DD145103A1 - PROCESS FOR THE PREPARATION OF BETA FUR-2-YL-ALPHA-HALOGENACRYLONITRILENE - Google Patents

Abstract

The invention relates to a process for the preparation of β-fur-2-yl-α-haloacryronitriles. Such compounds are valuable intermediates for the production of pharmaceuticals, Insecticides and fungicides. According to the object of the invention, a technically simple and economical Method for the synthesis of these compounds in good yields and on the basis of easily accessible To provide starting materials are, according to the invention ß- for-2-yl-acrylonitrile of general formula, for example, by reaction of the corresponding furfural with cyanoacetic acid can be obtained with halogen and a base in an inert solvent at temperatures in the range implemented between -20 ° and + 120 ° C. - Formula -

Description

-a- 2 1

Title aer invention

Process for the preparation of β-fur-2-yl-Cd-haloacrylonitriles

Field of application of the invention

The invention relates to a novel process for the preparation of .beta.-Fur-2-yl ~ & -halogenacrylonitriles. These compounds are valuable intermediates for the manufacture of pharmaceuticals, insecticides and fungicides «

Characteristics aer known technical solutions

It is known that β- (5-nitro-fur-2-yl) -06-bromoacrylonitrile can be prepared from 5-nitro-urofurane and 1-bromo-cyanomethyl-pentyl-phosphorane; H. Saikachi, S. Nakamura in Yakugaku Zasshi J88 / I (1968) 11Ο _β This method has the disadvantage that the required Wittig reagent must first be prepared over several stages. A technical application of this method is further complicated by the fact that a quantitative separation of the triphenylphosphine oxide formed in the reaction is possible only by column chromatography.

Object of the invention

It is an object of the invention to provide a technically simple and

economical method for the synthesis of ß-Fur-2-yl - # - halogenacry! nitriles using readily available

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Show starting materials, wherein the target products are easily isolated from the reaction medium.

Presentation of the VVesens of the invention

The object is achieved by a novel process for the preparation of .beta.-fur-2-yl- & -haloacrylonitriles of general formula I.

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in the R. hydrogen, nitro, halo alkyl, aralkyl or aryl and Hal halo, preferably chlorine or bromine, mean by according to the invention ß ~ fur-2 ~ yl-acrylonitrile of the general formula II

CH - CN

R obengeannte significance _t with halogen, preferably chlorine or bromine, and a base in an inert solvent are reacted at temperatures in the range between -20 and +120 ⁰ C.

Suitable β-fur-2-yl-acrylonitriles which are suitable for the process according to the invention are, for example, β-fur-2-yl-acrylonitrile, β- (5-naphtho-2-yl) -acrylonitrile, β- (5 Chloroform ~ 2 ~ yl) ~ acrylonitri.l, β- (5-bromo-fur ~ 2-yl) acrylonitrile, β- (5-methyl-fur-2-yl) -acrylonitrile, and β- 5- (p ~ nitro ~ phenyl) fur ~ 2 ~ yl / -acrylonitrile.

Used as halogenating agent is elemental halogen, such as chlorine and bromine

Both organic and inorganic bases can be used for the process according to the invention. Suitable organic bases are preferably tertiary amines, such as pyridine and

Triethylamine suitable, and as inorganic bases, for example, sodium acetate and sodium carbonate can be used.

Halogenated hydrocarbons, such as dichloromethane and dichloroethane, but also, for example, acetic acid, are suitable as inert solvents for the reaction according to the invention.

The reaction according to the invention can be realized in a simple manner by reacting β-fur-2-yl acrylonitrile in the abovementioned inert solvents with the halogen and then adding a base. On the other hand, however, β-fur-2-yl-acrylonitrile and base can also be initially charged in an inert solvent and reacted together with the halogen.

If the reaction is carried out, for example, with chlorine, the halogen is advantageously introduced into the reaction mixture in gaseous form. When using bromine as the halogenating agent, this is advantageously diluted with an inert solvent and added dropwise to the reaction mixture. * For less reactive β-fur-2-yl-acrylonitriles, it is advisable to bring the starting compound and bromine together with stirring to the required reaction temperature beforehand then followed by the reaction with the base.

The ratio of β-fur-2-yl-acrylonitrile to halogen is preferably 1 to 1 to 3. The reaction temperature is kept at -20 to -j-120 C, preferably in the range between -10 and +80 C. worked ,

The end products are obtained in yields above 60 % , and can be easily isolated from the reaction medium and easily purified by crystallization or distillation.

The β-fur-2-yl-acrylonitriles of the general formula II used as starting materials for the process according to the invention can be obtained by simple known processes, for example by reaction of the corresponding furfurals with cyanoacetic acid.

