Nitro dyes, preparation

Lake of acid yellow 1 Acid Yellow 1, Lake (10316). A nitro dye prepared by precipitation from an aqueous solution by a metal salt, i.e., aluminum or barium chloride. 

The synthesis of nitro dyes is relatively simple, a feature which accounts to a certain extent for their low cost. The synthesis, illustrated in Scheme 6.5 for compounds 140 and 141, generally involves a nucleophilic substitution reaction between an aromatic amine and a chloronitroaromatic compound. The synthesis of C. I. Disperse Yellow 14 (140) involves the reaction of aniline with l-chloro-2,4-dinitroaniline while compound 141 is prepared by reacting aniline (2 mol) with compound 144 (1 mol). 

Nitro dyes are the most important class of direct hair dyes they are substituted derivatives of nitrobenzene or nitrodiphenylamine [3, Nitro and Nitroso Dyes]. By proper selection of donor groups and substitution site on the benzene ring, a spectrum of dyes from yellow to blue violet can be prepared [9, pp. 247-250], [40] (Scheme 3). 

Uses dyestuff used to dye furs brown and reddish-brown dye intermediate in semi-permanent and permanent hair coloring products (produces brown and red shades on the hair) in different hair-dyeing preparations. 2-NITRO-P-PHENYLENEDIAMINE A... 

H chemical shifts were measured of dyes prepared by diazoniiun salt coupling with 2,2, 4,4 -tetrahydroxybenzophenone (mono and bisazo compounds), 3-amino-5-nitro[2,l]benzisothiazole, basic dyes derived from 3-(acetoacetamido)- pyridine, 5-sulfonylpiperidino- and morpholino-8-hydro-xyquinoline, 5,6-dichloro- and 6,7-dichloro-2-aminobenzothiazoles, H-acid, 1 -butyl-3-cyano-6-hydroxy-5-methyl-2( 1 //)pyndone, ethyl-2-hydro-... 

Naphthalenol also is used ia the preparation of azo, iadigoid, and nitro, eg, 2,4-dinitro-l-naphthol, dyes, and ia making dye iatermediates, eg, naphtholsulfonic acids, 4-chloro-1-naphthalenol, and l-hydroxy-2-naphthoic acid. 1-Naphthalenol is an antioxidant for gasoline, and some of its alkylated derivatives are stabilizers for plastics and mbber (68). 

Brightener structures of only moderate molecular size are of interest for white grounds in the transfer printing of polyester fabrics. Derivatives of 6-acetamidoquinoxaline with an electron-donating substituent (X) in the 2-position (11.48) were prepared by converting quinoxalin-2-one to 2-chloro-6-nitroquinoxaline and condensation with amines (X = RNH), alcohols (X = RO) or phenols (X = PhO), followed by reduction and acetylation (Scheme 11.19). The nitro intermediates (11.49) are also of interest as low-energy disperse dyes for polyester [61]. 

Al-Nitrosodiethanolamine, 2 449, 450 Nitroso dyes, 9 263-264 Nitro soluble dyes, 7 373t Nitroso soluble dyes, 7 373t Nitrosomonas, use in recirculating aquaculture biofiltration, 3 196 P-Nitrostyrenes, preparation by nitration of styrenes, 16 581 Nitrosyl chloride, 20 634 Nitrosyl complexes, osmium, 19 642 Nitrosyl perchlorate, 18 279 Nitrosyl tetrafluoroborate, 4 144t n-Nitrotoluene, 17 263... 

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]. 

In an interesting study, phthalocyanine complexes containing four anthraquinone nuclei (5.34) were synthesised and evaluated as potential vat dyes and pigments [18]. Anthraquinone-1,2-dicarbonitrile or the corresponding dicarboxylic anhydride was reacted with a transition-metal salt, namely vanadium, chromium, iron, cobalt, nickel, copper, tin, platinum or lead (Scheme 5.6). Substituted analogues were also prepared from amino, chloro or nitro derivatives of anthraquinone-l,2-dicarboxylic anhydride. 

