SU1608187A1 - Method of producing 5-methylpyrazoline - Google Patents

Abstract

The invention relates to heterocyclic substances, in particular the preparation of 5-methylpyrazoline for the synthesis of 3 (5) -methyl pyrazole. The goal is to increase the yield of the target product and simplify the process. The latter is carried out by the reaction of crotonaldehyde with hydrazine hydrate in the medium of N-methylpyrrolidone with their ratio = 1: 2: (1.75-2.75), at 0-60 ° С, preferably 0-20 ° С. These conditions allow to increase the yield of the target product to 95% while reducing the heating mode from 140-250 ° to 60 ° C and lower and the possibility of regenerating N-methylpyrrolidone for return to the process. 1 hp f-ly.

Description

The invention relates to an improved process for the preparation of 5-methyl pyrazoline, which can be used, for example, in the synthesis of 3 (5) -methyl pyrazole.

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

The goal is achieved by the fact that crotonaldehyde is reacted with hydrazine hydrate in N-methylpyrrolidone, taken in a 1: 2 ratio: (1.75-2.75), at 0-60 ° C.

P r. And m 8 p 1. In a four-necked flask with a volume of 1 l, - equipped with a mechanical stirrer, thermometer, dropping funnel, reflux condenser, 100 g (2 mol) of hydrazine hydrate 100 g (1 mol) of N-methyl pyrrolidone are placed. . The contents of the flask are cooled. With vigorous stirring

70 g (1 mol) of crotonic aldehyde per 100 g (1 mol) of N-methylpyrrolidone are added from the dropping funnel at such a rate that the temperature does not rise. The reaction time is 10 min.

The yield of 5-methylpyrazoline is 79.8 g (95%) to crotonaldehyde.

The reaction mixture is analyzed for hydrazine hydrate content by potentiometric titration with 0.1 n. hydrochloric acid solution. The content of organic components is determined by gas chromatography.

Example2. When the mixer is rotary-type, a mixer of 100 g (2 mol) of N-methyl pyrrolidone (100 g (2 mol) N-methyl pyrrolidone) is fed into the jacket with a stirrer and a continuous supply of coolant to the jacket with a temperature of up to one tank, and a solution of 70 g ( 1 mole)

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of creton aldehyde in 100 g (1 mol of N-methyl pyrupole. The feed rate of hydrazine hydrate and creton aldehyde solutions is controlled by a peristaltic pump. The feed rate of each solution is 4 l / h. The unit operates continuously. The temperature in the reaction zone does not exceed 20 ° C. The reaction mixture flows down the wall of the reactor in the form of a film and is collected in a receiver, from where it is transferred to a storage tank, and then to a distillation unit to isolate 5-methylpyrazoline and regenerate hydrazine hydrate and N-methylpyrrolidone

The yield of 5-methylpyrazoline is 79.4 g (94.5%). Regenerated hydrazine hydrate and N-methylpyrrolidone are returned to the synthesis site.

Froze Analogously to Example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 100 g (1 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 100 g (1 mol) of N-methylpyrrolidone are fed to the reactor. The temperature in the reaction zone is OC. The yield of 5-methylpyrazoline is 78.5 g (93.5%). EXAMPLE 4 Analogously to example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 100 g (1 mol) is fed to the reactor N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonaldehyde in 100 g (1 mol) of N-methylpyrrolidone. The temperature in the reaction zone is 65 ° C. The yield of 5-methylpyrazoline 67.2 g (80%).

Resin is contained in the reaction mixture at this synthesis temperature.

PRI me R 5. Similar to Example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 100 g (1 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 100 g (1 mol) of N are fed into the reactor. -methylpyrrolidone. In the reaction zone support -5 s. To complete the reaction, heating to 20 ° C is required, since at low temperatures of synthesis, crotonoaldazine is formed in the reaction mixture, which, when heated under the action of N-methylpyrrolidone, is converted to 5-methylpyrazoline. The yield of 5-methylpyrazalin 68 g (81%).

