DE942687C - Process for the preparation of a mixture of isomeric dimethoxydecdienes - Google Patents

Description

Process for the preparation of a mixture of isomeric dimethoxydecadienes The invention relates to an improved method for producing a mixture of isomeric dimethoxydecadienes of the formula CH30-C1oHlg-OCH3. In particular concerns they apply special catalytic agents or activators that not only accelerate the rate of chemical reaction with which the isomers Dimethoxydeca.diene are produced, but - what is more important - also the course regulate the implementation, so that a special isomer, namely the x, io-dimethoxydecadiene (3, 7), is predominantly produced. That is especially desirable because of this Isomers can be converted into sebacic acid, for which the demand is great.

It has been shown in the USA. Patent 2 075 3.2 that butadiene and chloromethyl methyl ether react with each other to form i-methoxy-5-chlorpenten- (3) together with the positional and geometric isomers of this product, all of the formula Have CH30 - CSHB - Cl. It is also known that these isomeric methoxychloropentenes can be coupled to form isomeric dimethoxydecadienes of the formula CH30-C1oHlo-OCH3. Here, 2 molecules of methoxychloropentenes react, splitting off yori chlorine atoms and forming a molecule of i, io-dimethoxydecadiene- (3, 7) together with the positional isomers and the geometric isomers of this compound. All positional isomers have the following formulas, but it should be noted that the cis and trans forms of the compounds I and III also occur in the mixture. CH30-CH2CH2CH = CHCH2CH2CH = CHCH2CH2-OCH3 (I) The relative amounts of isomer I in a mixture of isomers can be determined by first hydrogenating the dimethoxydecadienes to dimethoxydecanes and treating the mixture of dimethoxydecanes with a urea solution in methanol. Only the straight-chain dimethoxydecane of isomer I reacts to form a complex compound with the urea; this complex compound can then be separated from the other isomeric dimethoxydecanes, which are derived from isomers II and III.

Nickel carbonyl has already been proposed as a coupling agent for the conversion of the methoxychloropentenes to the dimethoxydecadienes. Furthermore, the patent ..... (application R 9072 IVb / i2 o) demonstrated the advantage of using finely divided metallic iron or nickel for this purpose.

The present invention is based on the finding that the implementation speed increases and the Ablaul, the implementation on the generation Larger amounts of i, io-dimethoxydecadiene (3, 7) can be directed if except the finely divided iron still a finely divided metal, which behind iron in or a salt of such a metal is used. the end For reasons of convenience and in view of the influence these additional substances have in conjunction with the iron coupling agent, they will hereinafter referred to as activators.

Such metals, as such or in the form of salts together used with iron are cadmium, cobalt, nickel, tin, lead, palladium, Copper, mercury, silver, gold and platinum. Although all of these metals according to the present invention in conjunction with the iron act as activators for reasons. the economy and effectiveness the use of metallic Copper, nickel, cobalt and mercury and the salts of these. Elements preferred. Of all of the above metals are all. Salts applicable - d. H. the water-soluble and water-insoluble salts of organic and inorganic acids. Preferred the salts of strong inorganic acids, namely the chlorides, sulfates, and nitrates and phosphates. But it can also z. B. Acetate, Farniiate, Oxalate, Benzoate and Phthalates are applied.

The iron should be in a finely divided form. With coarse metal files the yield of dimethoxydecadienes is extremely low. The iron should therefore be so finely divided that it can pass through a sieve with 3i36 meshes every square centimeter passes through. Since iron oxide inhibits the conversion, it is necessary that the metal is pure. This also applies to the activators when they are used in the metallic form will. At least 1/2 mole of iron per mole of methoxychlorpentene is used because the iron combines with the chlorine atoms which are split off from the methoxychloropentenes will. In particular, an excess of the order of 10 to 50% is recommended. The maximum amount of iron that can be used is only limited by economic and work-related considerations.

The amount of activator should be in the range from 1 to 15%, preferably from 2 to 80/0, calculated as metal and based on the weight of iron. if a salt is applied, it is to be used in an amount that is 1 to 150/0 metal in the salt, based on the iron, results.

The implementation of Methöxychlorpentenen with finely divided iron in Presence of the activators is at a temperature of about 10 ° = or preferably about 2o0 - carried out up to the reflux temperature of the reaction mixture.

