CAS NO. 106-47-8


EINECS NO. 203-401-0
MOL WT. 127.57
H.S. CODE 2921.42


Oral rat LD50: 300 mg/kg
SYNONYMS p-Chlorophenylamine; 4-chlorobenzenamine;
4-Chloro-1-aminobenzene; 1-amino-4-chlorobenzene; p-aminochlorobenzene; 4-Choraniline;






PHYSICAL STATE clear to yellow crystals

232 C

SOLUBILITY IN WATER soluble in hot water


Soluble: Ether; Carbon disulfide; Organic solvents; Alcohol

450 C



FLASH POINT 120 - 123 C
STABILITY Stable under ordinary conditions


Aromatic amines are much weaker bases than the aliphatics. One of the most important aromatic amines is aniline, a primary aromatic amine replacing one hydrogen atom of a benzene molecule with an amino group. It is a pale brown liquid at room temperature; boiling at 184 C, melting at -6 C; slightly soluble in water and freely soluble in ether and alcohol. It causes serious industrial poisoning.  The substance may have effects on the blood, resulting in formation of methaemoglobin. Repeated or prolonged exposures may be carcinogenic. Commercial aniline is obtained from nitrobenzene which is prepared from benzene with nitric acid by electrophilic substitution reaction or from chlorobenzene by heating  with ammonia in the presence of copper catalyst. It is also obtained as a by-product of coal tar. In commerce the term of aniline oil blue refers to the pure one while aniline oil red indicates a mixture of aniline and toluidines with equimolecular weights.

Considerable quantity of aniline is converted into 4,4กฏ-methylenedianiline (MDA) by the condensation reaction of formaldehyde with aniline in the presence of hydrochloric acid. MDA is is used as an epoxy curing agent, a corrosion inhibitor and molded plastics, and as an intermediate to prepare organic compounds used for polyurethane, spandex fibers, azo dyes, isocyanates and poly(amide-imide) resins. Other important aromatic amine compound as the starting material to produce polyurethane foam production is toluenediamine (TDA). TDA is the mixture of 2,4-diaminotoluene and 2,6-diaminotoluene, usually in a ratio of 80:20. Most of TDA is used in the manufacture of toluene diisocyanate (TDI), which is the predominant diisocyanate in the flexible foams and elastomers industries. TDI reacts with an alcohol to form urethane linkages. Other applications of TDA include to produce dyes, polyamides, antioxidants, hydraulic fluids, and fungicide stabilizers. Aniline is a starting moiety to prepare plant protecting agents. Examples include fenuron (CAS RN: 101-42-8), propham (CAS RN: 122-42-9), siduron (CAS RN: 1982-49-6), carboxin (CAS RN: 5234-68-4), fenfuram (CAS RN: 24691-80-3) and propachlor (CAS RN: 1918-16-7). Aniline is processed to produce a series of compounds being used in the rubber industry, e.g. diphenylguanidines, phenylenediamines mercaptobenzothiazoles, aniline ketones and etc. There are three isomers of phenylenediamine: ortho-, meta-, and para-phenylenediamine. They are low toxic diamines used as components of plastic composites and engineering polymers. They are used to produce aramid fibers, dyes including hair dyes, rubber chemicals (vulcanization accelerators and antioxidants), and pigments.

Aniline is the starting material in the dye manufacturing industry. It forms aniline colors when combined with other substances, particularly chlorine or chlorates. Aromatic amines are weaker bases reacting with strong acids to form amides. Anilide is an amide derived from aniline by substitution of an acyl group for the hydrogen of NH2.  Acetanilide is thus obtained from acetic acid and aniline. Aniline is converted into sulfanilic acid which is the parent compound of the sulfa drugs. Aniline is also important in the manufacture of rubber-processing chemicals, explosives, plastics, antioxidants and varnishes. Amines take part in many kinds of chemical reactions and offer many industrial applications. p-Chloroaniline, a chlorinated aniline at 4 position, is a slightly yellow crystalline solid; melts at 70 C, boils at 232 C; soluble in hot water and readily soluble in most organic solvents. The vapour pressure and octanol/water partition coefficient are moderate. It decomposes in the presence of light and air and at elevated temperatures. p-Chloroaniline is used as an intermediate in the production of a number of products, including agricultural chemicals (e.g. monuron, diflubenzuron, monolinuron), azo dyes and pigments (e.g., acid red 119, pigment red 184, pigment orange 44), cosmetics (as an antimicrobial agent but banned in some coumtries), bactericide or biocide (e.g., chlorohexidine, triclocarban) and pharmaceuticals.

When substituted benzene molecules undergo electrophilic substitution reactions, substituents on a benzene ring can influence the reactivity. Activating substituents that activate the benzene ring toward electrophilic attack can alter the reaction rate or products by electronically or sterically affecting the interaction of the two reactants. deactivating substituents removes electron density from the benzene ring, making electrophilic aromatic substitution reactions slower and more difficult than benzene itself. For example, a hydroxy or methoxy substituent in phenol and anisole increases the rate of electrophilic substitution, while a nitro substituent decreases the ring's reactivity. Electron donating substituents activate the benzene ring toward electrophilic attack, and electron withdrawing substituents deactivate the ring, making it less reactive to electrophilic attack. The strongest activating substituents are the amino (-NH2) and hydroxyl (-OH) groups.

Reactivity Effects

Activating substituents

Deactivating substituents


-NH2, -NHR, -NR2, -OH, -O-

-NO2, -NR3+, -CF3, CCl3





-CH3, -C2H5, -R, -C6H5

-F, -Cl, -Br, -I

Toluene, aniline and phenol are activated aromatic compounds. Examples of deactivated aromatic compounds are nitrobenzene, benzaldehyde and halogenated benzenes.

Activating substituents generally direct substitution to the ortho and para positions where substitutions must take place. With some exceptions, deactivating substituents direct to the meta position. Deactivating substituents which orient ortho and para- positions are the halogens (-F, -Cl, -Br, -I) and -CH2Cl, and -CH=CHNO2

When disubstituted benzene molecules undergo electrophilic substitution reactions, a new substituent is directed depends on the orientation of the existing substituents and their individual effects; whether the groups have cooperative or antagonistic directing effects. Ortho position is the most reactive towards electrophile due to the highest electron density ortho positions. But this increased reactivity is countervailed by steric hindrance between substituent and electrophile.

A nucleophilic substitution is a substitution reaction which the nucleophile displaces a good leaving group, such as a halide on an aromatic ring. This mechanism is called SNAr ( the two-step addition-elimination mechanism), where electron withdrawing substituents activate the ring towards nucleophilic attack. Addition-elimination reactions usually occur at sp2 or sp hybridized carbon atoms, in contrast to SN1 and SN2 at sp3. Chloro and bromobenzene reacts with the very strong base sodium amide (NaNH2) to give good yields of aniline. Other nucleophilic aromatic substitution mechanisms include benzyne mechanism and free radical (SRN1) mechanism.

Common reactions of substituent groups on benzene ring include:
  • Conversion of halogens into other various substituents
  • Modifying activating substituents
  • Oxidative degradation of alkyl chain
  • Reduction of nitro or carbonyl substituents
  • Reversibility of the aromatic sulfonation reaction


Clear amber liquid


99.5% min


0.2% max


0.5% max

HAZARD CLASS 6.1 (Packing group: II)
UN NO. 2018
This material is sensitive to prolonged exposure to air and darkens on exposure to light.