EXAMPLE 6 Analogously to example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 75 g (0.75 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic are fed into the reactor.

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aldehyde p 100 g (I mol) of N-methylpyrrolidone. The temperature in the reaction zone is not more. The yield of 5-methylpyrazoline 75.6 g (90%).

PRI me R 7. Similarly to example 2, a solution of 100 g (1 mol) 1 of idrazine hydrate in 150 g (1.5 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 100 g are fed into the reactor (. 1 mol) N-methylpyrrolidone. The temperature in the reaction zone is not more than 20 C. The yield of 5-methylpyrazoline is 79 g (94%).

EXAMPLE 8 Analogously to example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 50 g (0.5 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 100 g (1 mol ) N-methylpyrrolidone. The temperature in the reaction zone does not exceed 20 ° C. The yield of 5-methylpyrazoline 65.5 g (78%).

PRI me R 9. In analogy to example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 175 g (1.75 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 100 g (1 mol) of N are fed. -methylpyrrolidone. The temperature in the reaction zone does not exceed 20 C. The yield of 5-methylpyrazoline is 79.4 g (94.5%).

PRI me R 10. Analogously to example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 100 g (1 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 75 g (0.75 mol ) N-methylpyrrolidone. The temperature in the reaction zone is kept no more. 20 ° C. The yield of 5-methylpyrazoline is 73.9 (88%).

EXAMPLE 11 Analogously to Example 2, pacTBojp 100 g (2 mol) of hydrazine hydrate to 100 g (1 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 150 g (1.5 mol) are fed to the reactor. ) N-methylpyrrolidone. The temperature in the reaction zone does not support Bbmie 20 ° C. The yield of 5-methylpyrazoline is 78.1 g (93%).

EXAMPLE 12. In a manner similar to Example 2, a solution of 100 g (2 mol) of hydrazine hydroxide in 100 g (1 mol) of N-methylIl and prolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 50 g (O, 5 mol) N-methylpyrrolidone. In the reaction zone, the temperature is maintained not higher than 20 ° C. The yield of 5-methylpyrazoline 63,8 g (76%).

5 16 Example p 13. In a manner similar to Example 2, a solution of 100 g (2 mol) of hydrazine hydrate in 100 g is fed to the reactor. (1 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 175 g (1.75 mol) of N-methylpyrrolidone. The temperature in the reaction zone does not exceed. Yield of 5-methylpyrazolin 79.0 g (94%).

Isolation of the product in this case (as in Example 9) is more difficult due to more dilute solutions.

Example 14. A solution of 100 g (2 mol) of hydrazine hydrate in 100 g (1 mol) of N-methylpyrrolidone and a solution of 70 g (1 mol) of crotonic aldehyde in 100 g (1 mol) of N-methylpyrrolidone are fed to the reactor, similarly to example 2. The temperature in the reaction zone is 60 C. The yield of 5-methylpyrrolidone is 70.6 g (84% in terms of the crotonic aldehyde guide).

The proposed method is compared with the known, based also on the interaction of crotonic aldehyde with hydrazine hydrate, but in a vacuum environment.

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gas oil at 140–250 ° C in the presence of 1% sulfonic acid allows to increase the yield of the target product by 10–15% and reduce the synthesis temperature to. In addition, hydrazine hydrate and N-methylpyrrolidone after regeneration are again used to synthesize 5-methylpyrazoline.

The optimum process temperature is.

Claims (2)

1. A method of producing 5-methylpyrazoline by the interaction of crotonaldehyde and hydrazine hydrate in the presence of a solvent, characterized in that, in order to simplify the process and increase the yield of the target product, N-methylpyrrolidone is used as the solvent, with a ratio of crotonic aldehyde, hydrazinehydrate, N-methylpyrrolidone, equal to 1 : 2: (1.75-2.75) at O-sb. 2. The method according to claim 1, wherein the process is carried out at 0-20 ° C.