Naphthylamines Diazotization

Nitro-l-dictzo-2-napbtbol [called 4-Nitro-l -diazo-naphthol-(2) or 4-Nitro-naphthochinon (l 2)-diazid-(l) in Get], yel ndLs (from petr eth), mp 130-34° (dec) readily sol in acet, glacial acet acid St benz mod sol in ale si sol in w was prepd by diazotizing 2,4-dinitro-1-n aphthy lamin e (Refs 1, 4 St 6) J-Nitro-l-diazo-2-napbthol, crysts (from diox-ane), mp 160-62°(dec) was obtd when the 2, 7-dinitro-l-naphthylamine diazotized salt was poured into water contg Na acetate (Ref 8) Refs 1) Beil 16, 533 2) Beil 16, (365)... 

I-Naphthylamine readily diazotizes and couples to aromatic hydroxylic or basic compounds. It was thus used as a first component in a number of important monoazo dyes, but its use has been severely curtailed because of its potent carcinogenicity. It sulphonates to give naphthionic acid (l-naphthylamine-4-sul-phonic acid). 

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. 

Fluoronaphthalene [321-38-0] is prepared from 1-naphthylamine by the Balz-Schiemaim reaction in 52% yield or by diazotization in anhydrous hydrogen fluoride in 82% yield. Electrophilic substitution occurs at the 4-position, eg, nitration with fuming nitric acid in acetic acid gave 88% yield of l-fluoro-4-nitro-naphthalene [341 -92-4]. 

Phloroglucinol is Hsted in the Colourindex as Cl Developer 19. It is particularly valuable in the dyeing of acetate fiber but also has been used as a coupler for azoic colors in viscose, Odon, cotton (qv), rayon, or nylon fibers, or in union fabrics containing these fibers (157). For example, cellulose acetate fabric is treated with an aromatic amine such as (9-dianisidine or a disperse dye such as A-hydroxyphenylazo-2-naphthylamine and the amine diazotizes on the fiber the fabric is then rinsed, freed of excess nitrite, and the azo color is developed in a phloroglucinol bath at pH 5—7. Depending on the diazo precursor used, intense blue to jet-black shades can be obtained with excellent light-, bleach-, and mbfastness. 

Dinitronaphthalene ( Gamma-dinitronaph-thalene, 1,3-DNN), Bright yel needles from aq pyridine, mp 144°, bp subl (Refs 1 32) CA Registry No 606-37-1. It is prepd by the action of nitric ac/sulfuric ac on naphthalene at low temps (Refs 14 33) by the nitration of 1-MNN with a mixt of 17.3% nitric ac, 61.2% sulfuric ac, and 21.5% w, temp 59-75°, time 90min (Ref 52) by the action of powd Cu (Ref 18) or hydrazine (Ref 22) on l-chioro-2,4-dinitro-naphthalene by the diazotization of 2,4-dinitro-1-naphthylamine followed by redn of the dia-zonium salt with EtOH (Ref 25) or by the action of Br on 5,7-dinitro-l,2,3,4-tetrahydro-naphthalene followed by dehydrobromination (Ref 13). It is used to prep more highly nitrated naphthalenes... 

Dinitronaphthalene (1,4-DNN). Long yel needles from MeOH, mp 134° (Refs 6 34) CA Registry No 6921-26-2. It is prepd by the diazotization of 4-nitro-l-naphthylamine followed by treatment of the diazonium salt with powd Cu and Na nitrite (Ref 45)... 

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)... 

CA Registry No 24824-26-8. It is prepd by the diazotization of 6-nitro-2-naphthylamine followed by treatment of the diazonium salt with... 

Dinitro-1 -Naphthol (4,6-Dinitro-1 -oxy-naphthalene). Crysts from methanol (as Na salt), mp 240°. Sol in chlf. Prepn from 1,4,6-trinitro-2-naphthylamine by diazotization in AcOH-sulfuric acid to yield 4j6-dinitro-2-diazo-... 

If relatively basic and nucleophilic aromatic amines are diazotized in nitrosylsul-furic acid, C- instead of TV-nitrosation takes place as shown by Blangey (1938) for 1-naphthylamine, which gave in this system 4-nitroso-l-naphthylamine. A possible mechanistic explanation of Blangey s observation is given in Section 3.2. 

