DE2648004C2 - 4-Cyanvaleric acid esters and process for their preparation - Google Patents

Description

R ² —O —C - CH ₂ -CH ₂ -CH-CH ₃ (ΠΙ)

CN

wherein R ^{2 is} a methyl or alkyl radical optionally substituted by 1 or 2 hydroxyl groups with more than 2 carbon atoms or an ethyl radical substituted by heteroatoms or a cycloalkyl radical with 5 to 8 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms or the phenyl radical, the aforementioned Radicals can also be substituted by alkyl or alkoxy groups each having 1 to 4 carbon atoms or hydroxyl groups.

The invention relates to 4-cyanovaleric acid esters and a process for their preparation according to the above Claims.

It is from Bull, of the Chem. Soc. of Japan, Volume 40 (1967), pages 135 to 144 known that acrylonitrile with Carbon monoxide and methanol in the presence of cobalt carbonyl, pyridine and hydrogen essentially increase Can convert alpha-cyanopropionic acid methyl esters. According to the teaching of this publication, temperatures must be from 84 to 124 ° C can be used. The presence of some amount of hydrogen is essential for that Implementation of the reaction necessary. It is shown that a mixture of alpha- and beta-cyanopropionate

-to in a ratio of 1: 1 is then achieved when there is no addition of pyridine. Only in the case of these mixtures will at all a comparatively larger amount of the beta component is achieved, remains in the presence of pyridine the beta component is always a by-product. According to the information given in the test conditions, this increases The higher the pressure, the stronger the ratio of the alpha component to the beta component; Press from 60 to 190 bar are mentioned. If the hydrogen partial pressure is increased, the ratio of the alpha component increases to the beta component.

It is known from Liebigs Annalen der Chemie, Volume 596 (1955), page 127 that by heating 5-valerolactone and sodium cyanide 5-cyanovaleric acid and from it the corresponding ones by reaction with alcohols Ester can get. A corresponding reaction (US Pat. No. 2,736,740) by heating of 4-valerolactone with sodium cyanide gives 4-cyanovaleric acid. The procedures are regarding simple, safe and economical operation and the yield and purity of the end product are unsatisfactory.

The subject of patent 25 41 640 is a process for the preparation of 5-cyanovaleric acid esters by Implementation of pentenenitriles of the formula

■ I

R - C-CN (1)

H HH

I Il

where R 'denotes the radical H - C - C = C or the radical H - C = CC -
HHH HH

means with carbon monoxide and the hydroxyl group-containing compounds of the formula

R ² -OH (U)

in which R ² denotes an alkyl radical with 1 to 12 carbon atoms optionally substituted by 1 or 2 hydroxyl groups, a cycloalkyl radical with 5 to 8 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms or the phenyl radical, the aforementioned radicals also being substituted by alkyl or A ' koxy groups with 1 to 4 carbon atoms or hydroxyl groups can be substituted at a temperature of 140 to 300 ⁰ C and a pressure of 100 to 700 bar in the presence of metal carbonyls and basic, s a 5- or 6-membered nitrogen-containing ring containing heterocyclic compounds .

It has now been found that the method of Fatents25 41 640 can be developed if it is based on 2-Methyl-3-butenenitrile transfers as Peiitenenitril, and this is otherwise also for the production of 4-Cyanvaieriansäureestern suitable.

It has also been found that the process can be carried out advantageously if the reaction is carried out without the addition of in Hydrogen is carried out.

The reaction can be carried out by the following in the case of using 2-methyl-3-butenenitrile and methanol Equation can be reproduced:

CH ₂ = CH-CH-CH ₃ + CO + CH ₃ OH- »H ₃ CO-C-CH ₂ -CH ₂ -CH-CH ₃
CN CN

In view of the prior art, the method according to the invention provides a simpler and more economical one Ways 4-cyanovaleric acid esters in better yield and purity, especially on an industrial scale Scale. Toxic, operationally difficult to handle substances, such as sodium cyanide, are avoided; the process is more environmentally friendly. A special esterification operation is saved. All these advantageous results are surprising in view of the state of the art. You would have one instead considerable yield of methyl 2-methyl-3-cyanobutyrate and the formation of carboxamides and carboxylic acid esters or at least mixtures of numerous components must be expected as end products.

The 2-methyl-3-butenenitrile which is preferably used for the preparation of 4-cyanovaleric acid esters can be used by adding hydrocyanic acid to butadiene, for example in the presence of complex compounds containing nickel or copper chloride according to the procedure described in German Offenlegungsschrift 15 93 277 produce.

Preferred alcohols of the general formula II and substances are those in whose formulas R ^{2 has} the aforementioned meaning as an unsubstituted or substituted alkyl radical having 1 to 8 carbon atoms.

