DE1245939B - Process for the preparation of basic N Vmylamides - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

C07C

Int. CL:

German class: 12 ο - 19/03

Number: 1 245 939

File number: F 46433 IV b / 12 ο

Filing date: June 25, 1965

Opened on August 3, 1967

It is known, carboxamides or sulfonic acid amides of primary amines, which are still a Carry hydrogen atom, as well as lactams with unsubstituted nitrogen atom, in the presence of strongly alkaline Catalysts to be able to convert into the corresponding N-vinyl compounds with acetylene under pressure (German patent specification 877 757 and French patent specification 865 354).

It is also known to produce N-vinyl-substituted amides by pressure vinylation, which the further General formula 1 b) given below correspond to (U.S. Patent 2,628,224).

These known vinylation processes for amides have hitherto only been carried out using increased pressure. Because of the dangers involved in working with compressed acetylene, the known processes require expensive and complex high-pressure fittings, even if the work is carried out under pressures which are only slightly above normal pressure. In the case of open-chain, basic acid amides, for example N- (3'-dimethylaminopropyl) acetamide and its homologues, the reaction comes to a standstill very quickly when the pressure vinylation process is used. The desired N-vinyl-N- (3'-dimethylaminopropyl) -acetamide is obtained in this case only 9% iS ^he yield of theory. Side reactions give rise to a considerable amount of undesirable, non-distillable, tarry products, which further adversely affects the yield and economic efficiency of the process.

A process for the preparation of basic N-vinylamides of the general formula was found

R ₁ -OC-N- (CH ₂ VN ^ ² (Ib) CH
CH ₂

R ₁ -N-OC- (CH ₂ V-NC ^ ² (2b) CH

CH ₂

in which R _{1 is} an alkyl radical of 1 to 4 carbon atoms, R ₂ and R _{3 are} alkyl radicals of 1 to 4 carbon atoms, which form a five- or six-membered ring, optionally including

Process for the production of basic
N-vinyl amides

Applicant:

Farbwerke Hoechst Aktiengesellschaft

formerly Master Lucius & Brüning, Frankfurt / M.

Named as inventor:

Dr. Herbert Bestian,

Frankfurt / M. -Unterliederbach;

Dr. Harald Jensen, Frankfurt / M.-Bockenheim;

Dr. Hansjörg Vollmann, Frankfurt / M.

of a hetero atom, can be linked to one another, and η denotes the number 1, 2 or 3, by reacting basic amides of the general formula

R ₁ -OC-NH- (CH ₂ V

N-

respectively

R ₁ -NH-OC- (CH ₂ VN

R,

■ R »

(la)

(2 a)

in which R ₁ , R ₂ , R ₃ and η have the meanings given above, found with acetylene at elevated temperature in the presence of basic alkali metal compounds as a catalyst, which is characterized in that the reaction is carried out at about 90 to about 320 ^° C. under pressure between 150 Torr and normal pressure, preferably at normal pressure, and the vinyl amides formed are removed as they are formed.

In exceptional cases it can be advantageous at slightly increased pressure, for example up to about 3.0 atü to work. With regard to the strict safety measures when working with acetylene under pressure one will always strive to keep the overpressure as low as possible. In In some cases, especially when using high-boiling, basic amides, the use of reduced pressure, for example down to about 150 torr, may be useful.

It was not foreseeable that the vinylation, which had previously only been carried out at higher acetylene pressures of amides especially at pressures that are in the range of atmospheric pressure and possibly even more

709 619/716

borrowed lower, with better yield and higher Sales than the pressure vinylation can be carried out. On the other hand, it is astonishing that the The life of the catalyst in the present process can be increased so that even open-chain, basic acid amides can be converted into N-vinyl compounds in good yields. It is also surprising that under the conditions used, especially with regard to the high Temperature, even in the case of amino groups in the / J position, no cleavage with formation of the corresponding unsaturated compounds can be observed.

