PRODUCT IDENTIFICATION

TOXICITY

SMILES

CLASSIFICATION

PHYSICAL AND CHEMICAL PROPERTIES

208 - 210 C

SOLVENT SOLUBILITY

450 C

REFRACTIVE INDEX

DESCRIPTION AND APPLICATIONS

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. o-Chloroaniline is used as an intermediate in the production of a number of products, including agricultural chemicals, azo dyes and pigments and pharmaceuticals. 2-Chloroaniline is also used in petroleum solvents and fungicides.

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
Strong	-NH2, -NHR, -NR2, -OH, -O-	-NO2, -NR3+, -CF3, CCl3
Moderate	-NHCOCH3, -NHCOR, -OCH3,-OR	-CN, -SO3H, -COOH, -COOR, -COH, -COR
Weak	-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 S_NAr ( 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 S_N1 and S_N2 at sp^3. 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 (S_RN1) mechanism.

• 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

APPEARANCE

ASSAY

99.5% min

WATER

0.2% max