RU2036890C1 - Method of cyclopentene synthesis - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: method of cyclopentene synthesis involves dicyclopentadiene depolymerization, distillation off of obtained cyclopentadiene from high-boiling impurities, hydrogenation of cyclopentadiene on the palladium-containing catalyst and isolation of prepared cyclopentene, and depolymerization is carried out in liquid phase at 160-165 C for 3-4 h, and simulateneously cyclopentadiene is distilled off from high-boiling impurities. Cyclopentadiene hydrogenation is carried out in liquid phase at 30-40 C, under pressure 0.3-0.4 MPa for 1-1.5 h of liquid flow at hydrogenation zone. Then prepared cyclopentene is isolated and purified by dimerization of nonreacted cyclopentadiene, distillation off of cyclopentene-containing fraction from dicyclopentadiene, contacting distilled off fraction with titanium tetrachloride or aluminium bromide with simultaneous rectification. Then prepared cyclopentene is contacted with triisobutyl-aluminium, and the end product is isolated by final rectification. Prepared cyclopentene has 99.5% basic substance (not less), 0.5% cyclopentene (not more), 0.0001% cyclopentadiene (not more), 0.0005% piperylenes (not more), 0.0005% isoprene (not more), 0.001% water (not more), and 0.0001% oxygen-containing impurities (not more). EFFECT: improved method of synthesis. 1 dwg, 2 tbl

Description

 The invention relates to the synthesis of organic products, namely to the production of cyclopentene. The latter is used for the synthesis of cyclopentanol, cyclopentanone, glutaric acid and other products. In recent years, additional directions for the use of cyclopentene have been identified, presenting an increased demand for its purity. High purity cyclopentene can be used for the synthesis of the ketamine drug, as well as a monomer for the synthesis of cis-polypentenamer. This is a new type of synthetic rubber with unusually high frost resistance, which is higher than all known hydrocarbon rubbers. For this purpose, cyclopentene of the highest degree of purity is needed.

 A number of known methods for the preparation, isolation and purification of cyclopentene. The production of cyclopentene is mainly carried out by selective catalytic hydrogenation of cyclopentadiene (CPD), which, in turn, is obtained by thermal depolymerization of dicyclopentadiene (DPPD).

 There is a method of producing cyclopentene from dicyclopentadiene, which consists in thermal dedimerization of the latter with subsequent catalytic hydrogenation of cyclopentadiene in a boiling reaction mixture with feeding cyclopentadiene in a liquid phase for hydrogenation, isolation of the target product by condensation of gaseous reaction products and separation of cyclopentane and cyclopentadiene by distillation.

The invention is aimed at solving the following problem:
production of cyclopentene containing not less than 99.5% of the basic substance, not more than 0.5% cyclopentane, not more than 1 ppm (0.0001%) CPD, not more than 5 ppm (0.0005%) piperylene / cis and trans isomers of not more than 5 ppm (0.0005%) of isoprene, not more than 10 ppm (0.001%) of water and not more than 1 ppm (0.0001%) of oxygen-containing compounds (total). According to the proposed method, cyclopentene of such purity can be obtained from conventional "petrochemical" DCPD and is suitable for the most qualified use, for example, to obtain cis-polypentenamer or "ketamine".

Solution of the problem is achieved by a method of producing cyclopentene, dicyclopentadiene comprising depolymerization in the liquid phase, distilling cyclopentadiene obtained from high boiling impurities, the hydrogenation of cyclopentadiene to palladium-containing catalyst and isolating the resulting cyclopentene, consisting in that the depolymerization of dicyclopentadiene is carried out in the liquid phase at 160-165 ^{° C} and time stay in the depolymerization zone for 3-4 hours with simultaneous distillation of cyclopentadiene from high-boiling impurities, hydrogenation of cyclopentadiene, about uschestvlyaemom in liquid phase at ^about 30-40 C, pressure 0.3-0.4 MPa, and residence time of the liquid stream in a hydrogenation zone 1-1.5 hours, then the resulting cyclopentene was isolated and purified by dimerization of the unreacted cyclopentadiene, distillation fraction from tsiklopentensoderzhaschey dicyclopentadiene, contacting the distilled fraction with titanium tetrachloride or aluminum bromide with simultaneous distillation, contacting the obtained cyclopentene with triisobutylaluminum and isolating the target product by final distillation.

