DE2450863A1 - PROCESS FOR MANUFACTURING ORGANIC NITRILES - Google Patents

Description

PATENT AGENCY OFFICE 24 5G863 TlEDTKE - Bühling - KlNNE

TEL. (089) 53 9653-56 TELEX: 524845 tipat CABLE ADDRESS: Germaniapatent Munich

8000 Munich 2

Bavariaring 4

P.O. Box 20 2403 > ²⁵ October 1974

case H 26550/26722 - B 6281

IMPERIAL CHEMICAL INDUSTRIES LIMITED London, United Kingdom

Process for the production of organic nitriles

The invention relates to a method of manufacture organic nitriles, in particular by reacting olefinic compounds with hydrogen cyanide in the presence a catalyst.

The inventive method for the preparation of organic nitriles is characterized in that one an olefin with hydrogen cyanide in the presence of a catalytic amount of a copper salt, especially one Reacts copper (I) salt and a sulfide or thiol.

The sulfide or thiol used together with the copper (I) salt is preferably organic, but can also Copper sulfide or any sulfide can be used, and

(No) 503819/1180

Deutsche Bank (MQnchen) Account 51/61 070 Dresdner Bank (Manchen) Account 3939 844 Posticheck (Munich) Account 670 43-804

especially those with the copper (l) salt react with the formation of copper sulfide, as special Alkali metal sulfides.

The copper (I) salt is preferably more soluble in Shape used. When an organic thiol or sulfide is used, the cuprous salt is preferably one Salt soluble in the thiol or sulfide and in particular a copper (I) halide, especially copper chloride or copper bromide.

If a non-organic sulfide such as copper sulfide is used, a solution of a copper (I) halide, for example, by dissolving the copper (I) halide in an aqueous solution of an inorganic Compound in which it is soluble can be obtained. Particularly suitable solvents for copper (I) halides are concentrated aqueous solutions, especially saturated solutions, of ammonium halides, in particular Ammonium chloride, alkali metal halides or cyanides, in particular lithium chloride or lithium cyanide and aluminum chloride.

The class of organic thiols or sulfides includes organic compounds with the HS or -S groups contain, the dash symbols bonds with carbon atoms to symbolize. This class includes in particular compounds of the formulas:

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SH and R ₁ SR ₂

where R ₁ and Rp are aliphatic, cycloaliphatic, araliphatic or aromatic radicals and, in the case of sulfides, can be identical or different and bonded to one another, the S atom then belonging to a sulfur-containing heterocyclic ring. The radicals R ₁ and R ₂ can carry substituents such as hydroxyl, alkoxyl, carboxyl ester and halogen substituents and the aliphatic and cycloaliphatic radicals can contain unsaturated or multiple bonds between carbon atoms, and in particular ethylenic double bonds. In addition, the sulfur-containing heterocyclic rings can contain unsaturated carbon-carbon bonds and other heteroatoms, in particular nitrogen, oxygen or sulfur atoms. The heterocyclic rings are preferably 5-, 6- or 7-membered, in particular 5- or 6-membered.

Particularly suitable aromatic thiols and sulfides include those of the above general formulas in which R ₁ and R _{2 are} alkyl groups having 1 to 6 carbon atoms which, in the case of sulfides, can be the same or different and, in particular, are the same. Thiophene are also particularly suitable and sulfides of the above general formula in which R ₁ and R ₂ together form tetramethylene or pentamethylene groups. As examples of such

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-A-

particularly suitable compounds are methyl mercaptan, Ethyl mercaptan, propyl mercaptan, butyl mercaptan, amyl mercaptan, Hexyl mercaptan, dimethyl sulfide, diethyl sulfide, Dipropyl sulfide, dibutyl sulfide, diamyl sulfide, dihexyl sulfide, Methyl ethyl sulfide, thiophene, tetrahydrothiophene and pentamethylene sulfide should be mentioned.

Other suitable compounds include cyclohexyl mercaptan, Benzyl mercaptan, thiophenol, dicyclohexyl sulfide, dibenzyl sulfide, diphenyl sulfide, ditolyl sulfide, Thiodiglycol and thiomorpholine.

