DE2655794A1 - Prepn. of ethylene cyanohydrin from acrylonitrile and water - in presence of quat. ammonium hydroxide catalyst and formaldehyde, for use in prepn. of pharmaceuticals, plant protection agents, dyes, etc. - Google Patents

Abstract

Prepn. of ethylene cyanhydrin comprises reacting water with acrylonitrile in the presence of quat. ammonium hydroxides as catalyst and HCHO. The resulting reaction mixt. can be hydrogenated with H2 in the presence of ammonia and hydrogenation catalysts without sepg. the ethylene cyanhydrin, to give 3-aminopropanol-(1) in good yields. Ethylene cyanhydrin, is an important intermediate in the prepn. of solvents, e.g. for cellulose lacquers, dyestuffs plant protection agents, pharmaceuticals and plastics. It is also a starting material for the prepn. of plasticisers for PVC or the extraction of aromatics from crude oil.

Description

Process for the production of ethylene cyanohydrin

The invention relates to a new process for the preparation of ethylene cyanohydrin by reacting water with acrylonitrile in the presence of quaternary ammonium hydroxides and formaldehyde.

It is known to produce ethylene cyanohydrin by reacting ethylene oxide with hydrocyanic acid in the presence of alkaline earth salts (DBP 939 148). The procedure supplies large proportions of salts as by-products, isolation and purification of the end product are expensive Working with hydrocyanic acid requires extensive environmental protection measures.

According to the Russian patent specification 189 828, when acting of water in dioxane on acrylonitrile in the presence of an anion exchanger mixtures obtained from ethylene cyanohydrin and bis (cyanoethyl) ether. The conversion achieved of the acrylonitrile in this process is only 67.6% and with one Ethylene cyanohydrin yield of 40.88%.

A reaction of acrylonitrile with 100 to 400% excess over the leads to a stoichiometric amount of water in the presence of alkali and alkaline earth metal hydroxides practically exclusively for the formation of bis (cyanoethyl) ether (DAS 1 189 975).

In U.S. Patent 2,352,671, the reaction of 2 or one Mole of acrylonitrile with one mole of formaldehyde in the presence of alkaline condensing agents to the formal or semi-formal of ethylene cyanohydrin described; Water is in one Amount of at least one mole per mole of formaldehyde is used. Used as catalysts only alkali compounds, preferably alkali hydroxides and alkali cyanides, are given; Alkylamines are described as unsuitable catalysts.

It has now been found that ethylene cyanohydrin can be obtained by reacting Water with acrylonitrile in the presence of basic compounds is advantageous if the reaction with quaternary ammonium hydroxides as catalysts and in the presence is carried out by formaldehyde. It has also been found that one is advantageous the reaction mixture formed during the preparation without separation of the ethylene cyanohydrin hydrogenated with hydrogen in the presence of ammonia and hydrogenation catalysts.

The implementation can be represented by the following formulas: Compared to the known processes, the process according to the invention provides ethylene cyanohydrin in a simpler and more economical way in better yield and purity. All of these advantageous results are surprising because, with regard to German Auslegeschrift 1 189 975 and in particular US Pat. No. 2,352,671, the end products would be bis (cyanoethyl) ether, the formal or semi-formal of ethylene cyanohydrin or rather heterogeneous Expect mixtures of unreacted starting materials and these end materials. In particular, it was not to be assumed that the presence of formaldehyde would allow the formation of larger proportions of free ethylene cyanohydrin at all. The fact that the reaction mixture according to the invention can be hydrogenated and thus gives 3-aminopropanol- (I) in good yield is advantageous for a simple and economical preparation of this amino compound and surprising in view of the aforementioned publications. With reference to Houben-Weyl, Methods of Organic Chemistry, Volume 11/2, page 562, one would have expected di-γ-aminopropyl ether or di-γ-aminopropyl formaldehyde acetal as the end product of the aminating hydrogenation.

