DE2420107A1 - MANUFACTURE OF OMEGA CYANO DERIVATIVES OF UNSATURATED CARBONIC ESTERS - Google Patents

Description

Dr. F. Zumst3ir. sen. - Dr. E. Aesmann " Dr. R. KoenJgsberger - DIpi.-Phys. R. Holzbauer - Dr. F. Zumsteln Jun.

TELEPHONE: COLLECTIVE NO- 225341

TELEX 529979

TELEGRAMS: ZUMPAT CHECK ACCOUNT: MUNICH S1139-809. Bank code 70010080 BANK ACCOUNT: BANKHAUS H. AUFHÄUSER

ACCOUNT NO. 397997, bank code 700306O0

8 MUNICH 2,

BRÄUHAUSSTRASSE 4

97/90 / n
Case 2595 DT

STAMICARBON B.V., Geleen / Netherlands

e = scs ss st =: χ s = = 3 =

Production of omega cyano derivatives

unsaturated carboxylic acid ester

The invention relates to a process for the production of omega-cyano derivatives of unsaturated carboxylic acid esters.

It has been found that esters of omega-cyano-beta-alkoxycarboxylic acid can very conveniently be dealkoxylated to the corresponding unsaturated carboxylic acid esters · Here At the same time, an alcohol corresponding to the alkoxy group is formed The process according to the invention is characterized in that an omega-cyano-beta-alkoxycarboxylic acid ester of the general formula 1

NC- (CH ₀ ) -C-CH ₀ -C '2 η _t 2

OR

(1)

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in which η is an integer from 1 to 5 inclusive and the two R groups which may differ from one another represent an alkyl or cycloalkyl group with a maximum of carbon atoms, at elevated temperature in the gaseous state with activated carbon and / or a dehydration catalyst brings into contact with the formation of a compound of the general formula 2

HH ■ NC- (CH ₂ ) _n -C = CC ' (2)

in which η and R have the aforementioned meaning.

The compounds to be dealkoxylated according to the invention can be prepared by reacting ketene with an omega-cyanoacetal are produced [cf. the German patent specification. ... ... (patent application P 23 46 201.3) same Applicant]. These compounds, which

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according to can be obtained with the help of the general formula 2, are - with the exception of the compounds in which R represents an ethyl group and η is 1 or 2 - not yet described in the literature been. Such a compound can then be converted into the corresponding saturated compound provided with an omega-amino group by hydrogenation Transform compound that can be used to manufacture polyamides.

According to the invention, various omega-cyano-beta-alkoxycarboxylic acids can be used Dealalkoxylate esters. The esters according to formula 1 in which η is 2 or 3, the two R groups, are of particular practical importance are identical to one another and R represents a methyl or ethyl group. Esters of this type can be very conveniently made by reacting ketene with the methoxy or ethoxy acetal of beta-cyanopropionaldehyde or gamma-cyanobutyraldehyde, while from the Dealalkoxylated compound is the starting material for nylon-6 and nylon-7 can be won.

The method according to the invention can be carried out at different temperatures' take place, e.g. between 100 and 500. A good yield and a sufficiently rapid reaction exist when temperatures are used between 200 and 350 C.

Several substances known per se can be used as the dehydration catalyst. Examples of suitable dehydration catalysts are gamma aluminum oxide, silicon oxide, thorium oxide, aluminum phosphate, cobalt molybdate, copper chromite and aluminum silicate. The dealkoxylation is preferably carried out with the aid of activated carbon and / or gamma-aluminum oxide and / or copper chromite. The activated carbon and the Dehydration catalysts can be used in the form of a fixed bed or a so-called fluidized bed. The space velocity can vary, e.g. between 0.1 and 3 g of starting compound per ml of catalyst per hour. A space velocity between 0.25 and 1 g of starting material per ml of catalyst per hour is best suited for practice.

In the dealkoxylation according to the present invention, the compound to be prepared can have the general formula 2 of the formula sheet occur in both the eis and the trans figuration. It shows, that in practice a mixture of the two forms is created. Part of the so obtained Compound bit of general formula 2 can isomerize to a compound in which there is a double bond between the beta and the gamma carbon atom is located.

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In the process according to the invention, the is to be de-alkoxylated Compound preferably diluted with a gas, such as nitrogen, hydrogen and carbon dioxide, because this treatment is beneficial to the yield affects. If hydrogen is used for this dilution and a catalyst is used that also has a hydrogenating effect, E.g. copper chromite, it shows that a substantial part of the accruing Unsaturated cyanoester can be hydrogenated to the corresponding saturated cyanoester, which is then hydrogenated of the cyano group is converted into the corresponding omega-amino compound can be and this compound can, as already mentioned, serve as a basic material for the production of polyamides.

The gaseous reaction mixture obtained according to the invention can be worked up by subjecting the mixture to cooling to form a condensate which contains the desired product and contains any unreacted starting product, and then this condensate is separated by means of fractional distillation or extraction. The gaseous reaction mixture can, if desired, before cooling subjected to hydrogenation, e.g. with the aid of palladium-on-carbon as a catalyst. Then only the saturated omega-cyanocarboxylic acid is formed Esters, optionally mixed with the unreacted omega-cyanobeta-alkoxycarboxylic acids Ester. Such a result can of course also be obtained by hydrogenation of the gaseous reaction mixture after cooling resulting condensate can be reached.