The organic thiol or sulfide can form a complex with the copper (I) salt. In any case it is preferred that the thiol or sulfide is used in at least a stoichiometric amount based on the copper. Essential However, borrowed more than the stoichiometric amount can also be used. It is preferred to dissolve the copper (I) salt in a minimal amount of the thiol or Sulfide. For example, 0.5 to 5 parts by weight of thiol or sulfide can be used for each part by weight of copper (I) salt can be used to form a solution.

If copper sulfide is used, it is preferably copper (I) sulfide, for example by adding a Alkali metal sulfide (e.g. sodium sulfide) to an aqueous solution of a water-soluble copper salt (e.g. copper (II) sulfate or copper (II) halide) can be obtained.

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The ratio of copper sulfide to copper (I) salt is not critical: weight ratios within the range from 1: 1 to 10: 1 are suitable.

The inventive method can be performed over a wide temperature range, for example from -25 ° C to 200 ⁰ C. Due to the "deterioration" of the catalyst at high temperatures and because of the low reaction rate at lower temperatures, however, a work in the temperature range of 50 to 16O preferred ° C and especially from 90 to 135 C, where temperatures are very suitably from about 120 ⁰ C. In view of the volatility and toxicity of hydrogen cyanide, the reaction is preferably carried out in a closed vessel under the self-developed pressure or, if desired, under intentionally increased pressure, such as, for example, at pressures of 1 to 50 atm. If desired, a solvent such as a hydrocarbon solvent such as benzene, toluene or xylene, or a nitrile solvent such as acetonitrile, propionitrile, benzonitrile or adiponitrile can be used. Some agitation or stirring of the reactants is desirable. The response • will continue for a sufficient time to achieve an appropriate implementation. In the case of batchwise operation, the time will normally be between one hour and a period of several days, for example 5 days.

The olefin and the hydrogen cyanide can be equivalently 5OS 3 · 19/1180

molar proportions are used or an excess of one of the two can be provided, which is in particular in the molar range of olefin to hydrogen cyanide from 2: 1 to 1: 1O. The copper (I) salt is used in a catalytic amount: this usually falls in the range of 0.0005 to 0.1 moles per Moles of olefin. A proportion of this salt of from 0.005 to 0.05 mol per mol of olefin is preferred.

The organic nitrile formed in the process can be separated from the reaction mixture by any excess of olefin and / or hydrogen cyanide is first obtained by distillation or simple aeration removed from the apparatus. The organic nitrile can then be derived from the copper (I) salt residue and the organic thiol or sulfide by conventional methods such as filtration with or without extraction with solvents or distillation be separated. That. Process can be adapted smoothly to continuous operation.

The olefin used according to the invention is preferably a conjugated diolefin such as, for example Butadiene, isoprene, piperylene, hexa-2,4-diene and 2,3-dimethylbutadiene.

The method according to the invention is particularly valuable

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for the monohydrocyanation of butadiene to 3-pentene nitrile. In some cases some bis-hydrocyanation can be used to adiponitrile (adipin dinitrile) take place.

In US Pat. No. 2,509,859, the reaction of butadiene with hydrogen cyanide in the presence of, for example, copper. · (I) -chlprid to 3-pentene-nitrile described. Although the Reaction is referred to as catalytic, good yields of 3-pentenonitrile are only obtained if essentially Equimolar proportions of butadiene and copper (I) salt are used. With catalytic proportions such as, for example, 0.006 mol of copper (I) chloride per mole of butadiene, both the butadiene conversion and the yield of 3-pentenonitrile are low. When the invention However, processes yield catalytic amounts of cuprous salt when used in conjunction with one organic thiol or sulfide good butadiene conversions and good yields of 3-pentene nitrile (pentene (3) nitrile).

. . It has been suggested to use butadiene and hydrogen cyanide in the presence of catalytic amounts of to implement certain catalysts such as certain catalysts with zero-valent nickel, such as for example in GB-PS 1 104 140 is described. Such processes result in mixtures of linear pentenenitriles, which by further reaction with hydrogen cyanide are convertible to adiponitrile and branched methyl

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butenenitriles, which cannot be converted directly to adiponitrile. The problem encountered with these methods ratio of linear pentenenitriles to the generated branched Methylbutennitrilen is normally not more than 70 wt -.% (Or mole%). It is an advantage of the present process that the formed ratio of linear 3-pentene nitrile which is directly convertible to adiponitrile is much higher and is usually at least 80% by weight (or mol %) , ie the ratio of 3-pentene- nitrile to branched methylbutenenitriles is at least 4: 1. In addition, the catalysts with zero-valent nickel used in older processes are sensitive to moisture, while this is not the case for the catalysts according to the invention. Anhydrous conditions are therefore not required and it is therefore not necessary, for example, to particularly dry the olefin and the hydrogen cyanide.

