RU2174505C1 - Method of preparing functionally substituted methylene cyclobutane - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: described is the method of preparing functionally substituted methynele cyclobutane by reacting allene with ethylene derivative containing -COOH or -COOR, or -CN at elevated temperature followed by separation of reaction products and rectification isolation of desired product. Allene source is allene-containing gas having allene content from 10 to 80%, and ethylene derivative containing -COOR includes alkyl ethers wherein R is C₁-C₄; process is carried out in vapor phase at temperature of higher than 360 C and pressure of 0.1-1.0 MPa to conversion of allene of not higher than 60% at reactor outlet, reaction products are hardened and separated by rectification, desired product is withdrawn as commercial product, and unreacted allene and ethylene derivative are recycled to process. EFFECT: higher simplified process efficiency. 4 cl, 1 dwg, 1 tbl

Description

 The invention relates to the petrochemical industry and, more specifically, to a method for producing functionally substituted methylene cyclobutane.

 Functionally substituted methylenecyclobutanes are used as starting compounds for the production of liquid crystals, monomers in the production of various special polymers, in the synthesis of biologically active substances and in the synthesis of a number of compounds containing cyclobutane fragments in molecules.

A known method of producing a functionally substituted methylene cyclobutane - methylene cyclobutane-1,2-dicarboxylic acid anhydride (K. Alder and O. Ackermann, Chem. Ber. 90, 1697, 1957) [1]. In accordance with this method, allen is reacted with maleic anhydride at a pressure of ~ 20 atmospheres at temperatures of ~ 250 ^o C, the yield of substituted methylene cyclobutane in the calculation of the loaded allen is about 20%. This method does not allow to obtain any substituted methylenecyclobutanes in addition to the above, i.e. not universal.

There is also known a method for producing methylene cyclobutanecarbonitrile from allen and acrylonitrile (F. Caserio, et al, JACS, 80, p.5507-5513, 1958) [2]. The synthesis is carried out in toluene at 260-270 ^o C with the release of the target product ~ 60%. The process is described to obtain methylenecyclobutanecarbonitrile, accompanied by significant gum formation, which leads to unproductive consumption of reagents and complicates the selection of the target product.

More universal and closest in technical essence to the present invention is the method for producing substituted methylenecyclobutanes described in US patent N 2914541, CL. 549-240, 1959 [3]. In accordance with the patent, functionally substituted 3-methylenecyclobutanes are prepared by cycloaddition of ethylene derivatives containing COOH, COOR, CN, CONH ₂ groups to allens. Acrylic and methacrylic acids, as well as nitriles, amides and lower esters of these acids and other activated olefins. The process is carried out under pressure in a special autoclave, in the liquid phase in a solvent medium, in the presence of a polymerization inhibitor - hydroquinone or fentiazine, or without it. The method is carried out at high conversion of allen. In this case, allen with a purity of ~ 100% is used, which creates fire and explosion hazard conditions. The process is carried out in a batch mode, at a temperature of ~ 150-250 ^o C, depending on the used activated ethylene.

 The method [3] is characterized by the frequency of the process, low productivity of the target product. The process is quite lengthy and requires special equipment. A significant amount of by-products makes it difficult to isolate the desired methylene cyclobutanes. In addition, the implementation of the method of cycloaddition of activated olefins to allene in the liquid phase leads to a gradual decrease in the concentration of reagents in the reaction medium and a decrease in the rate of their conversion.

 The present invention, therefore, was the creation of a more productive method for producing a functionally substituted methylene cyclobutane while simplifying the technology for its implementation.

