Nitrosamine unsymmetrical

V-Nitrosamines typically are light yellow volatile soHds or oils. The electron delocalization in the NNO functionaUty sufficiendy restricts rotation around the N—N bond that the E (4) and Z (5) isomers of unsymmetrically substituted examples can often be separated (43). 

The results of the study reported here show clearly that, upon release into the atmosphere, N,N-dlmethylhydrazlne (UDMH) can be rapidly converted to N-nitrosodimethylamine by its reaction with atmospheric ozone. A similar conclusion can be reached concerning nitrosamine formation from other unsymmetrically disubstituted hydrazines ... 

The populations of the rotamers are affected by steric effects. Karabatsos and Taller (77) examined the populations of unsymmetrical nitrosamines and found that in methyl-terr-butylnitrosamine only one isomer was observable. Nelsen and associates (78) similarly found that the populations of conformers of 2-nitroso-2-azabicyclo[2.2.2]octanes (40) are affected by the substituent in the 3-position. 

Secondary amines react (1) with nitrous acid, yielding nilrosamines, yellow oily liquids, volatile in steam, soluble in ether. The secondary amine may be recovered by heating the nitrosamine with concentrated HO, or hydrazines may be formed by reduction of the nilrosamines, eg., methylamline from methylphenylnitrosamine, (i 1 i C. 11 )N 0. reduction yielding unsymmetrical methylphenylhy-drazine, CHjtCni )NHNH , (2) with acetyl or benzoyl chloride, yielding substituted amides, thus, diethylamine plus acetyl chloride to form. V A -diethylacetamide (C lio NOCCH . (3) with benzene sulfonyl chloride, yielding substituted benzene sulfonamides, thus, diethylamine reacts to form N. A -diethylbenzenesulfonamide. Cf,H. lSO>N( C/thJ) . insoluble in NaOH. 

Organic hydrazines or diazanes are substitution products of NH2—NH2 and have many properties similar to those of amines in being basic and forming acyl derivatives as well as undergoing alkylation and condensations with carbonyl compounds (Section 16-4C). Unsymmetrical hydrazines can be prepared by careful reduction of /V-nitrosamines. l,l-Dimethyldiazane is prepared in this way for use as a rocket fuel ... 

The dual nature of 4-aminotriazoles as aromatic amines and unsymmetric hydrazines gives rise to many interesting reactions (81HC(37)1, p. 161, 483, 607, 611) some of which are shown in Schemes 55-57. Although nitrous acid normally reacts with both amino and hydrazino groups, examples of selective reactivity are shown in Scheme 58. The nitrosamine from 4-benzylamino-1,2,4-triazole is cleaved by sodium hydroxide to triazole. 

The electrochemical reduction of A-nitrosamines in acid solution is a convenient and general synthetic route to dialkylated, unsymmetrical hydrazines [210]. Quite a few nitrosamines were reduced to hydrazines in the classic period, but later investigations [211,212] also indicate a continued interest in the reaction. 

The nitrosation of secondary amines is reversible in acid solution, so A-nitrosamines may be hydrolized at low pH. Such hydrolysis is especially important for diaryl nitrosamines but also significant for aryl akyl nitrosamines. The NO liberated in the hydrolysis may react with the reduction product from the A-nitrosamine, the unsymmetrical hydrazine, with formation of amine and N2O [213,214] ... 

Nitrous acid reacts with primary aliphatic amines in the presence of mineral acids with the formation of volatQe nitrosamines, which isomerise to stable diazohydroxides. Diazohydroxides are split into nitrogen and a primary alkyl cation, which may partly isomerise to a secondary cation and both cations are eliminated, which yields the corresponding alkene. Substitution reactions then yield primary and secondary alcohols and symmetrical and unsymmetrical secondary amines. I n the presence of hydrohalogen acids, both alkyl... 

Thiols have been activated by conversion into thionitrites (213) with dinitrogen tetroxide. The latter react readily with other thiols, sulphinic acids, and amines as shown in Scheme 31, resulting in unsymmetrical disulphides (214), thiosulphonates (215), and N-nitrosamines (216) respectively. 

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