Water is used in an amount between 1 and 100 moles, preferably from 1 to 30 moles per mole of formaldehyde and advantageously from 1 to 10 moles, preferably from 1 to 6 moles, in particular from 2 to 4 moles, of water per mole of acrylonitrile are used. Corresponding are molar ratios from 0.1 to 2, preferably from 0.2 to 1, in particular from 0.3 to 0.8 mol of formaldehyde per mol of acrylonitrile is advantageous. Formaldehyde comes as Gas or liquid, expediently in the form of its 30 to 50 percent by weight, aqueous solutions, for use. The reaction is generally carried out at one temperature from 0 to 1000 ° C., preferably from 20 to 80 ° C., without pressure or under pressure, continuously or carried out batchwise.

The reaction is carried out in the presence of quaternary ammonium hydroxides, expediently in an amount of 0.001 to 1, preferably 0.01 to 0.1 mol of quaternary ammonium hydroxide per mole of acrylonitrile. If appropriate, the quaternary compound can also be used in a mixture with tertiary amines, in particular the amines on which it is based, for example a solution of tetra (β-hydroxyethyl) ammonium hydroxide in triethanolamine. Quaternary ammonium hydroxides of the formula are expedient where R1, R2, R3 and R4 can be the same or different and each represent an aliphatic, cycloaliphatic, araliphatic or aromatic radical, 2 of the radicals R1, R2, R3 and R4 can also denote members of a heterocyclic ring together with the adjacent nitrogen atom. Preferred are those quaternary ammonium hydroxides of the formula I in which R¹, R², R³ and R4 can be identical or different and can be identical or different and each have an alkyl radical having 1 to 18, in particular 1 to 7 carbon atoms, a hydroxyalkyl radical, especially an AL-hydroxyalkyl radical 2 to 18, in particular 2 to 7 carbon atoms, a cycloalkyl radical with 5 to 7 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms or a phenyl radical, in each case 2 of the radicals R1, R2J, R3 and R4 together with the adjacent nitrogen atom are members of a 5 - Or 6-membered, heterocyclic radical which can contain an oxygen atom in addition to the nitrogen atom. The aforementioned radicals can also be substituted by groups which are inert under the reaction conditions, for example alkyl groups or alkoxy groups each having 1 to 4 carbon atoms, hydroxyl groups. Tetraisopropyl, tetran-butyl, tetraisobutyl, tetra-sec-butyl, tetra-tert-butyl, tetrapentyl, tetrahexyl, tetra-n-heptyl, tetraoctyl, tetranonyl, tetradecyl, tetraundecyl -, tetradodecyl ammonium hydroxide; (Tetra-ß-hydroxyethyl) ammonium hydroxide, (Tetra-γ-hydroxypropyl) -ammonium hydroxide, (Tetra-B-hydroxypropyl) -ammonium hydroxide, (Tetra-d; -hydroxybutyl) -ammonium hydroxide, (Tetra-γ-hydroxybutyl) -ammonium hydroxide, ( Tetra-ß-hydroxybutyl) ammonium hydroxide, tetra (, a -dimethyl-ß-hydroxyethyl) -ammonium hydroxide, tetra- (a-methyl-ß-hydroxypropyl) -ammonium hydroxide, tetra- (ß, ß-dimethyl-ß-hydroxyethyl) -ammonium hydroxide , Tetra- (a-ethyl-ß-hydroxyethyl) -ammonium hydroxide, tetra- (a-methyl-y-hydroxypropyl) ammonium hydroxide, tetra- (ß-methyl-y-hydroxypropyl) -ammonium hydroxide, tetra-ß-hydroxypentyl-ammonium hydroxide, Tetra-y-hydroxypentyl-ammonium hydroxide, Tetra-hydroxypenty1-ammonium hydroxide, Tetra-g-hydroxypentyl-ammonium hydroxide; by quaternary substitution with the above-mentioned substituents and / or with the phenyl, benzyl, cyclohexyl, toluyl, methylcyclohexyl, phenylethyl, phenylpropyl, phenylbutyl group on the nitrogen atom, correspondingly from aniline, benzylamine, o, m, p- Toluidine, triphenyl, tribenzyl, tricyclohexyl, tri (methylcyclohexyl), tri (phenylethyl), tri (phenylpropyl), tri (phenylbutyl) amine, in the 2-, 3-, 4-position simply or in the 2 Triphenylamine, pyrrolidine, pyrazolidine, imidazolidine, hexamethyleneimine, piperidine, morpholine, 4-, 2,3-, 2,6-, 2,5-, 3,4-, 2,5-positions resulting ammonium hydroxides, which can also be ammonium hydroxides with 4 of the above, but completely or partially different radicals, e.g. which can be obtained from N, N-dimethylaniline, N-methyl-N, N-diethylamine, N, N-dicyclohexyl- N-methyl-amine, N-methyl-N-ethyl-Nn-propylamine, resulting quaternary ammonium hydroxides; Dimethylbenzyldodecyl, cetyltrimethyl, methyltriethyl, dimethyldiphenyl, trimethyl (o-tert-butylphenyl), β-ethoxyethyl-dimethyl-lauryl, trimethyl-diphenylmethyl, trimethyl-n-dodecyl, trimethyl-β-hydroxyethyl -, n-propyl-trimethyl-, isoamyl-trimethyl-, benzyldimethyl-n-octyl-, benzyltrimethyl-, phenyltrimethyl-, dimethyldodecyl-phenyl-, trimethyl- (phenyl- (l) -ethyl) -, trimethyl- (phenyl- (2) ethyl ammonium hydroxide; N, N-ethylmethylpiperidinium, trimethylene piperidinium hydroxide.

