Ciba-geigy Corporation

Peter Furrer

Dieter Lohmann

Roland Darms

Gerd Greber

Hansrudolf Schwander

Harry Beyeler

The invention provides novel monoazo compounds of the formula I ##STR1## wherein X is hydrogen or halogen, R is hydrogen or C.sub.1 -C.sub.4 alkyl, R.sub.1 is C.sub.1 -C.sub.8 alkyl, cycloalkyl or ##STR2## wherein the phenyl radical can be monosulfonated, and R.sub.2 is C.sub.1 -C.sub.4 alkyl which is unsubstituted or substituted by a sulfo group, or is cycloalkyl, with the proviso that either R.sub.1 or R.sub.2 contains a sulfo group. The invention also provides a process for the production of the compounds of the formula I, as well as an intermediate of the formula IIb ##STR3## The novel monoazo compounds can be used as dyes for dyeing and printing textile material, especially wool and polyamide.

Monoazo compounds

A novel improved process for separating mixtures of 3- and 4-nitrophthalic acid is described. The said process comprises treating a mixture of 3- and 4-nitrophthalic acid, which mixture is free from inorganic acid residues, in an aqueous-organic medium containing 1-20 percent by volume of water, at a temperature of between 20.degree. and 100.degree. C., stepwise with a base capable of forming salts of 3- and 4-nitrophthalic acid, which salts are essentially insoluble in the reaction medium, the treatment being carried out by adding base until a pH value of about 2.8 is obtained, separating the precipitating product consisting mainly of a 3-nitrophthalic acid mono-salt, subsequently precipitating, by the addition of further base, a product consisting principally of a 4-nitrophthalic acid salt, and finally converting the resulting nitrophthalic acid salts separately into the corresponding free acids, and optionally purifying these. The 3- and 4-nitrophthalic acid can be obtained by the process according to the invention in a simple manner in an isomer-free form and in good to very good yields.

Process for separating mixtures of 3- and 4-nitrophthalic acid

A process for producing polyamide-polyamide-acid copolymers having an inherent viscosity of from 0.1 to 2.5 and cyclized derivatives thereof is disclosed, which process comprises reacting a polyamide-acid block having an average molecular weight of from 750 to 20,000 with a dicarboxylic acid dichloride and a diamine. The resultant polyamide-polyamide-acid copolymers are distinguished by good processing characteristics as well as good electrical, thermal and/or mechanical properties.

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Bottmingen, Switzerland

Peter Furrer