, U. S. ,Department of Agriculture. Article not copyrighted. (2) G. C. Harris and T. F. Sanderson, THISJ O U R N L . 7 0 , 3870 (1948). ( 3 ) N. A. Sorensen and T Rruun, Acta Cheiii. S r n n d . . l , 112 (,1947). ( 4 ) D. H. R Barton. T. Bruun and S . A Sorensen, .4c/o C h e m . 5 r i 1 ~ d 5, , 1 3 i 6 (1931) f i ) fa) 1,. J . Bellarny, " T h e Infrared Spectra o f Complex Rlole culeb," John \viley 'rnd S