It was found that the stated problem, in accordance with the present invention, is solved by a method for producing a functionally substituted methylene cyclobutane by reacting an allene with an ethylene derivative containing the group —COOH or —COOR or —CN at an elevated temperature, followed by separation of the reaction products and isolation of the target distillation product, characterized in that an allen-containing gas with an allen content of 10 - 80% is used as an allen source, an ethylene derivative containing a -COOR group is used, m alkyl ester with R = C ₁ -C _4, a process is carried out in the vapor phase at a temperature above 350 ^o C until the conversion of allene not more than 60% at the outlet of the reactor the reaction products are separated by rectification, and quenched, the desired product is withdrawn as a commodity, unreacted allene and an ethylene derivative are returned to the process, the method is preferably carried out up to a conversion of 20-30% at 400-550 ^o C and a pressure of 1-1.0 MPa, alkyl ether -COOC ₄ - butyl ether with a radical of normal, iso- or tertiary structure .

 Activated ethylenes containing a group can be used as raw materials: —COOH — acrylic and methacrylic acids; —COOR — methyl acrylate and methyl methacrylate; -CN - nitriles of acrylic and methacrylic acids.

 The implementation of the process in the vapor phase makes it possible to ensure an almost constant ratio of reacting substances and homogeneity of the reaction medium, resulting in a minimal temperature gradient both in the height of the reactor and in the radial direction.

 As a source of allen, a methylacetylenelenlene fraction with an allen content of 10 - 80% allen can be used. Other components: methylacetylene, propylene, propane and other phlegmatizers. The use of such raw materials does not affect the quality of the resulting target products, allows for the explosion and fire safety of the process and makes it more economical by reducing the cost of allen.

 The method in accordance with the present invention allows to organize the process in a continuous mode, with a practically constant concentration of reacting substances, and therefore with a constant speed. The process is highly selective, and when converting allene, ~ 30% of the reagents are spent mainly on obtaining the target products. Resin formation is minimal. This allows you to recycle unreacted substances for their subsequent use in the process. Hardening of the reaction products at the outlet of the reactor maintains the required conversion of allen. Limiting the conversion of allene to an upper limit of 60% made it possible not only to ensure high selectivity of the process, but also unexpectedly to increase the productivity of the process, and ultimately the yield of the target product. Thus, the set of essential features of the present invention provides a functionally substituted methylenecyclobutane more efficient and cost-effective than in the prototype method. In the present method for producing a functionally substituted methylene cyclobutane, it is not intended to use inhibitors other than those contained in commercial raw materials.

 Of particular note is the significant simplification of the instrumentation of the technological process, the control of technological parameters and the isolation of functionally substituted methylene cyclobutanes obtained in this process.

 The process is continuous, which creates undoubted convenience in its industrial development.

 For a better understanding of the invention, the drawing shows a flow diagram of the production of functionally substituted methylene cyclobutane.

 The stream of the ethylene derivative I is directed to the evaporator 1, at the outlet of which the stream I is mixed in predetermined proportions with the flow of the allene-containing gas II and this mixture is introduced into the heater 2. The raw material mixture heated to the required temperature is then sent to the reactor 3, in which the ethylene derivative is cyclic addition to allen. The reaction mass from the reactor 3 is introduced into the quenching apparatus 4, in which a part of the components of the product mixture is condensed. The gas-liquid mixture from the apparatus 4 is then sent to a separator 5, where the gas and liquid phases are separated. The gas phase — stream III — is recycled to the inlet of stream II, the liquid phase — stream IV is sent for separation to distillation unit 6, where the ethylene derivative V is recovered — the stream returned to recycling to the inlet of stream I, functionally substituted methylene cyclobutane VI, and heavy products reactions VII.

 The invention is illustrated by specific examples.

 Examples 1, 3. Obtaining methylenecyclobutanecarboxylic acids.

