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The photolyses of three N-methyl-N-nitrosoanilines and two N-methyl-N-nitroanilines in organic solvents have been studied in the range of 300-340 nm. The influence of solvent character and the presence or absence of oxygen play important roles in the product composition range. The primary photochemical process involves N-N fission, this being homolytic in aprotic solvents and heterolytic in methanol. Three novel mechanistic conclusions are proposed, namely photosolvolysis of a nitrosamine in methanol, photooxidation of nitrosamines in aprotic solvents and the production of biphenyl derivatives on photolysis of nitro-substituted nitrosamines and nitramines in aromatic solvents.The reaction of nitrogen dioxide with N-methyl-4-nitroaniline produces a variety of products. In the course of a study of these reaction products it became apparent that some of the Nnitroso and N-nitro compounds produced displayed interesting photochemical reactions. Our earlier studies on the photochemistry of many C-nitroso compounds 1 and a couple of Nnitroso compounds 2 had demonstrated the importance of solvent character in photolyses where nitric oxide was a primary photochemical product. It was therefore of interest to study the photolyses of aromatic N-nitroso compounds paying attention to any differences between protic and aprotic solvents. The compounds chosen in this investigation comprise three nitrosamines and two nitramines.

The growing interest in the chemistry of C-nitroso compounds (RN=O; R = alkyl or aryl group) is due in part to the recognition of their participation in various metabolic processes of nitrogen-containing compounds. C-Nitroso compounds have a rich organic chemistry in their own right, displaying interesting intra- and intermolecular dimerization processes and addition reactions with unsaturated compounds. In addition, they have a fascinating coordination chemistry. While most of the attention has been directed towards C-nitroso compounds containing a single -NO moiety, there is an emerging area of research dealing with dinitroso and polynitroso compounds. In this critical review, we present and discuss the synthetic routes and properties of these relatively unexplored dinitroso and polynitroso compounds, and suggest areas of further development involving these compounds. (126 references.).

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The rates of nitrosodealkylation of severat symmetrical tertiary amines R,N including trialkylamines (R = Me, Et, Pr", and Bun) and substituted trialkylamines (R = C6H5CH2, triethanolamine, and nitrilotriacetic acid) have been measured in aqueous acetic acid-acetate buffers. The rate of formation of diethylnitrosamine was found to be first order in nitrous acid, triethylamine, and in the hydrogen ion concentration for pH >3.1. Rates increased with decreasing amine basicity. The rate equation was consistent with rapid, reversible nitrosation by nitrous acid or acetyl nitrite and a rate-determining subsequent elimination.

Alkyliodo-strontium and -barium compounds can be prepared in tetrahydrofuran (thf) solution a t -78 "C in good yields, and solids of composition [MR(I)].nthf ( R = Me, Et, Pr", or Bu", M = Sr, n = 2 or 3 ; R = Et, M = Ba, n = 1 ) may be isolated. Characterisation of these products by analysis and other studies is reported. Co-condensation of alkyl halides with Ca, Sr, or Ba metal vapour a t low temperature in vacuo gives products which contain solvent-free alkylhalogenometal species (1 0-25%) which are also investigated. Dicyclopentadienyl compounds, [M(cp),] ( M = Ca, Sr, or Ba). and di-indenyl compounds, [M(C,H7),] ( M = Sr or Ba), are prepared in high yield by co-condensation reactions. Reactions between various unsaturated organic molecules and iodo(methy1)strontium and -barium compounds are reported and, except from Ph,CO, low yields of alkyl addition products are formed. The thermal decomposition of (ethyl) iodostrontium species produces a variety of hydrocarbon and other products, and studies on this system at 18 "C indicate the occurrence of some saturated C-C bond-cleavage reactions under mild conditions. RESULTS A N D DISCUSSION (i) €'re$aration of A LkyLhaEogcnometal Compounds.-(a) Reactions in solution. Alkylhalogenocalcium compounds have been produced in solution by various groups of workers but there is only one report involving Published in part as a preliminary communication: R. b.