DE1132128B - Process for the preparation of crystallized 1,3-dialkylcyclobutenolones - Google Patents

Description

GERMAN

PATENT OFFICE

W 28657 IVb / 12 ο

REGISTRATION DATE: SEPTEMBER 30, 1960

NOTICE
THE REGISTRATION
ANDOUTPUTE
EDITORIAL: JUNE 28, 1962

It is known to make l ^ -dialkylcyclobutenolone to produce spontaneous polymerization of more or less concentrated alkyl ketene solutions (H. Staudinger, Ber. German former Ges., Vol. 44, 1911, p. 533). The polymerization starts when heated of the alkyl ketene solution cooled to -80 ° C. suddenly with violent boiling and introduces it In addition to the desired dialkylcyclobutenolone, there are also considerable amounts of other liquid polymerization products. Apart from the by-products, this process is for lack of controllability the reaction in technology not applicable. Will the onset of a sudden Reaction avoided by permanent cooling of the alkyl ketene solution to -40 ° C., is still obtained less dialkylcyclobutenolone than with the sudden polymerization, so that the liquid polymers for Become main product.

It has also been proposed to carry out the polymerization in a very dilute solution (E. B. Reid and S. J. Groszos, J. Amer. Chem. Soc, Vol. 75, 1953, p. 1655). Also arise in this liquid polymers in larger quantities. Apart from the poor yields obtained Dialkylcyclobutenolone must use disproportionately large amounts of solvent in this process be redistilled, since only less than 1% alkyl ketene solutions are used.

The same disadvantages, such as high dilution and difficult controllability of the dimerization, are with Application of the reaction conditions of German Patent 628 321, which describes a process for the preparation of diketones, present. Apart from these disadvantages, one obtains among these Conditions larger amounts of other polymers.

If one tries, the spontaneous development of the heat of reaction by continuous introduction of alkyl ketenes in inert solvents at temperatures that require a momentary conversion ensure that they are significantly above the temperature of -40 ° C given above, around 0 ° C., instead of the desired 1,3-dialkylcyclobutenolones trimers are obtained Aldoketene (German exposition 1 081 455).

It has now been found that 1,3-dialkylcyclobuten- (l) -ol- (2) -one- (4) the general formula

R - C = C - OH

Ii

O = C-CH-R

where R is a straight-chain or branched, aliphatic radical, in very good shape

Process for the preparation of crystallized 1,3-dialkylcyclobutenolones

Applicant:

Wacker-Chemie G.m.b.H., Munich 22, Prinzregentenstr. 20th

Dr. Eduard Enk and Dr. Hellmuth Spes,

Burghausen (Obb.), Have been named as the inventor

and produce high purity with the formation of only insignificant amounts of by-products can, if one alkyl ketenes of the general formula

R-CH = C = O

where R has the abovementioned meaning, in inert solvents at low temperatures polymerized. The method is characterized in that the gaseous alkyl ketene at a temperature between 0 and -80 ° C, preferably between -30 and -80 ° C, and at a pressure of 30 Torr up to a pressure of about 2 atmospheres is introduced into the solvent, the concentration of the reaction product in the reaction space being about 60% of the reaction medium does not exceed.

The experiments show that the temperature of the Solvent must be above the temperature at which the polymerization begins, but below that temperature at which the polymerization mainly to trimeric aldoketene leads

The process can be carried out batchwise or continuously. With discontinuous Procedure, an alkyl ketene stream is introduced into a reaction vessel in which the Solvent brought to the desired temperature is located. This temperature is during of initiation maintained. After a short time, abundant crystals separate. Initiate the alkyl ketene can reach the pulpy consistency of the

209 617/430

Reafctionsproduktes to be continued. After completion the reaction becomes the pure white dialkylcyclobutenolone Sucked off, washed with a little solvent and dried. The filtrate can be used for another approach.

In the case of continuous operation, the alkyl ketene is absorbed in a dissolving device, the solvent of which, in the simplest case, circulates between a separating vessel and the dissolving device. The dialkylcyclobutenolone which settles in the separator is drawn off and nitrated. The filtrate can be returned to the circulation. Any gas absorption system from which the suspension can be flushed out with a sufficiently strong liquid flow is suitable as a solution device for this process. The absorption and reaction in a liquid ring pump, which serves both as a reaction vessel and to generate the vacuum required for the production of the alkyl ketene, offer particular advantages. ^zo

The reaction can be carried out over a wide range of pressures. Most of the time you get under Working pressure under which the alkyl ketene is produced, d. H. between about 30 and 400 torr. However, higher pressures up to about 2 atmospheres can also be used, as in the practice the reaction in the liquid ring pump, with the full pressure range from 30 torr to is passed through to atmospheric pressure or slightly overpressure.

The!, S-dialkylcyclobutenolones are white, crystalline Substances which, due to their reactivity, act as intermediates for further reactions suitable.

example 1

42.1 g of gaseous methyl ketene are absorbed ^{in 100 cm 3 of} ethyl acetate within 45 minutes at -50 ° C. under a pressure of 40 torr. The resulting l, 3-Dimethylcyclobuten- (l) -OL- (2) -one (4) is carried out at - 30 ⁰ C and suction filtered the filtrate evaporated to give additional 1,3-Dimethylcyclobutenolon fails. A total of 36.6 g of 1,3-dimethylcyclobutenolone with a melting point of 136 ° to 138 ° C. are obtained, which is 87% of theory. 5.5 g of the liquid dimer, that is 13%, based on the methyl ketene used, are found in the distillate of the filtrate. Trimeric methyl ketene does not form at this temperature.

