PERYLENE, a hydrocarbon whose preparation was described in 1910, since when the subject has become of importance in view of its application to vat colours. Perylene, does not appear to have been detected in coal tar. The hydro carbon itself was first obtained by the union of two naphthalene nuclei, but it is more conveniently prepared by heating 33-dinaph thol with a mixture of condensing and reducing agents. It is also formed on distilling dihydroxyperylene over zinc dust in hydro gen, or by dry distillation of calcium perylenetetracarboxylate. In organic solvents perylene exhibits a blue fluorescence, whilst in sulphuric acid a rich violet develops. On crystallization of the crude product, glistening bronze plates melting at 264-265° C are obtained, but when purified through its picrate, perylene melts at 273°-274° C.
Nitration of perylene yields mono- to tetra-nitro-derivatives: these compounds form vat dyes on treatment with aluminium chloride. The most important halogen derivatives are those in which positions or are occupied by chlorine or bro mine. Higher halogenated compounds are also known. Perylene derivatives have also been obtained by the condensation of sub stituted I :I'-dinaphthyls, such as 4 :4'-diamino-, 4 :4'-dicyano-, 4 and 2 by means of aluminium chloride:— The dihydroxy-derivatives of perylene are specially important. Of the 21 theoretically possible, 12 should be capable of forming quinones ; three of the latter have been isolated.
I : i 2-Dihydroxyperylene, prepared from 'f-dinaphthol, has been isolated as yellow leaflets. On passing air through an alkaline solution of dihydroxyperylene the crude quinone separates. The latter on treatment with lead peroxide and benzene crystallizes in reddish-brown needles, melting at 287° C, dissolving to a brown solution in sulphuric acid. The vat is yellow with green fluor escence and dyes cotton in yellow to brown shades.
3 :9-Dihydroxyperylene, obtained by oxidation of 3 :9-dichloro perylene by concentrated sulphuric acid and reduction of the product, crystallizes as yellow-orange needles. The corresponding quinone could not be isolated, but instead a compound, (C2G111002)2,H20, was obtained. The sulphuric acid colour is red, becoming green on addition of water. The vat is orange-red with a yellow-green fluorescence, dyeing cotton orange-red which in air changes through brown to olive green.
3 :1 o-Perylene quinone can be obtained by direct oxidation of perylene by aqueous chromic acid, by oxidation of 3 perylene or 3 :1 o-dichloroperylene or via the dihydroxy-com pound, by the action of aluminium chloride on a-dinaphthol. It crystallizes in bright yellow needles, melting above 35o° C, and giving in sulphuric acid a blue-red colour and intense fluorescence. The cherry-red vat dyes cotton carmine, changing to light yellow in air. The dihydroxy-derivative exhibits a red colour in sulphuric acid; the dibenzoate melts at Nitro-, amino-, and halogen derivatives of this quinone have been prepared.
A new class of vat dyestuff, containing the perylene nucleus and two carboxylic imide groups, has appeared in patent literature. The simplest dyestuff is formed on fusing naphthalimide or acenaphthenequinoneoxime with caustic alkali. See p. 636.
Hydrolysis of this product by concentrated sulphuric acid yields the parent tetracarboxylic anhydride which, on treatment with aliphatic or aromatic primary amines, forms N-substituted imide dyestuffs; the same products may be obtained by alkali fusion of N-substituted naphthalimides. These substances are re markable for the colours and fluorescences they exhibit in solu tion. The anhydride dissolves in alkali forming a yellow solution which shows a brilliant green fluorescence on dilution : in sulphuric acid the colour is bright pink with yellow-red fluorescence. The parent dyestuff, the di-imide, dissolves to a reddish purple with scarlet fluorescence, whilst the N-phenyl derivatives show a pur ple colour with less fluorescence. The dyestuffs form cherry-red vats and dye cotton violet changing to red in air : as the molecular weight of the substituent increases, the colour tends to blue. Nitro- and chlorinated derivatives of these dyestuffs have been prepared.
Corresponding dyestuffs, also containing the perylene nucleus, have been prepared by alkali fusion of imides of anthracene :9 dicarboxylic anhydride; these dye cotton in green shades. The perylene nucleus is also present in violanthrone, isoviolanthrone and many other products derived from benzanthrone, dibenzan throne and similar substances, by alkali fusion.
(J. G. M.)