According to the present method, for example the following compounds are vinylated: N- (3'-dimethylaminopropyl) - acetamide, N- (2 '- diethylaminoethyl) acetamide, N- (2'-dimethylaminoethyl) -acetamide, N- (dimethylaminomethyl) -acetamide, N- (3'-dimethylaminopropyl) - propionamide, N - (dimethylaminomethyl) -isobutyramide, N- (2'-morpholinoethyl) -acetamide, N- (2'-piperidinoethyl) propionamide, N- (2'-pyrrolidinoethyl) acetamide, N- (2'-N'-methylpiperazinoethyl) acetamide, Dimethylamino-acetic acid-N-methylamide or dimethylamino-isobutyric acid-N-ethylamide.

Strongly basic compounds of the alkali metals with inorganic or are suitable as catalysts organic residues such as sodium hydroxide, potassium hydroxide, sodium amide, lithium hydride, Sodium methylate, sodium ethylate or potassium t-butylate. It is preferred to use the alkali metals, such as, for example, sodium or potassium, themselves. The alkali metal compounds are particularly effective of the compounds used as starting amides. This is how you use, for example when converting N- (3'-dimethylaminopropyl) acetamide, that in the starting product is advantageous Well soluble sodium N- (3'-dimethylaminopropyl) acetamide as a catalyst. The alkali metal compounds is expediently made in situ by dissolving one of the alkali compounds listed above in the amide to be vinylated.

To perform the process passing acetylene, for example in a 1.2 to lOOfachen, preferably in a 3- to 30-fold molar excess, presented by the in a reaction vessel and at 90 and 320 ⁰ C, preferably 150 to 250 ° C heated, liquid mixture of amide and catalyst. The reaction temperature is expediently chosen so that the basic N-vinylamide formed in each case is discharged from the reaction mixture as quickly and completely as possible. The amide used as the starting product should remain as largely as possible under the reaction conditions. The optimum temperature to be maintained in the vinylation zone and the speed of the gas stream passed through are accordingly dependent on one another within certain limits in such a way that small gas velocities require higher temperatures and higher gas velocities require lower temperatures. The vapors leaving the reaction vessel together with the unused acetylene are condensed. They contain the main amount of the desired, basic N-vinylamide in addition to unconverted starting material and possibly small amounts of by-products. The desired basic N-vinylamide is isolated from the mixture by distillation, if appropriate under reduced pressure, by extraction or crystallization processes.

The process can be carried out batchwise, semicontinuously or fully continuously. This is done appropriately Unreacted acetylene freed from condensable vapors with the addition of fresh acetylene in the cycle back into the process. The unchanged, basic starting amide can also be used continuously be returned to the vinylation zone. It is preferable to work in such a way that you can both the excess acetylene as well as the unreacted, through a continuously operating distillation column separated starting amide, optionally after prior mixing, continuously into the Recirculates vinylation zone.

In addition, the amount corresponding to the converted amounts of acetylene and basic amide is used fresh starting products - also appropriately in a continuous manner - fed. The catalyst can be in an amount of 0.1 to 20 mol percent, advantageously in an amount of 0.1 to Apply 10 mol percent, based on the basic amide used. When working continuously, is it is generally expedient to feed part of the catalyst with the continuously fed amide.

The acetylene can be used in pure form or as a mixture with inert gases such as nitrogen will.

The present process allows the acyclic, basic N-vinylamides as a result of a considerably improved Yield to be produced more economically than is possible with the known pressure vinylation process is. A particular advantage lies in the elimination of the pressure equipment and the strict safety measures, which are required when working with compressed acetylene.

Basic N-vinylamides of the aforementioned general formulas (1 b) and (2b) are according to the present procedures have become conveniently accessible. The majority of those described in the exemplary embodiments Process products are new substances. The basic N-vinylamides obtainable according to the process provide valuable starting compounds for the production of new plastics, cosmetics and pesticides represent.

B e i s ρ i e 1 1

N-vinyl-N- (3'-dimethylaminopropyl) acetamide

a) In a four-necked flask with gas inlet tube, stirrer, internal thermometer and descending condenser, a stream of acetylene is passed into a mixture of 288.4 g of N- (3'-dimethylaminopropyl) acetamide and 3.9 g of potassium at 215 ° C. with vigorous stirring 180 liters per hour until no more amide passes over. In this way, within 2 hours, 274 g of a yellowish colored condensate are obtained, which has a refractive index n ² S = -1.4665. Distillation through a column gives 49 g of N-vinyl-N- (3'-dimethylaminopropyl) acetamide, b.p. ₂₀ 130 ° C, n% ° --- 1.4825, and 199 g of N- (3 ' -Dimethylaminopropyl) acetamide with a _{b.p. 2o} 155 to 157 ° C and nl ° = 1.4615. 19.8 g of a dark brown, water-soluble residue remain in the reaction flask.

