SU1216186A1 - Method of producing 2-methyl-3-ketothiophane - Google Patents

Description

This invention relates to an improved process for the preparation of 2-methyl-3-ketothiophane.

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silt

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(i)

which has organoleptic properties. /

The purpose of the invention is to increase the yield of the target product and simplify the process. . ,

EXAMPLE 1 To a solution of 2.34 g (0.0096 mol) of 1,4-dibromopentan-3-one in 12 ml of dilute acetic acid (5: 1), 1.02 mm are added successively during stirring. (0.013 mol) of thioacetic acid, 4.12 g (0.014 mol) of soda and 0.3 g (13% of the mass of the initial ketone) of resin KU-2. The mixture is stirred for 12 hours at 20 ° C and heated at 4 hours. After cooling, the reaction mass is treated with a saturated solution of soda to pH 8.5 and extracted with ethyl acetate. The extract is dried over magnesium sulfate and evaporated, the residue is distilled in vacuo. Obtain 0.7 g (60%) of 2-metsh1-3-ketothiophane

ten

(I) ;, bp. 105-108 C / 35 mm, p 1.5373..Rj 0.45 (those benzene, spotting in UV light and Ij). PMR spectrum (CCI, b, ppm): 1, 30 t (CH3), 2.30 m () 2.90 m (), 4.10 k (). Mass spectrum, m / z M (116), 45 (CHS).

Example 2. To a solution of 2.71 g (0.013 mol) of 1-chloro-4-bromopentanone-2 in 14 ml of dilute acetic acid (5: 1), 1.27 g (0.017 mol) of thioacetic acid are successively added with stirring. , 4.86 g (0.017 mol) of soda and 0.3 g (11% of the mass of the initial ketone) of the resin KU-2. The mixture is stirred for 24 hours at and 4 hours at 105 seconds. The treatment is carried out as in Example 1. 0.96 g (64%) of 2-methyl-3-ketothiophane (G) is obtained, b.p. 84-8b ° C / 20 mm.

EXAMPLE 3 To the solution of 3.1 g (0.02 mol) of 1,4-dichloropentanone-3 in 20 MP of diluted acetic acid (5: 1), 2.3 g (0, 03 mol) of thioacetic acid, 7 g (0.025 mol) of soda and 0.4 g (13% of the mass of the starting ketone) of the resin KU-2. The mixture is stirred for 24 hours at 20 ° C and 4 hours at 100 ° C. The treatment is carried out in the same way as

 . 7

16186

 1. 1. 1.5 g of (,) -stil-3-ketothiofang (I) are obtained, b.p. 84 - 86 ° C / 20 mm.

PRI me R 4. To the solution

5 2.34 g (0.0096 mol) of 1,4-dibromopentan-3-one in 12 ml of dilute acetic acid (5: 1) are added 1, (0.013 mol) of thioacetic acid with stirring

10 acids, 4.12 g (0.014 mol) of soda and 0.3 g (13% of the mass of the initial ketone) of resin KU-2. The mixture was stirred for 12 hours at 25 ° C. and heated at 100 ° C. for 4 hours. After treatment, as described in 5 in Example 1, 0.68 g (58%) of 2-methyl-3-ketothiophane (1) is obtained.

Justification of the selected molar ratio.

Theoretically, 1 mole of the original

20 halogen ketones require 1 mole of thioacetic acid. However, in view of the instability and decomposition of thioacetic acid, in order to achieve the maximum expression of the desired product, it is necessary to take some excess (0.3-0.5 mol). It is impractical to use a larger excess of thioacetic acid for economic reasons. I Theoretically per 1 mole of the initial ke-.

30 tons requires 1 mole of soda. However, in order to provide a higher reaction rate and achieve the maximum yield of the target product, it is necessary to take some excess soda (0.3JC, 0.5 mol). A large excess does not give an additional increase in yield and is not economically feasible. Increasing the amount of resin does not give an additional increase in yield and is not economically feasible. Reducing the amount of resin leads to a decrease in the reaction rate and a decrease in the yield of the target product. Thus, the optimal molar ratio of the reagents bromeketone-thioacetic acid - soda - resin (may.%) Is 1: (1.3-1.5): (1.3-1.5): (11-13 ). Comparative examples.

50 EXAMPLE 5. To a solution of 2.34 g (0.0096 mol) 1,4-dibromopentanone in 12 ml of diluted acetic acid (5: 1), 0.91 ml are added successively with stirring.

55 (0.012 mol) of thioacetic acid, 4, -12 g (0.014 mol) of soda and 0.3 g (13% by weight of the starting ketone) of resin KU-2. The mixture is stirred

40

12 h and heated at 4 h. The reaction was processed in the same manner as in Example 1. 0.5 g (43%) of 2-methyl-3-ketothiophane (I) was obtained, b.p. 105-108 ° С / 35 mm. Thus, when the molar ratio of the starting ketone, thioacetic acid and soda is 1: 1.2: 1.5, the yield of the target product decreases to 43%.