As alcohols of the formula II, for. B. possible: methanol, isopropanol, ethanol, dodecanol, n-propanol, tert-butanol, nonanol, sec-butanol, n-hexanol, n-butanol, iso-butanol, 2-ethylhexanol, benzyl alcohol, Ethylene glycol, methyl glycol, propanediol (1,3), butanediol (1,4), propanediol (1,2), neopentyl glycol, 2,4-pentylene glycol, 2,3-butylene glycol, hexanediol (1,6), cyclopentanone, cyclohexanol, cycloheptane, cyclooctanol, Phenylethyl alcohol, n-pentanol, phenylpropanol, phenol, n-heptanol, n-octanol, n-decanol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2,3-dimethylphenol, 3,4-dimethylphenol, 2,6-dimethylphenol, 3,5-dimethylphenol, 2,3-dimethoxyphenol, 3,4-dimethoxyphenol, 3,5-dimethoxyphenol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 2,3-diethylphenol, 3,4-diethylphenol, 2,6-diethylphenol, 3,5-diethylphenol, 2-ethoxyphenol, 3-ethoxypnenoi, 4-ethoxyphenol, 2-n-propylphenol, 3-n-propylphenol, 4-n-propylphenol, 2,3-di-n-propylphenol, 3,4-di-n-propylphenol, 2,6-di-n-propylphenol, 3,5-di-n-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-butylphenol, 3-butylphenol, 4-butylphenol, 2-isobutylphenol, 3-isobutylphenol, 4-isobutylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2,3-diethoxyphenol, 3,4-diethoxyphenol, 2,6-diethoxyphenol, 3,5-diethoxyphenol.

The alcohols of the formula II can be used in a stoichiometric amount or in an excess, preferably in a ratio of 1 to 10 moles of alcohol of the formula II per mole of 2-methyl-3-butenenitrile are reacted.

If excess 2-methyl-3-butenenitrile is used in the case of polyhydroxy alcohols, corresponding di- or polyesters of 4-cyanovaleric acid are formed. The alcohol required for the reaction can also be used as a solvent at the same time, in which case the amount is advantageously 10 to 50 moles of alcohol of the formula II per mole of 2-methyl-3-butenenitrile. If appropriate, organic solvents which are inert under the reaction conditions can also be used, such as aromatic hydrocarbons, e.g. B. benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, isopropylbenzene, methylnaphthalene; Ether, e.g. B. ethyl propyl ether, methyl tert-butyl ether, n-butyl ethyl ether, di-n-butyl ether, diisobutyl ether, diisoamyl ether, diisopropyl ether, anisole, phenetole, cyclohexyl methyl ether, diethyl ether, ethylene glycol dimethyl ether. Tetrahydrofuran, dioxane, thioanisole, beta.beta'-dichlorodiethyl ether; Ketones such as methyl ethyl ketone, acetone, diisopropyl ketone, diethyl ketone, acetophenone, cyclohexanone and mixtures thereof. The solvent is advantageously used in an amount of 1 to 15 mol, preferably from 2 to 10 moles, relative to 1 mole of the starting material of the formula I. The reaction is generally conducted at a temperature from 140 to 300 ⁰ C, preferably from 140 to 25O ⁰ C, in particular from 150 to 200 ⁰ C, under pressure, generally from 100 to 700, advantageously from 160 to 350, in particular from 180 to 350 bar, carried out continuously or batchwise. If, at temperatures between 100 and 14O ⁰ C in a way, a reaction occurs with a significantly poorer yields of end product.

Carbon monoxide comes in a stoichiometric amount or in excess, preferably in an amount of 10 up to 50, in particular from 20 to 30, moles of carbon monoxide per mole of 2-methyl-3-butenenitrile are suitable. Usually the process is advantageously carried out without the addition of hydrogen or in a hydrogen-free reaction medium

the end; smaller amounts of hydrogen produced by the reaction components, e.g. B. by carbon monoxide, introduced or during the reaction, e.g. B. from carbon monoxide and water, can be present be.

The reaction is carried out in the presence of basic, a 5- or 6-membered, nitrogen-containing ring containing heterocyclic compounds carried out. Preferred heterocyclic compounds are unsubstituted or by alkyl groups, alkoxy groups each having 1 to 4 carbon atoms, hydroxyl groups substituted 5- or 6-membered heterocyclic rings, to which one or two aromatic, optionally substituted with alkyl groups, alkoxy groups each having 1 to 4 carbon atoms, hydroxyl groups Cores can be fused: among the fused compounds are those with only one fused Core preferred. Preferred heterocyclic rings in particular have only one nitrogen atom as a heteroatom, but can also contain an additional nitrogen atom or an oxygen atom, and also contain 2 or 3 double bonds. There are amounts from 0.1 to 2, preferably from 0.1 to 1 mol of heterocyclic Compound per mole of starting material I into consideration.

