NL8102925A - PROCESS FOR PREPARING 3-ACYLAZOPROPIONIC ACID ESTERS. - Google Patents

Description

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Process for preparing 3-acylazopropionic acid esters.

; The invention relates to a new process for preparing 3-acylazopropionic acid esters, as well as their isomeric formylacetic acid ester acylhydrazones.

Methods for the preparation of formyl acetic acid-5-ethyl ester semicarbazone (W. Wislicenus, H.W. Bywaters, Liebigs Ann.

Chem. 356, (19071 50) and formylacetic acid ethyl ester ethoxycarbonylhydrazone (R. Raap, RG Micetich, Can. J. or Chem. U6, (1968) 1057) are already known. The preparation of these compounds takes place by reaction of the sodium salt of the formylacetic acid ester with the corresponding hydrazine derivatives, which requires the synthesis and isolation of the formylacetic acid ester sodium salt. However, the latter compound can be prepared only in complicated and lengthy processes in addition to an unsatisfactory yield. (German Patent 708 513; British Patent 588 512).

The present invention therefore has for its object to provide a process which allows a technically simple preparation of 3-acylazopropionic acid esters, as well as the isomers thereof, in high yield. This problem is solved according to the invention by using a process for preparing 3-20 acylazopropionic acid esters of the general formula 1, wherein R 1 is a C 2 -

C8 -alkyl group and Rg represent an alkoxy group, preferably a C 1 -C 2 -alkoxy group, or an amino group, the process being characterized in that acrylic acid esters of the general formula 2 with hydrazine derivatives of the general formula 3, optionally using an inert -25 release agent and / or in the presence of catalysts, are converted into 3-acylhydrazinopropionic acid esters of the general formula b, and these compounds are oxidized in an inert solvent by the action of oxidizing agents to form the desired products, formulas 2 to with 4 R ^ and have the meanings mentioned above.

As alkyl groups can be mentioned for example: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, n-pentyl, n-hexyl and others.

As the alkoxy groups can be mentioned, for example, methoxy, ethoxy, propoxy, butoxy and others.

-8102925! ·. ! 2 i 1! Thus, in the method of the invention; ; use of easily accessible starting compounds, while allowing technically simple and harmless preparation of the desired products with high yields.

5: Particular embodiments of the process according to the invention consist in that the conversion of the acrylic acid esters of formula 2 with hydrazine derivatives of formula 3 takes place at temperatures from -20 ° C to + 150 ° C, preferably at 0 ° C to 50 ° C, and at a pressure of 98 - 981 kPa, preferably at 98 kPa, if desired using a base or acid catalyzed reaction, and equimolar amounts of the acrylic acids; ters of the formula 2 and of the hydrazine derivatives of the formula 3; that the oxidation of the 3-acylhydrazino-propion; acid esters of the general formula U with oxidizing agents; 15: Lined at temperatures from -20 ° C to + 100 ° C, preferably from -5 ° C: to + 50 ° C, and using a 3-acylhydrazino-propionic acid ester of the formula ih, which is not from the reaction mixture is isolated and can be reacted continuously.

| The method according to the invention is carried out in a technically simple and elegant manner. The synthesis of the 3-acylhydrazinopropionic acid esters of the formula h is carried out according to the invention by starting from acrylic acid esters of the formula 2 and reacting them with approximately equimolar amounts of hydrazine derivatives of the formula 3, in aqueous medium in inert organ solvents, preferably in an aqueous or alcoholic medium, if desired also by using no solvent at all. It is recommended that the acrylic acid ester be added in portions or diluted with a solvent, such as, for example, C 1 -C 2 alcohol, to a solution of the hydrazine component diluted with water or C 1 -C 2 alcohol. The alcohol / water mixing ratio can be varied within wide limits, while both alcohol alone and water alone can be used. Preferably, the alcohol / water weight ratio is 1: 1. The addition of the reactants can also be effected in reverse order.

The reaction takes place at temperatures of -20 ° C

up to + 150 ° C, preferably from 0 - 50 ° C. The pressure can be 98 - 981 kPa - 81 02 9 2 5 ij- .... .... ..... ... ...