The reduction of aromatic nitro-compounds is of exceptionally great interest, not only scientifically, hut also technically. The conversion of the hydrocarbons of coal tar into useful products began with the discovery of the nitration process the conversion, on the technical scale, of the nitro-group of nitrobenzene into the amino-group gave aniline, the starting material for the preparation of innumerable dyes and pharmaceutical products to aniline were added the homologous toluidines, xylidines, naphthylamines, and so on. 

Uses Intermediate for phthalic anhydride, naphthol, 1,4-naphthoquinone, 1,4-dihydro-naphthalene, 1,2,3,4-tetrahydronaphthalene (tetralin), decahydronaphthalene (decalin), 1-nitro-naphthalene, halogenated naphthalenes, naphthol derivatives, dyes, explosives mothballs manufacturing preparation of pesticides, fungicides, detergents and wetting agents, synthetic resins, celluloids, and lubricants synthetic tanning preservative emulsion breakers scintillation counters smokeless powders. 

Diphenyl-diacetylene is the parent hydi ocarhon of indigo blue, and the dye itself can be prepared by means of tliis reaction, starting with o-nitro-phenyl-propiolic acid. By loss of carbon dioxide the acid becomes o-nitro-phenyl-acetylene, the copper derivative of which passes to di-ortho-nitrophenyl-diacety-lene ... 

Most reported phthalocyanine derivatives (sulfo-, nitro-, amino-, triphenylmethyl-, polymeric, etc.) are copper complexes, although at present the synthetic chemistry of other d- and /-metal Pc derivatives is being rapidly developed (Examples 30-36) [5,6,116-118]. Some of them (in particular, copper phthalocyanine sulfonic acids) are of industrial interest because of their usefulness as dyes. Phthalocyanine sulfonic acids themselves are prepared both by urea synthesis from sulfonated phthalic anhydride and by the sulfonation of the phthalocyanine [6], Some substituted metal phthalocyanines can be obtained by chemical or electrochemical reduction [118e]. Among a number of reported peculiarities of substituted phthalocyanines, the existence of three electronic isomers for magnesium derivative PcMn was recently confirmed [118f]. 

Most of the processes relate to the reduction of organic compounds, particularly the reduction of nitro-compounds, but oxidation methods have been utilised successfully, and in many cases substitution products and dye-stuffs have been prepared by electrolytic means. 

A number of other authors have carried out the nitration of 2-methylnaphtha-lene, mainly as a step in the preparation of a new intermediate for dyes. Lesser, Glasser and Aczel [40] nitrated 2-methylnaphthalene in the presence of acetic acid and Vessely and Kapp [41] used nitric acid alone at low temperature (5-15°C). They obtained a 58% yield of l-nitro-2-methylnaphthalene and an oil which contained 4-Nitro-, 6-nitro- and 8-nitro-2-methylnaphthalenes. Vessely and his co-workers [42, 43] identified qualitatively most of the mononitro derivatives of 2-methylnaphthalene and their reduction products. 

Chemical properties. A chlorine atom ortho or para to a nitro group is especially reactive and is readily substituted. Numerous examples of such reactions, utilized in the preparation of explosives, are given later in the descriptions of preparation methods for dinitrophenol, dinitroanisole, hexanitrodiphenylamine, hexanitro-diphenyl sulphone, dinitroaniline, tetryl, etc. Chlorodinitrobenzene reacts with sodium sulphide and sulphur to yield sulphur dyes. The action of sodium disulphide results in the formation of tetranitrodiphenyl sulphide (p. 554). 

Nitro-2-cyanomethylbenzimidazole, an intermediate in the synthesis of cyanine dyes, was prepared from l,2-diamine-4-nitrobenzene and methyl cyanoac-etate in nitrobenzene (Scheme 2.42) [369],... 

Iodobenzene prepared by this procedure may contain traces of nitro compounds. The test for these is to reduce a sample with stannous chloride (or tin) and hydrochloric acid, and treat the resulting acid solution in the cold with a solution of sodium nitrite. If a phenolic odor is obtained on boiling the solution, nitro compounds are still present. A more delicate test can be made by adding the reduced solution, after treatment with sodium nitrite, to an alkaline solution of /3-naphthol an azo dye is formed if nitro compounds were originally present. 

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