Amines, Aromatic

Aniline ignites readily, burning with a smoky flame characteristic of aromatic compounds.

Aniline is a weak base. Aromatic amines such as aniline are, in general, much weaker bases than aliphatic amines because of the electron-withdrawing effect of the phenyl group. Aniline reacts with strong acids to form anilinium (or phenylammonium) ion (C6H5-NH3+). Although aniline is weakly basic, it precipitates zinc, aluminum, and ferric salts, and, on warming, expels ammonia from its salts. Chemistry of aniline includes oxidation of aniline results in the formation of new C-N bonds. In alkaline solution, azobenzene results, whereas arsenic acid produces the violet-coloring matter violaniline. Chromic acid converts it into quinone, whereas chlorates, in the presence of certain metallic salts (especially of vanadium), give aniline black. Hydrochloric acid and potassium chlorate give chloranil. Potassium permanganate in neutral solution oxidizes it to nitrobenzene, in alkaline solution to azobenzene, ammonia and oxalic acid, in acid solution to aniline black. Hypochlorous acid gives 4-aminophenol and para-amino diphenylamine. Aniline derivatives are highly susceptible to electrophilic substitution reactions. Boiled with carbon disulfide, aniline gives sulfocarbanilide (diphenylthiourea) (CS(NHC6H5)2), which may be decomposed into phenyl isothiocyanate(C6H5CNS), and triphenyl guanidine (C6H5N=C(NHC6H5)2). Aniline and its ring-substituted derivatives react with nitrous acid to form diazonium salts. Aniline reacts with nitrobenzene to produce phenazine in the Wohl-Aue reaction.

Aniline is moderately toxic, whereas many of its derivatives are highly toxic, e.g. chloroaniline.

Anilines are organic compounds which contain an amino group attached to a benzene ring. Aniline is a precursor to many industrial chemicals, and its main use is in the manufacture of precursors to polyurethane. Like most volatile amines, it possesses the somewhat unpleasant odor of rotten fish. Aniline is colorless, but it slowly oxidizes and resinifies in air, giving a red-brown tint to aged samples. The largest application of aniline is for the preparation of methylene diphenyl diisocyanate (MDI). Other uses include rubber processing chemicals, herbicides, additives to rubber, and dyes and pigments. Aniline derivatives such as phenylenediamine and diphenylamine are antioxidants, and anilines are also found in pharmaceuticals such as paracetamol (acetaminophen, Tylenol). Aniline itself is also used on a smaller scale in the production of the intrinsically conducting polymer polyaniline.

1-aminopyrene, aniline, cyclohexyl anthranilate, dinitroaniline, metolachlor, naphthylurea, propanil, toluidine.