NL7907083A - PROCESS FOR PREPARING 1,4-DICYANOBUTES. - Google Patents

Description

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Halcon International, Inc., of New York, New York, Ver. St. v. America -

Process for the preparation of 1, U-dicyanobutenes

The invention relates to a process for the preparation of 1,1H-dicyanobutenes, which are valuable intermediates in the preparation of adiponitrile.

Adiponitrile is an important raw material because it can be easily converted into hexamethylenediamine, the latter of course being a constituent of nylon 6,6. Due to developments in the field of acrylonitrile preparation, acrylonitrile has become available in quantities and at a price that make this material very suitable as a potential raw material for the preparation of adiponitrile.

One of the pathways to the adiponitrile involves the conversion of acrylonitrile to a 3-halopropionitrile by adding a hydrogen halide, after which this halopropititrile is coupled using certain coupling agents. (See, for example, Belgian patents 7 ^ 6. ^ 15, 7 ^ 6,035 and 7 ^ 6.1 * 17).

Other pathways involve the electrolytic conversion of acrylonitrile to adiponitrile or the reductive coupling of acrylonitrile using various metal amalgams. Such a method is described, for example, in U.S. Pat. No. 3,162,678. In addition, the reductive dimerizations of acrylo-nitrile in the presence of ruthenium-type catalysts have been proposed to prepare adiponitrile. (See, for example, Belgian Patent Specification 677,989).

Yet another method contemplated is the direct dimerization of acrylonitrile to the linear 1, U-dicyano-butene or mixtures containing this compound. United States Patent 3,538,11 * 1 describes a catalytic method for performing the linear dimerization. For various reasons, the methods proposed so far for converting acrylonitrile to adipinitrile to 7907033 i / laten 2 leave desires. Disadvantages of these known methods include high energy consumption, the use of expensive reagents as catalysts, slow reaction rates or selectivities.

As is known, the dimerization of aerylo-5 nitrile proceeds at high speed under suitable conditions, but with the branched dimer, 2-methylene glutaronitrile, as the main product. (See the formula sheet | reaction a).

It has been found that 2-methylene glutaronitrile can be isomerized to 1, U-dicyanobutenes.

The process according to the invention is therefore characterized in that 2-methylene glutaronitrile is subjected to an isomerization reaction. This isomerization can take place at a temperature of 100-700 ° C, preferably 100-00 ° C and more preferably 150-350 ° C in the presence of basic catalyst and hydrogen cyanide or a source of hydrogen cyanide, the isomerization mixture 1 being used. U-dieyanobutenes isolate. This isomerization is shown on the formula sheet (reaction b).

The isomerization is preferably carried out in the liquid phase at a pressure of, for example, 101-300 KPa, but can also be carried out in the vapor phase.

The Catalyst used is soluble or insoluble in the reaction medium. Insoluble catalysts can be suspended as such in a distributed form or on a support such as coke, charcoal, alumina, silicon alumina, aluminum silicate or silica gel in the reaction medium. The amount of catalyst is generally 0.01 - 1000 mmoles of catalyst and preferably 0.05 - 500 mmoles of catalyst per liter of reaction solution.

As noted above, the isomerization reaction requires the presence of hydrogen cyanide or a source of hydrogen cyanide in the reaction system during isomerization, ie, a material capable of providing hydrogen cyanide under the reaction conditions.

Preferably 1,2, U-tricyanobutane is used as the source of hydrogen cyanide.

In addition, succinonitrile, acidified cyanide salts, tertiary phosphine-HCN addition compounds and tertiary amine-HCN addition compounds are eligible.

7907083 3 i '' *

The amount of cyanogen or cyanogen source can vary considerably. Cyan hydrogen itself is usually used in an amount of 0.01 - 5.0 moles per mole of 2-methylene glutaronitrile. A cyanogen-providing compound such as 1,2'-tricyanobutane can make up 0.1-999 parts by weight of the reaction mixture.

Examples of suitable basic catalysts are a compound * with an alkali metal as the cation part; an alkaline earth metal; a metal from groups IIB, IIIB, IVB, VB, VIB, VIIB and VIII of the periodic table; a metal of the lanthanide series; indium; thallium; lead 10 as well as ammonium or phosphonium cations.

These cations can be linked to a wide variety of anions including cyanide, cyanate, acetate, propionate, butyrate, octate, benzoate, salicylate, acetylacetonate as well as other anions derived from relatively weak acids. Phenolates, alkoxides, carbonates, sulfonates, amides, phosphates, polyphosphates, oxides and hydroxides are also readily useful. Further suitable are heterocyclic amines, for example, pyrrole and pyridine as well as aryl, alkyl and cycloalkylamines; phosphines, arsines and stibins, and further quaternary ammonium and phosphonium hydroxides. Basic ion exchangers are also eligible.

