Pyrazolone pigments

P.R.lll is chemically related to the pyrazolone pigments P.O.34 and P.R.37. Its hue is somewhat bluer than that of its pyrazolone counterparts it equals that of Signal Red (RAL 3000). The lightfastness of P.R.lll is somewhere between that of P.O.34 and of P.R.37. P.R.lll performs similarly as far as other fastness properties are concerned. The pigment lends itself particularly to the coloration of rubber and PVC excellent dielectrical properties also render it suitable for cable insulations. Thermally, P.R.lll is not sufficiently stable to be used in polyolefins, styrene, ABS, and similar plastics. 

In the same way acetoacetarulides and pyrazolones can be used as coupling components. Larger molecules can be formed in the pigment series by using a benzidine derivative as the middle component as, eg, in Vulcan Fast Red B [6358-87-8] (141) (Cl Pigment Red 38 Cl 21120). 

Pigments derived from pyrazolones include Hansa Yellow R, l-phenyl-3-methyl-4-[(2,5-dichlorophenyl)azo]-5-hydroxypyrazole and Pigment Chrome Yellow, 1-phenyl-3-methyl-4-[(o-tolylazo]-5-hydroxypyrazole, as examples of monoazo compounds. 

Pyrazol-5-one, 3-methyl-1 -phenyl-4-phenylazo-methylation, 5, 264 Pyrazol-5-one, pyridyl-biological activity, 5, 295 Pyrazol-5-one, l-(4 -carbamoylphenyl)-3-methyl-azo pigments from, 1, 334 Pyrazol-5-one, 3-methyl-l-phenyl-azo dyes from, 1, 330 azo pigments from, 1, 334 Pyrazolones acetylated acylotropy, 5, 264 analytical applications, 5, 300 anions... 

Pyrazoles, 13 599 Pyrazolinone couplers, 19 254-255 Pyrazolo-(3,2,-c)-5-triazole couplers, 19 256 Pyrazolobenzimidazole couplers, 19 256 Pyrazolone dyes, 19 285 Pyrazolone Orange, 19 435 pigment for plastics, 7 367t Pyrazolone reds, 19 437 Pyrazolones, 9 283 13 599... 

The last group of metal-free azo pigments are the pyrazolone compounds, the most commonly used examples being made from the coupling component l-phenyl-3-methylpyrazol-5-one, also used in making azo dyes. The two most important pigments are... 

Rd and Rk represent substituents such as CH3, OCH3, OC2H5, Cl, Br, N02, CF3 in important azo pigments, RD and RK are identical. In some cases, the coupling component may also be a pyrazolone derivative ... 

A number of commercially available yellow monoazo pigment lakes are based on a pyrazolone sulfonic acid derivative as a coupling component. An example is the aluminum tartrazine lake, listed in the Colour Index as Pigment Yellow 100,... 

Recent patents [5-7] also describe yellow pyrazolone monoazo pigment lakes based on the general structure... 

The oldest monoazo yellow pigment is Pigment Yellow 1, which continues to be produced and shipped on a large scale. Its discovery and introduction in 1910 was followed by the development of a variety of related pigments of this type, not all of which have turned into a commercial success. A few, such as pyrazolone-based Pigment Yellow 10, are still produced by some regional companies and are targeted for smaller niche applications. 

Acetoacetarylides and l-aryl-pyrazolone-5 are the two most common coupling components. The former affords diarylide yellow pigments (Sec. 2.4.1), while the latter produces disazopyrazolone pigments (Sec. 2.4.3). 

P.R.41 is also known as pyrazolone red. It has lost most of its commercial importance in recent years. P.R.41 production is now limited to the USA, where it is mostly employed to lend color to rubber. To a lesser extent, P.R.41 is found in PVC excellent dielectrical properties make it a suitable candidate for PVC cable insulations. The pigment provides a medium to bluish red of limited brilliance, it is much bluer than P.R.38. P.R.41 is somewhat less fast than P.R.38, which is also true for its stability to a variety of organic solvents. However, it parallels P.R.38 in its alkali and acid resistance. P.R.41 is very lightfast in rubber 1% pigment concentrations equal step 6-7 on the Blue Scale, which meets practically any require-... 

Pigment Orange 13 [3520-72-7] 21110 disazo pyrazolone (Pyrazolone Orange) coupling of tetrazotized 3,3 -dichloro-benzidine with l-phenyl-3-methyl-pyrazolone... 

A second example is the yellow pyrazolone salt, Pigment Yellow 191 [129423-54-7]. It is the calcium salt of diazotized 2-amino-4-chloro-5-methyl-benzenesulfonic acid coupled with 3-methyl-1-[3 —sulfophenyl]-5-pyrazolone and provides a reddish yellow pigment for use in plastics applications. It shows very good heat stability and excellent resistance to nonpolar solvents and commonly used plasticizers (qv). It finds applications in high density polyethylene, polystyrene, and ABS, and shows satisfactory lightfastness. 

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