1- Naphthylamine, 5-amino diazotization

Dinitronaphthalene (Delta-dinitronaphtha-lenet 1,6-DNN). Crysts from acet ac, mp 166-67°, bp at 10mm 235°, 360° with decompn (Refs 2 31) CA Registry No 60746-5. It is prepd by the nitration of 2-nitronaphtha- ene with nitric ac/sulfuric ac in hot acet ac (Ref 21) by diazotization of 5-nitro-2-naphthyl-amine followed by treatment of the diazonium salt with Na cobaltinitrite, yield 40% (Ref 36) or by removal of the amino group from 1,6-dinitro-2-naphthylamine by diazotization followed by redn (Ref 17). The temp of expin is 492°(Refl7)... 

Stilben-4-yl)naphthotriazoles (2) are prepared by diazotization of 4-amino-stilbene-2-sulfonic acid or 4-amino-2-cyano-4 -chlorostilbene, coupling with an ortho-coupling naphthylamine derivative, and finally, oxidation to the triazole. 

Other 7- substituents that have been introduced include the dialkylamino, acetamido, hydroxy, alkoxy and alkylthio groups (B-71MI11209). Acylation of the 7-amino group by heterocycles such as cyanuric chloride and its derivatives was inevitable, as was incorporation of a 7-triazole substitution pattern by diazotization of the 7-amino group and o-coupling with 2-naphthylamine followed by triazolization (94). 

Arylnaphthalenes. Arylnaphthalenes can be prepared by replacement of the amino group of naphthylamines by aryl groups. a-Phenyl-naphthalene can be prepared satisfactorily only through the stabilized diazonium salt method, but /3-phenylnaphthalene is obtained readily by several procedures. A considerable number of derivatives of /3-phenylnaphthalene have been prepared. An example is 5-nitro-6-methoxy-2-phenylnaphthalene (XII), which can be obtained in 19% yield from the nitromethoxy-/3-naphthylamine and benzene. From the reaction between diazotized /S-naphthylamine and nitrobenzene and sodium acetate, /S-(2-nitrophenyl)-naphthalene (XIII 14%) and /3-(4-nitrophenyl)-naphthalene (XIV 26%) are formed. 

The 1,3-isomer has been obtained from 2,4-dinitro-a-naphthylamine, the amino group being removed by the conventional method, after diazotization (Liebermann [29]) ... 

Diazotization.—Like aniline and other aromatic primary amines they undergo diazotization. The resulting diazo compounds undergo the various diazo reactions (p. 601) by means of which the naphthalene group becomes coupled as an azo compound with other naphthalene or benzene rings. These azo compounds are dyes. The most important dyes of this group are derived from mixed amino and sulphonic acid or mixed amino and hydroxyl derivatives of naphthalene and will be considered a little later. Not only, however, may the naphthylamines >deld diazo compounds and through them azo compounds but they may be coupled as azo compounds with a diazotized benzene compound. 

Reagent for Nitrites in Water.— An illustration of such a reaction is one which is the basis of the colorimetric determination of nitrites in water. When sulphanilic acid, para-amino benzene sulphonic acid, is diazotized and the resulting diazo compound treated with alpha-naphthylamine the benzene ring and the naphthalene ring become coupled as an azo compound which is red in color. 

Congo Red.—When benzidine is diazotized a double diazo or tetrazo compound results (p. 575) from the diazotization of both of the amino groups. This diazonium or tetrazonium salt reacts with two molecules of naphthylamine sulphonic acid, naphthionic acid, forming a double azo or disazo compound. The sodium salt of this compound is Congo red. The reactions are ... 

Asymmetric derivatives can be synthesized by 4-amino-4 -nitrostilbene-2,2 -disulfonic acid however, their preparation is more expensive, and they show little advantage over the symmetrical compounds. The principal effects of structural variations are changes in solubility, substrate affinity, acid fastness, etc. The bistriazinyl brighteners are anployed principally on cellulosics such as cotton or paper. 2-(Stilben-4-yl)-naphthotriazoles (34, 35) are prepared by diazotization of 4-aminostilbene-2-sulfonic acid or 4-amino-2-cyano-4 -chlorostilbene, coupling with an orthocoupling naphthylamine derivative, and finally, oxidation to the triazole. 

The standard method for the determination of nitrite in seawater is based on the reaction of nitrite with an aromatic amine leading to the formation of a diazonium compound which couples with a second aromatic amine. The product is an azo dye which is quantified by spectrophotometry. Early methods were modifications of the Griess-Ilosvay procedure where the nitrite diazotized with sulphamic acid. The diazonium salt then coupled with 1-naphthylamine. The method described below is generally accepted for seawater analysis and is based on the method proposed by Shinn (1941) and adapted for seawater by Bendschnei-der and Robinson (1952). This method is very sensitive and is unaffected by the presence of other constituents normally occurring in seawater. Sulphanilamide hydrochloride is used as the amino compound, which after diazotization is coupled with N-(l-naphthyl)-ethylene-diamine dihydrochloride. 

According to another method, the OP insecticides were detected by the Griess reacdrai. This method can be used for aromatic amino containing pesticides, such as ethyl parathion, methyl-para-thion, and fenitrothion. After reduction with stannous chloride, these insecticides were diazotized and coupled with 1-naphthylamines. The metabolite, p-nitrophenol, derived from fenitrothion, also gave a positive reaction (160b). 

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