Amines acid thiocyanation

Chloro-4,6-bis(trichloromethyl)-s-triazine (115) reacts with primary and secondary alkanols to displace only chlorine. Although stable to these acid-catalysis conditions, the trichloromethyl groups can be replaced stepwise, after chlorine, with sufficient alkoxide ion. With one mole of nucleophile, the chlorine was replaced by arylsul-fonylhydrazides, hydrazine, heterocyclic amines, hydroxylamine, thiocyanate, or triethylphosphite. Chlorine is also more reactive than pentafiuoroethyl and heptafluoropropyl groups on s-triazines. a,a-Dihaloalkyls have been little investigated. 

Mirvish, S.S., A. Cardesa, L. Wallcave, and P. Shubik Induction of lung adenomas by amines or ureas plus nitrite and by A-nitroso compounds Effects of ascorbate, gallic acid, thiocyanate, and caffeine J. Natl. Cancer Inst. 55 (1975) 633-636. 

Care must be exercised in using sodium nitrite near other chemicals. It is incompatible with ammonium salts, thiocyanates, thiosulfates, and strong reducing agents. In acid solutions, sodium nitrite evolves toxic NO in the presence of secondary amines it can form nitrosamines which are suspected carcinogens. 

Bromo-6,7,8,9-tetrahydro-l//-3-benzazepin-2-amine(6) with thiocyanate ion undergoes substitution of bromide to give the thiocyanatotetrahydro-l//-3-benzazepine 7.105 Attempts to replace bromide by azide ion failed, as did diazotization of the amine group with sodium nitrite in 6 M sulfuric acid. Oddly, treatment of the aminobromo compound with sodium borohydride in methanol results not in reduction, but in methoxy-debromination to give the 2-methoxy derivative which, on the basis of HNMR spectral data, is best represented as the 2-imino tautomer 8. 

Recently nitrosamines have attracted attention because of their marked carcinogenic activity in a wide variety of animal species Q, ). Nitrosamines are likely to be carcinogens in man as well human exposure to these compounds is by ingestion, inhalation, dermal contact and vivo formation from nitrite and amines Nitrite and amines react most rapidly at an acidic pH A variety of factors, however, make nitrosation a potentially important reaction above pH 7 these include the presence of microorganisms, and the possibilities of catalysis by thiocyanate, metals and phenols, and of transnitrosation by other nitroso compounds. 

In addition to benzenoid diazo components, diazotised heterocyclic amines in which the amino group is attached to a nitrogen- or sulphur-containing ring figure prominently in the preparation of disperse dyes [87,88], since these can produce marked bathochromic shifts. The most commonly used of these are the 6-substituted 2-aminobenzothiazoles, prepared by the reaction of a suitable arylamine with bromine and potassium thiocyanate (Scheme 4.31). Intermediates of this type, such as the 6-nitro derivative (4.79), are the source of red dyes, as in Cl Disperse Red 145 (4.80). It has been found that dichloroacetic acid is an effective solvent for the diazotisation of 2-amino-6-nitrobenzothiazole [89]. Subsequent coupling reactions can be carried out in the same solvent system. Monoazo disperse dyes have also been synthesised from other isomeric nitro derivatives of 2-aminobenzothiazole [90]. Various dichloronitro derivatives of this amine can be used to generate reddish blue dyes for polyester [91]. 

The aminothiazole ring of the novel opioid derivative 191 is produced on reaction of the corresponding amine with potassium thiocyanate and bromine in acetic acid (Equation 126) <2004JME1886>. 

A more satisfactory solution to the mechanism of these substitutions now seems experimentally feasible. It is likely that the trisamino chelate (XXXIII) could be completely resolved by salt formation with a suitable optically active acid. The optically pure amine could then be converted by electrophilic cleavage into optically active bromo-, chloro-, and thiocyanate-substituted chelates. It would thus be a simple matter to determine whether these substitutions proceed with complete retention of asymmetry. Further, the question of a symmetrical five-coordinate intermediate in racemization of such compounds could probably be elucidated by a study of solvent polarity or salt effects on the kinetics of the racemization of these chelates. 

Reduction of WO with thiocyanic acid leads to colored species which have been used for tungsten analysis.193 The color of these species are pH dependent and the structures of some of them are still uncertain. The following sequence of equilibria have been suggested on the basis of several isolated amine salts (equations 7-11).88,194 Of these species, it is believed that the... 

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