Example 2

45 g of gaseous methyl ketene are absorbed under a pressure of 40 torr within 40 minutes in 100 cm ^{3 of} ethyl acetate, which is cooled to -80 ° C. in a carbonic acid bath. The 1,3-dimethylcyclobuten- (l) -ol- (2) -one- (4) formed is filtered off with suction after heating to -30 ° C. and the filtrate is evaporated, further 1,3-dimethylcyclobutenolone precipitating out. A total of 41 g of 1,3-dimethylcyclobutenolone with a melting point of 136 ° to 138 ° C. are obtained, that is 91.1% of theory. In the distillate of the filtrate, 2.48 g of the liquid dimer are found, that is only 5.5%, based on the methyl ketene used. Trimeric methyl ketene is not formed.

If, on the other hand, gaseous methyl ^{ketene is introduced into 100 cm 3 of} ethyl acetate at the temperatures listed below at 80 torr, the introduction is interrupted after 100 g of methyl ketene have been absorbed and the 1,3-dimethylcyclobuten- (1) -ol- (2) -one is sucked in - (4), only the following yields of 1,3-dimethylcyclobutene- (l) -ol- (2) -one- (4) are obtained:

-30 ⁰ C 75,4O / o

-1O ⁰ C 52.70 / o

+ 1O ⁰ C 22.60 / ₀

of the introduced methyl ketene. Example 3

Gaseous methyl ketene is introduced as in Example 1 to -5O ⁰ C in 100 cm ^{3 of} dibutyl ether, trichlorethylene, ethyl chloroformate and hexachlorobutadiene. The yields of 1,3-dimethylcyclobutenolone are after working up as in Example 1 for dibutyl ether 80.40 / ₀ , for trichlorethylene 66.1%, for ethyl chloroformate 94.6% and for hexachlorobutadiene 75.1% of the methyl ketene introduced.

Example 4

^{54 g of gaseous ethyl ketene are absorbed in 100 cm 3 of} ethyl acetate within 45 minutes at -50 ° C. under a pressure of 70 torr. The 1,3-diethylcyclobuten- (l) -ol- (2) -one- (4) formed is filtered off with suction at -30 ° C. and the filtrate is evaporated, further 1,3-diethylcyclobutenolone precipitating out. A total of 45.9 g of 1,3-diethylcyclobutenolone are obtained, that is 85% of the ethyl ketene used. 6% of the ethyl ketene reacts to form the liquid dimer.

Example 5

66 g of gaseous isopropyl ketene are absorbed under a pressure of 60 torr within 60 minutes in 100 cm ^{3 of} ethyl acetate, which is cooled to -65 ° C. in a carbonic acid bath. The 1,3 - diisopropylcyclobutene - (1) - oil - (2) -one- (4) formed is filtered off with suction after heating to -30 ° C. and the filtrate is worked up as in Example 2. A total of 58.7 g of 1,3-diisopropylcyclobutenolone with a melting point of 102 ° C. are obtained, which is 89.0% of the isopropyl ketene used. The amount of the incidentally formed liquid dimer is only 3.1 g, corresponding to 4.7% of theory.

Example 6

At the lower end of the reaction ^{tube of a circulation apparatus, 160 g of methyl ketene per hour in 1800 cm 3 of} ethyl acetate are introduced at -50 ° C. under a pressure of 120 torr. The apparatus consists of a reaction tube and a separating vessel, which stand next to one another at the same height and are connected to one another by two lines attached at different heights. The reaction medium is circulated by introducing the methyl ketene according to the mammoth pump principle between the reaction tube and the separating container in such a way that it flows through the lower line from the separating container into the reaction tube and through the upper line in the opposite direction.

The resulting!, S-dimethylcyclobutenolone sets is deposited in the separator and is continuously withdrawn as a suspension via a lock. Man obtained by filtering an average of 146 g!, S-dimethylcyclobutenolone per hour accordingly 91.3% of the methyl ketene used. The reaction liquid withdrawn with is, if necessary after replenishing with fresh ethyl acetate, fed back into the cycle.

Example 7

10

With a liquid ring pump, the liquid circuit of which is via a brine cooler and a separator for the separation of the exhaust gas and the solid reaction product which settles out are performed using ethyl propionate as the operating fluid at a pump temperature of -50 to -60 ° C hourly 1200 g of methyl ketene sucked under a pressure of 70 torr. That during the compression Methylketene dissolving in the reaction liquid to 2 atmospheres reacts simultaneously to 1,3-dimethylcyclobutenolone, which is from the Separator is continuously withdrawn. 1110 g of 1,3-dimethylcyclobutenolone are obtained per hour, that is 92.5% of the methyl ketene sucked in.

Claims (3)

PATENT CLAIMS: 1. Process for the preparation of crystallized 1,3-dialkylcyclobutene- (l) -ol- (2) -onen- (4) the general formula 30 RC = C-OH O = C-CH-R where R is a straight-chain or branched aliphatic radical, by polymerization of alkyl ketenes of the general formula R-CH = C = O wherein R has the abovementioned meaning, in inert solvents at low temperatures and optionally in vacuo, as characterized in that the gaseous alkyl ketene at a temperature between 0 and -80 ° C, preferably between -30 and -80 ° C, and at a Pressure of 30 torr to an excess pressure of about 2 atmospheres is introduced into the solvent, the concentration of the reaction product in the reaction space not exceeding about 60% of the reaction medium. 2. The method according to claim 1, characterized in that the 1,3-dialkylcyclobutene- (l) -ol- (2) -one- (4) formed in the case of continuous operation, is removed from the reaction liquid to the extent of its formation. 3. The method according to claim 1 and 2, characterized in that the polymerization in one Liquid ring pump is carried out. Considered publications:
German Patent No. 628,321;
German interpretative document No. 1 081 455. © 209 617/430 6.62