Table 3-1. Equilibrium constants Kxno (Scheme 3-28) and rate constants for diazotization of aniline (Ar2, Scheme 3-29) and of 1-naphthylamine (k2 and k-2/k Scheme 3-34) in water by nitrosyl chloride, nitrosyl bromide, nitrosyl thiocyanate, S-nitrosothiuronium ion [(NH2)2CSNO], and dinitrogen trioxide at 25 °C.

For substituted anilines (Thompson and Williams, 1977) and for 1-naphthylamine and a series of derivatives thereof (Castro et al., 1986a), k2 and the ratio Ar 2/Ar3 have been determined for nucleophilic catalysis with Cl-, Br-, SCN-, and SC(NH2)2. The values of k2 correspond fairly well to those found for the diazotization of aniline, but those of Ar 2/Ar3 increase markedly in the above sequence (Table 3-1). As k3 is expected to be independent of the presence of Cl- or Br- and to show little dependence on that of SCN- or thiourea, the increase in k 2/k3 for this series must be due mainly to 2. Indeed, the value of log(Ar 2/Ar3) shows a linear correlation with Pearson s nucleophilicity parameter n (Pearson et al., 1968). This parameter is based on nucleophilic substitution of iodine (as I-) in methyl iodide by various nucleophiles. The three investigations on nucleophilic catalysis of diazotization demonstrate that Pearson s criteria for bimolecular nucleophilic substitution at sp3 carbon atoms are also applicable to substitution at nitrogen atoms. 

The development of azo pigment lakes was initiated by the discovery of Lithol Red by Julius (BASF) in 1899. Lithol Red, which is synthesized by an indirect diazotization procedure using 2-naphthylamine-l-sulfonic acid as a diazonium compound, was initially employed in the form of its calcium and barium salts, which were precipitated onto inorganic carrier materials. The pigment was used in its pure form after it became apparent that the carriers contribute very little to the application properties of the product. Lithol Red is one of the earliest colorant developed specifically for application as pigment. 

For a representative and relatively recent example of a comparative kinetic investigation of diazotization of aniline and 1-naphthylamine with various catalysts X-, reference is made to the work of Castro and coworkers98. These authors found that the (overall) rates decrease under comparable conditions in the order X = Cl- > Br- > N()2 >... 

Dinitro- l-diazo-2-napbtkol, crysts (from dioxane), mp 158°(decomp) was obtd when diazotized 2,4,7-trinitro-l-naphthylamine was poured into water (Ref 4)... 

An early example of a monosubstituted stilbene was introduced by Geigy as Tinopal RBS (89) and used for cotton and polyamide (nylon). Conversion of the sulfonic acid group into A-ethylsulfonamide, via the sulfonyl chloride, yields an FBA for polyester and plastics (55USP2713057). The triazole ring is formed by diazotization of the 4-aminostilbene followed by coupling with 2-naphthylamine and oxidation with ammoniacal copper(II) sulfate, occasionally in pyridine (21CB2191). 

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). 

LltholReds. Lithol Red or Pigment Red 49 1/7103-38-4] is one of the most important of the precipitated salt pigments. They comprise a family of sodium (PR 49), barium (PR 49 1), calcium (PR 49 2), and strontium (PR 49 3) salts of diazotized Tobias acid or 2-naphthylamine-l-sulfonic acid coupled with 2-naphthol. The most popular are the barium and calcium salts, the former being yellower in shade. These reds are used where brightness, bleed resistance, and low cost are of primary importance. They are neither resistant to heat nor chemicals, and are used primarily in printing inks and some inexpensive air-dried industrial paints where good durability is not required. 

Ion-pair HPLC (194,195) was used to separate amaranth from its subsidiary dye l-(4-sulfo-l-naphthylazo)-2-naphthol-6-sulfonic acid disodium salt (fast red E) and from its intermediates 1-naphthylamine 4-sulfonic acid (naphthionic acid) and 2-naphthol-3,6-disulfonic acid disodium salt (R-salt). Ion-pair HPLC was also used for the determination of total free and bound nonsul-fonated aromatic amines in amaranth after diazotization and coupling with R-salt (198). 