The use of a solvent is recommended to the implementation to facilitate. Alcohols are generally good solvents; of them is ethanol the best. Many other alcohols have also been studied. It was found that the i. to 7 carbon atoms containing alcohols, such as. B. butyl, hexyl and benzyl alcohol, which have an advantage over the higher alcohols, than they are separated more easily and more clearly from the reaction mixture by distillation can be. to other preferred solvents include acetonitrile, Dimethylformamide, propionitrile, butyronitrile and dioxane.

The reaction is carried out under normal positive or negative pressure. For reasons of effectiveness, the use of normal or positive pressure is preferred.

The following examples, in which all parts are parts by weight, serve only to explain the method according to the invention.

Example i 1/2 mole (67.5 parts) of a mixture of isomeric methoxychloropentenes, CH30 - GH, - Cl, was dissolved in 100 parts of ethanol. The solution was stirred and placed under carbon dioxide, while you 16.8 parts (0.3 M01) hydrogen-reduced Iron was added of a particle size that passed through a 3136 mesh screen each square centimeter passed through it. The mixture was further vigorously stirred and Heated to reflux temperature for 22 hours. It was then cooled and charged with i5o Parts of water and = 05 parts of diethyl ether shaken. The ether layer was separated washed with water and then dried over a desiccant. The ether became removed by distillation and the crude product was fractionally distilled. It was a 6, #% yield of isomeric dimethoxydecadienes obtained, the i, io-dimethoxydecadiene (3, 7) made up 50% of this mixture.

The above procedure has now been modified to be more effective the so-called activators with regard to the control of the implementation process check. This modification consisted in the addition of an activator in the form of the sulfate of copper or cobalt or nickel or of mercury chloride in an amount of 2% of the metal in question, based on the weight of the iron. The implementation went as described above and the overall isomer yields were substantial the same; but in each case the amount obtained was i, io-dimethoxydecadiene- (3, 7) at least 3o0 /, higher than when iron was used alone. In the cases in which copper or nickel sulfate was used, the increases were in the Yield of i, ro-dimethoxydecadiene- (3, 7) 500 / or 520/0.

Example 2 According to a procedure which corresponds to that described in Example i, 0.5 mol of a mixture of isomeric methoxychloropentenes dissolved in 80 parts of acetonitrile were reacted with 0.3 mol of commercially available, powdered, hydrogen-reduced iron. The mixture was stirred, covered with carbon dioxide and q. Heated to reflux temperature for hours. The product was worked up in the manner described in Example i and a 720% yield of isomeric dimethoxydecadienes was obtained. Analysis showed that 52% of this mixture consisted of i, io-dimethoxydecadiene- (3, 7).

The same procedure was followed in several cases, only nickel sulfate, nickel chloride or Raney nickel was used in conjunction with iron. The results were as follows: percent Percent isomer I. Percent total i, io-di- Activator nickel, yield of methoxy- related i, io-d- decadiene- on iron methoxy- (3.7) decadien in that mixture No ......... 0 72 52 NiS04 - 6H20 2.6 75 72 Ni'SO4-6H20 6.5 8o 8o NiS04 - 6H20 13.0 75 75 NiC12 - 6H20 6.5 77 75 Raney nickel 6.5 82 72 In the absence of an activator, but in the presence of iron, the reaction in acetonitrile takes 2 to 3 hours (as measured by titration of the chlorine ion). If an activator as described above is used in conjunction with the iron, a violent, exothermic reaction takes place in about 1 hour; the reaction is complete in about another 1/2 hour. When the iron, the activator and the acetonitrile together. If the mixture of methoxychloropentenes is added for 11/2 hours, the exothermic reaction begins in about 15 minutes and the reaction is essentially complete in about a further 1/2 hour. There is always the advantage of; that the reaction product contains the i, io-dimethoxydecadiene- (3, 7) in an unusually high amount.

Claims (1)

PATENT CLAIM: Process for the preparation of a mixture of isomeric dimethoxydecadienes of the formula CH30 - C " H" - OCHS by reacting a mixture of isomeric methoxychloropentenes of the formula C H3 0 - C, H8 Cl in a solvent with finely divided iron at a temperature of 10 ° to the reflux temperature of the reaction mixture, the iron being in such a finely divided form that it passes through a 3136 mesh per square centimeter sieve and being present in an amount which is at least 1/2 mole per mole of the methoxychloropentenes, characterized That the reaction is carried out in the presence of an activator which consists of a metal behind the series of iron or a salt of such a metal, the activator being calculated as the metal in an amount from i to i50 /, and based on the weight of the Iron related, is used.