 The scheme of the method is shown in the drawing.

The initial DCPD is subjected to depolymerization in a reactor 1, combined with a distillation column, where the temperature is maintained at 160-165 ^о С and a residence time of 3-4 hours. Monomeric CPD is selected as a distillate, which is fed to liquid phase hydrogenation in a reactor 2 filled with a palladium-containing catalyst. Hydrogen is supplied directly to the reactor through a switchgear. The reactor temperature is maintained at 30-40 ^{° C,} pressure 0.3-0.4 MPa, and residence time of the liquid flow of 1-1.5 hours. The hydrogenation product was supplied to column 3, where dimerization occurs unreacted CPE. The DCPD formed in the cube of the column is returned to recycling. In the form of a distillate, a cyclopentene-containing fraction is taken, which enters the distillation column 4 for purification from diene and olefin hydrocarbons, in the cube of which it is contacted with titanium tetrachloride or aluminum bromide. At the same time, part of the impurities is taken in the form of distillate. Then cyclopentene is distilled off with a basic substance content of at least 99.5 wt. Concentrated cyclopentene is sent to column 5 to remove impurities of water and oxygen-containing compounds by contact with triisobutylaluminum. Purified cyclopentene suitable for use as a monomer for polymerization is selected as a distillate. Distillation products of columns 1,4,5 are sent for destruction by burning.

PRI me R 1. The experiment is carried out in laboratory conditions. Thermal depolymerization of DCPD is carried out in a glass reactor, which is a 200 ml flask equipped with two remote boilers with electric heating, attached to a packed distillation column 500 mm long and 20 mm in diameter. The column is filled with a metal nozzle (nichrome spirals) and has an efficiency of 8 theoretical plates. The reactor was charged with 190 ml of the DCPD and heated to ^{160 °} C at atmospheric pressure. The residence time of the reaction mixture in the reactor is 4 hours. In the form of a distillate with a reflux ratio of 5, a monomeric CPD with a yield of 95 wt. High boiling products are removed from the bottom of the reactor.

The obtained monomeric CPD is hydrogenated in the liquid phase in a 200 ml steel autoclave equipped with a heating jacket. 150 ml of CPD and 25 g of catalyst 2 wt. palladium on alumina, pre-activated in a stream of hydrogen for 1 h at 400 ^about C at atmospheric pressure and a hydrogen supply of 1000 h ^-1 . Hydrogenation is carried out at 30 ^about C and a pressure of 0.3 MPa for 1 h. The conversion of the CPD is 93.2 wt. selectivity for cyclopentene 97.2 wt.

The hydrogenate is treated to dimerize the unreacted CPD and isolate the cyclopentene-containing fraction. The dimerization is carried out in the cube packed distillation column with a theoretical plate number ^of 8 at 70 ° C for 8 hours. The then removed as the distillate at a reflux ratio of 5 tsiklopentensoderzhaschuyu fraction. DCPD is unloaded from the cube and returned to thermal depolymerization.

A cyclopentene-containing fraction in an amount of 600 ml was loaded into a cube of a distillation column 3 m long, 0.1 m in diameter with 35 theoretical plates. 360 ml of a 12% solution of titanium tetrachloride in toluene were loaded therein. Purification was carried out for 16 hours at 60 ° ^C with simultaneous selection as the distillate nizhekipyaschey C ₅ fraction composed mainly of pentenes, a reflux ratio of 100. Then, as the distillate withdrawn cyclopentene in an amount of 300 ml with a content of basic substance 99.5 wt.