Preferred quaternary ammonium hydroxides are also basic ion exchangers. A series of basic ion exchangers that can be used for the process is in Houben-Weyl, Methods of Organic Chemistry, Volume 1/1, Page 529, Section Anion Exchange, listed. If necessary, you can use exchangers of other forms, e.g. in the chloride form, by appropriate treatment with e.g. caustic soda, caustic soda and carbon dioxide, Transfer soda or sodium bicarbonate to the hydroxide solution.

Strongly basic ion exchangers are preferably used in their hydroxide form with tetraalkylammonium or trialkyl-hydroxyalkylammonium groups, or polyvinylbenzylammonium resins, E.g. the exchange resin commercially available under the name (R) Amberlite IRA-400, or polystyrene divinylbenzyl trialkylammonium resins such as that under the designation (R) Amberlite IRA-900 commercially available resin was used. Shape and grain size of the Exchangers can be chosen arbitrarily within a wide range, preferably exchangers of 0.7 to 1.6 eq per liter of exchanger volume are used. In general an amount of 1 to 1,000, preferably 10 to 100 mol of acrylonitrile per val Exchanger applied. If you work discontinuously, e.g.

in a stirred vessel, the exchanger is generally used in an amount between 1 and 1,500, preferably between 15 and 150 percent by volume, based on Acrylonitrile, applied. The process can also be carried out continuously, e.g. the starting materials via exchange columns (ratio length to diameter e.g. 10 to 1) conducts, generally 10 to 1,000 volume percent Exchanger, based on the average per hour passed through the exchanger Amount of acrylonitrile, used. After the reaction, the exchanger can in the usual way, e.g. by treatment with aqueous bicarbonate or soda solution, sodium hydroxide solution (possibly together with carbon dioxide) and subsequent rinsing with water, reactivated and reused. In the case of continuous operation, the Usually one exchange column is used alternately for the reaction and the other regenerated.

Regarding the manufacture and details of the use of ion exchangers we refer to the chapter 'Ion exchangers in volume 1/1 of the mentioned work.