! 3 I; : gene, however. It is preferred to use 98 kPa. As the solvents inert to the reaction components, mention may be made of C 1 -C 2 alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, see-butanol, tert-butanol, halogenated hydrocarbons ,. .5: such as methylene chloride, chloroform, and carbon tetrachloride, aliphatic; chemical and aromatic hydrocarbons, such as petroleum ether. pentane, cyclohexane, benzene, toluene, and xylene, ethers such as diethyl ether, tetrahydrofuran, dicxane, and ethylene glycol diethyl ether, ethyl sulfides such as acetonitrile, and carboxylic acid amides such as dimethylformamide.

"10: It is recommended that the reaction be catalytically completed with a" base "or an acid. As basic catalysts, usually alkali metal hydroxides, alkali metal alcoholates, tertiary amines such as 1. L trethylamine and Ν, ethyl-dimethylaniline, benzyl trialkylammonium hydroxides, such as, for example, benzyl trimethyl arammonium hydroxide and. dialkylcarbon-15 acids, such as dimethylformamide, and dimethylacetamide.

Sulfuric acid, phosphoric acid, acetic acid, lactic acid and boron trifluoride are used for the acid catalysis.

I! After the reaction has ended, the reaction mixture is optionally processed by a method known per se. After removing the solvent, the residue is fractionally distilled under reduced pressure or from suitable solvents, such as ketones, alcohols, nitriles, esters, ethers and chlorinated hydrocarbons, such as, for example, acetone, methanol, ethanol, acetonitrile, ethyl acetate, dlisopropyl ether and chloroform, recrystallized. Reaction products are obtained in the form of colorless crystals or as colorless liquids, which are stable at room temperature.

However, insofar as a continuous process is chosen, the reaction product of the general formula h need not be isolated, but can be further processed directly.

The 3-acylazopropionic acid esters of the general formula I are then prepared according to the invention in inert organic solvents with respect to the reactants by reacting the 3-acylhydrazinopropionic acid esters of the formula U with conventional oxidizing agents in an aqueous medium, the oxidizing agents are used in stoichiometric amounts as well as in excess. The 81 02 9 2 5 “"

J

It is recommended that the oxidizing agent be added portionwise as an aqueous solution or diluted with a solvent to the solution of the 3-acylhydrazinopropionic acid esters diluted with water or with a solvent. to add. The addition of the reactants can also take place in reverse order. This reaction step takes place at the same time; temperatures from -20 ° C to + 100 ° C, preferably from -5 ° C to + 50 ° C. The reaction time can be 0.5-5 hours depending on the reaction temperature.

As solvents inert to the reactants, the following may be mentioned: aliphatic and flavoring; hydrocarbons, such as cyclohexane, heptane, ligroin, henzene, chlorhenzene, toluene and xylene, as well as halogenated hydrocarbons; such as methylene chloride, chloroform, carbon tetrachloride and 1,2-dichloroethane.

; 15 In. In the presence of these solvents, the crude solutions can also be further processed, since they also behave as inert in the successive stages.

Examples of suitable oxidizing agents which suitably determine the choice of the solvent are: nitric acid, potassium dichromate, potassium permanganate, mercury oxide, ammonium and sodium nitrate, sodium chlorate, chlorine, alkali earth alkali hypochlorites, ammonia hydrogen peroxide, iron (III) chloride, nitrous oxide and lead (IV) oxide.

After the completion of the reaction, the reaction mixture is processed in a manner known per se, for example by distilling off the solvent used under reduced or normal pressure or by extraction, the organic solvents used during the course of the reaction simultaneously as an extractant for the 3-acylazopropionic acid esters. can serve. The extracts are then processed in a known manner, for example after the respective drying by distilling off the solvent used at normal or reduced pressure. In this way, 3-acylazopropionic acid esters are obtained in the form of light yellow colored crystals or oils, in very pure form and with very high yields, so that they can be converted without further purification.

In the oxidation of the 3-acylhydrazinopropionic acid es- 8102925! ·; , Μ. As follows from examination of the core resonance spectra, 5 compounds of the formula 1+ generate primary compounds of the structural formula 1.

