Reaction is effected between (1) a secondary amine of the formula RNHCH2R1, in which R is an organic radicle, other than an acyl radicle, and -CH2R1 is an aliphatic radicle containing at least one negative substituent, this term being defined to mean a hydroxy, ketonic, carboxylic, sulphonic or nitrile group, and (2) an aromatic nitro compound containing halogen linked directly to the aryl nucleus; the reaction yields tertiary amino compounds by elimination of hydrogen halide between the NH group of reagent (1) and the halogen atom of reagent (2). Suitable reagents of type (1) are N-alkyl-o - aminoalkylene carboxylic and sulphonic acids, such as N-methyl-, N-ethyl-, N-propyl-, N-butyl-, N-dodecyl-, N-octadecyl-, N-oleyl- or N - cyclohexyl - b - aminopropionic acid or -b -aminoethanesulphonic acid, N-aryl-b -aminopropionic acids such as N-phenyl- or N-naphthyl-b -aminopropionic acids, N-phenyl- or N-naphthyl-b -aminoethanesulphonic acids and similarly substituted aminopropanesulphonic acids or aminohydroxypropanesulphonic acids, N - hydroxyethylaniline, N - b ,g - dihydroxypropylaniline, and N-b -hydroxy-g -ethoxypropylaniline; the amine may contain other substituents such as a nitro, alkyl, alkoxy, acetyl-amino or tertiary amino group, and when the amine contains an aryl radicle, the latter may be substituted by a thiosulphonic group or any of the substituents specified above, such as a carboxylic or sulphonic group; in any event, however, the amine must not contain a primary amino group or an additional secondary amino group. Suitable reagents of type (2) are 2 - nitrochlorobenzene, 2 : 4 - dinitrochlorobenzene, 4-nitrochlorobenzene-2-sulphonic acid, 2 - nitrochlorobenzene - 4 - sulphonic acid, 2 : 4-dinitrochlorobenzene - 6 - sulphonic acid, 2 : 4-dinitrochlorobenzene - 6 - carboxylic acid, 2 : 6-dinitrochlorobenzene - 4 - carboxylic acid, 1-chloro-2 : 4-dinitronaphthalene, 1 : 3-dichloro-4 : 6-dinitrobenzene, 2 : 6-dichloro-3 : 5-dinitro-toluene, and compounds of the type RXR, in which R is 3-nitro-4-halogenphenyl and X is a -CO-, -SO2-, -CH2-, -NH-, -CH2 CH2-, or -CH : CH- group. The reaction may be effected by heating the reagents to 60-200 DEG at atmospheric or raised pressure in the presence or absence of a solvent or diluent, an acid-binding agent and/or a catalyst : the latter may be copper acetate or borate or copper powder. Some of the products are useful as dyes, and others as intermediates for dyes. Examples are given in which (1) N-m-tolyl-b -aminopropionic acid (from m-toluidine and acrylic acid) and 2 : 4-dinitrochlorobenzene yield N - m - tolyl - N - (2 : 4 - dinitrophenyl) - b -aminopropionic acid; N - (4-methoxyphenyl)-N-(2 : 4 - dinitrophenyl) - b - aminopropionic acid and N - (2-methoxy-5-methylphenyl)-N-(2 : 4-dinitrophenyl) - b - aminopropionic acid are similarly obtainable from 2 : 4-dinitrochlorobenzene and, respectively, N - (4 - methoxyphenyl)-b -aminopropionic acid (from p-anisidine and acrylic acid) and N-(2-methoxy-5-methyl)-b -aminopropionic acid (from 2-methoxy-5-methylaniline and acrylic acid); corresponding products are obtainable from N-phenyl-b -aminopropionic acid or its substitution products, or N-cyclohexyl-b -aminopropionic acid, and also from carboxylic or sulphonic acids of 2 : 4-dinitrochlorobenzene; (2) N-(1-naphthyl)-b -aminopropionic acid (from 1-naphthylamine and acrylic acid) and 2 : 4-dinitrochlorobenzene yield N-(1-naphthyl)-N-(2 : 4-dinitrophenyl)-b -aminopropionic acid; corresponding products are obtainable from N-(2-naphthyl)-b -aminopropionic acid or substituted N-naphthyl-b -aminopropionic acids, and also from carboxylic or sulphonic acids of 2 : 4-dinitrochlorobenzene; (3) N-phenyl-b -aminopropionic acid and 2 : 6-dinitrochlorobenzene-4-sulphonic acid yield N-phenyl- N - (2 : 6- dinitro - 4 - sulphophenyl)- b -aminopropionic acid; (4) N-butyl-b -aminopropionic acid (from n-butylamine and acrylic acid) and 2 : 4-dinitrochlorobenzene yield N-butyl-N-(2 : 4 - dinitrophenyl) - b - aminopropionic acid; (5) N-o-tolyl-b -aminopropionic acid (from o-toluidine and acrylic acid) and 1 : 3-dichloro-2 : 4 - dinitrobenzene yield a product of unspecified constitution; (6) N-phenyl-b -aminoethanesulphonic acid and 2 : 4-dinitrochlorobenzene-6-carboxylic acid yield N-phenyl-N-(2 : 4-dinitro-6-carboxyphenyl)-b -aminoethanesulphonic acid; the product dyes wool in reddish-brown shades; corresponding products are obtainable from substituted N-phenylaminoethanesulphonic acids and 2 : 4-dinitrochlorobenzene-6-carboxylic (or sulphonic) acid; (7) N - (4 - methoxyphenyl) - b - aminopropionic acid (2 mols.) and 4 : 41-dichloro-3 : 31-dinitrodiphenylsulphone (1 mol.) yield N : N1-di(4-methoxyphenyl) - N : N1 - di(b - carboxyethyl)-4 : 41-diamino - 3 : 31-dinitrodiphenylsulphone; corresponding products are obtainable from 4 : 41-dichloro-3 : 31-dinitrobenzophenone and from N - (4 - methoxyphenyl) - b - aminoethanesulphonic acid; the products dye wool in reddish-brown shades; (8) N-hydroxyethylaniline and 2 : 4 - dinitrochlorobenzene - 6-sulphonic acid yield a product of unspecified constitution, which dyes wool in bluish-grey shades; a yellow dye is similarly obtainable from N-phenyl-b -aminopropionitrile and 2 : 4-dinitrochlorobenzene-6-sulphonic acid; (9) N-phenylglycine and 2 : 4-dinitrochlorobenzene yield N-phenyl-N-(2 : 4-dinitrophenyl)glycine; corresponding products are obtainable from N-(o-carboxyphenyl)glycine and from other nitrohalogenbenzenes. A sample has been furnished under Sect. 2(5), of N - (g - oxobutyl) - N - (2 : 4 - dinitrophenyl)-aniline, obtained by condensing N-(g -oxobutyl)-aniline with 2 : 4-dinitrochlorobenzene.