Organometallic compounds such as, for example, cyclopentadienyl sodium and butyllithium are also active catalysts, because it is known that such compounds can react with hydrogen cyanide and are therefore easily converted into the corresponding metal cyanides. In addition, it should be noted that quaternary ammonium and phosphonium compounds can also be formed by an in situ formation of quaternary groups during the reaction when heterocyclic amines, tertiary amines or tertiary phosphines are added as catalysts to the systems used. Compounds that undergo such a characteristic reaction to quaternary groups include trioctylamine, triphenyl-30 phosphine, tributylphosphine, tricylohexylphosphine and 1, h-diazabicyclo (2,2,2) octane.

Suitable solvents that can be used in the process of the invention include hydrocarbons (alkanes, cyclo-volcanoes and aromatics), ethers, alcohols, esters, dialkyl sulfoxides, dialkylamides and nitriles. Polar solvents are preferably used, 7907083 5 * Ok, because this allows higher reaction rates. Preferred solvents are generally polar solvents which do not react with methylene glutaronitrile, hydrogen cyanide or dicyanobutenes under the reaction conditions. Examples of such solvents are nitriles such as propionitrile, acetonitrile, adiponitrile and 2-methylene glutaronitrile itself.

1,2,3-Triyanobutane is preferred.

Small amounts of conventional polymerization inhibitors (e.g., t-butyl catechol, sulfur, and hydroquinone) can often be used successfully to minimize possible polymerization.

The trialkyl and eyloalkylphosphines are surprisingly more effective catalysts than the corresponding amines. This was not to be expected since the phosphines are much weaker bases than the amines and therefore could be assumed to be less active. The phosphines are as active as the strong base LiOH on a molar basis.

Preferred catalysts are an amine, phosphine or a compound of Cs, Rb, K, Na, Lin, Mg, Ca, Sr, Ba, Cd, Tl,

Pb, Mn or a rare earth.

Example I

A mixture of 0.5 mole of 2-methylene glutaronitrile and 0.25 mole of hydrogen cyanide was passed through a reaction tube containing 5 ml of a catalyst consisting of 90% activated carbon (carrier) and 10% cesium cyanide at a temperature of 255 ° C and a feed rate of 0.75 mol / hour. The reaction product was analyzed by gas-liquid chromatography and found to be 1 wt%. 1,1'-dicyahobutene-1 / (trans / claim) and 0.1 wt. # 1, - dicyano-butene-2 (trans / claim) in addition to 1,2, - - tricyanobutane and 2, methylene-glutaronitrile contain.

Example II

A mixture consisting of H, 5 mmol 2-methylene-glu-30 taronitrile, 37 mmol 1,2, U-tricyanobutane and 1 mg LiOH in U0 ml adiponitrile was heated in a closed reactor at 2U8 ° C for 15 minutes in an argon atmosphere. . The reaction mixture was then cooled to room temperature, extracted with b5 ml of water to remove the basic catalyst and analyzed by gas liquid chromatography. Analysis showed that the mixture contained 0.7 mmol 2-methylene glutaronitrile and 3.1 mmol 1, H-dieyanobutene (composed of approximately 95% 1, H-dicyanobutene-1 trans and cis isomers), 7907083 C Contained "<5. The 1,2 U-tricyanobutane" was found to be unchanged in an amount of 37 nmol.

Example III

A mixture consisting of ko mmol of 2-methylene-glu-5 taronitrile, 36 mmol of hydrogen cyanide and 2 mg of LiCTT in Uo ml of adiponitrile was heated at 253 ° C in closed reactor in a nitrogen atmosphere for 20 minutes.

The reaction mixture was then cooled to room temperature and extracted with 100 ml water. In gas-liquid chromatographic analysis, the mixture was found to contain 2.8 mmol of 1, U-dicyanobutene-1 (trans / cis) and 35 mmol of 1,2, U-tricyanobutane.

