Diarylide pigments are

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

s that are used as

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

s in inks and related materials. They often are yellow or yellow-green. To some extent, these organic compounds have displaced

cadmium sulfide Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow solid.Egon Wiberg, Arnold Frederick Holleman (2001''Inorganic Chemistry'' Elsevier It occurs in nature with two different crystal structures as the rare m ...

from the market. They exist as yellow powders of low solubility in water.K. Hunger. W. Herbst "Pigments, Organic" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim, 2012.

Production

The formation of these pigments involves the reaction of diazotized aromatic diamines (derivatives of

benzidine Benzidine (trivial name), also called 1,1'-biphenyl-4,4'-diamine (systematic name), is an organic compound with the formula (C6H4NH2)2. It is an aromatic amine. It is a component of a test for cyanide. Related derivatives are used in the produc ...

) with coupling components, typically derivatives of

acetoacetanilide Acetoacetanilide is an organic compound with the formula CH3C(O)CH2C(O)NHC6H5. It is the acetoacetamide derivative of aniline. It is a white solid that is poorly soluble in water. It and many related compounds (prepared from various aniline der ...

. By varying both of these components, a wide variety of pigments have been produced. A related family of organic pigments are the simpler arylides, which arise from the coupling of monodiazonium salts with the same coupling partners. The molecular structures of these molecules is more conjugated than represented in the images shown below. The pigments' colors can range from yellow to green. One of the most common diarylide yellow pigments is Pigment Yellow 12. Its

CAS number A CAS Registry Number (also referred to as CAS RN or informally CAS Number) is a unique identification number assigned by the Chemical Abstracts Service (CAS), US to every chemical substance described in the open scientific literature. It inclu ...

is . Other diarylide yellow pigments include ‘’’yellow 13’’’ , ‘’’yellow 17’’’ and yellow 83 . These pigments share the same backbone and vary in color depending on substitution of the benzene rings. Worldwide production of color organic pigments was estimated to be about 250,000 metric tons (t) in 2006, with about 25%, or 62,500 t, being diarylide yellows. File:PigmentYellow13.png, Pigment Yellow 13 File:PigmentYellow83.png, Pigment yellow 83 File:PigmentYellow81.png,

Pigment Yellow 81 Pigment Yellow 81 is an organic compound that is classified as a diarylide pigment. It is used as a yellow colorant. The compound is synthesized from three components. Treatment of 2,4-dimethylaniline with diketene gives an acetoacetylated ani ...

File:PigmentYellow17.png, Pigment Yellow 17 File:PigmentYellow14.png, Pigment Yellow 14 File: YellowPig5thTry.png ,

Pigment Yellow 16 Pigment Yellow 16 is an organic compound that is classified as a diarylide pigment. Pigment Yellow 16 is used as a yellow colorant, and is classified as an arylide yellow. Also called permanent yellow, its color index number is 20040. The com ...

Uses

The diarylide yellows are the most common yellow pigments used in printing as well as a wide variety of other applications. Due to their stability, diarylide yellows are used in

ink Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thi ...

s, coatings, and as

plastic colorant Plastic colorants are chemical compounds used to color plastic. Those compounds come in a form of dyes and pigments. The type of a colorant is chosen based on the type of a polymeric resin, that needs to be colored. Dyes are usually used with polyc ...

s. The pigment is insoluble. It is a standard pigment used in printing ink and packaging industry. The diarylide yellow pigment Yellow 12 is one of the three main colored pigments used in the four color process of

color printing Color printing or colour printing is the reproduction of an image or text in color (as opposed to simpler black and white or monochrome printing). Any natural scene or color photograph can be optically and physiologically dissected into three ...

. As such, its use is ubiquitous in printing both in commercial applications and in home color printers, as well as in

textile printing Textile printing is the process of applying color to fabric in definite patterns or designs. In properly printed fabrics the colour is bonded with the fibre, so as to resist washing and friction. Textile printing is related to dyeing but in ...

Toxicity and hazards

Diarylide yellow pigments are considered to be non-toxic. There is, however, evidence that these pigments degrade when exposed to temperatures above 200 °C to release

3,3'-dichlorobenzidine 3,3'-Dichlorobenzidine is an organic compound with the formula (C6H3Cl(NH2))2. The pure compound is pale yellow, but commercial samples are often colored. It is barely soluble in water and is often supplied as a wet paste. It is widely used in the ...

, a carcinogen that is listed in the U.S. EPA’s

Toxics Release Inventory The Toxics Release Inventory (TRI) is a publicly available database containing information on toxic chemical releases and other waste management activities in the United States. Summary of requirements The database is available from the United St ...

. 3,3’-Dichlorobenzidine is structurally similar to one of the

polychlorinated biphenyl Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by t ...

congeners, PCB 11 (3,3’-dichlorobiphenyl), and some evidence indicates that the use of diarylide yellow pigments introduces PCB 11 to the environment.http://ehp.niehs.nih.gov/121-a86/
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References

{{reflist Pigments Organic pigments Shades of yellow Diarylide pigments

Production

Uses

Toxicity and hazards

See also

References