 The stream of ethylene derivative I — acrylic or methacrylic acid — is sent to heater 1, at the outlet of which stream I is mixed in predetermined proportions with the flow of allene-containing gas II and this mixture is introduced into heater 2. The raw material mixture heated to the required temperature is then sent to reactor 3, in which the cycloaddition of an ethylene derivative to allen takes place. Then the reaction mass from the reactor 3 is introduced into the quenching apparatus 4, where some of the components of the product mixture are condensed. The gas-liquid mixture from the apparatus 4 is then sent to a separator 5 for separating the gas and liquid phases. The gas phase - stream III, after the implementation of the necessary technological operations, is returned to recycling to the inlet of stream II. The liquid phase - stream IV, is sent for separation in the distillation unit 6. In the distillation unit 6 allocate: an ethylene derivative - stream V, returned to recycling to the input of stream I; functionally substituted methylene cyclobutane VI; and heavy reaction products VII.

 The ratio of the obtained products: ~ 10% 2-methylene- and 90% 3-methylenecyclobutanecarboxylic acids. The results are shown in the table.

Example 2 ^* (comparative) Obtaining methylenecyclobutanecarboxylic acids.

 Obtaining methylenecyclobutanecarboxylic acids is carried out by liquid-phase cycloaddition of acrylic acid to allene in an autoclave in accordance with the conditions of the prototype method. The process conditions and synthesis results are shown in the table.

 Examples 4, 5, 6, 8. Preparation of methylenecyclobutanecarboxylic acid esters.

 The process is carried out analogously to examples 1,3 using esters of acrylic and methacrylic acids. The modes and results of the synthesis of methylenecyclobutanecarboxylic acid esters are shown in the table.

Example 7 ^* (comparative). Obtaining esters of methylenecyclobutanecarboxylic acids.

 The preparation of methylenecyclobutanecarboxylic acid esters is carried out analogously to Example 2 using methyl acrylate instead of acrylic acid. The process conditions and synthesis results are shown in the table.

 Examples 9, 10, 13. Obtaining nitriles of methylenecyclobutanecarboxylic acids.

 The method is carried out analogously to examples 1, 3, using acrylo- and methacrylonitrile, respectively. The process conditions and synthesis results are shown in the table.

Examples 11 ^* , 12 ^* (comparative). Obtaining nitriles of methylenecyclobutanecarboxylic acids.

Obtaining nitriles of methylenecyclobutanecarboxylic acids is carried out analogously to example 2 ^* using acrylonitrile instead of acrylic acid in the liquid phase. The process conditions and results are shown in the table.

 As can be seen from the data given in the table, in accordance with the present invention, the productivity of the process for the target products is more than 10 times the productivity of the prototype method.

 Moreover, in addition to increasing the productivity of the installation, the yield of the target products also increases due to an increase in the selectivity of the process of cycloaddition and recycling of raw materials, which ensures the efficiency of the process. In addition, the technology for producing functionally substituted methylene cyclobutanes from the point of view of hardware design, process control and isolation of target products has been greatly simplified.

 A method of obtaining a functionally substituted methylene cyclobutane, in accordance with the present invention, can be carried out in serial industrial plants of petrochemical plants without significant capital investments. The technology for obtaining the target products is simpler, more convenient and economical than in the prototype method.

Claims (4)

1. A method of producing a functionally substituted methylene cyclobutane by reacting an allene with an ethylene derivative containing a —COOH or —COOR or —CN group at an elevated temperature, followed by separation of the reaction products and distillation of the target product, characterized in that they use an allen source Allen-containing gas with an Allen content of 10 - 80%, alkyl esters with R = C ₁ -C ₄ are used as an ethylene derivative containing a COOR group, the process is carried out in the vapor phase at temperatures above 350 ° C and 0.1–1.0 MPa before allene conversion is not higher than 60%, at the outlet from the reactor the reaction products are quenched and separated by distillation, the target product is taken as a commercial product, unreacted allen and an ethylene derivative are returned to the process.  2. The method according to claim 1, characterized in that the process is preferably carried out before the conversion of allen 20-30%.  3. The method according to p. 1 or 2, characterized in that the process is carried out preferably at 400-550 ° C and 0.3-0.6 MPa. 4. The method according to claim 1, characterized in that the alkyl ether - SOOC ₄ - butyl ether with a radical of normal, iso- or tertiary structure.

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