In solution, these compounds have the. tendency to rearrange to formyl acetic ester-acylhydrazo-; 5 nes of the general formula 5, which as a result are isomers of. the compounds of formula 1.

The preparation of the compounds of the general formula 5, that is to say of the formyl acetic ester acylhydrazones, therefore also falls within the scope of the present invention. : - | 0 The compounds of the general formula V are on the other hand; in an isomeric equilibrium with compounds of the general formula -6, the preparation of which therefore also forms part of the present invention. If desired, an irreversible rearrangement of the compounds of the structural formula 1 in the isomeric form of the structural formula 5 and 6, respectively, can be carried out in a targeted manner, which means: dermal subject of the present invention.

To this end, according to the invention, the 3-acylazo-propionic acid esters of the general formula I, in which and Rg have the meanings mentioned above, are treated with catalysts, if desired using an inert solvent.

A particular embodiment of this process characteristic consists in that a 3-acylazopropionic acid ester of the formula 1 is converted to the acylhydrazone of at temperatures from -20 ° C to + 50 ° C, preferably at 0 ° C to 30 ° C. the formyl acetic ester 25 of the formula 5 and the enhydrazine of the formula 6.

This reaction can proceed with an acid or a Lewis acid as well as with a base as a catalyst. As acid catalysts, mention may be made, for example, of hydrochloric acid, sulfuric acid and nitric acid. acid,. HgCl 2 O 2 S 1 SO 2, NI 2 Cl, Nh 2 Br, HgBr 2, (CH) SiOSO 2 CF SnCl 2, BF 3, p-toluenesulfonic acid hydrate, acetic acid and trifluoroacetic acid.

As base catalysts may be mentioned oxides, hydroxides, alcoholates, carbonates of the alkaline earth and alkali metals, ammonia, tertiary amines such as triethylamine and N, N-dimethylaniline and pyridine bases. The isomerization reaction takes place suitably in an aqueous medium and / or in organic solvents.

8102925 'Μ ~ ^! i

• I

As inert solvents can be mentioned: halogenated hydrocarbons, such as methylene chloride, chloroform, 1,2-dichloroethane and carbon tetrachloride, aliphatic and aromatic! hydrocarbons, such as petroleum ether, pentane, heptane, cyclohexane, henzene, toluene, xylene and chlorhenzene, ethers such as diethyl ether, tetrahydrofuran, dioxane and diisopropyl ether, and alcohols such as methanol and ethanol.

The reaction takes place at ambient temperatures: from -20 ° C to + 50 ° C, it is preferable from 0 ° C to 30 ° C.

10 In practice, action is taken in such a way that the! crude solution of the 3-acylazopropionic acid ester an appropriate catalyst is added and then the generally solid reaction products by filtration, freezing or removing the solvent are isolated in the form of colorless crystals. These can be obtained from i »''! Suitable organic solvents, such as ketones, alcohols, nitriles, esters, ethers and chlorinated hydrocarbons, such as the aforementioned acetone, methanol, ethanol, acetonitrile, ethyl acetate, diisopropyl ether and chloroform, are easily recrystallized while being room temperature stable. In general, the compounds are; 20, however, are formed with such a high purity that they can be further converted without recrystallization.

The products prepared according to the invention are. important starting materials for the preparation of 1,2,3-thiadiazole-5-carboxylic acid derivatives, from which valuable agents for the protection of plants and agents for controlling harmful organisms as well as pharmaceutical products can be prepared.

This preparation of 1,2,3-thiadiazole-5-carboxylic acid derivatives of the general formula 7 can, for example, be carried out in a manner known per se by the products obtained in the process according to the invention and the general formula 55 in which the above-mentioned meaning property, with thionyl chloride.

The process according to the invention furthermore opens a new advantageous route of calculation for compounds of the formula 7 by reacting the primary-formed products of the general formula 1, which directly with thionyl chloride of the formula SOClg into the desired products of the formula 7 can be converted, 8102925 l · i 7 'thus saving a process stage. This method too; brand is an object of the present invention.