b) According to the drawing, a heatable reactor 1 with an internal thermometer and gas inlet pipe 13 connected to a cooler 2, which the gases coming from the reactor 1 leave upwards can. The condensate from the cooler 2 flows together with that from a downstream condenser

Sator 3, via a control valve 4 in the lower third of a correspondingly dimensioned, 150 cm high Vacuum column 5, which is operated with a circulation heater 6. The column bottom is by means of a Pump 7 returned to reactor 1; as will the starting product with catalyst by means of a pump 8 from a storage vessel 9 to the extent in pumped up the reactor 1, in which the N -Vinyl - N - (3'-dimethylaminopropyl) - acetamide at the top of the column is removed via a storage vessel 11 after cooling by the condenser 10. That the reactor 1 and the coolers 2 and 3 leaving the acetylene is returned to the reactor 1 by means of a gas pump 12 through the inlet pipe. Consumed Gas is replenished; a small part of the cycle gas can be discharged as exhaust gas.

In a 1-1 reactor, 888 g N- (3'-dimethylaminopropyl) acetamide are charged and dissolved at 120 g ⁰ C 2 potassium therein. 200 g of N- (3'-dimethylaminopropyl) acetamide are added to the bottom of the column. The reactor is then heated to 180 to 200 ° C. and about 100 liters of acetylene are passed through the mixture every hour for a period of 31 hours. During this time, 3642 g of N- (3'-dimethylaminopropyl) acetamide, in which 51 g of potassium are dissolved, are pumped into the reactor, while 2080 g of N-vinyl-N- (3'-dimethylaminopropyl) -acetamide go off together with 1045 g of starting product. The vinylation mixture has a refractive index n ² S = 1.4700. The experiment is terminated without any decrease in the vinylation being observed.

For continuous operation, a conversion of 71% and a yield result of 68 ° / ₀ of theory.

Example 2 N-vinyl-N- (2'-diethylaminoethyl) acetamide

In the apparatus described in Example 1, b) 750 g of N- (2'-diethylaminoethyl) acetamide are placed and a mixture of 3 g of sodium in 247 g of N- (2'-diethylaminoethyl) acetamide is added. In the heater at the bottom of the column 200 g N- (2'-diethylaminoethyl) acetamide are added, the reactor to 190 ⁰ C and heated hourly 8001 acetylene passed through the mixture. 1432 g of N- (2'-diethylaminoethyl) acetamide, in which 18 g of sodium are dissolved, are pumped into the reactor over the course of 17 hours. A mixture of 644 g of N-vinyl-N- (2'-diethylaminoethyl) acetamide and 671 g of starting amide with a refractive index of n ² S = 1.4688 is taken off at the top of the column.

The experiment is terminated after 17 hours without any decrease in the vinylation being observed is.

For continuous operation the result is a conversion of 53% and a yield of 74% of theory. Analysis for C ₁₀ H ₂₀ N ₂ O (184.3).

Calculated .... C 65.16, H 10.94, N 15.21, O 8.69, vinyl 14.63 ° / ₀ ;

found .... C 65.2, H 11.2, N 15.0, O 8.7, vinyl 14.4%.

Bp. ₂₀ 130 to 132 ° C.

Kp. _Loo 171 to 173 ° C.

ng = 1.4790.

The product used as the starting N- (2'-diethylaminoethyl) acetamide is prepared as follows: In a steel autoclave with 2-1 Hubrührer 520 g of methyl acetate and 588 g of 2-Diäthylaminoäthylamin- (l) are stirred at 14O ⁰ C for 8 hours . The excess methyl acetate and the methanol formed are then distilled off at normal pressure. The main fraction obtained is N- (2'-diethylaminoethyl) acetamide, Κρ. _7β0 263 to 265 ° C, n ² S = 1.4590.

Analysis for C ₈ H ₁₈ N ₂ O (158.2).