For example, quinoline, isoquinoline, imidazole, 1-methylimidazole and 1-propylimidazole are preferred.

2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, 2,4,6-trimethylpyridine and especially pyridine; there are also pyrrolidone, ^ '- pyrroline, ^ ² -pyrroline, / 1 ³ -pyrroline, alpha-pyrrolenine, beta-pyrrolenine, pyrrole, isooxazole, oxazole, pyrazole, pyrazoline, pyrazolidine, imidazolidine, 3-imidazoline, 2,3 , 4,5-tetrahydropyridine, pyridazine, pyrimidine, pyrazine, piperazine, indoline, indole, 2-H-indole, indolenine, isoindoline, isoindole, indolizidine, indolizine, benzoxazole, indazole, benzimidazole, 1,2,3,4-tetrahydroisoquinoline , Cinnoline, quinanzoline, quinoxaline, phthalazine, carbazole, acridine, phenoxazine, phenazine, 4-methoxypyridine, 2-methylbenzoxazole, 2-methylquinoline, 4-methylimidazole, 1-methylindole, 2-methylindole, 3-methylindole, 3-methylisoquinoline, 2 -Methylpiperazine, 2-methylpyrazine, 3-methylpyrrole, 2-methylpyrrole.

2-ethylpyridine, into consideration.

The metal carbonyls are pure carbonyls, carbonyls whose carbon monoxide is partially replaced by neutral ones or charged ligands is substituted, and carbonyl hydrogen in question, expediently those of iridium, Iron, nickel, ruthenium, rhodium and particularly preferably those of cobalt. Regarding the manufacture the carbonyls are referred to Ullmanns Enzyklopadie der technischen Chemie, Volume 12, pages 312 to 324. Instead of the aforementioned carbonyls, the corresponding metals or metal compounds are also used, which can form such carbonyls under the reaction conditions into consideration. As a metal compound The halides, in particular iodides and chlorides, acetates, oxides, sulfates of the aforementioned can expediently be used Metals, e.g. B. cobalt acetate tetrahydrate can be used. Substituents of the substituted carbonyls are z. B. Trialkyl compounds, triaryl compounds and trihalides of phosphorus, amines, isonitriles, Cyanide ions; Halogens, e.g. B. in the form of carbonyl halides such as chlorides or iodides. Appropriate 0.005 to 0.1, preferably 0.0i to 0.05 moles of carbonyl compound are used per mole of starting material Formula I.

There come z. B. as metal carbonyls and derivatives of metal carbonyls into consideration: Fe (CO) ₅ , Ni (CO) ₄ , Ru (CO) ,, Rh ₂ (CO) ₈ , Ir ₂ (CO) ₈ ; ((C ₆ Hs) ₃ P) ₂ Ni (CO) ₂ , ((C ₆ Hj) ₃ P) Fe (CO) ₄ , Ni (CN - C ₆ H ₅ J ₄ , K ₂ [Ni (CO) ₂ (CN),], IR (CO) ₂ Br ₂ ; HCo (CO) ₄ , H ₂ Fe (CO) ₄ , HRh (CO) ₄ , preferably dicobalt octacarbonyl Co ₂ (CO) ₈ .
The reaction can be carried out as follows. A mixture of 2-methyl-3-butenenitrile, the starting material of the formula II, carbon monoxide, the base and the metal carbonyl, optionally together with a solvent, is kept at the reaction temperature and the reaction pressure for 1 to 20 hours. A mixture of 2-methyl-3-butenenitrile, alcohol of the formula H, base and metal carbonyl in a suitable solvent will advantageously be placed in a reactor filled with nitrogen or argon. After carbon monoxide has been injected at room temperature, the temperature is increased up to the reaction temperature. If necessary, carbon monoxide is then injected in order to achieve the reaction pressure. The reaction is then expediently carried out for 1 to 20 hours under the specified conditions, then the mixture is cooled and let down. The end product is now from the mixture in the usual way, for. B. by fractional distillation isolated. Depending on its boiling point, the heterocyclic compound either remains in the distillation residue or is distilled off. Cobalt carbonyl remains in the residue during the distillation, which is

so, if necessary, after adding base, without any significant reduction in the yield for further carbonylations lets use.