The synthesis of the 1,2,3-thiadiazole-5-carboxylic acid esters with. the formula 7 takes place here by starting from 3: 5. aeylazopropibric acid esters with, the formula 1 by reaction with thionyl chloride. The reaction is carried out at temperatures between -20 and + 100 ° C. preferably between -5 and + 50 ° C. The reaction time may vary from 1 hour to 20 hours depending on the reaction temperature.

! To synthesize 1,2,3-thiadiazole-5-carboxylic acid esters; The reactants can become in approximately equimolar amounts. applied. However, thionyl chloride can also be used as a solvent in a large excess.

However, it is recommended to use the 3-acylazopropionic acid esters and thionyl chloride in a 1: 3 molar ratio.

The reaction may also proceed in the presence of solvents inert to the reactants. As examples of such solvents, mention may be made of: halogenated hydrocarbons, such as methylene chloride, chloroform and carbon tetrachloride, aliphatic and aromatic hydrocarbons, such as petroleum ether, pentane, cyclohexane, benzene, toluene and xylene, ethers, such as diethyl ether, tetrahydrofuran , dioxane, ethylene glycol diethyl ether and diethylene glycol diethyl ether, as well as esters such as ethyl acetate.

As a rule, the 3-acylazopropionic acid ester, optionally also dissolved or suspended in a suitable solvent, is added portionwise to the thionyl chloride optionally diluted with organic solvents, but the addition of the reactants may also be in reverse order. executed. The hydrogen chloride formed during the reaction can be continuously removed from the reaction vessel by an inert gas stream or by applying reduced pressure.

After completion of the reaction, the reaction mixture is processed in a manner known per se. La. Distilling off the solvent and excess thionyl chloride, the residue can be fractionally distilled; either excess thionyl chloride is decomposed with saturated soda solution. sodium or potassium hydrogen carbonate solution, sodium acetate solution or with sodium or ore) 2 9 2 r. I; 8 potash or directly with water and the reaction solution is immersed; steam distillation or extraction, in which the solvents used during the reaction can simultaneously serve as extraction solvent. The extracts are then processed in a known manner; for example, after the appropriate drying and distillation of the solvent, the residue is fractionally distilled under reduced pressure or simply digested with a suitable solvent, such as an aliphatic hydrocarbon, such as pentane, hexane, cyclohexane or petroleum ether.

In this way, 1,2,3-thiadiazole-5-carboxylic acid esters are obtained in very pure form and with very high yields, so that they can be further converted into the desired end products without purification.

The method according to the invention is further elucidated on the basis of the following examples.

Example I

| a) Preparation of 3-semicarbazido-propionurmethyl ester

173.0 g, 20 (1.5 mol) of powdered semicarbazide hydrochloride was suspended in 300 ml of methanol in a 2 liter three neck round-bottomed flask equipped with stirrer, thermometer and reflux condenser with drying tube; a sodium methylate solution freshly prepared from g (1.5 mole) of sodium and 500 ml of methanol was added thereto over a period of 10 minutes, the internal temperature being kept between 15 ° and 20 ° C. The reaction mixture was then stirred for an additional 15 minutes at 20 ° C, after which the sodium chloride was aspirated. The filtrate was collected in a 2-liter three-necked round-bottom flask, after which 90 ml (1.0 mol) of acrylic acid methyl ester was added at 20 ° C with stirring for one hour. The reaction mixture was then allowed to stand at room temperature for 3 days, after which it was filtered once more and then the filtrate was concentrated under reduced pressure at 0 ° C. 205 g of a yellow oily product were obtained, which was then stirred for 1 hour with 1 liter of ethyl acetate at room temperature. The undissolved substance was filtered off and the filtrate was then concentrated to 500 ml at 100 ° C.

White crystals were obtained by rubbing, which were reduced. pressure. aspirated at room temperature and dried to constant weight.

