Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1992-02-27
1994-08-30
Cintins, Marianne M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D21506
Patent
active
053429508
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an improved process for preparing quinophthalone derivatives of the formula I ##STR4## where the group A completes substituted or unsubstituted heteroaromatic rings and the group B completes a substituted or unsubstituted aromatic ring, by reacting a methyl-substituted heterocyclic compound of the formula II ##STR5## with an anhydride of an aromatic dicarboxylic acid of the formula III ##STR6## or the corresponding free dicarboxylic acid (IIIa) in the presence of an acid and of an organic solvent.
As will be known, the quinophthalone derivatives I are yellow dyes. They are prepared by reacting 2-methylquinoline derivatives or other heterocycles which contain an activated 2-methyl group with aromatic o-dicarboxylic acids or anhydrides--heretofor in the presence of inert high-boiling solvents such as o-dichlorobenzene (U.S. Pat. No. 1,963,374), trichlorobenzene (Helv. Chim. Acta 50 (1967), 2200) or nitrobenzene (J. Org. Chem. 23 (1958), 373).
The reaction in phenol as solvent in the presence or absence of acidic condensing aids such as iron chloride, copper halides or phenolates of inorganic bases is described in DE-A-24 35 097.
However, these solvents not only are physiologically unsafe but also have various technical and ecological disadvantages.
It is an object of the present invention to use more suitable solvents.
We have found that this object is achieved by a process for preparing the above-defined quinophthalone derivatives I by reacting a methyl-substituted heterocyclic compound II with an anhydride III of an aromatic dicarboxylic acid or with the corresponding free dicarboxylic acid IIIa in the presence of an acid and of an organic solvent, which comprises using an alkyl benzoate as organic solvent.
With the alkyl benzoates to be used according to the present invention the nature of the alkyl moiety is basically immaterial, provided the alkyl benzoate in question is liquid under reaction conditions, as will usually be the case for esters having alkyl moieties of up to 6 carbon atoms. Esters of higher alkanols, for example those of from 6 to 12 carbon atoms, generally require superatmospheric conditions.
Suitable alkyl benzoates are accordingly propyl benzoate, isopropyl benzoate, butyl benzoate and isobutyl benzoate, but ethyl benzoate is preferable, and particularly good results are obtained with methyl benzoate.
The alkyl benzoate is conveniently used in the form of the crude, technical-grade ester, because the impurities present therein, for example methyl p-methylbenzoate, do not interfere.
The amount of alkyl benzoate is not critical and therefore may be varied within a wide range. The general range is from 3 to 20 times, preferably from 4 to 12 times, the weight of the starting compound II.
Suitable acids for the condensation reaction are the customary inorganic acids such as boric acid and preferably organic acids. Suitable organic acids are in particular aliphatic C.sub.1 -C.sub.12 -carboxylic acids, preferably C.sub.1 -C.sub.3 -carboxylic acids, araliphatic carboxylic acids, preferably phenylacetic acid, and aromatic carboxylic acids such as toluic acid and preferably benzoic acid.
Advantageously, the acid is used in an amount of from 0.001 to 1 mol, preferably from 0.01 to 0.8 mol, per mole of heterocycle II.
The starting compounds II and III or IIIa are known or obtainable by known methods.
Having regard to the dyes I, preferred starting materials II are 2-methylpyridine, 2-methylbenzimidazole, 2-methylbenzothiazole, 2-methyl-4-quinazolone and very particularly preferably 8-aminoquinaldine.
If the starting compound II still contains free amino groups as substituents, they likewise react with the starting compounds III to form imides. Particularly important dyes of this kind, e.g. Pigment Yellow 138, are derived from 8-aminoquinaldine.
Suitable starting compounds III are phthalic anhydride, pyromellitic anhydride, naphthalic anhydride, tetrabromophthalic anhydride and very particularly preferably tetrachlorophthalic anhydride.
Having regard to a high space
REFERENCES:
patent: 1963374 (1934-06-01), Ogilvie
patent: 3108109 (1963-10-01), Clarke
patent: 3639405 (1972-02-01), Walker
Chimia, Band 24, Sep. 1970, Sauerlander AG Verlag, (Aarau, CH), B. K. Manukian et al.: "Chinophthalone", Seiten 328-339.
Hoch Helmut
Kilpper Gerhard
BASF - Aktiengesellschaft
Cintins Marianne M.
Spivack Phyllis
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