The reaction can be carried out as follows: a mixture of acrylonitrile, Formaldehyde, water and basic compound is during 0.5 to 60, appropriate Maintained at the reaction temperature for 1 to 20 hours. The reaction can be carried out batchwise, e.g. in stirring apparatus, or continuously, e.g. in stirring kettles, kettle cascades or via exchange columns. The end product can be extracted from the reaction mixture can be isolated in the usual way, e.g. by fractional distillation.

In a preferred embodiment of the method, the first Implementation according to the invention carried out and the reaction mixture then without separation of the end product aminatingly reduced.

Based on acrylonitrile, ammonia can be used in stoichiometric amounts or in excess, usually in an excess of up to 1,000 percent by weight, preferably in the case of continuous hydrogenation used in amounts of 10 to 30 moles per mole of acrylonitrile will. In the discontinuous procedure, there are 2 to 6 moles of ammonia per mole of acrylonitrile preferred. Ammonia can be in any phase, e.g. as a gaseous or liquid ammonia, and also in a solvent which is inert under the reaction conditions dissolved, added.

The reaction is carried out with hydrogen in the presence of a hydrogenation catalyst. The hydrogenation catalyst used is generally noble metals such as ruthenium, platinum and rhodium or chromites of zinc and copper or one or more metals with an atomic number between 24 and 29, usually cobalt, iron or nickel catalysts, for example corresponding sintered catalysts that have up to Can contain 30 percent by weight copper, manganese, iron and / or chromium; cobalt, nickel and iron are preferably used. The hydrogenation catalyst is generally added in amounts of 0.5 to 20, preferably 1 to 10 percent by weight, based on acrylonitrile. Hydrogen is generally used in an excess, expediently from 10 to 50, preferably from 1 to 10 mol of H2, based on used. Chromium, manganese, copper, alkalis and / or phosphoric acid can be used as activating catalyst additives. As a rule, such amounts of hydrogen are added to the reaction mixture at the beginning and during the course of the reaction that a corresponding reaction pressure is always established at the reaction temperature. The hydrogenation expediently takes place at a reaction pressure between 50 and 300, preferably between 120 and 260 atm, continuously or discontinuously; the reaction temperature is advantageously between 20 and 1500C, preferably between 60 and 1000C. Inert gases, such as nitrogen, can also be used in addition to hydrogen to adjust the pressure accordingly.

It is advisable not to use any additional organic solvent. Solvents which are inert under the hydrogenation conditions may optionally be used, for example cyclic ethers, such as dioxane or tetrahydrofuran, or primary or second alkanols with expediently 1 to 8 carbon atoms. They can be added to the reaction mixture individually or in any mixture. In general, the solvent is used up to 10 times the amount by weight, based on The hydrogenation can be carried out as follows: The hydrogenation catalyst is added to the reaction mixture, optionally together with the solvent, in a reactor and the reaction space is flushed with nitrogen. Then ammonia is added and hydrogen is injected up to the aforementioned reaction pressure.

Before or after the addition of hydrogen, the reaction mixture is increased brought the aforementioned temperature and while it was at this temperature with initiation held by more hydrogen until no more hydrogen from the reaction is consumed; in general, this reaction time is between 1 and 10 hours. The reaction mixture is then cooled and, if necessary, filtered. From the filtrate the end product is processed according to the usual methods, e.g. by fractional distillation, severed. In the direct hydrogenation of the reaction mixture, in addition to 3-aminopropanol- (l) usually also shares of 1,3-diaminopropane, which is also used, e.g. for production of textile finishing agents, can be recycled (Ullmanns Encyklopadie der Technische Chemistry (4th edition), Volume 7, page 382).

The ethylene cyanohydrin made by the process of the invention is an important intermediate for the production of solvents, e.g. for Cellulose lacquers> dyes, pesticides, pharmaceutica and plastics. They are also valuable starting materials for the manufacture of plasticizers for polyvinyl chloride or for aromatics extraction from crude oil. Regarding the use refer to the aforementioned publications and Kirk-Othmer, Encyclopedia of Chemical Technology (2nd edition), Volume 6, pages 673 to 675, referenced.