3-pentenonitrile is necessary for the further reaction with hydrogen cyanide in the presence of a catalyst to achieve of adiponitrile is particularly valuable. Adiponitrile can form hexamethylenediamine, a valuable intermediate for the polycondensation with dicarboxylic acids to be hydrogenated to polyamides. This is particularly beneficial, for example Adipic acid with hexamethylene diamine Polyhexamethylene adipamide (nylon 6,6), i.e. one for the production of moldings and for melt spinning processes to achieve

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synthetic fibers well known polyamide. .

The invention is explained below with the aid of examples. _; . ,

Example 1 '

A mixture of 30 ml (19.5 g) of butadiene, 15 ml of hydrogen cyanide and a solution of 1.8 g water-free '''copper (I) -chlörid in 3 ml of thiophene was 17 hours in a closed container at 120 ⁰ C heated. After removing excess butadiene and hydrogen cyanide by evaporation, the product liquid (22.8 g) was distilled to obtain a first fraction (1.7 g), which mainly consisted of low-boiling material including thiophene, but which contained a Content 'of 4.1 % (0.07 g) 3-pentenonitrile was found and a second fraction (14.2 g), in which a content of 74.5 %' (10.1 g) '3- Pentene nitrile and 6.7 % (0.9 g) 2-methyl-3-buten-nitrile was found. The residue was 4.7 g. The conversion of butadiene into mononitrile was 40% and the yield of 3-pentenonitrile (based on the butadiene converted in this way) was 91.6 % and that of 2-methyl-3 -Butene nitrile at 8.4 % '. "''' ■ ""

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Example 2

A mixture of 10.4 g of butadiene, 7 ml of hydrogen cyanide and a solution of 1.2 g of anhydrous copper (I) chloride in 2 ml of di-n-propyl sulfide was ^{heated to 145 °} C. for 17 hours in a closed container . After removing excess butadiene and hydrogen cyanide by evaporation, the product liquid (14.6 g) was distilled to give 11.34 g of distillate and a residue of 2.11 g. A content of 66 % (7.48 g) 3-pentene-nitrile and 3.7% (0.42 g) 2-methyl-3-buten-nitrile was found in the distillate. The conversion of butadiene into mononitrile was 50.6 % and the yield of 3-pentenonitrile (based on the butadiene thus converted) was 94.8 % and of 2-methyl-3-butenenitrile was 5.2 %.

Example 3

Anhydrous copper (I) chloride (0.6 g) was added in 0.9 ml Di-n-propyl sulfide (or the compound given in the table below) dissolved and the solution in a given nitrogen-filled tube. After flushing with nitrogen, 5 ml of hydrogen cyanide (redistilled from Phosphorus pentoxide) condenses in the tube at -78 C and then 10 ml of butadiene (purified by passing through

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through an ion exchange column) distilled into the tube, which was then sealed. The mixture was stirred magnetically and heated to the reaction temperature for the reaction time (indicated in the table). The tube was then cooled to -78 ⁰ C and opened. Unreacted butadiene and hydrogen cyanide were distilled off and the remaining liquid was filtered off from the solid catalyst. The liquid was then analyzed for 3-pentene-nitrile, 2-methyl-3-buten-nitrile and adiponitrile by gas-liquid chromatography.

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link Reaction conditions
worked duration
(Hours) Shares in the product liquid
(Weight? 0 2-methyl
3-butene
nitrile Adipo-
nitrile Relationship:
3-pentene nitrile:
2-methyl-3-butene
nitrile ■ - Dimethyl sulfide Temp.
(° c) 17th 3-pentene
nitrile 1.7 - ■ 14.3 13.6 Diethyl sulfide 100 17th 24.5 1.99 - 11.85 9.05 Di-n-propyl
sulfide 100 17th 23.6 4.52 - 7.45 - Il 100 17th 33.7 3.24 ■ - 17.5 3.72 Il 130 17th 57.1 5.48 - 11.8 Di-isoamylsulfic 145 17th 64.6 - - - Diphenyl sulfide 100 17th 16.0 1.23 - 16.5 Thiodiglycol 100 17th 20.3 - 3.0 η 10Q 26th 2.4 __ 3.6 Thiophene 100 17th . 7.9 4.16 0.95 Il 100 17th 56.4 6.2 traces Thiophene oil 160 17th 56.0 traces 3.4 Di-n-propyl
sulfide 100 17th 24.5 4.8 1.5 65 17.8

