SU364591A1 - METHOD OF OBTAINING a-SUBSTITUTED p-DICK'GONS - Google Patents

Description

one

The invention relates to a process for the preparation of hardly accessible organic reagents, namely cc-substituted | 3-diketones, used as starting products for a number of organic syntheses.

A known method for producing cc-substituted p-diketoi, for example, 7-butyl-6,8-tridecanedio, by condensation of acid anhydrides in the presence of boric anhydride or aluminum chloride at a temperature of 150-200 ° C. The method is carried out at a high temperature (150-200 ° C) for 5-9 hours, the yield of the target product is 20-40%.

The proposed method is simple to perform, allows to obtain new compounds not described in the literature with a yield of 45-60% at a lower temperature (20-60 ° C) with a reaction time of 1 hour.

The method consists in the interaction of cc-haloketones with acid halides in the presence of metallic zinc in ethyl acetate at a temperature of 20-60 ° C, followed by hydrolysis and separation of the reaction by known methods.

The structure of the obtained α-substituted p-diketones was proved by the formation of crystalline pyrazoles with 2,4-dinitrophenylhydrazine, as well as by UV and PC spectroscopy. IR spectra obtained (Z-diketones (liquid

2

film) show a broad absorption band of the carbo} P1lpoy group in the region of 1730-1700 slg, and in the CCLi solution (0.1% solution) a doublet is observed at 1760 and

1730 cm which confirms the presence of two at C-0 groups. At 3440-3430 and 1634 cmpo there are peaks of low intensity, which indicates the appearance of the enol form of the p-diketones in the solution of CCl.i. UV spectra

p-diketones, as one would expect, have two maxima: at 220-230 and 270-285 nm, and the intensity of the R-band is small.

The method is carried out as follows.

In a round-bottom flask equipped with a stirrer, a reflux condenser and a dropping funnel, zinc is placed in the form of fine chips and anhydrous ethyl acetate. Then, with stirring, a mixture of α-haloketone and acid halide is gradually added. The ratio of the initial products with; -halide ketope: acid halide: zinc 1: 1.5: 1.5. After 1 hour, the reaction is stopped. The reaction mixture is drained from an excess of zinc and

hydrolyzed with dilute acetic acid, the ether layer was separated from the aqueous, washed with saturated NaHCOs, again with water, and dried with anhydrous sodium sulfate. After distilling off the solvent the product

distilled.

When measure 1. Synthesis of 3-acetylheptanol-4.

0.15 g-atom of zinc and ethyl acetate are introduced into a three-neck flask. A mixture of α-bromo-propyl ketone (0.1 g mol) and acetic acid chloride (0.15 g-mol) is then primed in the mix. The reaction proceeds at room temperature. At the end of the reaction, the mixture is heated with lO min, cooled, and then decomposed with 10% acetic acid, the organic layer is washed with water, with 10% NaHCOs solution, again with water and dried with procate NajSO.i. After distilling off the solvent, 3-acetylheptanone-4 is distilled. Melting point of 5-methyl-4-ethyl-3-n-propyl-1 - (2,4-dinitrophenyl) pyrazole-1.2 69.5-70 ° C.

Example 2. Synthesis of 4-butyrylnonanone-5. In the same apparatus as in example 1 is placed zinc (0.15 g-atom) in the form of thin chips and ethyl acetate. Then a mixture of a-bromobutyl ketoi; a (0.1 g-mol) and oxychloride (O, 5 g-mol) is added dropwise. Next, the mixture is hydrolyzed with dilute acetic acid, the ethyl acetate layer is washed with water, saturated with sodium bicarbonate solution, again with water, and dissolved in sodium sulfate. After distilling off ethyl acetate, 4-butyrylnonanone-5 was distilled in vacuo.

The table shows the compounds obtained by the proposed method.

Subject invention

The method of producing a-substituted p-diketones, characterized in that, in order to expand the range of products obtained, a-haloketone is reacted with

acid halide at a temperature of 20-60 ° C in the presence of metallic zinc and in ethyl acetate medium, followed by hydrolysis and isolation of the target product by known methods.