Hoechst Aktiengesellschaft

Reinhard Zunker

Joachim Ribka

Ernst Spietschka

Klaus Hunger

Wolfgang Rieper

Siegfried Schiessler

Otto Fuchs

Jurgen Rochlitz

Dieter Weber

2,5-Bis-(4'-aminophenyl)-1,3,4-oxadiazoles which are chlorinated in the phenyl nuclei are obtained by condensing hydrazine or a hydrazine yielding agent with equal or different chlorinated benzoic acids or acylating acid derivatives having in para-position to the acid group an amino group or a group capable of being transformed into the amino group, and, thereafter, effecting ring closure of the so-obtained bis-hydrazide to yield the oxadiazole. The products are bis-diazo components, especially for pigments having a very high tinctorial strength, clear and pure shades, a good fastness to light, to heat and to solvents.

1,3,4-Oxadiazoles

N,N'-dimethyl-perylene-3,4,9,10-tetracarboxylic acid diimide is obtained as a valuable pigment of a pure red shade, by reacting perylene-3,4,9,10-tetracarboxylic acid anhydride at low temperatures with a dilute aqueous solution of at least the four-fold molar amount of methylamine. The so-obtained bis-ammonium salt of the bis-N-methyl amide is then heated without isolation to effect ring closure while splitting off two mols of water and two mols of methyl amine. The product can be used without any finish operation or can be after-treated to yield a pigment of an exceptionally high transparency or of a good hiding power.

Process for the preparation of a

This invention relates to a compound of the formula ##STR1## wherein R is a phenylene or naphtylene group. The invention also relates to a process for making the novel compounds of the invention and also to an electrophotographic recording material employing the novel compounds of the invention.

Diamine condensation products in double layer photoconductive recording

Monoazo dyestuffs of the formula ##SPC1## Wherein R.sub.1, R.sub.2 and R.sub.3 are identical or different and are hydrogen, alkyl or alkoxy, preferably having 1 to 2 carbon atoms, or halogen, especially chlorine, X is hydrogen or halogen, preferably chlorine and A is acetoacetyl or and a process for preparing them by coupling diazotized amines of the general formula ##SPC2## With coupling components of the formula ##SPC3## Where R.sub.1, R.sub.2, R.sub.3, X and A have the above meaning. These new pigments may be used for dyeing and printing of material or synthetic materials. They have good fastness properties, especially an improved fastness to heat.

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Kelkheim (Taunus), Germany

Reinhard Zunker