1,4-Diaminobenzene

p-Phenylenediamine

Names
Preferred IUPAC name Benzene-1,4-diamine
Other names Paraphenylenediamine 1,4-Diaminobenzene 1,4-Phenylenediamine
Identifiers
CAS Number	106-50-3 Y
3D model (JSmol)	Interactive image
ChemSpider	13835179 N
ECHA InfoCard	100.003.096
KEGG	C19499 N
UNII	U770QIT64J N
InChI InChI=1S/C6H8N2/c7-5-1-2-6(8)4-3-5/h1-4H,7-8H2 N Key: CBCKQZAAMUWICA-UHFFFAOYSA-N N InChI=1/C6H8N2/c7-5-1-2-6(8)4-3-5/h1-4H,7-8H2 Key: CBCKQZAAMUWICA-UHFFFAOYAD
SMILES Nc1ccc(N)cc1
Properties
Chemical formula	C6H8N2
Molar mass	108.14 g·mol−1
Appearance	White crystalline solid, darkens upon exposure to air
Melting point	145 to 147 °C (293 to 297 °F; 418 to 420 K)
Boiling point	267 °C (513 °F; 540 K)
Solubility in water	10% at 40°C, 87% at 107 C, 100% at 140 C
Vapor pressure	<1 mmHg (20°C)
Magnetic susceptibility (χ)	-70.28·10−6 cm3/mol
Hazards
R-phrases (outdated)	R23 R24 R25 R36 R37 R38 R40 R42 R43
S-phrases (outdated)	S26 S36 S37 S39
Flash point	156 °C; 312 °F; 429 K
Lethal dose or concentration (LD, LC):
LD50 (median dose)	80 mg/kg (rat, oral) 98 mg/kg (rat, oral) 145 mg/kg (guinea pig, oral)
LDLo (lowest published)	250 mg/kg (rabbit, oral) 100 mg/kg (cat, oral)
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 0.1 mg/m3 [skin]
REL (Recommended)	TWA 0.1 mg/m3 [skin]
IDLH (Immediate danger)	25 mg/m3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

p-Phenylenediamine (PPD) is an organic compound with the formula C₆H₄(NH₂)₂. This derivative of aniline is a white solid, but samples can darken due to air oxidation. It is mainly used as a component of engineering polymers and composites. It is also an ingredient in hair dyes and is occasionally used as a substitute for henna.

PPD is produced via three routes. Most commonly, 4-nitrochlorobenzene is treated with ammonia and the resulting 4-nitroaniline is then hydrogenated:

In the DuPont route, aniline is converted to diphenyltriazine, which is converted by acid-catalysis to 4-aminoazobenzene. Hydrogenation of the latter affords PPD.

PPD is a precursor to aramid plastics and fibers such as Kevlar and Twaron. These applications exploit PPD's difunctionality, i.e. the presence of two amines which allow the molecules to be strung together. This polymer arises from the reaction of PPD and terephthaloyl chloride. The reaction of PPD with phosgene gives the diisocyanate, a precursor to urethane polymers.

This compound is a common hair dye. Its use is being supplanted by other aniline analogues and derivatives such as 2,5-diamino(hydroxyethylbenzene and 2,5-diaminotoluene. Other popular derivatives include tetraaminopyrimidine and indoanilines and indophenols. Derivatives of diaminopyrazole give red and violet colours. In these applications, the nearly colourless dye precursor oxidizes to the dye.

PPD is easily oxidized, and for this reason derivatives of PPD are used as antiozonants in production of rubber products. The substituents, naphthyl, isopropyl etc. affect the effectiveness of their antioxidant roles as well as their properties as skin irritants.