S T U D I E S involving the initial stages of a u t o x i d ation of u n s a t u r a t e d f a t t y acids have i n d i c a t e d t h a t oxygen m i g h t a d d d i r e c t l y across the double b o n d (1,2) or at the " a c t i v e " methylene g r o u p s (3, 4, 5) a d j a c e n t to the double bond. F a r m e r and co-workers (6, 7) have shown t h a t oxygen a d d s across the double bonds in a c o n j u g a t e d system. However, tile initial point of a d d i t i o n to a n o n c o n j n g a t e d system is still open to question, t I i l d i t c h a n d co-workers (1, 2) believe that oxygen a d d s to the double bond, the b o n d shifts a n d h y d r o p e r o x i d e s are formed. ()n the other hand, B e r g s t r o m (3) a n d F a r m e r and eoworkers (4) suggested t h a t o x y g e n a d d e d d i r e c t l y onto the active m e t h y l e n e g r o u p a n d f o r m e d h y d r operoxides at t h a t point. F a r m e r (8) has r e c e n t l y modified this meehanism and suggested t h a t oxygen m a y a d d to the double b o n d m o l n e n t a r i l y before f o r m i n g h y d r o p e r o x i d e s at the active m e t h y l e n e groups.I t would seem t h a t b y c o m p a r i n g the results obt a i n e d from the s i m u l t a n e o u s o x i d a t i o n a n d h y d r o g enation of p u r e n o n e o n j u g a t e d a n d c o n j u g a t e d linoleie acid it might be possible to d e t e r m i n e the site of hyd r o p e r o x i d e formation. Ill the p r e s e n t p a p e r such comparisons were made with the use of A:','2 a n d A~o, ~2 m e t h y l linoleate a n d • ~-" a n d ~o , ~ linolcic or alkali c o n j u g a t e d linoleic acid. ExperimentalPreparation of Malerials: All m a t e r i a l s were prep a r e d aecording to metho(ls a l r e a d y d e s c r i b e d in the l i t e r a t u r e . The A'-'. r, linolcie acid or its m e t h y l ester was p r e p a r e d f r o m corn oil ' a c c o r d i n g to the m e t h o d of Rollet (9), the alkali e o n j u g a t e d linoleic acid was p r e p a r e d a c c o r d i n g to the m e t h o d of H o h n a n a n d E l m e r (10) and the A~", ~ linoleic acid or its m e t h y l ester was p r e p a r e d from d e l l y d r a t e d castor oil 5 acc o r d i n g to the metllod of Von Mikusch (11). The iodine value of tile A 9, ~ linoleic a n d the specific a b s o r p t i o n coefficient of tile alkali c o n j u g a t e d a n d the A~o,~2 linoleic acid i n d i c a t e d t h a t t h e y h a d a p u r i t y of 98 and 97% of the theoretical vahte respectively.Oxidation Procedure: Two o x i d a t i o n p r o c e d u r e s were used. I n one, A 9' ~2 or • ~2 m e t h y l linoleate was oxidized in a closed system at 30~ The a p p ar a t u s was s i m i l a r to the semi-micro h y d r o g e n a t o r shown in F i g u r e 1 except that the flask a n d b u r e t t e of the l a t t e r were smaller. A 200 ml. flask was con-x The subject ma~ter of this paper has been undertaken in cooperation with the Office of Naval Research." The opinions or conclusions contained in this report ...

Pyrroles and Related Compounds. Part X1V.t The Structure and Transformations of Oxophlorins (Oxyporphyrins) * By A. H. Jackson, G. W. Kenner," and K. M. Smith, The Robert Robinson Laboratories, The University ofBlue oxophlorins are relatively strong bases and accept one proton ( o n nitrogen) to form green monocations; addition of a second proton (to the oxo-group) occurs in strongly acidic media to afford the dications derived from the tautomeric hydroxyporphyrins. Oxophlorins also form metal complexes derived from the hydroxyporphyrin structure, and these compounds are fairly strong acids. Several alkyl and acyl derivatives of the hydroxyporphyrin structure are described. The ferrichloride complex of one oxophlorin has been degraded to glaucobilin-IX pdimethyl ester through the pure verdohaemin.Liverpool OXOPHLORINS (I) are intermediates in the synthesis of porphyrins from b-oxobilanes, described in the preceding Paper. It was apparent that these compounds are congeners of the oxyporphyrins,' prepared long ago l y 2 to which the tautomeric hydroxy-structure (11; R3 = H) had been assigned, although Lemberg had suggested that in the free state the oxyporphyrin is probably present in the keto-form.' The ' oxyt Part XII, A

The pyrrole Ib has been converted by several routes into 5-carboxy-porphobilinogen (IIe), the lactam of which is easily decarboxylated to porphobilinogen lactam (IVc). Hydrolysis of the latter gives porphobilinogen (V).

The field ionization and electron impact mass spectra of eleven coumarins have been compared. In the field ion spectra thc molecular ions were the base peaks and structurally diagnostic fragment ions formed by direct cleavage were present, whereas the molecular ions were weak in the electron impact spectra and fragment ions formed by rearrangement were dominant. Crude coumarin mixtures obtained from natural sources have been successfully examined using field ionization and gas chromatography + field ionization mass spectrometry.

Hydroxytryfitamines. Part I I .