Process for the preparation of 1,4-diaminoanthraquinones
AssigneeCiba-Geigy Corporation
InventorRudolf Blattner
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Abstract
The invention relates to an improvement of the process for the preparation of 1,4-diaminoanthraquinones by oxidation of the corresponding 2,3-dihydro-1,4-diaminoanthraquinones with nitrobenzene, which improvement is brought about by carrying out the reaction under reduced pressure.
Claims19
In a process for the preparation of a 1,4-diaminoanthraquinone of formula (1) ##STR4## wherein each of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 independently of one another is hydrogen, C.sub.1 -C.sub.12 -alkyl which is unsubstituted or substituted by phenyl, hydroxy, cyano, sulfo or dialkylamino, naphthyl, or phenyl which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl, phenoxy, C.sub.1 -C.sub.4 -alkylcarbonyl or phenyl, by oxidation of a 2,3-dihydro-1,4-diaminoanthraquinone of formula (2) ##STR5## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined above, with nitrobenzene, at elevated temperature, in the presence of an organic base and/or an inorganic base, wherein the improvement comprises carrying out the reaction at a temperature in the range from 100.degree. to 200.degree. C. at reduced pressure while simultaneously distilling off 3 to 20 moles of nitrobenzene per mole of compound of formula (2).
A process for the preparation of an anthraquinone imide, which process comprises oxidizing a 2,3-dihydro-1,4-diamino-anthraquinone of formula (2) ##STR7## wherein R.sub.1 is hydrogen and each of R.sub.2, R.sub.3 and R.sub.4 independently of one another is hydrogen, C.sub.1 -C.sub.12 -alkyl which is unsubstituted or substituted by phenyl, hydroxy, cyano, sulfo or dialkylamino, naphthyl, or phenyl which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl, phenoxy, C.sub.1 -C.sub.4 -alkylcarbonyl or phenyl, with nitrobenzene, said reaction being carried out at a temperature in the range from 100.degree. to 200.degree. C. at reduced pressure while simultaneously distilling off 3 to 20 moles of nitrobenzene per mole of compound of the formula (2), and subsequently condensing the resultant 1,4-diaminoanthraquinone, without isolating it, with an aromatic halogen compound in the presence of a base and a copper catalyst to give the anthrimide, the condensation being effected by heating the halogen compound and the resultant suspension of the 1,4-diaminoanthraquinone very rapidly to the reaction temperature.
Dependencies are inferred from the claim text.