For final purification, 300 ml of cyclopentene is loaded into a cube of a similar distillation column. 2 ml of an 80% solution of triisobutylaluminum are loaded there. Cleaning is carried out for an hour at 60 ^about With the simultaneous selection in the form of distillate of dried and purified cyclopentene with a water content of 0.001 wt. and oxygen compounds 0.0001%
Analysis of the target product for the content of microimpurities, which are essential for its application in various fields of technology, was carried out according to the developed sensitive methods.

 The determination of water in cyclopentene is based on its interaction with Fischer's reagent, which is a solution of sulfur dioxide in pyridine and iodine in methanol. The end of titration is set electromechanically. The minimum detectable concentration is 2 ppm.

The determination of small amounts of C ₄ -C ₅ hydrocarbons and CPD in cyclopentene is carried out by GLC with a thermal conductivity detector (column l 3 m, d 5 mm, stationary phase 15% squalane on diatomite brick, T _number 40 ^о С, carrier gas flow rate hydrogen 40-50 ml / min) and LHM-8MD, model 3 with an ionization flame detector (column l 6 mm, d 3 mm, stationary phase of 15% triethylene glycol and n-butyric acid (TEGNMK) on diatomaceous brick, T _count 30 ^о С, nitrogen carrier gas flow rate 40-50 ml / min.

Acyclic C ₄ -C ₅ hydrocarbons, the relative retention time of which is shorter than that of cyclopentene, are adsorbed in the TEGNMK trap at -78 ^о С, and then are desorbed at room temperature by a carrier gas stream into the column of the LHM-8MD device, where they are separated. The sensitivity of the method is 1 ppm.

 The main results of the experiment are given in table 1.

The quality of the obtained cyclopentene, along with the analysis, is additionally evaluated by its control polymerization under standard conditions. The polymerization is carried out in a glass flask equipped with a stirrer, a thermometer and a loading device. 36 ml of toluene, 21 ml of cyclopentene and 1.3 ml of toluene solution of tungsten hexachloride concentration of 0.047 mol / L are loaded into the flask in an argon stream. The mixture is cooled to 4 ^° C and 1.4 ml of epichlorohydrin and 1.7 ml of a solution of dimethyldiallylsilane in toluene are added in a concentration of 0.072 mol / L. Polymerization was carried out for 1 hour at 2-4 ° ^C. The polymer was isolated by precipitation fold excess of ethanol, the antioxidant is charged NG 2246 and dried in vacuo to constant weight.

Polymer microstructure was determined by IR on the device "A AFR-302", intrinsic viscosity method expiration in Ubbelohde viscometer at 25 ^C. The polymer yield of 25.2 wt. content of cis units 63% of trans units 30% intrinsic viscosity 1.4 dl / l, mol.m. 500,000.

 PRI me R 2. The experiment is carried out as described in example 1, but the following parameters are changed.

Depolymerization temperature ^about 165 C, the residence time in the depolymerization zone 3 hours, the hydrogenation temperature is 40 ^{° C,} the residence time in the hydrogenation zone for 1.5 hours, the pressure is 0.4 MPa. As a reagent for the chemical purification of the cyclopentene-containing fraction, anhydrous powdered aluminum bromide is used in an amount of 1.3 g per 100 ml of cyclopentene. The main results of the experiment are given in table.2.

 The polymerization of the obtained cyclopentene is carried out under conditions similar to the conditions of example 1. The polymer yield was 38.5 wt. content of trans units 30%; content of cis units 70%; intrinsic viscosity 2.1 dl / g.

PRI me R 3. The experiment is carried out on a semi-factory installation. Raw petrochemical DCPD with a basic substance content of 86 wt. in the amount of 2600 l is subjected to thermal depolymerization in a steel reactor of a capacitive type with a volume of 120 l, combined with a packed distillation column of continuous action with a height of 6 m, a diameter of 0.1 m, equipped with a remote boiler and a shell-and-tube type condenser. The shell space of the reboiler continuously supplied coolant transformer oil AMT-300 at a temperature of 250 ^C. The preheated to 138 ^C. DCPD was continuously fed to the reactor at a rate of 10 l / h and simultaneously collected as the distillate column monomeric CPD a reflux ratio of 5, with speed of 6 l / h. High boiling products are continuously withdrawn from the cube of the column at a speed of 4 l / h, part of which is sent to recycling, and part to destruction by burning.

