P-naphthol pigments

As with p-naphthol pigment lakes, there is only a limited number of BONA pigment lakes that are marketed in large volume. Two of these pigments, however, maintain an important position within the pigments industry. Table 20 lists the currently available BONA pigment lakes. 

Monoazo pigments Disazo pigments P-Naphthol pigments Naphthol AS pigments Benzimidazolone pigments... 

Naphthol AS pigments, 9 425 Naphthol couplers, 19 252-253 in chromogenic chemistry, 19 251 a-Naphthol derivatives, 21 145 P-Naphthol derivatives, 21 145 Naphthol dyes, 9 182, 407 08 Naphthol reds/maroons, 19 437-438 Naphtholsulfonic acids, 9 356 N aphthopyrans... 

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. 

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. 

Toluidine reds n. Pigment red 3 (12120). Series of red dyestuffs made by diazotizing 2-nitro-p-toluidine and coupling this with P naphthol under alkaline conditions. By altering the conditions of preparation, reds of different shade, brilliance, strength, etc. are obtained. 

Amino-chromenes represent an important class of compounds being the main components of many naturally occurring products. They can be utilized as cosmetics, pigments widely [91], and potential biodegradable agrochemicals [92]. These compounds have been of interest to the medicinal chemist for many years. Hj pSlaPjWjQO, J was used successfully as an efficient catalyst in the reaction of aldehydes, malononitrile, and a- and P-naphthol for the synthesis of 4 and 5 (Scheme 3.33). 

See azo pigments group naphthol AS sub-group and azo pigments group p-naphthol sub-group. 

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

Azo pigments group P-Naphthol sub-group Vermilionette Colour Index (1971) 12070 Heaton (1928) 3 84 Herbst Hunger (1997) 279 Keijzer (1999)... 

Toluidine red, Cl Pigment Red 3 Colour Index, 1971), is hy volmne one of the 20 largest organic pigments in the world. A fj-naphthol azo pigment q.v.), it is diazotised 2-nitro-p-toluidine coupled with alkaline P-naphthol, and was first synthesised in 1904 by Meister Lucius and Bruning (Herbst and Hunger, 1997 de Keijzer, 1999). It is used extensively in conjunction with molybdate red q.v.). 

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