Glyoxal sodium hydrogen sulphite addition compound reacts with 2,4-diaminopentane dihydrochloride to yield 5,7-dimethylhexahydro-l,4-diazepin-2-one, but glyoxal monohydrate reacts with 1.3-diaminopropane and 2.4-diaminopentane under alkaline conditions to produce more complex substances. Cyclohexane-I ,2-dione condenses with 1.3-diaminopropane to form 2.3.4.6.7.8-hexahydro-I H -I ,5-benzodiazepine, but di-imines formed from two molecules of dicarbonyl compound and one of diamine result from the reactions of 1.3-diaminopropane with benzil, camphorquinone, and isatin. Complex products are obtained from o-quinones and diaminopropane. 1,3-diketones and 1.3-diamines react to produce open-chain compounds formed from two molecules of ketone and one of amine. 2,3-Dihydro-I H-1.4-diazepine is apparently formed from malonaldehyde and ethylenediamine, but 1.2-diaminocyclohexane reacts with malonaldehyde to give 1,2-bis(2-formylvin~lamino~cycl o hexane.

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WHEN incremental constants for carbon, hydrogen, and double bonds, such as those of Eisenlohr,l derived from Lorentz-Lorenz molecular refractivites for aliphatic compounds, are applied to cyclic hydrocarbons, the values obtained (Rcalc.) are significantly different, in many cases, from those derived from M , dZ0, and nD20 (Robs.). In the case of aromatic compounds, for example, Robs. -RCalc., although 0 -& 0-2 for the benzene series, becomes about +2.5 for the naphthalenes if the constant for an isolated double bond derived from the aliphatic series is used. This deviation (the exaltation) increases with degree of condensation of rings.If the values for double bonds are omitted (which, in any case, probably have no validity outside the class from which they were derived), it has been found that Robs. -Rcalc, can be used to characterise ring systems.New constants for carbon and hydrogen were derived from the two homologous series of cyclohexanes and decalins, on the assumption that Robs. -Rcalc. = 0.

London E l 5 4LZ 2.3-Dihydro-5.6-diphenylpyrazine reacts with alcoholic alkali to form 2.3-diphenylpyrazine and 5,5'.6,6'-tetraphenyt-2,2'-bipyrazinyl, not 2,3.6,7-tetraphenyl-I ,4,5,8-tetra-azabiphenylene. 2.3- pyrazine undergoes an analogous reaction, but 2,3-dihydro-5,6-bis-(p-nitrophenyl) pyrazine yields only a n apparently polymeric material. The reaction of pp'-dinitrobibenzoyl with ethylenediamine produces not only 2,3-dihydro-5,6-bis-(p-nitropheny1)pyrazine. but also NN'-bis-(p-nitrobenzoy1)ethylenediamine.ALTHOUGH biphenylene has been extensively studied, little has been published about its heterocyclic analogues. The benzodiazabiphenylene (1) has been prepared'l and the benzocyclobutathiophen (2) is the only reported analogue without additional fused rings.The study of such compounds would be of particular interest in connection with the influence of the heteroatoms on bond structure and the stability of the fourmembered ring. (3) Ar = Ph (4) Ar = p-MeO*C,H4 (5) Ar = $-HOC,H4 (6) Ar = $-0,N.C,H4 (7) Ar = Ph (8) Ar = p-MeO*C,H, (9) Ar = p-O,N*C,H, (12) Ar = Ph (13) Ar = p-MeOC,H,The literature does, in fact, contain a reference to a compound to which a tetra-azabiphenylene structure was ascribed. Mason and Dryfoos found3 that 2,3-dihydro-5,6-diphenylpyrazine (3) reacted with alcoholic potassium hydroxide to yield mainly 2,3-diphenylpyrazine (7) together with a compound (' tetraphenyldipiazine ') to which they ascribed the molecular formula C,N,(C,H,),, presumably representing the structure (10); no attempt was made to confirm the structure. ' Tetraphenyldipiazine ' was also obtained from the dihydropyrazine under other conditions, but few experimental details were given. More recently, Burata re-ported4 the preparation of a compound identical with ' tetraphenyldipiazine ' from attempted Diels-Alder-