The reactor was maintained depolymerization temperature ^about 165 C and residence time of the liquid stream DCPD 4 hours.

Monomeric CPP in the amount of 1500 l is subjected to liquid phase hydrogenation. Hydrogenation is carried out continuously in a steel tubular reactor with a fixed bed of palladium-containing catalyst supported on alumina. The reactor temperature is maintained at 35 ^{° C,} pressure 0.35 MPa, the residence time of the liquid stream for 1.3 hours, the molar ratio of hydrogen CPD 1.8: 1. The conversion of the CPP is 90.5 wt. the selectivity of the process is 96.5 wt.

Hydrogenated in the amount of 1450 l served in a distillation column of periodic action with a height of 12 m, a diameter of 0.3 m, a volume of 0.5 m ³ . The bottom of the column is thermally dimerization unreacted CPE at ⁷⁰ ° C for 16 hours in the operation. Then the cyclopentene-containing fraction is distilled off, and the resulting DCPD from the cube is returned to recycling.

 The cyclopentene-containing fraction is sent for purification from diene and olefin hydrocarbons. Purification is carried out by contacting the fraction with titanium tetrachloride with simultaneous distillation.

To do this, 230 l of cyclopentene-containing fraction from 140 l of a 12% toluene solution of titanium tetrachloride are loaded into a cube of a similar distillation column. In operation of the column for 16 hours at a temperature of 60 ^{° C} cube carried contacting purified fraction with titanium tetrachloride. At the same time, in the form of a distillate with a reflux number of 150, a fraction of C ₅ hydrocarbons, primarily consisting of pentenes, and then cyclopentene 99.5 wt. The selected cyclopentene in the amount of 800 l is fed for final purification in a similar distillation column. 500 l of cyclopentene and 3.5 l of a 90% solution of TIBA in toluene are loaded into the cube of the column. The cube maintained at 60 ° ^C with a residence time of the reaction mixture for 4 hours. The collected as the distillate trademark cyclopentene. Received 700 l of cyclopentene. The purified product contains 99.6 wt. cyclopentene, 0.4 wt. cyclopentene, 1 ppm of CPD, 5 ppm of cis and transpiperylene, 1 ppm of isoprene, 50 ppm of pentenes, 10 ppm of water and 1 ppm of oxygen-containing compounds.

The resulting cyclopentene is used for polymerization in order to obtain a new highly frost-resistant synthetic rubber cyclopentanamer. The polymerization is carried out at a semi-plant in a reactor equipped with a mixing device and a cooling jacket. The polymerization batch is prepared directly in the reactor by sequentially loading a dry nitrogen atmosphere calculated amounts of toluene shestihloristogo tungsten and cyclopentane, followed by aging for 1-1.5 hours at 2-4 ^{° C} and stirring. Then, an activator (epichlorohydrin) and a silicon-containing catalyst are introduced. After reaching the equilibrium concentration of the polymer, the reaction mixture enters a container containing the calculated amount of stopper of a 5% solution of ethanol with agidol 2. Then, the polymer solution is fed through a chip former to a degassing system, where it is separated from hydrocarbons and dried. The polymer yield of 27.1 wt. content of trans units 29% content of cis units 68% intrinsic viscosity 1.9 dl / g

Claims (1)

METHOD FOR PRODUCING cyclopentyl comprising depolymerization of dicyclopentadiene in the liquid phase, distilling the resulting cyclopentadiene from high boiling impurities, the hydrogenation of cyclopentadiene to palladium-containing catalyst in the liquid phase and recovering the resulting cyclopentene, characterized in that the selection of cyclopentene carried out by keeping tsiklopentensoderzhaschey fraction at 70 ^o C for 18 August h with its subsequent contact with titanium tetrachloride or aluminum bromide with simultaneous distillation, contacting the floor scientific cyclopentene with triisobutylaluminum and isolation of the target product by final distillation.

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