DE2642140C2 - Process for the production of benzoyl cyanide - Google Patents

Description

15th

The invention relates to a method of manufacture of benzoyl cyanide from benzoyl chloride and alkali cyanide, benzoyl cyanide is an important intermediate for the manufacture of herbicides.

It is known that benzoyl cyanide can be produced by the action of superstoichiometric amounts of copper (I) cyanide on benzoyl chloride. The reaction is conducted at temperatures up to 80 ° C in acetonitrile or benzonitrile or in ether with the addition of stoichiometric amounts of lithium chloride or lithium iodide executed (Bull. Soc. Chim. France 1972, p 2402-2403) or at temperatures of 220 to 23O ⁰ C in Absence of solvents (Org. Synth. Coll. Vol. 3, pages 112 to 114). These processes give yields of 65% at best.

It is also known to convert benzoyl chloride to benzoyl cyanide by means of alkali cyanide in a two-phase system consisting of water and one with water not miscible solvent in the presence of a quaternary To implement alkylammonium salt (Tetrahedron Letters No. 26 (1974), pages 2275 to 2278). With this one Process, the yields are only 60%.

It is also known to produce benzoyl cyanide from benzoyl chloride by reaction with anhydrous hydrogen cyanide and to produce at least equimolar amounts of pyridine (Z. Phys. Chem. 192 (1943), pages 200 to 201). This procedure gives yields of 78%.

The disadvantage of the known processes is that a considerable amount of by-products, in particular the Dimers of benzoyl cyanide, benzoyloxyphenylmalodinitrile, are formed. As a result, it's not just that The yield of benzoyl cyanide is unsatisfactory, but its purity can also be from benzoyl cyanide separate its dimer only with considerable difficulty and only incompletely.

There has now been a process for the preparation of benzoyl cyanide from benzoyl chloride and alkali metal cyanide found, which is characterized in that the reaction is carried out in an inert organic solvent in the presence of benzoic anhydride or of substances that react with benzoyl chloride benzoic anhydride form, is executed. According to this process it is possible to produce a pure benzoyl cyanide with at least Win 90% yield.

To carry out the process according to the invention, benzoyl chloride is reacted with alkali metal cyanides, preferably with sodium cyanide or potassium cyanide. It is generally desirable ^b5 to take at least stoichiometric amounts of cyanide. It is advantageous to use about 1.05 to 2.0 equivalents of cyanide,

40

45 in particular from 1.05 to 1.5 equivalents of cyanide per mole of benzoyl chloride.

According to the invention, the reaction is carried out in an organic solvent which is inert towards the reaction parts. Suitable solvents are, for example, ethers such as dioxane and ethyl glycol diethyl ether or esters such as butyl acetate. Particularly suitable are aromatic hydrocarbons such as ethylbenzene and in particular benzene, toluene and xylenes, ^{or aliphatic hydrocarbons such as cyclohexane and especially ligroin with a boiling range from about 90 to 140 0} C, or halogenated, preferably chlorinated, aromatic or aliphatic hydrocarbons, such as Trieb'oräthylen and especially chlorobenzene, dichlorberizole and tetrachloroethane. Mixtures of these solvents can also be used.

The amount in which the solvent is used depends to a certain extent on its type In general, it is advantageous to use at least about 40 ml of solvent per mole of benzoyl chloride. It is advantageous to use about 70 to 2000 ml, in particular 100 to 350 ml, of solvent per mole of benzoyl chloride used.

According to the invention, the reaction takes place in the presence of benzoic anhydride or of substances which can convert benzoyl chloride to benzoic anhydride. As such substances are water that Benzoic acid and the metal salts of benzoic acid, especially the alkali metal salts of benzoic acid, especially suitable Other carboxylic acids, mainly aliphatic, cycloaliphatic, preferably saturated, optionally substituted by halogen or acrylic groups, mono- or polycarboxylic acids, especially those with 6 to 18 carbon atoms, or aromatic or heteroaromatic, optionally on the ring by alkoxy or nitro groups, in particular by alkys groups or halogen, substituted carboxylic acids, the metal salts, in particular the alkali, alkaline earth and ammonium salts, these carboxylic acids or the anhydrides of these carboxylic acids in question. Examples of this Carboxylic acids are acetic acid, chloroacetic acid, phenylacetic acid, isobutyric acid, cyclohexanecarboxylic acid, Lauric acid, adipic acid, oleic acid, methylbenzoic acids, chlorobenzoic acids, terephthalic acid, nicotinic acid, Furancarboxylic acid and thiophenecarboxylic acid. Mixtures of such substances or are also suitable Mixtures of benzoic anhydride with such substances.