Ausführungsbeaspiele

Example 1:

a) To 48.6 g of acetic anhydride and 0.5 g of conc. Sulfuric acid are added dropwise at -10 ⁰ C 18.9 g nitric acid (d = 1.5 g / cm} "is added to this mixture with stirring over an hour at -20 ⁰ C a solution of 11.9 g (O _f l mol ) ß-Fui-2-yl-acrylonitrile (Isomerenverhäitnis. 37% Z, 63% e) are added dropwise in 54 g of acetic anhydride Subsequently, the mixture is stirred at this temperature 5.Stunden is then warmed to 0 ⁰ C, 1 Ig ice. After vacuuming, 10 g (61 %) of β- (5-nitro-fur-2-yl) acrylonitrile (isomer ratio: 30 % Z ₁ 70% E) of melting point 75 ° are obtained up to 100 ^° C _e

b) A solution of 1.64 g (10 mmol) of β- (5-nitro-fur-2-yl) acrylonitrile (E / Z isomer mixture) and 2 g (12.5 mmol) of bromine in 10 ml of dichloroethane Heated to 60 ⁰ C for 30 minutes. 0.9 g (12 mmol) of sodium acetate and 20 ml of acetic acid are added to the reaction mixture and the mixture is heated to 60 ^° C. for 2 hours. After cooling, the mixture is poured into 100 ml of water, the organic phase is separated off and the aqueous phase is extracted twice each time. After drying and evaporation of the extracts, 2.5 g of crude product are obtained. After recrystallization from ethanol, 1.6 g (66 % ) of .beta .- (5-nitro-fur-2-yl) -o-bromoacrylonitrile ( e / Z Isomerengf

receive.

Isomeric) of melting point 70 ° to 100 ⁰ C.

Example 2:

A solution of 1.64 g (10 mmol) of β (5-nitro-fur-2-yl) acrylonitrile {E / Z isomer mixture) and 3 _{S of} 2 g (20 mmol) of brora in 10 ml of acetic acid becomes 8 hours heated to 60C. Thereafter, 1.6 g (20 mmol) of sodium acetate and 10 ml of acetic acid are added and the mixture is heated for a further 2 hours to 60 ° C. After cooling, it is poured into 100 ml of water and extracted four times with 50 ml of dichloromethane. After drying and evaporation of the organic phase, 2.5 g of crude

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domestic product. Recrystallization from ethanol gives 1.3 g (54 %) of β- (5-nitro-fur-2-yl) -α-bromoacrylonitrile (E / Z isomer mixture) of melting point 70 ° to 105 ° C.,

Example 3:

To a solution of 11.9 g (0.1 mol) of β-fur-2-yl-acrylonitrile (isomer ratio: 37 % Z, 63 % E) and 15.8 g (0.2 mol) of pyridine in 60 ml. Dichloromethane is added at -10 ⁰ C with stirring in one hour, 32 g (0.2 mol) of bromine, dissolved in 60 ml of dichloromethane. The mixture is then stirred for one hour at -10 ⁰ C, one hour at ^{0 0} C and then allowed to stand overnight at room temperature · The reaction mixture is poured into 100 ml of water, the organic phase is separated and the aqueous solution extracted four times with 50 ml ether. The combined organic phases are washed with dilute hydrochloric acid and water and evaporated. This gives 13.7 g of oily crude product. By distillation at 75 to 95 ⁰ C and 0.05 Torr to obtain 11.2 g of a mixture of 7.5 g ß-Fur-2 ~ yl-W-bromoacrylonitrile (isomer ratio: 60 % Z ₁ 40 % E) and 3.7 g of β- (5-bromo-fur ~ 2 ~ yl) ~ 0-bromoacrylonitrile (isomer ratio: 26 % Z, 74 % E). The mixture can be separated by fractional distillation.

Example 4 ::

11.9 g (0.1 mol) of β-fur-2-yl-acrylonitrile (isomer ratio: 37 % Z, 63 % E), 23.7 g (0.3 mol) of pyridine and 48 g (0.3 mol ) Bromine are reacted analogously to Example 3. This gives 12.8 g of crude product containing 2 g of β-furyl-2-bromoacrylonitrile (isomer ratio, 73 % Z, 27 % E) and 10.8 g of β-, (5-bromo-fur-2-) yl) - (i-bromacryranitrile (isomer ratio: 43 % Z, 57 % E)) .beta .- (5-bromo-fur ~ 2-yl) - C ~ bracrylonitrile can be obtained by distillation or recrystallization from n-hexane in pure form to be obtained.

Example 5:

Into a solution of 11.9 g (0.1 mol) of β-fur-2-yl-acrylonitrile and 23.7 g (0.3 mol) of pyridine in 40 ml of dichloromethane is passed under stirring at -5 C in one hour 21.3 g (0.3 mol) of chlorine, followed by stirring for another hour at this temperature and then allowed to stand overnight at room temperature. After working up analogously to Example 3, 4.7 g of ß ~ (5 ~ chloro-fui-2-yl) -C £ ~ chloroacrylonitrile of boiling point 80 ° to 95 ⁰ C at 0.1 Torr ·

Claims (3)

invention claim Process for the preparation of .beta.-fur-2-yl-oi-haloacrylonitriles of the general formula I. CH ^ C- in which R is hydrogen, nitro, halogen, alkyl, aralkyl
or aryl and halo halogen, preferably chlorine or bromine, characterized in that .beta.-fur-2-yl-acrylonitriles of the general formula II in which R has the abovementioned meaning, with halogen, preferably chlorine or bromine, and a base in an inert solvent at temperatures in the range of -20
be implemented to +120 ⁰ C. 2, method according to item I _1, characterized in that are used as bases pyridine, triethylamine, sodium acetate or sodium carbonate « 3. The method according to item 1, characterized in that the inert solvent is halohydrocarbons or
Acetic acid can be used.