The parts mentioned in the examples are parts by weight.

Example 1 1,590 parts of acrylonitrile, 1,200 parts of 40 percent by weight Formaldehyde solution and 500 parts of water are in the presence of 600 parts by volume Polyvinylbenzylammonium resin sold under the designation (R) Amberlite IRA-400 (OH-Form) commercially available, stirred for 18 hours, the temperature from 230C on 420C rises. After the ion exchanger has been separated off, it is distilled by filtration one from the reaction mixture at 75 ° C and 25 Torr through a Sambey damper 1 120 parts of water and 118 parts of unreacted acrylonitrile. By fractional Distillation of the residue (2,010 parts) gives 1,480 parts of ethylene cyanohydrin from boiling point 85 to 860C at 0.4 Torr, corresponding to a yield of 75% of the Theory, based on converted acrylonitrile.

Example 2 1,173 parts of acrylonitrile, 960 parts of 40 percent by weight Formaldehyde solution and 1,112 parts of water are combined with 134 parts of a 40 percent by weight Solution of tetra (ß-hydroxyäthy1) ammonium hydroxide in triethanolamine for 7 hours 400C stirred.

The reaction mixture is then worked up analogously to Example 1.

239 parts of unreacted acrylonitrile and 939 parts are obtained Ethylene cyanohydrin from boiling point 85 to 860C at 0.4 torr, corresponding to a yield of 75% of theory, based on converted acrylonitrile.

Example 3 1 173 parts of acrylonitrile, 960 parts of 40 percent by weight Formaldehyde solution and 1,112 parts of water are combined with 134 parts of a 40 percent by weight Solution of tetra (ß-hydroxyethyl) ammonium hydroxide, as described in Example 2, Stirred for 7 hours at 40.degree. 80 parts of reaction mixture are then added hourly at 800C and 250 bar together with 272 parts NH3 and 9 parts H2 over 750 parts a manganese / phosphoric acid / cobalt catalyst (5: 4: 91 percent by weight) continuously directed.

Fractional distillation of the reaction mixture gives hourly 13> 57 parts of 1,3-diaminopropane with a boiling point of 52 to 580C at 50 torr, corresponding to a yield of 35% of theory, based on the acrylonitrile used, and 22.02 parts of 3-aminopropanol- (1) boiling point 110 to 11200 at 50 torr, respectively a yield of 56% of theory, based on the acrylonitrile used.

Example 4 3 180 parts of acrylonitrile, 2400 parts of 40 percent by weight Formaldehyde solution and 1,000 parts of water are in the presence of 1,400 parts by volume Polyvinylbenzylammonium resin sold under the designation (R) Amberlite IRA-400 (OH-Form) is commercially available, stirred for 24 hours at 40.degree. After filtration it becomes Amination hydrogenated as in Example 3 reaction mixture. By fractional distillation of the hydrogenation mixture, 18.36 parts per hour of 1,3-diaminopropane at the boiling point are obtained 53 to 60 ° C. at 50 torr, corresponding to a yield of 34% of theory on acrylonitrile used, and 30.64 parts of 3-aminopropanol- (l) from the boiling point 111 to 11300 at 50 torr, corresponding to a yield of 56% of theory on the acrylonitrile used.

Claims (2)

Claims 1. Process for the preparation of ethylene cyanohydrin by reacting water with acrylonitrile in the presence of basic compounds, characterized in that the reaction with quaternary ammonium hydroxides as catalysts and is carried out in the presence of formaldehyde. 2. The method according to claim 1, characterized in that the Reaction mixture formed during preparation without separating off the ethylene cyanohydrin hydrogenated with hydrogen in the presence of ammonia and hydrogenation catalysts.