81 02 9 2 5 i '9

Yield: 13 ^, ^ g = 83, W

Melting point: 67 - 69 ° C.

b1) Preparation of 3-carbamoylazopropionic acid methyl ester

In a 1 liter three-necked flask equipped with thermo-; 5 µm and stirrer, 16.1 g (0.1 mol) of 3-semicarbazido-propionic acid methyl ester were dissolved in 100 ml of water, followed by 2 ^ 6.0 g (0.3 mol) of an approx. 10% freshly prepared sodium hypochlorite solution over 20 minutes was added, keeping the internal temperature between 5 and 7 ° C. After 10 minutes of stirring in an ice bath, 85 g of sodium chloride was added to the yellow reaction solution thus obtained, after which it was carefully extracted 5 times with 100 ml of chloroform each time. The extracts dried with magnesium sulfate were concentrated under reduced pressure at 0 ° C. A yellow crystalline product was obtained.

Yield: 12.9 g = 81.1 $.

Melting point: 85 - 87 C (with decomposition).

b2) Preparation of 3-carbamoylazopropionic acid methyl ester

In a 1 liter three-necked flask equipped with stirrer and thermometer, 16.1 g (0.1 mol) of 3-semicarbazido-propionic acid-20 methyl ester were dissolved in a mixture of 150 ml of water and 10.3 g of approximately 95% strength. sulphuric acid. A solution of 9.79 g (0.0333 mol) of potassium dichromate in 70 ml of water and 13.8 g of approximately 95% sulfuric acid was added dropwise over a reaction temperature of 7-10 ° C under ice-cooling. The mixture was then allowed to react for a further 10 minutes, after which 20.0 g of solid potassium hydrogen carbonate was added. Yellow crystals were then separated. The reaction solution was intensively extracted five times with 300 ml of chloroform each time. The chloroform extracts dried with magnesium sulfate were concentrated at 1 + 0 ° C under reduced pressure. Yellow crystals were obtained.

30: Yield: 9.0 g = 56.5 $.

Melting point: 85 - 87 ° C (with decomposition), c) Preparation of 3-semicarbazono-propionzutirmethyl ester

In a 250 ml three-necked flask equipped with thermometer and stirrer, 15.9 g (0.1 mol) of 3-carbamoylazo-propionic acid methyl ester were dissolved in 100 ml of chloroform, after which 0.5 ml of triethylamine was added, the internal temperature was kept at 30 ° C by cooling. Subsequently, at room temperature for an additional 1 hour ex- 8102925 Π I - “'- - - j. stirred for 10 to 10 hours and then the crystal slurry formed is evaporated to dryness at 0 ° C under reduced pressure. The residue was digested with 150 ml of diisopropyl ether, filtered off and dried under reduced pressure to constant weight.

; Yield: 1U, 5g = 91.1%; Melting point: 159 ° C (with decomposition).

Example II

a) Preparation of 3-ethoxycarbonylhydrazino-propionic acid methyl ester I In a 1 liter three-necked flask equipped with stirrer, thermometer and reflux condenser, 11 µg (1.1 mol) of hydrazino-formic acid ethyl ester was dissolved in 600 ml of ethanol, then 90 ml (0.1 mol) acrylic acid methyl ester at 20 ° C was added for 1 hour. The reaction mixture was allowed to stand in a closed flask at room temperature for b days, after which the reaction solution was concentrated under reduced pressure at 50 ° C. The liquid thus obtained was distilled under reduced pressure.

Yield: 111.1 g = 58, b%.

Boiling point: 110 - 111 ° C / 13.33 Pa.

b) Preparation of 3-ethoxycarbonylazo-propionic acid methyl ester In a 250 ml three-necked flask equipped with stirrer and thermometer, 9.5 g (0.05 mol) of 3-ethoxycarbonylhydrazino-propionic acid methyl ester were dissolved in 50 ml of water, after which 82 g (0.1 mol) of an approximately 20% freshly prepared sodium hypochlorite solution was added over 20 minutes, keeping the internal temperature between 5 and 25 T ° C. A yellow oil was separated during this. Thereafter . the mixture was stirred for an additional 10 minutes in an ice bath and extracted three times with 75 ml of chloroform each time to give a yellow viscous oil after drying with magnesium sulfate and evaporation of the chloroform phases at 10 ° C under reduced pressure.

