(partly with the collaboration of H. P. L. GITSELS).53rd Communication about derivatives of pyridine and gdnoline.From cracked distillates of Californian petroleum we isolated a mixture of basic nitrogen compounds distilling up to 125" at 1.5 mm. The part of this mixture of bases, which boiled up to 172.5" at 760 mm was examined very systematically. this mixture consists of homologues of pyridine. Next portion of boiling range 172.5-215" at 760 mm also consists of homplogues of pyridine; in this boiling range only three fractions were systematically examined.The portion of boiling range 215" at 760 mm to 147.5" at 30 mm was again examined systematically. Besides pyridine hornologues these fractions contain quinoline. isoquinoline and homologues of these compounds. The fractions boiling above 147.5" at 30 m m have not been examined; it is probable that these fractions contain numerous homologues of quinoline and isoquinoline. W e isolated in all 31 basic nitrogen compounds in the form of the picrates and -(or) picrolonates. All these bases, except one, belong to the pyridine, quinoline, or isoquinoline type. The following compounds were identified: all possible isomers of the monomethyl pyridines and of the dimethylpyridines; 2.3.6 and 2.4.6 trimethylpyridine; 4-ethylpyridine and three isomeric methyl-ethyl pyridines in which the methylgroup occurs in the 2-position (namely: 2,4-; 25-and 2.6) ; 2-ethyl-4-methylpyridine; quinoline. five isomeric methylquinolines (namely 2-, 3-, 4-, 7-, 8-) and 2.8-dimethylquinoline; isoquinoline; I-methyl-and 3-methyl-isoquinoline.Besides these compounds of which the structure could be identified, five bases of yet unknown structure were isolated. The base C&N (b.pt. about 147") and the two isomeric bases CsHiiN (b.pt. 157.6 resp. 167.5) and the base CioHisN (b.pt. 188") are probably pyridine homologues.The base CiiHiaN isolated from the fraction boiling a t 142.5-145" at 30 mtn is perhaps a trimethylpyrindane. Details are given about the hydrogenation of the mixture of bases by chemical and catalytic methods.
1.The nitrogen content of crude petroleum. A summary of earlier investigations into the content of combined nitrogen in crude petroleum, for the greater part dating from before 1900, is found in the work of E n g 1 e r -H 6 f e r 1). In their reports it is stated that the nitrogen contents are widely divergent for the various kinds of petroleum of different crigins and vary from 0.05 % or less to more than 2 %. For a number of Californian oils M a b e r y 2 ) found nitrogen contents varying between 0.91 and 2.39 %, determined by the D u m a s method; the K j e 1 d a h 1 method, however. gave much lower figures for the same samples, viz. from 0.25 % to 0.88 %. It is clear, therefore, that M a b e r y ' s data, often quoted in the literature, are not founded on a sound basis.