Calculated .. C 60.72, H 11.46, N 17.70, O 10.3%; found .. C 60.6, H 11.6, N 17.3, O 10.3%.

Example 3
Dimethylaminoacetic acid-N-methyl-N-vinylamide

The apparatus described under Example 1, b) is filled with 700 g of dimethylaminoacetic acid methylamide in the reactor and charged in the column part with 200 g of the same compound. Over the course of 32 hours the ammonia-free solution of 63 g of sodium amide in 2500 g of dimethylaminoacetic acid methylamide is introduced into the reactor entered uniformly and at the same time at the top of the column the vinylamide formed in a mixture with the difficult to separate Starting amide removed. The acetylene circulation is 4001 per hour, the reactor temperature 185 ° C.

The top product consists of 521 g of dimethylaminoacetic acid-N-methyl-N-vinylamide and 1805 g of starting amide, which corresponds to a conversion of 28% and a yield of 61% of theory.

The new vinylamide purified by redistillation boils at 20 Torr at 96 ° C. The refractive index η ² ?

is 1.4811.

Example 4
N-vinyl-N- (2'-morpholinoethyl) acetamide

in Example 1, b) the apparatus described are additionally heated in which all incoming and outgoing lines, are introduced into the reactor in 1030 g of N- (2'-Morpholinoäthyl) -acetamide and at 120 ⁰ C dissolved therein 12 g of sodium amide . The ammonia that develops is drawn off in vacuo. 200 g of N- (2'-morpholinoethyl) acetamide are added to the vessel at the foot of the column.

The reactor is then ^{heated to 190 to 210 °} C. and 1200 l of acetylene is passed through the reaction mixture every hour for a period of 22 hours. During this time, 2605 g of a mixture of N- (2'-morpholinoethyl) acetamide and 5 mol percent of sodium amide dissolved therein are continuously pumped into the reactor. At the top of the column, 2312 g of a vinylation mixture are taken off, from which 1488 g of N-vinyl-N- (2'-morpholinoethyl) acetamide are obtained as a colorless liquid, _{boiling point} 120 to 121 ° C, n ^s S = 1, 5060.

Analysis for C ₁₀ H ₁₈ N ₂ O ₂ (198.3).

Calculated. C 60.57, H 9.15, N 14.13, O 16.15 ° / _O ; found .. C 60.6, H 9.3, 'N 14.1, 0 16.0%.

The N- (2'-morpholinoethyl) acetamide used as the starting material can be obtained from 2-morpholinoethylamine and methyl acetate. F. 90 to 91 ⁰ C (from diisopropyl ether).

60

Claims (4)

Patent claims: 1. Process for the preparation of basic N-vinylamides the general formula R, (Ib) ■ R. (2 B) CH
CH ₂ R ₁ -N-OC- (CH ₂ VN:
CH Il CH ₂ in which R _{1 is} an alkyl radical of 1 to 4 carbon atoms, R ₂ and R _{3 are} alkyl radicals of 1 to 4 carbon atoms, which can be linked to one another to form a five- or six-membered ring, optionally including a hetero atom, and η is the number 1 , 2 or 3, by reacting basic amides of the general formula 20th R ₁ -OC-NH- (CH ₂ ) ^ - N: (la) respectively R ₁ - NH- OC- (CH ₂ ), - (2a) R ₃ in which R ₁ , R ₂ , R ₃ and _{n have} the meanings given above, with acetylene at elevated temperature in the presence of basic alkali metal compounds as a catalyst, characterized in that the reaction is carried out at about 90 to about 320 ^° C. under pressures between 150 torr and normal pressure, preferably normal pressure, and the vinyl amides formed are removed as they are formed. 2. The method according to claim 1, characterized in that the reaction is carried out at temperatures between about 150 and about 250 ° C. 3. The method according to claim 1 or 2, characterized in that the unreacted Acetylene and the unreacted basic amide are continuously returned to the reaction zone. 4. The method according to claim 1 to 3, characterized in that the reaction is carried out in the presence of sodium or potassium or the alkali metal compounds of the starting amides used Performs compounds as catalysts. Considered publications:
German patent specifications No. 877 757, 890 508:
U.S. Patent Nos. 3,144,396, 2,717,886. 1 sheet of drawings 709 619/716 7. 67 © Bundesdruckerei Berlin