RU2082710C1 - PROCESS FOR PREPARING α,β-UNSATURATED AROMATIC OR HETEROAROMATIC KETONES - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: claimed invention describes process for preparing a,β-unsubstituted ketones of formula la-m wherein R is n, 2 is OH, RC₆H₄CH = CHC(O)Ar, 4-Cl, 4-Br, 2-F. 4-OCH₃, 3-NO₂, . Ar is 4-NO₂ and Ar = RC₆H₄, by condensation of

(II) and RC₆H₄CHO (III) in the presence of sulfonated carbon. Reaction of equimolar amounts of II and III is carried out at temperature of 80-120 C in aprotic solvents (benzene, toluene, cyclohexane) with azeotropic distillation of water or without solvent for 0.5-1.0 h. Yield of I is 85-96 %. Example. Mixture of 0.096 mole of 4-bromoacetophenone and 4-nitrobenzoidehyde, 0.05 g of sulfonated carbon and 10 ml of cyclohexane are boiled in Dean-Stark trap for 40 minutes. Precipitate of 4-nitro, ArCOCH₃-bromoalkanol in admixture with carbon after mixture becomes cool is separated, washed with methanol and crystallized from alcohol to give 94 theoretical % chalcone with melting temperature of 165-167 C. EFFECT: more efficient preparation process. 2 cl, 1 tbl

Description

 The invention relates to synthetic organic chemistry, and in particular to methods for producing α, β unsaturated carbonyl compounds of aromatic and heterocyclic series, many of which are biologically active, and are also widely used as semi-finished products for the synthesis of various heterocyclic and other hard-to-reach compounds.

Known methods for producing a, β unsaturated ketones of aromatic series (chalcones) by croton condensation of the corresponding methyl ketones and aldehydes in protic solvents (lower aliphatic alcohols, acetic acid) in the presence of various basic and acid catalysts [1] for example, in a solution of glacial acetic acid in the presence of acetate ammonium [2]
The disadvantages inherent in these methods for the synthesis of chalcones are the need to neutralize the catalysts, the complexity of the regeneration of solvents after separation of the target products, the formation in the process of significant quantities of contaminated water effluents. This can be avoided by condensation in anhydrous conditions with heterogeneous catalysts.

 The aim of the invention was to develop a method for producing chalcones and similar compounds in aprotic solvents under conditions of heterogeneous catalysis.

 The goal is achieved by carrying out the reaction in the presence of sulfonated carbon [3] excluding the use of protic solvents.

The reaction is carried out with stirring equimolar amounts of aldehyde and ketone; 0.5-1% sulfonated coal at a temperature of 80-120 ^o C in non-polar solvents (cyclohexane, benzene, toluene and others) with separation of water in the Dean-Stark trap or without solvent. At the end of the reaction (0.5-1 h), the carbon is filtered off, the solvent is distilled off, and the residue is recrystallized. Coal can be used in this process repeatedly (at least 5-7 times). When using liquid carbonyl compounds (benzaldehyde, acetophenol, anisic, toluyl aldehydes, etc.), the reaction can be carried out in the absence of a solvent without distillation of water.

 The method is easy to use and can be implemented on an industrial scale.

Example 1. 4'-bromhalcon
4.15 g (0.039 mol) of freshly distilled benzaldehyde, 6 g (0.030 mol) of 4-bromoacetophenone, 0.1 g of sulfonated coal was heated in a boiling water bath with stirring for 30 minutes. The hot solution was decanted from the coal cake and cooled. The crystallized product was washed with 50% alcohol and recrystallized from aqueous alcohol. Received 8.26 g (95% of theory.) Product with a melting point of 104-105 ^o C (lit. melting point 104-105 ^o C [4]).

Example 2. 4-nitro-4'-bromhalcon
1.9 g (0.0096 mol) of 4-bromoacetophenol, 1.45 g (0.0096 mol) of 4-nitrobenzaldehyde, 0.05 g of sulfonated charcoal and 10 ml of cyclohexane were mixed. The resulting mixture was heated in a water bath with water separation in a Dean-Stark trap. After 40 minutes, the precipitate of chalcone in a mixture with charcoal was filtered off, washed with aqueous methanol and recrystallized from alcohol. Received 3.08 g (94% of theory.) Chalcone with a melting point of 165-167 ^o C (lit. melting point 166 ^o C [4]).

Example 3. Butyl ether 5- (3-phenyl-1-oxoprop-2-enyl) pyroslytic acid
A mixture of 2.4 g (0.0114 mol) of butyl alcohol 5-acetylpyroslisic acid, 1.3 g (0.0123 mol) of benzaldehyde in 20 ml of benzene, 0.05 g of sulfonated coal was heated in a boiling water bath with a Dean-Stark trap . After an hour, the solution separated from coal was evaporated in a vacuum of a water-jet pump. The residue was recrystallized from cyclohexane. Received 3.0 g (88% of theory.) With a melting point of 104-105 ^o C (lit. melting point 104-105 ^o C [5]).

Example 4. 5- [3- (4-Nitrophenyl) -1-oxoprop-2-enyl] pyroslytic acid butyl ester
A mixture of 3.7 g (0.0176 mol) of 5-acetylpyroslisic acid butyl ester, 2.66 g (0.0176 mol) of 4-nitrobenzaldehyde, 30 ml of toluene and 0.06 g of sulfonated coal was heated to separate the water in a Dean trap. Stark for an hour. The reaction mixture was decanted from coal and evaporated in vacuo of a water-jet pump. Recrystallization from alcohol gave 5.5 g (91% of theory) of a product with a melting point of 160-161 ^° C (lit. melting point 161-162 ^° C [5]). Other compounds of the general formula R ₁ —CH═CHCOR ₂ shown in the table are similarly prepared.

Claims (2)

1. The method of producing α, β-unsaturated aromatic or heteroaromatic ketones by condensation of the corresponding aldehyde and methyl ketone in the presence of a catalyst, characterized in that sulfonated coal is used as a catalyst and the process is carried out at 80 120 ^° C.  2. The method according to claim 1, characterized in that the process is carried out in the presence of aprotic non-polar solvents, such as benzene, toluene, cyclohexane.

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