DE1618442A1 - Process for the preparation of cyclic ss-diketones - Google Patents

Description

Process for the preparation of cyclic β-diketones.

Terephthalic acid diesters can be condensed according to the literature, as is known from a few examples, with aliphatic or araliphatic ketones in moderate yields by means of the technically difficult to handle and expensive sodium amide. Thus, from diethyl terephthalate and acetophenone with sodium hydroxide, 4-carbethoxydibenzoylmethane was produced, and terephthaloyl diacetone was obtained from diethyl terephthalate and acetone with sodium amide. [Soc. London, 27: 1491 (1910); J. pr. Chem. [2], 74, 128 (1906)] It has now been found that cyclic β-diketones of the general formula (COOR) \ <CO-GS R | n <leta 0 in which R is a straight-chain alkyl radical with 1 to 8 C "atoms, an itoalkyl radical with 3 to 8 C atoms, benzyl or cyclohexyl and R1 is a ring member consisting of 3 to 5 CH @ groups, on which, if necessary, in a benzene nucleus via 2 adjacent carbon atoms can be fused, n + m * 2 and the restriction applies that m can only be 0 or 1 and consequently n can only be 2 or 1, can be obtained in a simple and advantageous manner when using tere- or isophthalic diesters the general formula COOR ara or or COOR, meta in which R stands for identical radicals of the type indicated above or for phenyl, with 1 to 4 times the polar amount of a cyclic ketone of the general formula in which R1 has the meaning given above, in the presence of a mixture of 1 to 4 times the molar amount of an alkali metal alcoholate of the general formula MeOR, where Me = sodium or potassium and R is the first mentioned radicals, and at least the amount equimolar to the alkali metal alcoholate on dimethyl sulfoxide, optionally in the presence of an inert organic solvent at temperatures between -20 and + 70 ° C.

After it is known from the literature that mainly from aromatic Carboxylic acid esters, alkali metal alcoholates and dimethyl sulfoxide under mild conditions-n β-ketosulfoxides are always formed [e.g. German patent specification 1 207 381 and Chem.

Soc. 8S, 3410 (1963) 3, it was surprising and unforeseeable that in the inventive condensation of an aromatic dicarboxylic acid diester preferably cyclic β-diketones are obtained with a cyclic ketone.

The tere- and isophthalic acid diesters are those with similar, aliphatic, cycloaliphatic and araliphatic alcohols with 1 to 8 carbon atoms or with phenol.

Suitable tere- or isophthalic acid diesters are, for example Dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-tert-butyl, Diisopropyl, di-n-pentyl-, dipentyl- (2) -, di-tert-pentyl-, di-4-methylpentyl- (2) -, Di-2-ethyl-heryl (1), dicyclohexyl, dibenzyl and diphenyl esters.

The cyclic ketones that can be used for the implementation are 3 to 7-ring ketones, both the unsubstituted as well as those still on a benzene nucleus is fused.

Examples include cyclopentanone, cyclohexanone, suberone, hydrindones, Tetralone and Benzsuberone.

Under alkali metal wood logs are those of sodium and potassium with straight or branched chain alcohols with 1 to 8 or 3 to 8 carbon atoms presided over. Suitable alcoholates are, for example, sodium or potassium methylate, -ethylate, -propylate, -isopropylate, -butylate, -isobutylate, -tert-butylate, -n-pentylate, -pentoxide- (2), -tert-pentoxide-, -4-methyl-pentoxide- (2), -2-ethyl-n-hexoxide- (1), -cyclohexylat und -benzylat The alcoholates are in an amount of 1 to 4 mol, based on in each case 1 mol of the ester component used; however, they are already sufficient generally the stoichiometrically calculated amounts.

The dimethyl sulfoxide used to carry out the process, which must be practically anhydrous, wind in at least the alkali imet allalkohola t used molar corresponding amount. It is also possible in the implementation yet other solvents that must be inert, such as aliphatic and aromatic Add hydrocarbons or ethers or excess methylene components. Above all, it is advantageous in the case of condensation below the melting point of Dimethyl sulfoxide (80C) a solvent which can be mixed with the latter admit. As particularly suitable to avoid the freezing point of dimethyl sulfoxide decrease, the likewise aprotic, strongly polar N, N-dimethylformamide has proven.

The reaction temperature in the reaction according to the invention is moving between -20 and + 70 ° C, preferably between -10 and + 50 ° C.

Whether in 4- or 3-position of the benzene nucleus of the ester component through a carboxylic acid residue-substituted mono-ß-diketones or the Bls-ß-diketones are formed, can in general through the ratio of tere- or isophthalic diester to alkali metal alcoholate, of course, if there is a sufficient amount of methylene component, they can be controlled. In general the mono-ß-diketones are formed with a molar ratio of tere- or isophthalic diester to alkali metal alcoholates such as 1: 1, with a molar ratio of 152 and with smaller fourths one obtains the bis-ß-diketones.

If you want in the cases m = 1, n a 1, i.e. in the 4- or 3-position of the benzene nuclei a carboxylic acid ester radical bearing benzoyl ketones transesterifications avoid, so the tere- resp.

Isophthalic diester and the alkali metal alcoholate have the same alcohol base own. In the case of phenyl esters, transesterification always takes place.

The β-diketones still produced by the present process are versatile and valuable intermediate products for the production of dyes, Chemotherapeutics, pesticides and plastics.

The following example explains the process in more detail. The specified melting points are uncorrected. the Ferric chloride reactions were carried out with a 1% solution of FeCl3 in methanol. All operations were carried out under a nitrogen atmosphere.

