US 5,387,704 A · Preparation of anthraquinones

Abstract

Process for preparing amino- and carbamoyl-substituted anthraquinones by Diels-Alder reaction of an N-butadienylcarbamic acid ester of the formula H.sub.2 C.dbd.CH--CH.dbd.CH--NH--COOR.sup.2, wherein R.sup.2 is alkyl or phenylalkyl, with a 1,4-naphthoquinone or with 1,4-benzoquinone to form a carbamoyl-substituted hydroanthraquinone intermediate and by oxidation of this intermediate with an oxygen-containing gas in a tertiary amine and in the presence of a copper salt to obtain a carbamoyl-substituted anthraquinone product. The Diels-Alder reaction and the oxidation reaction can be carried out as a one-pot synthesis or in separate steps. The carbamic acid ester reactant provides a blocking group represented by --COOR.sup.2, and this blocking group is optionally removed by treatment of the carbamoyl-substituted anthraquinone with an alkaline hydroxide solution.

Claims20

Dependent claims

A process for preparing an anthraquinone of the formula ##STR10## wherein R.sup.1 is hydrogen or ##STR11## R.sup.2 is C.sub.1 - to C.sub.8 -alkyl or C.sub.7 - to C.sub.20 -phenylalkyl, and

R.sup.3, R.sup.4, R.sup.5 and R.sup.6, independently of one another, are hydrogen, C.sub.1 - to C.sub.8 -alkyl, C.sub.7 - to C.sub.20 -phenylalkyl, C.sub.1 -to C.sub.8 -alkoxy, C.sub.1 - to C.sub.8 -haloalkyl, nitro, cyano, halogen, amino, C.sub.1 - to C.sub.8 -alkylcarbonyl, benzoyl, N-C.sub.1 - to C.sub.8 -alkylphenylamino, C.sub.1 - to C.sub.8 -alkylsulfonyl, phenylsulfonyl, aminocarbonyl or nitrobenzyl, which process comprises:
reacting an N-butadienylcarbamic acid ester of the formula ##STR12## where R.sub.2 has the abovementioned meanings, with a 1,4-naphthoquinone of the formula ##STR13## where the substituents R.sup.3 to R.sup.6 have the abovementioned meanings, at from 0.degree. to 150.degree. and in a molar ratio of the ester II to the 1,4-naphthoquinone III of 0.5:1 to 2.5:1, and
reacting the resulting carbamoyltetrahydroanthraquinone with an oxygen-containing gas in a tertiary amine and in the presence of a copper salt.

Dependencies are inferred from the claim text.

Preparation of anthraquinones

Life of this patent

Preparation of anthraquinones

Life of this patent

Abstract

Claims20