DE1468872A1 - Process for the preparation of 2,4-dicyanobutene- (1) - Google Patents

Description

It is known that acrylonitrile can be diinerized by heating at 200 Ws under pressures of 20 to 150 atmospheres in the presence of a polymerization inhibitor. 1,2 = dicyanocyclobutane is obtained in low yields. ICoyner, Hillmann, J * Am »Chem.Soe. JJ _f 524 (1949)}. It is also known that when treating acrylonitrile with triphenylphosphiiia in the presence of ethanol 1 ₃ 1,4,4-tetrakis- (β "cyanoethyl)" 1,4-di- cyanobutene - \ 2) and a considerable amount β -Ethoxyproplonitrile

(Art 7ft Para. ?. Mr 1 Council? 1 des Xndsrungsges. V. 4. 5.196V ^T

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obtained lTakashina, Price, J. Am, Chem. Soco 84, 489-91 (1962)]. It was the production of dialkyl-2-methylenglutaraten by Described heating of aeryl esters in the presence of aliphatic tertiary phosphines (American patent 3 074 999), but it is known that acrylonitrile in the presence of these same phosphines behave differently and polymerize to an amorphous product with increased molecular weight (American patent specification 2,675,372) »

It has now been found that the reaction when using acrylonitrile in the presence of catalytic amounts of a tertiary aliphatic, cycloaliphatic !! or aromatic phosphines in the presence a polymerization inhibitor is heated, steered in a different direction and you get 2,4-dicyanobutene- (1) in good yields or oc- = methylenglutaric acid nitrile,

The phosphines that can be used as catalysts are tertiary phosphines of the formula

in which R ₁ , Rp and R ,, which can be the same or different from one another, denote alkyl, cycloalkyl or aryl radicals which optionally carry substituents which are not reactive towards acrylonitrile, for example trloyclohexylphosphine, tricyclopentylpho.3

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BATH ORIGINAL

ph In, Dialkylary! .phosphine, Alkyldiarylphosphine and Trialkylphosphine. It is sufficient to use catalytic amounts of phosphines in the order of magnitude of 0.1 to 1 mol per 100 mol of treated acrylonitrile in order to obtain good yields of poorer product. They are added to the acrylonitrile in the form of solutions in an inert solvent, such as, for example, Dloxan, these solutions being prepared and stored in the absence of air under an inert atmosphere a

Hydroquinone and tert-butylpyrocatechol can be used as a polymerisation inhibitor. Acetylacetone, phenol, guaiacol, α «naphthol,

p-methoxyphenol
Use o-Phenylphenol, MethyIhyrtroohlnon and in general the products known for stabilizing Vi.ny! monomers. The Inhibitorpenge to be used varies depending on the nature of the same from 1 t ⁴ s 4 moles per 100 moles of treated acrylonitrile. The reaction can be carried out in bulk, but it is preferably carried out in a solvent medium which is an aliphatic, eyeloaliphatic or aromatic hydrocarbon, a linear or cyclic ether such as dioxane, a polar solvent such as acetonitrile or dimethylformamide, or whole in general, any solvent which does not react with acrylonitrile under the reaction conditions can be. One works under an atmosphere of inert gas nitrogen, argon) at atmospheres =

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pressure or in the autoclave under the simple autogenous pressure of the reaction components. The temperature at which the reaction can be carried out in practice varies from 50 to 1.80 ° C., preferably from 95 to 125 ^° C. The heating time depends on the catalyst used and can be several hours. After the reaction has ended, the 2,4-DlCyBnObUtCn- (I) is separated off by careful rectification. The 2.4 ~ Dicyanobuten- (1) 1st a clear liquid product having a boiling _{l5 0} "75 to 78 * C. The reaction can be carried out continuously. The product is an intermediate in organic synthesis for the production of difunctional products that are used in polyesters, polyamides and other condensates.

The following examples illustrate the invention without implying any sign of it.

In a bit, an ascending cooler, a dropping funnel and a nitrogen feed line put 150 cM flask with 16 g of acrylonitrile, 1 g of hydroquinone and 60 cm of dioxane. "To rinse old nitrogen that Heaktionenaese heated to reflux and then sun sets slowly ine solution of 0.6 g Trioyolohexylphosphin in 20 com dioxane under an inert atmosphere • to. This addition takes about 20 minutes. When it is over

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one to heat continues "20 minutes at 95 ⁰ C, and then rapidly cooled to 20 ⁰ C from. After adding 50 mg of tert-butyl catechol to the reaction mass, the mixture is distilled under an absolute pressure of 0.15 mm Hg. A fraction of 8.85 g of a colorless and viscous liquid with a refractive index n is ^{isolated at 75 to 80 ° C.} ^ of 1, ^ 550, which consists of a = methyleneglutaric acid nitrile, which is identified by elemental analysis, infrared spectrography, and NMR spectrography. The yield is $ 55.3 >> based on the acrylonitrile used.

