Naphthol pigments orange

Pigment Orange 5 [3468-63-1] 12075 monoa2o (Dinitraniline Orange) coupling of dia2oti2ed 2,4-dinitroaniline with 2-naphthol... 

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. 

P.O.44 has lost most of its commercial importance and is at present only applied to a limited extent. This is also true for other pigments whose synthetic route involves 3,3 -dimethoxybenzidine as a diazo component. P.O.44 provides a very reddish orange shade, which is much redder than the color of the (3-naphthol pigment P.O.5. Although P.O.44 is more resistant to solvents than P.O.5, the reverse is true for lightfastness. Standardized letterpress proof prints containing P.O.44, for instance, equal step 3 on the Blue Scale, while equally deeply shaded P.O.5 prints equal step 6 on the Blue Scale. 

Nitrosylsulfuric acid, prepared by dissolving sodium nitrite in concentrated sulfuric acid, is employed for amines of low basicity, whose diazonium salts will hydrolyze in dilute acid. In order to synthesize Pigment Orange 5, for instance, 2,4-dinitroaniline is dissolved in concentrated sulfuric acid and diazotized preferably with nitrosylsulfuric acid. Coupling is carried out with a (3-naphthol suspension, produced by acidifying a sodium naphtholate solution. 

J-Naphthol pigments come in shades from yellowish orange to bluish red. They are tinctorially weak and in some applications considerably less strong even than monoazo yellow pigments. 

Only very few (3-naphthol pigments continue to play an important role in today s pigment industry. The list of important products includes Toluidine Red (P.R.3) and Dinitroaniline Orange (P.O.5). Other compounds, such as P.R.6, Parachlor Red, which is the positional isomer of P.R.4 P.O.2, Orthonitroaniline Orange, which is the positional isomer of the para toner P.R.l are only of regional importance. Table 16 lists the commercially available (3-naphthol pigments. The Colour Index numbers are listed along with the common names, since older products are frequently referred to by these names. 

Examples of technically important colorants based on 2-naphthol are Pigment Orange 5, Pigment Red 3 (see Chapter 6.1.1) and the azo dye Acid Orange 7. 

Azo pigments were essentially unknown until around the turn of the century, when coupling reactions were first carried out with (3-naphthol as a coupling component. However, since the range of available colors was somewhat restricted at the time, it was not possible to manufacture shades of yellow beyond that of Dini-troaniline Orange (2,4-dinitroaniline-> 3-naphthol). The discovery of acetoacetic... 

Chloro-4-nitrophenyl) azo]-2-naphthalenol CAS 2814-77-9 EINECS/ELINCS 220-562-2 Synonyms 1-[(2-Chloro-4-nitrophenyl) azo]-2-naphthol Cl 12085 D C Red No. 36 Flaming red Paranitroaniline red, chlorinated Permanent red R Pigment red 4 Tiger orange Vulcan red R... 

Chlorinated Para Reds Pigment Red 4 (12085). There are two varieties of chlorinated para red (1) Ortho-chlor-papa nitraniline and (2) Para-chlorotho nitraniline both are diazotized and coupled to beta naphthol. Both are light yellow shade reds of the tolui-dine red orange. 

Azo pigments group P-Naphthol sub-group Dinitroanilim orange, Pam red... 

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