Benzoic anhydride and the substances that convert benzoyl chloride to benzoic anhydride can, can in, based on the benzoyl chloride, stoichiometric or superstoichiometric amounts can be used. However, substoichiometric amounts are preferably used, namely in generally about 0.01 to 0.3 mol, in particular 0.03 to 0.1 mol per mol of benzoyl chloride.

The reaction temperature depends, if appropriate, on the type of solvent and the others Implementation participant. In general, temperatures come from about 80 to 170.degree. C., in particular 100 up to 150 ° C, in question. Albeit the pressure largely can be chosen arbitrarily, it is advantageous not to deviate significantly from normal pressure. In some In some cases, due to the presence of volatile substances, it may be appropriate at one of the temperature appropriate increased pressure to work.

Example! 1

A mixture of 140.5 g (1.0 mol) benzoyl chloride, 22.6 g (0.1 mol) benzoic anhydride, 73.5 g (1.5 mol) Sodium cyanide and 300 ml of xylene were refluxed for 8 hours at the boiling point (140 to 145 ° C) held. The mixture was then cooled and filtered with suction. The backlog in the consisted essentially of sodium salts, was washed with xylene. The filtrate was fractionated distilled The benzoyl cyanide obtained had a boiling point of 92 to 96 ° C. at 19 mbar. The yield was 119 g, corresponding to 91%, based on the amount used Benzoyl chloride.

Example 2

To a mixture of 294 g (6 mol) of sodium cyanide, 26 g (0.25 mol) of sodium benzoate and 500 ml of xylene 702.5 g (5 mol) of benzoyl chloride was added dropwise. The mixture was meanwhile and then at 135 ° C for half an hour held. After cooling, it was filtered with suction. The filtrate was fractionally distilled. That Benzoyl cyanide had a boiling point of 92 to 96 ° C at 19 mbar. The yield was 611 g, correspondingly 94%, based on the benzoyl chloride used.

Example 3

The procedure of Example 2 was followed, except that 4.5 g (0.25 mol) of water were used instead of sodium benzoate The benzoyl cyanide had a boiling point of 115 to 117 ° C. at 45 mbar. The yield was 598 g, corresponding to 92%, based on the benzoyl chloride used.

Example 4

The procedure was as in Example 2, except that 18 g (0.15 mol) of benzoic acid were used instead of sodium benzoate and 500 ml of chlorobenzene were used instead of xylene. The yield was 601 g. corresponding to 93%, based on benzoyl chloride used.

- B e i s ρ i e I 5

To a mixture of 19.5 g (0.3 mol) of potassium cyanide, 3 g (0.01 mol) of 4-chlorobenzoic anhydride and 80 ml of ligroin with a boiling point of 110 to 140 ° C were Added dropwise 28.1 g (0.2 mol) of benzoyl chloride.

"'During this time, and then for a further half an hour, the mixture was kept at 125 to 135 ° C. After the cooling was filtered with suction and washed with ligroin. The filtrate was at 45 mbar evaporated to a temperature of 117 ° C was. 26 g of residue remained. According to the gas chromatogram, this consisted of 94% benzoyl cyanide and 3% from 4-chlorobenzoyl cyanide and benzoic anhydride.

- ,, - ι examples

The procedure was as in Example 5, but 1.6 g were used instead of 4-chlorobenzoic anhydride (0.01 mol) of the sodium salt of 4-methylbenzoic acid is used. 26 g of a product were obtained 95% from benzoyl cyanide, 1% from 4-methylbenzoyl cyanide and 4% benzoic anhydride.

Example 7

^{3 (1} The procedure was as in Example 5, but 2.0 g (0.01 mol) of lauric acid were used instead of 4-chlorobenzoic anhydride. From the reaction mixture, the benzoyl cyanide was recovered by distillation. It had a boiling point of 113-115 ⁰ C. at 40 mbar The yield was 23.2 g, corresponding to 89%, based on the benzoyl chloride used.

Claims (2)

Patent claims: ! ... Process for the production of benzoyl cyanide from benzoyl chloride and alkali cynanide, characterized in that the reaction in one inert organic solvents in the presence of benzoic anhydride or substances that form benzoic anhydride with benzoyl chloride, is carried out. 2. The method according to claim t, characterized in that that the reaction is carried out at temperatures from about 80 to 170.degree.