4-Cyanvaleric acid esters are valuable starting materials for the production of dyes, pesticides, fibers, especially polyamide fibers, and plastics. Hydrogenation to 4-methyl-5-aminovaleric acid esters and elimination of the alcohol gives 5-methyl-2-piperidone, which is used as an extraction and solvent. This lactam can (Houben-Weyl, Methods of Organic Chemistry, Volume 11/1 (1957), pages 593 and 594) be reduced to 3-methylpiperidine with copper chromite. 3-methylpiperidine is the starting material for the production of nicotinic acid and its derivatives. 3-methyl-pyridine (beta-picoline) can be produced directly from the lactam by dehydration (CuO / Cr ₂ Oj) and niacin (nicotinic acid) from the pyridine derivative:

CH ₃

CH ₂ = CH-CH-CN + CO + CH ₃ OH

+ 2H ₂

H ₃ CO-C-CH ₂ -CH ₂ -CH-CH ₃

CN

CH ₃

Il I

H ₃ CO-C-CH ₂ -CH ₂ -CH-CH ₂ NHj

H ₃ C

-H ₂
-H ₂ O ^

CH ₃

+ 1.5O ₂ -H ₂ O ^

-CH ₃ OH

COOH

(see also Chem. techn. 1979, p. 365).

The previous large-scale routes went to the production of niacin from a) acetaldehyde, formaldehyde and ammonia or from b) acetaldehyde and ammonia from:

4CH ₃ CHO + 3CH ₂ O + 2NH ₃

-4H ₂ O CH ₃ CHO + NH ₃ >

H ₃ C

[ -7H ₂ O ^

CH ₂ -CH ₃

ENT ₃ HOOC

COOH

COOH

In comparison to these processes, the process according to the invention is surprising and advantageous. The use of ammonia is saved. There is no pyridine as a by-product. The oxidation to pyridinedicarboxylic acid and the decarboxylation, which removes 2 carbon atoms per pyridine starting material without recycling, are avoided. On the other hand, the alcohol R ² OH separated in the new way can be recycled. With regard to the easily accessible starting material acetaldehyde, the starting material according to the invention has the additional advantage that it can be used in large quantities as an unusable by-product, e.g. B. in the production of adiponitrile by butadiene / hydrocyanic acid conversion. Compared with the previous processes, the substances according to the invention therefore enable a more economical, technically simpler and more environmentally friendly way of producing nicotinic acid and its derivatives with regard to overall production. With regard to the use, reference is made to the publications mentioned.

The parts mentioned in the following examples are parts by weight.

example 1

A shaking autoclave filled with argon is charged with a mixture of 40.5 parts of 2-methyl-3-butennilril, 3.4 parts of dicobalt octacarbonyl, 6.5 parts of pyridine, 40 parts of methanol and 25 parts of acetone. The pressure is brought to 200 bar by injecting carbon monoxide. The autoclave is then ^{heated to 160 °} C., the pressure is adjusted to 300 bar by forcing in more carbon monoxide and the reaction mixture is shaken under these conditions for 4 hours. After cooling, letting down the pressure in the autoclave and passing air through the reaction mixture, it is filtered. Fractional distillation gives 52.2 parts of methyl 4-cyanovalerate (74.1% of theory), boiling point 108 to 110 ° C./21 mbar, η ?? = 1.4270.

Example 2

In the same way as in Example 1, a mixture of 40.5 parts of 2-methyl-3-butenenitrile, 6.8 parts of dicobalt octacarbonyl, 13 parts of pyridine and 75.1 parts of isopropanol are reacted. The reaction is carried out under the conditions of Example 1 at 160 ^° C. and 300 bar with a reaction time of 4 hours. Fractional distillation gives 55.7 parts of isopropyl 4-cyanovalerate (66% of theory), boiling point 100 to 102 ° C./13 mbar, n $ = 1.4282.

Claims (2)

Claims -. 1. A process for the preparation of 4-cyanovaleric acid esters, characterized in that in the method according to patent 25 41 640, in which a pentenenitrile with carbon monoxide and the hydroxyl group containing compounds of the formula R ² - OH (II) in which R ² denotes an alkyl radical with 1 to 12 carbon atoms, optionally substituted by 1 or 2 hydroxyl groups, a cycloalkyl radical with S to 8 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms or the phenyl radical, the aforementioned radicals also being substituted by alkyl or alkoxy groups each having 1 to 4 carbon atoms or hydroxyl groups can be substituted at a temperature of 140 to 300 ^° C. and a pressure of 100 to 700 bar in the presence of metal carbonyls and basic heterocyclic compounds containing a 5- or 6-membered nitrogen-containing ring is implemented, 2-methyl-3-butenenitrile is used as the pentenenitrile. 2. 4-Cyanvaleric acid ester of the formula