Substituted ureas were determined, at the beginning, by colorimetric analysis. This determination is based on a basic or acidic hydrolysis leading to the corresponding aniline, followed by diazotation and coupling with /V-(l-naphthyl)-ethylendiamine (40,58,148-152), 1-naphthol (153), or /V-ethy I-1 -naphthylamine (154) to obtain an azo-dye. Nevertheless, this method is time consuming and does not differentiate between the pesticide and metabolites, unless they are previously separated (154). 

It was prepd by the action of sodium sulfite on 3-nitronaphthalene-l-diazoacetate, previously obtd by diazotizing 3-nitro-l-naphthylamine and treating the diazonium chloride with aq sodium acetate (Ref 5)... 

Naphthylamines, Naphthylam inesulfonic Acids. Some examples (35-38) are mentioned here other compounds can be found among the diazo components (see Figure 2.2), because most naphthylaminesulfonic acids can be employed both for diazotization and for coupling purposes. 

C. I. Direct Black 51, 27720 [3442-21-5] (13) is produced by coupling a mixture of diazotized 3- and 5-aminosalicylic acid to 1-naphthylamine and subsequent alkaline coupling to y acid. 

The most important dyes of the type D->M->K are black and navy blue wool dyes, which contain as the middle component M chiefly 1-naphthylamine or 1-naphthylamine-7-sulfonic acid and as the coupling component K A-phenyl peri acid (A-phe ny 1 a m i n o n a p h th a 1 c n c - 8 - s u 1 fo n i c acid), A-tolyl peri acid, and naphthol or 1-naphthylamine derivatives. Examples of these high-yield and very wash- and lightfast dyes are C.I. Acid Black 24, 26370 (see Section 3.9.3), which is manufactured by coupling diazotized 1-naphthylamine-5-sulfonic acid to 1-naphthylamine, further diazotization of the aminomonoazo dye, and coupling to iV-phenylperi acid and C.I. Acid Blue 113, 26360 [3351-05-1] (20). This blue dye is very important in the dyeing of wool and polyamide. 

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 diazotization of the amines is carried out in the usual manner. The volume of water is kept at a minimum since the success of the reaction depends in part on the efficiency with which the unstable intermediate is extracted from the aqueous layer by the organic liquid. Either the previously prepared amine hydrochloride is employed or a paste of the hydrochloride is prepared by dissolving the amine in concentrated hydrochloric acid and then cooling rapidly with stirring. For diazotization a nearly saturated solution of sodium nitrite (1 g. in 2 cc. of water) is used. Little work has been done with very weakly basic amines in the diazo reaction.48 In one instance, the base, l-nitro-2-naphthylamine, was diazotized by means of nitrosylsulfuric acid in sulfuric acid benzene was added and then sodium hydroxide until the mixture was slightly alkaline.49 For the very weak bases, the nitrosoacetyl reaction is recommended, since it is carried out entirely under anhydrous conditions. 

The same interchange occurs in the naphthalene series. Diazotization of l-nitro-2-naphthylamine in hydrochloric add results in replacement... 

Conversion of stabilized diazo compounds to hydrocarbons does not depend upon the reducing action of ethyl alcohol, for the reaction takes place smoothly in acetone, ether, nitrobenzene, benzene, chloroform, apd carbon tetrachloride. No acetaldehyde is produced when ethanol is the solvent. In the absence of metals, however, when the stabilized salts of diazotized a-naphthylamine are treated with ethyl alcohol, acetaldehyde, naphthalene, a-ethoxynaphthalene, and tar are obtained. 

One mole of a-naphthylamine is dissolved in a mixture of 3000 cc. of hot water and 100 cc. of concentrated hydrochloric add. After cooling to 0°, 200 cc. of hydrochloric add (sp. gr. 1.18) is added and the a-naphthylamine is diazotized, in the usual manner, with one mole of sodium nitrite. The diazo solution thus obtained is poured into a solution of 600 g. of anhydrous sodium arsenite in 2000 cc. of water., ... 

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]) ... 

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