Naphthol orange derivatives

The hydrogen attached to the nitrogen atom (1) has no effect on the indicator properties, and may be replaced by alkyl groups. Slotta and Franks have determined the indicator characteristics of such substituted a-naphthol orange derivatives. Their findings are summarized in the following table. The color intensity of the alkaline form increases with the atomic weight of the... 

Indicator Propbrtiks of Substituted oi-Naphthol Orange Derivatives... 

It dyes wool and silk in an acid bath, producing an orange shade, which is somewhat redder and not so bright as that obtained with the corresponding /S-naphthol orange. The calcium salt is amorphous and insoluble. Owing to the sensitiveness which these dyestuffs exhibit towards alkalies, the /8-naphthol derivatives are of considerably more importance. 

Azoic Dyes. These are used to produce cost-effective heavy yellow, orange, red, maroon, navy blue, brown, and black shades and are ptinted alongside other dye classes to extend the coloristic possibiUties for the designer. Two approaches are adopted. The common method ia the United States is to use both a naphthol derivative and a stabilized color base, usually in the form of a diazo imino compound in the same print paste. This mixture is soluble in dilute caustic soda and no coupling takes place at this stage. The dried prints are passed through steam at 100—105°C that contains acetic and/or formic acid vapor. As neutralization takes place on the print, the coupling occurs rapidly and the insoluble azoic dye is formed. 

For orange colours, simple 2-naphthol derivatives are the most commonly used coupling components as, for instance, in 2,4-dinitroaniline—>2-naphthol (4.118 Cl Pigment Orange 5). As in the yellow series, superior disazo pigments can be prepared using 3,3 -dichlorobenzidine as tetrazo component with derivatives of 1 -phenyl-3-methylpyrazol-5-one as couplers. 

Further bromination of 3,4,6-tribromo-5-hydroxybenzo[6]thio-phene affords the 2,3,4,6-tetrabromo derivative in the absence of acetate ion, and 3,4,4,6-tetrabromo-4,5-dihydrobenzo[6]thiophen-5-one in the presence of acetate ion. 421 On treatment of 3,4-dibromo-, 4,6-dibromo-, 3,4,6-tribromo-, or 2,3,4,6-tetrabromo-5-hydroxybenzo-[6]thiophene with nitric acid in acetic acid, the corresponding unstable orange crystalline 4-bromo-4-nitro-4,5-dihydrobenzo[6]thio-phen-5-one is obtained.152,421 Hence, once both positions ortho to the hydroxyl group in 5-hydroxybenzo[6]thiophene are occupied by bromine, the properties of these compounds are analogous to the properties of l-bromo-2-naphthol which, on bromination in acetic acid in the presence of acetate ion, affords l,l-dibromo-l,2-dihydro-naphthalen-2-one whereas, in its absence, it affords l,6-dibromo-2-naphthol.616 The behavior of l-bromo-2-naphthol and its derivatives on nitration is similar to that of 4,0-dibromo-5-hydroxybenzo[6]thio-phene and its derivatives.162,616... 

In the industrial manufacture of acid azo dyes usually aniline derivatives are used as the diazo components. The coupling components for orange to blue shades are commonly aniline, naphthol, naphthylamine and aminonaphthol derivatives, whereas phenylpyrazolones are much used for preparing dyes in the yellow and orange shades. 

This acid is obtained bj reducing the corresponding nitro-acid (p. 171) with ferrous chloride and alkali. It is instantly soluble in an excess of normal hydrochloric acid, and with sodium nitrite gives an orange-brown solution which couples with j8-naphthol. The monohydrochloride of the arsinic acid crystallises in clear prisms calcium, magnesium and barium salts may be obtained. The acetyl derivative separates in small prisms, sparingly soluble in boiling water, readily soluble in acids, sym.-Carbamide of 3-amino-4-piperidinophenylarsinic acid,... 

The azo dyes used in this study were l-phenylazo-2-naphthol-6-sulfonate (2) and seven derivatives with substituents in the meta or para positions of the phenyl ring (3-9). These were selected as representative l-azo-2-naphthol sulfonate dyes and because the substituents on phenyl ring would allow a systematic study of the mechanism of their oxidation by metalloporphyrin-catalysed systems in aqueous solution. Dye 2 is commercially available (as Acid Orange 12) and was purified by reciystallisation whilst the others (3-9) were prepared by standard diazonium ion/2-naphthol coupling reactions. The purities of all the dyes were checked by TLC, MS and H NMR spectroscopy. Table 1 reports the measured pl values of all the azo dyes used in this study. 

Orange II is an example of an azo dye prepared from a hydroxyl derivative. It is made by condensing the diazo derivative made from sulphanilic acid with /3-naphthol it is a salt of the acid of the following formula OHC6H4N2C10H6OH. 

The product is rendered soluble in water by converting it into a sulphonic acid. Primuline dyes cotton directly a lemon-yellow color. In order to deposit an ingrain color on cotton dyed with primuline, the cloth is first treated with a dilute acidified solution of sodium nitrite. Primuline, which contains an amino group, is thus converted into a diazonium salt. The material is next washed with cold water, and immersed in a solution of one of the naphthols, naphthylamines, or their derivatives. Azo compounds are formed in this way directly in the fabric, and, as a result, various shades of yellow, orange, scarlet, or maroon may be obtained. 

Borman nitrated PPO to give 11 that has a nitro-substituent on the polymer backbone. This material was then reduced to the amino-substitued polymer 12 that was then converted to the diazonium salt. (Scheme 4) The latter reacted with (3-naphthol to give an orange colored polymeric dye. The amino-substituted polymers 12 were reacted with dianhydrides or diglycidyl ethers to give cross-linked products." Alkylation of 12 with dimethyl sulfate gave the dimethyl derivative. 

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