Example: To a solution of 2.34 g (0.0096 mol) of 1,4-dibromopentan-3-one in 12 MP of diluted acetic acid (5: 1), 1.02 ml (0.013 mol) of thioacetic acid are successively added with stirring, 2.9 g (0.01 mol) of soda and 0.3 g (13% of the mass of the starting ketone) of resin KU-2. The mixture is stirred for 12 hours at 20 ° C and heated at 100 ° C for 4 hours. After the treatment described in Example 1, 0.6 g (51%) of 1,4-dibromopentan-3-one is obtained. Thus, when the molar ratio of the final bromoketone, thioacetic acid and soda is 1: 1.3: 1.1, the yield of the target product decreases to 51%.

Example 7. To a solution of 2.34 g (0.0096 mol) of 1,4-dibromopentan-3-one in 12 ml of dilute acetic acid (5: 1), 1.02 ml (0.013 mol) of thioacetic acid are added with stirring , 4.12 g (0.014 mol) of soda and 0.23 g (10% by weight) of the resin KU-2. After the treatment described in example 1, 0.55 g (47%) of 2-methyl-3-ketothiophane (I) is obtained. Thus, a decrease in the amount of resin from 13 to 10% (by weight from the initial ketone) causes a decrease in the yield of the target product to 47%.

EXAMPLE 8 To a solution of 2.34 g (0.0096 mol) of 1,4-dibromopentan-3-she in 12 MP of diluted acetic acid (5: 1), 1.02 mp was added successively with stirring. (0.013 mol) of thioacetic acid, 4, .12 g (0.014 mol) of soda and 0.3 g (13% of the initial ketone content) of resin KU-2. The mixture is stirred for 12 hours at and heated for 4 hours at. After the treatment described in Example 1, 0.5 g (43%) of 2-methyl-3-ketothiophane is obtained. Thus, a decrease in the reaction temperature from 20 to a decrease in yield of about 43%.,

Example 9. To a solution of 2.34 g (0.0096 mol) 1,4-dibromopentane-Z10

It in 12 ml of diluted acetic acid (5: 1) is sequentially added with stirring, 1.02 mp (0.013 mol) of thioacetic acid, 4.12 g (0.014 mol) of soda and 0.3 g (13% by weight of the starting ketone ) resin KU-2. The mixture is stirred for 12 hours at 30 ° C. and heated for 4 hours at. After the treatment described in Example 1, 0.63 g (54%) of 2-methyl-3-ketothiophane (I) is obtained. Thus, increasing the temperature from 25 to 30 ° C causes a decrease in yield to 54%.

Example 10. To a solution of 2.34 g

 5 (0.0096 mol) of 1,4-dibromopentan-3-one in 12 ml of diluted acetic acid (5: 1) are sequentially added with stirring 1.02 ml (0.013 mol) of thioacetic acid,

20 4.12 g (0.014 mol) of soda and 0.3 g

(13% of the mass of the initial ketone) resin KU-2. The mixture is stirred for 12 h at 20 s and heated for 4 h at 90 s. After the treatment described in Example 5, 0.4 g (34%) of 2-methyl-3-ketothiophane (1) is obtained. Thus, lowering the reaction temperature from 100 to 90 ° C causes a decrease in yield to 34%.

Example 11. To a solution of 2.34 g (0.0096 mol) of 1,4-dibromopentan-3-one in 12 MP of diluted acetic acid (5: 1), 1.02 MP (0.013 mol) of thioacetic acid are added successively with stirring. , 4, 12 g (0.014 mol) of soda and 0.3 g (13% by weight of the starting ketone) of the resin KU-2. The mixture is stirred for 1 2 hours at and heated for 4 hours at 100 ° C. After the treatment described in example 1, 0.42 g (36%) of 2-methyl-3-ketothiophane (I) is obtained. Thus, raising the reaction temperature to causes a decrease in yield to 36%.

Therefore, to achieve the maximum yield of the target product, the process should be carried out first at 20–25 s and then at 100–105 s.

A similar decrease in the yield of the target product is observed in Examples 2 and 3 beyond 20-25 ° C and 100-105 C. The ratio of acetic acid and water (5: 1) ensures simultaneous and complete dissolution of soda (inorganic reagent) and

starting ketone (organic reagent).

The reaction mass is treated with IpacTBOpOM soda to pH 8.5. Wherein

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five

0

five

S1216186. "

The pH is completely neutralized with acetic acid with a high consumption of acid. Similar results can be obtained and therefore cannot be obtained economically at a pH of 8.5, but this is advantageous.

Claims (2)

METHOD FOR PRODUCING 2-METHYL3-KETOTHIOPHANE based on oxygen halide-containing compound and sulfur-containing carboxylic acid using an alkaline agent and heating, characterized in that, in order to increase the yield of the target product and simplify the process, 1, 4-dihalogenopentanone-3 is reacted with thioacetic acid and sodium carbonate in a molar ratio of 1: (1.3-1.5):: (1.3-1.5) in the presence of KU-2 resin, taken in an amount of 11-13% by weight of the starting 1,4-halogenopentanone- 3, in an aqueous solution of acetic acid at 20-25 ° C. followed by heating the reaction ion mixture to 100-105 C. (ϊ)