The invention is illustrated by the following examples.

example 1

Through a vertically arranged tubular reactor (clear width 20 mm and length 470 mm), provided with a heating jacket and two zones of inert ceramic »material with an intermediate zone of 50 ml of catalyst, a gaseous mixture is produced for a few hours at a catalyst temperature of 275 C passed from hydrogen and the methyl ester vori 4-cyano-2-nethoxybutane-carboxylic acid. 26.2 g of methyl ester and 1.5 mol of hydrogen are passed through every hour. Copper chronite (33% by weight CuO, 38% by weight ⁰ ^ ₃ O, 9% by weight BaO, grain size 3 μm, bulk density 151 g per 100 el) is used as the catalyst. The space velocity is 0.524 g of methyl ester per ■! Catalyst per hour.

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The gaseous reaction mixture obtained in this way enters a collecting vessel one that is constantly cooled to around 20 C. Condense every hour about 26 g of product in this collecting vessel.

As evidenced by a gas chromatographic, mass spectrometric and nuclear magnetic resonance analysis, the condensed product contains 51% by weight of unreacted starting material, 9.3% by weight of methanol, 20.2% by weight Methyl ester of 4-cyanobutane carboxylic acid and 15.5 wt .-% methyl ester of 4-cyanobutylenecarboxylic acid. The ratio between alpha-beta unsaturated Product and beta-gamma-unsaturated product in the latter methyl ester is 7: 3.

The yield of dealalkoxyIated ester is, based on the unset starting product, 87.5%.

The unsaturated methyl ester separated by distillation is a clear liquid with a boiling point of 110 to 115 ° C / 10 mm Hg. Analysis: Calculated (in%): C 6042
H 6.52; N 10.06; 0 23.00. Found in %)
C 59.3; H 6.6; N 10.1; Ö 24.0 ..

Example II

The experiment from example I is repeated ... but will now instead of copper chromite 40 ml activated carbon (sticks made of charred peat, diameter 1.5 mm. length 1 to 5 mm, debris weight 52.6 g per 100 ml) used.

Every hour 10.48 g of methyl ester and. 0.85 mol of hydrogen passed through. The space velocity is 0.262 g methyl ester per ml Catalyst per hour.

No dealalkoxylated saturated ester is formed. The degree of implementation is 50%. The yield of unsaturated dealoxylated Ester is 86% (ratio between alpha-beta-unsaturated and beta-gamma-unsaturated Product is 7: 3).

Example III

The experiment of Example I is _{repeated with 30 ml of Al 0} O -Si0 _o catalyst -% gamma-Al 0, bulk density 83.3 g each: diameter, length also 3 mm).

(13% by weight gamma-Al 0, bulk density 83.3 g per 100 ml, rods of 3 mm

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Methyl ester and 0.2 mol of nitrogen are passed through every hour for 12.6 hours. The space velocity is 0.42 g of methyl ester per ml of catalyst per hour. The temperature of the catalyst is 280 C. It no dealalkoxylated saturated ester is obtained. The degree of implementation is 58%. The yield of unsaturated dealalkoxylated ester corresponds to 78% (The ratio between the alpha-beta unsaturated and beta-gamma-unsaturated product is 7: 3).

Example IV

The experiment of Example II is repeated. Now, however, the methyl ester of 5-cyano-2-methoxypentane is used as the starting material.

There are 10.0 g of methyl ester and 0.9 mol of hydrogen per hour passed through. The space velocity is 0.25 g of methyl ester per ml of catalyst per hour. The temperature of the catalyst is 280 C.

No dealalkoxylated saturated ester is formed. Of the

Degree of implementation is 42.2 %. The yield of unsaturated dealalkoxylated ester is 70.0% (ratio between alpha-beta-unsaturated ester and beta-gamma-unsaturated ester 7: 3). The methyl ester separated by distillation is a clear liquid with a boiling point of 132 to 140 ° C / 10 mm Hg.

Analysis , calculated (in%): C 62.72; H 7.23; N 9.15; 0 20.90. Found (in%): C 63.1; H 7.4; N 9.1; 0 20.4.

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Claims (8)

Claims 1. Process for the production of unsaturated omega-cyano derivatives carboxylic acid ester, characterized in that one is an omega-cyano-beta-alkoxycarboxylic acid ester of the general formula 1 2 η, 2 ν OR O ^R in which η is an integer from 1 to 5 inclusive and the two R- · Groups represent an alkyl or cycloalkyl group with a maximum of 10 carbon atoms, at an elevated temperature in gaseous state with activated carbon and / or a dehydration ska catalyzer brings into contact with formation a compound of the general formula 2 H H η NC- (CH ₂ ) _n -C = CC (2) XR in which η and R have the aforementioned meaning 2. The method according to claim 1, characterized in that of an ester with the general formula 1 is assumed, in which η shows the value 2 or 3, the two R groups same and represent a methyl or ethyl group. 3. The method according to any one of claims 1-2, characterized in that that contact with the catalyst is brought about at a temperature between 200 and 350.degree. 4. The method according to any one of claims 1-3, characterized in, that the starting compound with activated carbon and / or gamma-aluminum oxide and / or copper chromite in contact brings. 409847/1128 5. The method according to any one of claims 1-4, characterized in that that the space velocity is set between 0.25 and 1 g of starting compound per ml of catalyst per hour, 6. The method according to any one of claims 1-5, characterized in that that contact is made with the catalyst in the presence of a diluent gas. 7. omega-cyanoester of the general formula 2 given in claim 1, in which η and R have the meaning given in claim 1 have, with the exception of the compounds in which R represents an ethyl group and η is 1 or 2. 8. omega-cyanoester of the general formula 2 given in claim 1, in which η is 3 and R is a methyl or Represents ethyl group or in which η has the value 2 and R represents a methyl group. 409847/1 128