_: ■ 2A508-63;

Example '4 . '

Anhydrous copper (I) chloride (0.6 g) was dissolved in 1 ml of di-n-propyl sulfide in a tube filled with nitrogen and then 8.2 g of isoprene was added. After purging with nitrogen, 5 ml of hydrogen cyanide (distilled from phosphorus pentoxide) were added and the tube was closed. The mixture was stirred magnetically and heated to 110 ° C. for 17 hours. After cooling, the tube was opened, excess volatile material was distilled off and the residue was distilled to obtain 8.2 g of mononitriles ( 71-7% isoprene conversion) with more than 95 % of it in 4-methyl-3-pentene-nitrile.

Example 5

In an experiment carried out similarly to Example 4, except that 1.74 g of anhydrous copper (I) bromide, 2 ml of di-n-propyl sulfide, 13 g of butadiene and 10 ml of hydrogen cyanide were used and to 100 ^{0 for 14 hours} C., the conversion of butadiene to mononitriles was 14.5 % and 3-pentenonitrile was obtained as the product in a yield of 95 % (based on the converted butadiene).

Example 6

In a similar to Example 4 carried out

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Experiment 0.6 g of anhydrous copper (I) chloride, 1.0 g of dibenzyl sulfide, 6 g of butadiene and 5 ml of hydrogen cyanide were used as reactants and the mixture was ^{heated to 100 °} C. for 4 hours. In this way, a yellow product with a yield of 4.45 g of mononitriles was obtained in the distillation (corresponding to a butadiene conversion of 49.4 %), 94.2 % from 3-pentenonitrile and 5.8 % from 2 -Methyl-3-buten-nitrile.

Example 7

In an experiment carried out similarly to Example 4, 0.8 g of anhydrous copper (I) bromide, 1 ml of thiophene, 6.5 g of butadiene and 5 ml of hydrogen cyanide were used as reactants and the mixture was ^{heated to 100 °} C. for 17 hours. A conversion of butadiene to mononitriles of 48 % was achieved, 3-pentenonitrile in a yield of 82.2 % and 2-methyl-3-butenonitrile in a yield of 17.8 % (based on the converted butadiene ) obtain.

Example 8

In an experiment carried out similarly to Example 4, 0.6 g of anhydrous copper (I) chloride, 1 g of dibenzyl sulfide, 8 g of isoprene and 5 ml of cyano

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hydrogen is used and heated to 140 ⁰ C for 20 hours, filtered off the liquid product from the solid catalyst and distilled ^c to obtain 4.93 g of 4-methyl-3-pentene-nitrile having a boiling point of 158 to I62 ° C and more than 97 % ± low purity. The isoprene conversion was 44.1 %.

Example 9

Copper (I) sulfide (0.5 g) became a solution of anhydrous copper (I) chloride (0.5 g) in 3 ml of a saturated solution of ammonium chloride in water at 20 ° C added. Hydrogen cyanide (6 ml) and butadiene (2 ml) were then added and the mixture heated to 75 ° C for 12 hours in a closed container. After cooling to ordinary temperature, the container was ventilated to remove butadiene and hydrogen cyanide and the liquid product separated from the catalyst and analyzed by gas-liquid chromatography. A conversion of butadiene of 18% was found and the product contained 3-pentenonitrile and adiponitrile in a weight ratio of 8: 1.

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Claims (3)

Claims 1. Process for the production of organic nitriles by reacting an olefin with hydrogen cyanide in the presence of a copper catalyst, thereby ge indicates that the catalyst used is a copper (I) salt in conjunction with a sulfide or thiol is used. 2. The method according to claim 1, characterized in that the sulfide or thiol is an organic sulfide or Thiol is used. 3. The method according to claim 1, characterized in that copper sulfide is used as the sulfide. 509819/1180