Example 2

The same experiment is repeated, except that the reaction is carried out in an autoclave with a capacity of 125 ecm performs with sideways movement, the only one in the course the pressure maintained the reaction is that of the reaction components, which one continues for 1 1/2 hours at 95 ° C heated after addition of the catalyst solution. 9.6 g of α-methyleneglutaric acid nitrilo are obtained. Yield: 58.8%.

Examples 3 to 8

The procedure is as in Example 1, always starting from 16 g Acrylonitrile, the polymerization inhibitor and the phosphine being the products given in the table below, the also shows the results achieved.

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attempt catalyst Inhibitor Reaction
duration Weight of
received
Dinitrile yield t 3 Tricyclohexylphosphate
phin 0.6 g Acetylacetone
0.5 g 1h 45 min
at 95 ^° C 7.15 g 44.7 % 4th Dibutylphenylphosphate
phin 0.5 g Hydroquinone
1 g 2h 40 min
at 95 ^° C 6.05 g 37.8 % co 5 Tributylphosphine
0.6 g Hydroquinone
1 g 1h
at 95 ^° C 6.86 g 42.9 # 3982 6th Trioyclopentyl
phosphine 0.3 g Hydroquinone
1 g 1h 15 min
at 95 ^° C 7.7 g 48.1 % Ω -j 7th
8th Tricyclohexyl
phosphine 0.6 g
Tricyclopentyl
phosphine 0.5 g Iron (II) -
acetylacetonate
1 p
tert-butyl
catechol 1h 30 min
at 95 ^° C
1h 5 min
at 95 ^° C 7.27 g
8 g 45.4 %
50 %

Example 9

Example 1 is carried out and then 265 g (5 mol) of acrylonitrile, dissolved in 1100 ecm of dir, the equivalent of 8.8 g (8 · 10 "mol) of hydroquinone r, w flow and se did drop by drop while maintaining the A solution of 1.3 g of tricyclohexylphosphine Jn 100 com dioxane is added (addition takes 20 minutes). Heating continued for 5 hours and the temperature rises to 98 ^° C. The reaction moisture is then concentrated by adding one in a water jet ~ VXkUU ¹ Ii the niohtt "set acrylonitrile (83 g), and the dioxane was removed. the fell · hei this concentration resulting residue is then * n a vacuum of 0.15 mm Hg distilled. one gets between 75 and 8O ⁰ C a fraction of 122 g of ff-methyleneglutaronitrile, yield 67 %, based on converted acrylonitrile.

Venn "repeated the same experiment, but in the absence of hydroquinone", niobically no α-methyleneglutaronitrile forms, but only traces of a polymer, whereby the acrylonitrile remains practically unchanged.

Example 10

You work as in the previous example, but start with a solution of 265 g of acrylonitrile in 800 ecm! toluene with one;

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Content of 4.4 g (4 x 10 6 mol) of hydroquinone and a solution of 1.2 g of trieyelohexylphosphine in 100 ecm of dioxane. At the At the end of the process, 1 ^ 4 g of a-methylenglutaric acid nitrile are obtained, what a 50 #igen yield, based on the used Acrylonitrile.

Examples 11-15

The procedure is as in Example 9, but the hydroquinone is replaced by another stabilizing agent and a-methyleneglutaronitrile is thus likewise obtained with yields which are from 40 to 55%, based on the acrylonitrile used.

The results of these various experiments are as follows Table specified:

Inhibitor molar amount 10 " ² MoI yield
Wt .- ^ phenol 16 · 10 " ² MoI 52 Guaiacol 8th · 10 ~ ² MoI 51 α-naphthol 8th · W CVl
O O MoI
MoI 40.5 o-phenylphenol
p-methoxyphenol 8.8
8th · 54.8
55

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Claims (2)

Claims 1. A process for the preparation of 2,4-dicyanobutene (1), characterized in that one acrylonitrile in the presence of a Polymerization inhibitor and catalytic amounts of a tertiary phosphine of the formula in which R ₁ , R ₂ and R- ,, which can be the same or different from one another, denote saturated aliphatic, cycloaliphatic or aromatic hydrocarbon radicals, heated, the reaction optionally being carried out in a liquid solvent medium which is inert towards acrylonitrile under the reaction conditions. 2. The method according to claim 1, characterized in that the catalyst used is a tricycloalkylphosphine. 909826/1371