1,4-Diamino-2-nitrobenzene

Description

o-Nitro-paraphenylenediamine (ONPD) is a hair dye and a sensitizer in hairdressers.

Chemical Properties

Dark red crystal Powder

Uses

This compound is used in hair and fur dyes.

Uses

2-Nitro-4-phenylene-diamine is a dyestuff used to dye furs brown and reddish-brown; dye intermediate in semi-permanent and permanent hair coloring products (produces brown and red shades on the hair); in different hair-dyeing preparations.

Definition

ChEBI: A primary amino compound that is p-phenylenediamine in which one of the hydrogens attached to the benzene ring is replaced by a nitro group. It is a cosmetic hair dye intermediate that is used in permanent hair colouring products (diluted 1:1 ith an oxidising agent prior to application).

General Description

Almost black needles with dark-green luster or black powder.

Air & Water Reactions

1,4-Diamino-2-nitrobenzene may be sensitive to prolonged exposure to light and air. Insoluble in water.

Reactivity Profile

1,4-Diamino-2-nitrobenzene is incompatible with strong oxidizing agents.

Fire Hazard

Flash point data for 1,4-Diamino-2-nitrobenzene are not available; however, 1,4-Diamino-2-nitrobenzene is probably combustible.

Flammability and Explosibility

Non flammable

Contact allergens

ONPD is a hair dye and a sensitizer in hairdressers and consumers who are generally sensitive to PPD too.

Safety Profile

Suspected carcinogen with experimental carcinogenic and neoplastigenic data. Poison by intraperitoneal route. Moderately toxic by ingestion. An experimental teratogen. Other experimental reproductive effects. Mutation data reported. When heated to decomposition it emits toxic fumes of NOx,.

Synthesis

0.5 moles (ca. 103.1 g) of 1,4-p-phenylenediamine sulfate I, 1.1 moles (ca. 231 g) of analytically pure trifluoroacetic anhydride, 1.6 moles (ca. 162 g) of triethylamine, and 250 ml of analytically pure dichloromethane, were added to the reactor and stirred thoroughly for 1 hour at room temperature. Filtration gave 142.5 g of N1,N4-ditrifluoroacetyl-p-phenylenediamine II.

N1,N4-ditrifluoroacetyl-p-phenylenediamine II (60.3 g, 0.2 mol) was added to 300 ml of analytically pure acetic anhydride and stirred thoroughly to form a suspension. 25 mL of analytically pure concentrated nitric acid was added dropwise to the reaction system at room temperature. Stirring was continued for 6 hours after the addition. The reaction solution was then filtered and the filter cake was washed once with 200 ml of water and once with 200 ml of analytically pure ethyl acetate. After sufficient drying, 36.3 g of N1,N4-ditrifluoroacetyl-2-nitro-p-phenylenediamine III was obtained.

The 36.3 g of N1,N4-ditrifluoroacetyl-2-nitro-p-phenylenediamine III was mixed into the reaction solution. -2-nitro-p-phenylenediamine III, 53 g of sodium carbonate and 400 mL of water were added to the reactor and heated to reflux for 1 hour. At the end of the reaction the reaction system was brought down to room temperature. The reaction system was filtered to give 16.1 g of 2-nitro-p-phenylenediamine. The total yield of the three-step reaction was 50%; the product was a reddish black solid with a melting point of 136-137 ??C.