Aniline yield

Note.—Esters of carbamic acid upon boiling with aniline yield carbanilide (m.p. 238°), ammonia and the corresponding alcohol. 

Mono-substitution products of primary amines cannot easUy be prepared by direct action of the appropriate reagent for example, bromination of aniline yields largely the 2 4 6-tribomo derivative and nitration results in much oxidation. If, however, the amino group is protected as in acetanilide, smooth substitution occurs. Thus with bromine, />-bromoacetanilide is the main product the small quantity of the ortlio isomeride simultaneously formed can be easily eliminated by crystallisation. Hydrolysis of p-bromoacetanilide gives/ -bromoaniline ... 

Attention has previously (see Diazonium Sails) been drawn to the fact that unless an excess of hydrochloric (or mineral) acid is used in the diazotisation process, coupling occurs between the diazonium salt and the amine to give diazoamino compounds. Thus phenyldiazonium chloride and aniline yield diazoaminobenzene. This substance may be conveniently prepared by dissolving two equivalents of aniline in three equivalents of hydrochloric acid, and adding one equivalent of sodium nitrite in aqueous solution followed by two equivalents of sodium acetate ... 

Reaction with anilines yields the Herz compounds, which are intermediates for certain sulfur dyes (qv) as well as vulcanizing agents for mbber (149). 

The acid promoted cyclization of AT-(2-chloroallyl)enaminones (Scheme 35a) provides the expected 3-methyltetrahydroindoles, whereas similar treatment of iV-(2-chloroallyl)anilines yields unexpectedly 2-, rather than 3-, methylindoles (Scheme 35b) (75JCS(Pl)U46). The course of the latter cyclization is not resolved although various intermediates, such as those shown, have been considered. The ring closure in the furan synthesis shown in Scheme 35c is catalyzed by mercury(II) ion (79JCs(Pl)316l). 

The second point is somewhat less obvious but is readily illustrated by the synthesis of 1,3,5-tribromobenzene. This particular- substitution pattern cannot be obtained by direct brornination of benzene because bromine is an ortho, para director. Instead, advantage is taken of the powerful activating and ortho, para-directing effects of the fflnino group in aniline. Brornination of aniline yields 2,4,6-tribromoaniline in quantitative yield. Diazotization of the resulting 2,4,6-tribromoaniline and reduction of the diazonium salt gives the desired 1,3,5-tribromobenzene. 

Condensation of normeperidine (81) with 3-chloropropan-l-ol affords the compound possessing the alcohol side chain (88). The hydroxyl is then converted to chlorine by means of thionyl chloride (89) displacement of the halogen by aniline yields pimino-dine (90). ° Condensation of the secondary amine, 81, with styrene oxide affords the alcohol, 91 removal of the benzyllic hydroxyl group by hydrogenolysis leads to pheneridlne (92). ... 

It yields a chloride, thujyl chloride, Cj H jCl, by the action of phosphorus pentachloride, which on treatment with aniline yields up HCl, with the formation of the terpene thujene. 

The yield of 3//-azepine appears to be influenced by substituents on the azide ring although no in-depth study has been reported. 4-Halophenyl azides, in most cases, give rise to complex mixtures of products.177 4-Tolyl azide, on thermolysis in aniline, yields 5-methyl-iV-phenyl-3//-azepin-2-amine (18% mp 157-158°C), whereas the thermolyses of 4-methoxy-, 4-methyl-, 4-chloro-, and 4-nitrophenyl azides in a range of arylamines (4-chloro-, 4-methoxy-, and pen-tafluoroaniline) yield only azo compounds and uncharacterized tarry products.178... 

Illb with aniline yields bis(phenylamino)tetramethyldisilazane IVb (see scheme below) in a reversible reaction whose equilibrium is shifted to the right with decreasing temperature. 

Thiophenyl acetates (366 R = Me) and propionates (366 R = Et) react with electrogenerated polysulflde ions S3 in DMF to yield thiocarboxylate ions, thiolate ions, and phenyl tetrasulfanide (367), the last deriving from the reaction of thiolate ions with sulfur (Scheme 48). Smdies of the aminolysis by a set of substimted anilines of Y-aryl dithio-2-thiophenates (368 X = S) and dithio-2-furoates (368 X = O) in acetonitrile have shown that the rate-determining step in these reactions is the departure of the thiophenolate ion from the zwitterionic tetrahedral intermediate T= = (Scheme 49). Experiments with deuteriated anilines yielded k i/IcQ values of 1.7-1.9,... 

Aromatic amines are hydrogenated in the rings by catalytic hydrogenation. Aniline yields 17% of cyclohexylamine and 23% of dicyclohexylamine over platinum dioxide in acetic acid at 25° and 125 atm [5]. A better yield (90%) of cyclohexylamine was obtained by hydrogenation over nickel at 175° and 180... 

Recently a novel reaction between the azlactone 76, R = Ph R = Me, and cinnamylidene aniline yielding the adduct 79 has been described.This result has been interpreted as involving a Diels-Alder cycloaddition between cinnamylidene aniline and the valence tautomeric ketene 78, R = Ph R = Me. 

Further examples are given, but without yields. Yields after subsequent reaction with aniline. Yields of R,Sand R,fl-dlastereomers respectively. Mixture of diastereomers. 

Treatment of dimethyl l-phenyl-2-oxo-l,llb-dihydro-2//-pyrimido[2,l-a]-isoquinoline-3,4-dicarboxylate (64) with 20% hydrochloric acid, with sodium methylate in methanol, or with aniline yielded ring-opened products (Scheme 3) (67CB1094). 

Form, Na Replaced, % lag ft Electro-negalivity for Metal Yield of Aniline, % Yield of Benzene, %... 

The decrease of aniline yields (mole 8 ) during nitrobenzene reduction with various alcohols, temperature - 450°C, donor acceptor ratio-3, HLSV-l... 

In the triazolopyridine series it has been observed19 that a chloro substituent in an ortho position to the methyl group of tolyl heterocycles exerts an additional activating effect. Thus, in the case of triazolopyridine (19), reaction with Schiff s base from benzaldehyde and p-chloro-aniline yields the expected stilbene (20), whereas no reaction is observed in the case of the analog lacking the chlorine atom. 

Thus, with methyl and also ethyl cyanoacetate, the anilinomethylene chromonedione (220) (this form has been found94 to predominate in dimethylsulfoxide solution rather than the tautomeric structure of the formal SchifFs base from 3-formyl-4-hydroxycoumarin and aniline) yields, initially, with potassium hydroxide in DMF, following hydrolysis, the pyronocoumarin 221. 

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