Example IV

A mixture consisting of h, 5 mmol of 2-methylene-glutaronitrile, 37 mmol of 1,2,4-tricyanobutane, 20 ml of adiponitrile, 10 mg of hydro-15 quinone, 0.1 g of triphenylmethanol and 20 mg of tricyclohexylphosphine was heated for 30 minutes in a closed reactor at 250 ° C in an argon atomosphere. The reaction mixture was cooled to room temperature and extracted with 0.5 ml of 0.1 g of acetic acid containing water and analyzed by gas-liquid chromatography. It was found to contain 2.0 mmol of 1, U-dicyanobutene-1 (trans / cis) in addition to 1.0 mmol of 20 1-methylene glutaronitrile.

Example V

A mixture consisting of U, 5 mmol 2-methylene-glutaronitrile, 37 mmol 1,2, U-tricyanobutane, 20 ml adiponitrile and 1 mg HaCH was heated in a closed reactor at 250 ° C for 60 minutes in an argonat-25 atmosphere. During the reaction, three samples of 2 ml each were taken, which were extracted with 2 ml of water and analyzed by gas-liquid chromatography.

The reaction time and conversion ratio were as follows: 30 Reaction time Product analysis in mmol min. 2 MGN 1 DCBs (trans / cis) 0 U, 5 0 15 k92 0.3 30 3.3 0.6 35 60 1.9 1.2 x 1, U-dicyanobutene- * 1 7907083 5 6

Example VI

Example V was repeated in the presence of 0.5 ml Sulfolane-W. Isomerization was completed after 15 minutes. The reaction mixture contained 10 mole% 2-methylene glutaronitrile and 90 mole. 5? 1.1 + dieyanonobutenes.

Example VII

A mixture consisting of k, 5 ml of 2-methylene-glutaronitrile, 37 mmol of 1,2, H-triyyanobutane, 20 ml of adiponitrile and 10 mg of 1,1-diazabieyclo (2,2,2) octane (triethylenediamine) was added for 2 heated in a closed glass reactor in an argon atmosphere at 250 ° C for an hour. The mixture was then cooled to room temperature, extracted with 1 + 5 ml of 0.1 g of acetic acid-containing water and analyzed by gas-liquid chromatography. The yield of 1, U-dicyanobutene-1 (trans / cis) was 1k%. The conversion of 2-methylene glutaronitrile was 3b%.

Example VIII

2-Methylene glutaronitrile was continuously isomerized to 1,1'-dicyanobutenes in a reactor equipped with a stirrer and heaters. 0.30 mol / hour 2-methylene glutaronitrile, 19 mol / hour 1.2, 1 + tricyanobutane and 0.0015 mol / hour LiCN catalyst were fed to the reactor. The reaction mixture was kept at 255 ° C for 0.3 hours.

A liquid product stream was continuously discharged and passed to a distillation column. At the top of the column, a mixture of 2-methylene glutaroni trile and 1, U-dicyanobutenes was removed at 100 ° C and 2.9 KPa absolute pressure.

The bottom product contained 1.2 + tricyanobutane (0.9 mol / hr J high molecular by-products and catalyst. The tricyanobutane was separated from the by-products and catalyst and returned to the reactor. The top fraction was condensed and distilled to give 0 2.08 mol / h 2-methyl-glutaronitrile (containing 25 µl of U-dicyanobutene-1 trans) was separated as an overflow at 160 ° C and 6.7 KPa absolute pressure. The product was condensed and returned to the reactor. The bottom product, which consisted of a mixture of the cis- and trans-1, U-dicyanobutene-1 and 1,1 + -dicyanobutene-2, was recovered at a rate of 0.19 mol / hour.

7907083

Claims (4)

1. Process for the preparation of 1,1-dicyanobutenes, characterized in that 2-methylene glutaronitrile is subjected to an isomerization action. 2. Process according to claim 1, characterized in that 2-methylene-glutaronitrile is isomerized "at a temperature of 100-700 ° C in the presence of a basic catalyst and cyanogen or a source of cyanogen and from the isomerization mixture 1, U-dicyanobutenes isolates. 3. Process according to claim 1 or 2, characterized in that the isomerization is carried out in the liquid phase. U. Process according to claim 2 or 3, characterized in that 1,2,4-tricyanobutane is used as a source of cyanogen. 5. Process according to claim 2, 3 or U, characterized in that the basic catalyst is an amine, phosphine or a compound of Cs, Rb, K, Na, Li, 1%, Ca, Sr, Ba, Cd , Tl, Pb, Mn or a rare earth. 7907083 CHt a) 2CR = CH-C = N-►Na C-C-CH ^ -CH ^. C 1 CH 4 b) N 5 C-C-CH-CH-C-N HCN 3 n C-CH-CH-CHrCH. C-: N λ catalyst ^ 807083 Halcon International, Inc., New York, New York, USA St. America