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Aniline, an organic used to make , drugs, explosives, plastics, and photographic and rubber chemicals.

Aniline was first obtained in 1826 by the destructive of indigo. Its name is taken from the specific name of the indigo-yielding plant Indigofera anil (Indigofera suffruticosa); its is C6H5NH2. Aniline is prepared commercially by the catalytic of or by the action of ammonia on . The reduction of nitrobenzene can also be carried out with borings in aqueous acid. When aniline is heated with organic acids, it gives , called anilides, such as from aniline and acetic acid. Monomethylaniline and can be prepared from aniline and methyl alcohol. Catalytic reduction of aniline yields . Various oxidizing agents convert aniline to quinone, , , p- aminophenol, and the aniline .

Formula: C6H5NH2 : 93.13 g/mol IUPAC ID: Phenylamine Boiling point: 184.1 °C Density: 1.02 g/cm³ : -6.3 °C

Preparation:-

First, is nitrated with a concentrated mixture of and at 50 to 60 °C to yield nitrobenzene. The nitrobenzene is then hydrogenated (typically at 200–300 °C) in the presence of metal catalysts:

The reduction of nitrobenzene to aniline was first performed by Nikolay Zinin in 1842, using inorganic sulfide as a reductant (Zinin reaction). The reduction of nitrobenzene to aniline was also performed as part of reductions by Antoine Béchamp in 1854, using iron as the reductant (Bechamp reduction). Aniline can alternatively be prepared from ammonia and derived from the cumene process. In commerce, three brands of aniline are distinguished: aniline oil for blue, which is pure aniline; aniline oil for red, a mixture of equimolecular quantities of aniline and ortho- and para-; and aniline oil for safranine, which contains aniline and ortho- and is obtained from the distillate (échappés) of the fusion.

Related aniline derivatives:- Many analogues of aniline are known where the is further substituted. These include toluidines, , chloroanilines, aminobenzoic acids, nitroanilines, and many others. They often are prepared by of the substituted aromatic compounds followed by reduction. For example, this approach is used to convert into toluidines and chlorobenzene into 4-chloroaniline.[6] Alternatively, using Buchwald-Hartwig coupling or Ullmann reaction approaches, aryl halides can be aminated with aqueous or gaseous ammonia. Reaction:- The chemistry of aniline is rich because the compound has been cheaply available for many years. Below are some classes of its reactions. Oxidation:- The oxidation of aniline has been heavily investigated, and can result in reactions localized at or more commonly results in the formation of new C-N bonds. In alkaline solution, azobenzene results, whereas acid produces the violet-coloring matter violaniline. converts it into quinone, whereas , in the presence of certain metallic salts (especially of ), give aniline black. Hydrochloric acid and potassium give chloranil. in neutral solution oxidizes it to nitrobenzene; in alkaline solution to azobenzene, ammonia, and ; in acid solution to aniline black. gives 4-aminophenol and para-amino . Oxidation with persulfate affords a variety of polyanilines. These polymers exhibit rich and acid-base properties.

Polyanilines can form upon oxidation of aniline.

Electrophilic reactions at :- Like , aniline derivatives are highly susceptible to electrophilic substitution reactions. Its high reactivity reflects that it is an enamine, which enhances the electron-donating ability of the ring. For example, reaction of aniline with sulfuric acid at 180 °C produces , H2NC6H4SO3H. If bromine water is added to aniline, the bromine water is decolourised and a white precipitate of 2,4,6-tribromoaniline is formed. To generate the mono-substituted product, a protection with is required:

Aniline can react with bromine even in room temperatures in water.

Acetyl chloride is added to prevent tribromination. The reaction to form 4-bromoaniline is to protect the with acetyl chloride, then hydrolyse back to reform aniline. The largest scale industrial reaction of aniline involves its alkylation with . An idealized equation is shown:

2 C6H5NH2 + CH2O → CH2(C6H4NH2)2 + H2O The resulting diamine is the precursor to 4,4'-MDI and related diisocyanates. Reactions at nitrogen:- Basicity:- Aniline is a weak base. Aromatic such as aniline are, in general, much weaker bases than aliphatic amines. Aniline reacts with strong acids to form anilinium (or phenylammonium) + ion (C6H5-NH3 ). Traditionally, the weak basicity of aniline is attributed to a combination of inductive effect from the more electronegative sp2 carbon and effects, as the on the nitrogen is partially delocalized into the pi system of the benzene ring.

The nitrogen's electron was delocalized to the ring. This is why that aniline is less basic than most amines. Missing in such analysis is consideration of solvation. Aniline is, for example, more basic than ammonia in the gas , but ten thousand times less so in aqueous solution. Acylation:- Aniline reacts with acyl chlorides such as acetyl chloride to give amides. The amides formed from aniline are sometimes called anilides, for example CH3-CO-NH-C6H5 is acetanilide. At high temperatures aniline and carboxylic acids react to give the anilides.

N-Alkylation:- N-Methylation of aniline with at elevated temperatures over acid catalysts gives N- methylaniline and dimethylaniline:

C6H5NH2 + 2 CH3OH → C6H5N(CH3)2 + 2H2O N-Methylaniline and dimethylaniline are colorless liquids with boiling points of 193–195 °C and 192 °C, respectively. These derivatives are of importance in the color industry. Aniline combines directly with alkyl iodides to form secondary and tertiary amines. derivatives:-

Boiled with carbon disulfide, it gives sulfocarbanilide (diphenylthiourea) (CS(NHC6H5)2), which may be decomposed into phenyl (C6H5CNS), and triphenyl (C6H5N=C(NHC6H5)2)

Diazotization- Aniline and its ring-substituted derivatives react with to form diazonium salts. Through these intermediates, aniline can be conveniently converted to -OH, -CN, or a halide via Sandmeyer reactions. This diazonium salt can also be reacted with NaNO2 and phenol to produce a dye known as benzeneazophenol, in a process called coupling. The reaction of converting primary into diazonium salt is called diazotisation. In this reaction primary aromatic amine reacts with sodium nitrile and with 2 moles of HCl which is known as Ice cold mixture because the temperature use to be 0.5°C and it forms benzene diazonium salt as major product and water and sodium chloride. Other reactions:- It reacts with nitrobenzene to produce phenazine in the Wohl-Aue reaction. Hydrogenation gives cyclohexylamine. Being a standard reagent in laboratories, aniline is used for many niche reactions. Its acetate is used in the aniline acetate test for carbohydrates, identifying pentoses by conversion to . It is used to stain neural RNA blue in the Nissl stain. Uses:-

The largest application of aniline is for the preparation of methylenedianiline and related compounds by condensation with formaldehyde. The diamines are condensed with to give methylene diphenyl diisocyanate, a precursor to urethane polymers.

Most aniline is consumed in the production of methylenedianiline, a precursor to .

Other uses include rubber processing chemicals (9%), (2%), and dyes and (2%). As additives to rubber, aniline derivatives such as phenylenediamines and diphenylamine, are antioxidants. Illustrative of the drugs prepared from aniline is (acetaminophen, Tylenol). The principal use of aniline in the dye industry is as a precursor to indigo, the blue of blue jeans. Aniline is also used at a smaller scale in the production of the intrinsically conducting polymer polyaniline. Used a mixture of aniline and as a fuel, with nitric acid as an oxidizer. The combination is hypergolic, igniting on contact between fuel and oxidizer. It is also dense, and can be stored for extended periods.