Example 7 76.8 g (0.8 mol) of sodium tert-butoxide and 200 cm 3 of dimethylsutoxide are heated together for 35 minutes with stirring at 60 ° C., an almost clear, slightly browning solution being formed. It is then cooled to about 18 ° C. and a mixture of 67.9 g (0.2 mol) of di-terephthalic acid [4-methylphenyl (2) ester] and 79.4 g (0.81 mol) of cyclohexanone within Added in 2 portions for 6 minutes. Rinse with a further 60 cm3 of dimethyl sulfoxide. The temperature then increases briefly to 34 ° C, but is then immediately reduced to 22 ° C by cooling. The reaction mixture is now kept at 22 ° to 240 ° C. for 25.5 hours, with stirring. It is then cooled to room temperature and decomposed with 10% strength, ice-cold hydrochloric acid. The slightly yellowish, solid product is filtered off with suction, washed neutral and finally dried in vacuo at approx. 60 ° C. 58.0 g of a crude product which does not melt clear at 100 ° -130 ° and which consists mainly of 2,2'-terephthaloyl-bis-cyclohexan-1- or -1'-one, is obtained consists. 0 0 % vy C> Recrystallized from a mixture of ethanol / butanol (1s1), the almost colorless crystals melt at 148-1498C.

C20H22O4 (326.4) % li cal. 73.6 6.8 found 73 * 656.8 Iron-III-chloride reaction: red-violet.

Example 2 In a mixture of 70 ml of dimethyl sulfoxide and 70 ml of N, N-dimethylformamide carry in 26.4 g (0.2 mol of powdered hydrindone- (1) with stirring and then cool the whole thing to -100C.

Now 39.2 g (0.4 mol) are added in 4 portions within 5 minutes Potassium isopropoxide was added and, after a further 10 minutes, 27.8 g (0.1 mol) of di-tert-butyl isophthalate. The now brown-black solution is then kept at -6 to -7 ° C. for 13.5 hours. The work-up takes place analogously to Boispisl 1. Finally, 22 g of an ocher-colored at 145-152 ° C. are obtained melting crude products, which mainly consist of 2,2'-terephthaloyl-bis- [hydrindone- (1) respectively.

)] consists.

Uncrystallized from butanol or 1,4-dioxane, the yellow, highly light-reflecting crystals at 222 to 222.5 ° C.

C26H18O4 (394.4) % C% H calc. 79.2 4.6 found: 79.35 4.75 Iron-III-chloride reaction: brownish green.

Example 3 A mixture of 38.2 g (0.25 mol) of sodium 2-ethyl-hexylate- (1) and 125 cm3 of dimethyl sulfoxide is stirred for 33 minutes at 60 ° C. $ Then # end it is cooled to approx. 20 ° C. and 100 cm3 of N, N-dimethylformamide are added. Now is on 80C further cooled and a. Mixture of 95.5 6 (0.26 mol) isophthalic acid di- [2-ethylhexyl (1) ester] and 36.5 s (0.25 mole) of tetralone- (1) added.

The reaction mixture is stirred for 18.3 hours. on 7.5 to 8.5 ° C and then decomposes as described in Example 1.

The oily β-diketone is taken up in ether, the ethereal solution is deacidified by washing with water and dried. After removal of the solvent vird fractionally distilled. The fraction with the boiling point 165-168 ° C / 0.07 mm Hg (30.7 g) provides pure 2 / [3'-Carbo- [2 "-ethyl-hexyl- (1" ) -oxy] -2-benzoyl-] tetralone- (1).

C26H30O4 (406.5) calc. 76.8 7.4 found 77.0 7.5 Iron-III-chloride reaction: brown.

Example 4 97.1 g (0.3 mol) of dimethyl terephthalate are in 400 cm3 of dimethyl sulfoxide are stirred in. Then 292.4 g (2 mol) of tetralone (1) added. Immediately afterwards, 108 g (2 mol) of sodium methylate are added in such a way that that a temperature of 300C is not exceeded, The reaction mixture is then stirred for 73 hours at 24 to 27 ° C, the resulting in the course of time thick enolate dispersion by adding another 100 cm3 of dimethyl sulfoxide, in easily stirrable form remains. After the usual decomposition with ice cold 5 to 10% strength Salic acid and further treatment as in the previous examples results in yellow, crystalline crude product that does not melt clear at 203 to 220 ° C.

The crude yield of 2,2'-terephthaloyl-bis-tetralone- (1) or

- (1 ') is 150 g. Recrystallized from dioxane or cyclohexanone, the yellow prisms obtained melt at 218 to 219 ° C.

C28H22O4 (422.5) % C% H ber, 7g, 6 5.25 found, 79.45 4.75 Iron-III-chloride reaction: green

Claims (1)

Claim: Process for the production of cyclic β-diketones of the general formula (COOR) m \. para park or CO-CH R meta t \ CO / J n in which R is a straight-chain alkyl radical with 1 to 8 carbon atoms, an isoalkyl radical with 3 to 8 carbon atoms, benzyl or cyclohexyl; and R is a ring member consisting of 3 to 5 CE2 groups, to which a benzene nucleus can optionally also be fused via 2 adjacent carbon atoms, n + m = 2 and the restriction applies that m is only 0 or 1 and n consequently can only be 2 or 1, characterized in that one tere- or isophthalic acid diester of the general formula COOR -, zasoh COOR, ~ <meta in which R stands for identical radicals of the type indicated above or for phenyl, with 1 to 4 times the molar amount of a cyclic ketone of the general formula in which R1 has the meaning given above, in the presence of a mixture of the 1 to 4-fold molar amount of an alkali metal alcoholate of the general formula MeOR, where Me = sodium or potassium and R represents the first-mentioned radicals, and at least the amount equimolar to the alkali metal alcoholate on dimethyl sulfoxide, optionally in the presence of an inert organic solvent at temperatures between -20 and + 70 ° C with one another.