Yield: 8.7 g = 92, b%. n ^: 1, M2lu c) Preparation of. 3-ethoxycarbonylhydrazonopropionic acid methyl ester

In a three-necked flask equipped with stirrer and thermometer, 18.8 g (0.1 mol] 3-ethoxycarbonylazopropionic acid-35-methyl ester was dissolved in 100 ml of chloroform, after which 0.1 ml of triethylamine was added at 30 ° C. added, whereby as a result of the exothermic reaction 81 02 9 2 5!

ι I; 11 course had to be cooled. Stirring was then continued for 1 hour at room temperature, after which the reaction solution was concentrated under reduced pressure at 0 ° C. The residual oil was digested with 50 ml of diisopropyl ether and the crystals thus obtained were filtered off and dried 5: 5.

; Yield: 17.9 g = 95.2%.

; ; Melting point: 60 - 61 ° C.

Example III

Preparation of 3-semicarhazono-propionic acid methyl ester '10 (continuous run)

In a 1 liter three-necked flask equipped with thermometer and stirrer, 16.1 g (0.1 mole) of 3-semicarbazidone was added. ; propionic acid methyl ester dissolved in 100 ml of water, after which 1 ^ -1.6 g (0.2 mol) of an approximately 10% Ts fresh under cooling with ice over 20 minutes. prepared sodium hypochlorite solution was added, keeping the internal temperature between 5 and T ° C. The yellow reaction solution was stirred for an additional 20 minutes in an ice bath, after which 66 g of sodium chloride was added and then carefully extracted 5 times with 100 ml of chloroform each time. The chloroform phases dried with magnesium sulfate were concentrated to 100 ml under reduced pressure at 100 ° C. 0.5 ml of triethylamine was added to the chloroform solution concentrated to 100 ml, the internal temperature being kept at 30 ° C by cooling. After stirring for 1 hour at room temperature, the crystal slurry thus obtained was evaporated to dryness under reduced pressure at 0 ° C. The residue was digested with diisopropyl ether, then suction filtered under reduced pressure and dried to constant weight.

Yield: 12.0 g = 15.5%.

Melting point: 158.5 - 159.5 ° C (with decomposition).

Example 3? Y

Preparation of 3-ethoxycarbonylhydrazonopropionic acid methyl ester (continuous run)

In a 500 ml three-necked flask, equipped with stirrer and thermometer, 19> 0 g (0.1 mol) 3-ethoxycarbonylhydrazino-propionic acid methyl ester was dissolved in 100 ml of water, after which 1U of 1.6 g (0.2 mol) of about 10% sodium hypochlorite solution, 81 µl 2 µl 2: 2 II 12 was added, keeping the internal temperature between 5 and 7 ° C. A yellow oil was separated during this. The mixture was then stirred for 10 minutes, extracted three times with 150 ml of chloroform each time and the chloroform phase concentrated to 10 ml after drying with magnesium sulfate.

I "To the chloroform solution concentrated to 100 ml! 0.5 ml of triethylamine was added, whereby the temperature should not exceed 30 ° C. After stirring for an additional 1 hour at room temperature, the reaction solution was evaporated under reduced pressure at 0 ° C; the oily residue was diluted with 50 ml of diisopropyl ether; stirred and the formed colorless crystals aspirated and dried. Yield: 12.9 g = 68.5 $.

Melting point:. 59-61 ° C. "; Example V, 15 'Preparation of 3-ethoxycarbonylhydrazone-propionic acid methyl ester

19.0 g (0.1 mol) of 3-ethoxycarbonylhydrazino-propionic acid methyl ester were dissolved in 150 ml of water in a 50 ml ml three-necked flask equipped with stirrer and thermometer, followed by a solution of 9> 79 g in 15 minutes. (0.0333 mol} potassium dichromate in 70 ml: 20 water and 17> 2 g (0.167 mol) 95% sulfuric acid were added, the internal temperature was kept between -2 and 0 ° C for 30 minutes, then twice with 40 ml of chloroform extracted After drying with magnesium sulfate, the chloroform solution was evaporated under reduced pressure at 100 ° C. The residual oil was digested with diisopropyl ether and the crystals thus obtained were filtered off.

