Para Red
Encyclopedia
Para Red is a chemical dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

. Chemically, the dye is similar to Sudan I
Sudan I
Sudan I , is a lysochrome, a diazo-conjugate dye with the chemical formula of 1-phenylazo-2-naphthol. Sudan I is a powdered substance with an orange-red appearance. The additive is mainly used to colour waxes, oils, petrol, solvents and polishes...

. The dye was discovered in 1880 by von Gallois and Ullrich, and was the first azo dye. It dyes cellulose fabrics a brilliant red, but is not very fast. The dye can be washed away easily from cellulose fabrics if not dyed correctly. Throughout making Para Red, the solution will become acidic and basic. Small amounts of byproducts may be left over after the Para Red dye is made that may be acidic or basic, but if made correctly there are little of these and the byproducts have no effect.

Synthesis

Para Red is prepared by diazotisation of para-nitroaniline
4-Nitroaniline
4-Nitroaniline, p-nitroaniline or 1-amino-4-nitrobenzene is an organic compound with the formula C6H6N2O2. It is an organic chemical compound, consisting of a phenyl group attached to an amino group which is para to a nitro group. The chemical structure of p-nitroaniline is shown at the right...

 at ice-cold temperatures, followed by coupling with β-naphthol
Naphthol
Naphthol may refer to:* 1-Naphthol* 2-Naphthol...

:

UK food alert

In the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, the dye is not permitted in food. The UK's Food Standards Agency
Food Standards Agency
The Food Standards Agency is a non-ministerial government department of the Government of the United Kingdom. It is responsible for protecting public health in relation to food throughout the United Kingdom and is led by a board appointed to act in the public interest...

 (FSA) stated that "the Agency’s independent scientific experts have advised that, although there are very limited data available, it would be prudent to assume that it could be a genotoxic carcinogen".

On 21 April 2005, the FSA announced that some batches of Old El Paso
Old El Paso
Old El Paso is a brand applied to a range of Mexican-style foods, including dinner kits, tacos and tortillas, sauces, condiments, rice and refried beans.Old El Paso products are marketed across the globe. The brand is owned by General Mills...

dinner kits had been contaminated with the dye, and issued an alert. Also, reported on the 5 May 2005, the dye was found in 35 products which have now been taken off supermarket shelves. The products were mainly cooking sauces, though some are also spices.
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