Yield: 12, U g = 65.9 $

Melting point: 57-6l ° C.

Example VI

Preparation of 1,2,3-thiadiazole-5-carbohydrate methyl ester In a 250 ml three-necked round-bottom flask equipped with stirrer, thermometer and condenser with branch tap, 21.8 ml - (0.3 mol) thionyl chloride was added to -10 ° G cooled, then 15.91 g (0.1 mol) of 3-carbamoylazo-propionic acid methyl ester was added portionwise over 15 minutes, keeping the internal temperature between -5 ° C and 0 ° C. After the addition was complete, the yellow reaction solution was stirred for an additional 2 hours, during which the internal temperature was allowed to slowly rise to + 2 ° C. 81 0 2 9T5 13. Then it was diluted with 60 ml of chloroform and then carefully decomposed with 60 ml of a saturated potassium hydrogen carbonate solution, keeping the internal temperature between 10 and 20 ° C. The chloroform phase was separated, washed with neutral solution of 30 ml of potassium hydrogen carbonate, dried with magnesium sulfate and concentrated under reduced pressure at 40 ° C. was distilled under reduced pressure from a water jet pump.

Yield: 11.6 g = 80.5 $.

: 10 Boiling point: 110 - 111 ° C / 1866.5 Pa.

81 02 9 2 5

Claims (8)

A process for the preparation of 3-acylazo-propionic acid esters of the general formula 1, wherein a C 1 -C 8 alkyl group and R 2 represent an alkoxy group, preferably a C 1 -C 20 alkoxy group, characterized in that acrylic acid esters of the general formula 2 with. Hydrazine derivatives of the general formula 3, optionally using an inert solvent and / or in the presence of a catalyst, are converted to 3-acylhydrazino-propionic acid esters of the general formula k and these compounds are converted into an inert solvent by oxidizing agents to the desired products are oxidized, the formulas 2 - k having the aforementioned meanings. 2. Process according to claim 1, characterized in that the reaction of the acrylic acid esters of the formula II with the hydrazine derivatives of the formula III takes place at temperatures from -20 ° C to + 150 ° C, preferably 0 - 50 ° C and at a pressure of 98 - 981 kPa, preferably at 98 kPa, optionally using a base or acid catalyzed reaction and equimolar amounts of the acrylic esters of the formula II and of the hydrazine derivatives with formula 3 are applied. A method according to claim 1, with. characterized in that the oxidation of the 3-acylhydrazino-propionic acid esters of the general formula h with conventional oxidizing agents is carried out at temperatures from -20 to + 100 ° C, preferably from -5 to + 50 ° C, and that a 3-acylhydrazino propionic acid ester of the general formula k is used, which is not isolated from the reaction mixture and is reacted continuously. * 1. Process according to any one of claims 1-3, characterized in that compounds of the general formulas 5 and 6 are prepared. 5. Process according to claim k, characterized in that compounds of the general formula 1, if desired using a solvent, are treated with catalysts, wherein and R2 have the aforementioned meanings. Method according to claim 5, characterized in that 8102 9 2 5 .1 · i *. \ 15 'a triacylazo-propionic acid ester of the formula 1 at temperatures from -20 to + 50 ° C, preferably at 0 ° C to 30 ° C to the acylhydrazone of the formylacetic acid ester of the formula 5 and to the enhydrazine of the formula 6 is diverted. A process according to claim 1 for preparing 1,2,3-thiadiazole-5-carboxylic acid derivatives of the general formula 7 wherein R 1 has the above meaning. Method according to claim 7, characterized in that; ; compounds of the general formula 1 are reacted with thionyl chloride of the formula s ° d 2, which has the above meaning. 9. Process according to claim J, characterized in that compounds of the general formula (5) are reacted with thionyl chloride, and having the above-mentioned meanings. 10. A method according to any one of claims 1 to 9 for preparing plant protection agents and pest control agents, and for preparing pharmaceutical products. - 81 0 2 9 2 5