RU2618527C1 - Method for carrying out the process of reversible isomerization of norbornadiene in a quadricyclean - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: continuous distillation column has been installed to organize the continuous flow of the process and ensure the material and heat balance of the flows between the photochemical and catalytic modules allowing efficient separation of components such as norbornadiene and quadricyclan and directing them to the appropriate modules, regulating the cyclicity of the transformations.

EFFECT: increase in quantitative yield quadricyclane, requiring no further purification from the impurities, and the number of cycles to ensure continuity of the process.

3 cl, 2 ex, 2 tbl, 1 dwg

Description

The present invention relates to chemical technology, and in particular to a method for co-organizing the photoreaction of the valence isomerization of norbornadiene to quadricyclane and the catalytic isomerization of the latter to norbornadiene. The invention may find application in the field of energy for the accumulation of solar energy and its conversion into heat.

The prior art method for the conversion of norbornadiene to quadricyclane in a photochemical module in the presence of a xenon lamp (Oriel 6269) and a monochromator in a 12.5 × 50 mm quartz cuvette, followed by separation of unreacted norbornadiene on a 3.18 mm × 1.83 m steel column [Cartas LR, Greenberg DB Determination of the energy storage efficiency of the photoisomerisation of norbornadiene to quadricyclane as a potential means for the trapping of solar energy. / J. Solar Energy. / 1985, V. 34, No. 1, pages 93-99]. Irradiation occurs within 2 hours, while the yield of quadricyclane was about 70% at 298 K.

The disadvantage of this method is the low yield of quadricyclane.

Also known is a method for producing a quadricyclane using a photochemical module consisting of special mercury lamps and an Electro-Lite Corp. photoreactor equipped with appropriate filters [US 20040054244 A1 (Exciton, Inc.) 03/18/2004]. The process proceeds in a flow reactor for 216 minutes at 25 ° C. The conversion reaches 90% due to the use of pre-purified norbornadiene and the addition of triethylamine to reduce the number of adverse reactions.

The disadvantage is that this method is expensive, energy-intensive, requiring pre-treatment of norbornadiene.

At the moment, in the scientific and patent literature, no descriptions of methods for the joint conduct of photochemical and catalytic processes within the framework of a single technological scheme have been found.

The technical result of the present invention is to increase the quantitative yield of quadricyclane, which does not require additional purification from impurities, as well as the number of cycles ensuring the continuity of the process.

The technical result is achieved by the method of carrying out the process of reversible isomerization of norbornadiene into a quadricycle to ensure the material and heat balance of the flows, which consists in the fact that for the implementation of the process continuity after the photochemical module, a distillation column and a catalytic module are installed, which make it possible to regulate the cyclic transformations.

In the proposed method, the use of norbornadiene without prior purification is allowed. In addition, the number of reagents used can be reduced due to an increase in the selectivity of the processes.

A schematic flow diagram of a method for carrying out the process of reversible isomerization of norbornadiene into quadricyclane is shown in FIG. one.

The photochemical module (module 1) includes a 250 ml quartz reactor and a light energy source, which is used as an immersion mercury lamp with a variable power of 1 kW and an adjustable radiation wavelength in the range 300–473 nm (flux 0). To cut off short-wave radiation, special Schott Glass Co. light filters (WG 225, WG 280, WG 295, etc.) made of borosilicate glass are installed. The energy passing through the test solution is recorded using a photodetector - a silicon photodiode (Oriel 7183), located behind the reactor. From the photoreactor (module 1), the reaction stream (stream 1-2) enters the tray distillation column (module 2).

Continuous distillation column (module 2) is made of quartz glass with a height of 600 mm, a diameter of 60 mm, is equipped with a heated cube of 1 l, devices for controlling the reflux ratio and sampling. The efficiency of the column is 8 theoretical plates. At the column outlet, norbornadiene with a purity of 99.95% (stream 2'-1), a quadricyclone with a purity of 99.90% (stream 2-3) and an unreacted sensitizer (stream 2``-1) are obtained. The column sizes were selected based on the boiling points of the components involved in the processes: norbornadiene (boiling point 90.2 ° С), quadricyclane (boiling point 108 ° С) and acetophenone sensitizer (boiling point 202 ° С).

The catalytic module (module 3) consists of a flow-through installation, which includes a reactor consisting of a 13X18T stainless steel tube measuring 65 × 2.5 cm and an isothermal zone length of ~ 20–25 cm, which allows varying the amount of loaded catalyst in the range of 10 ÷ 40 cm ³ due to changes in the volume of the nozzle. Temperature control is provided by a gradientless electric furnace with programmable heating in the temperature range of 20-800 ° C. The temperature inside the reactor is maintained with an accuracy of ± 2 ° С with a meter-controller (IRT-5920) equipped with programmed control. The design of the reactor and electric furnace include the presence of built-in thermocouples that allow temperature measurement directly in the catalyst bed.

To supply a liquid reagent (stream 2-3) to the catalyst bed, a piston high-precision dispenser (HPP 5001) is used, which provides a feed rate in the range of 0.1–5 ml / min. If necessary, a condensation and product selection unit, consisting of two sequentially cooled separation vessels, is provided in the reactor (module 3). The norbornadiene stream with unreacted quadricyclane (stream 3-2) is again sent to the distillation column (module 2) for separation. The heat generated during the reaction (stream 0 ') can be used for heating.

Throughout the entire process flow diagram, the pressure is recorded by the AIR-20 electronic sensor and maintained by pressure regulators. The circulation pump, equipped with a control panel and a device for measuring the flow rate of the fluid, provides a medium circulation in the range of 0.5 ÷ 30 l / h.

The reaction product sampling unit, designed for on-line GLC analysis, includes a three-way valve, a rheometer and a gas meter (GSB-400, GOST 6463-53), directly connected to the analytical unit, which includes three Crystal 4000 chromatographs.

The invention is illustrated by the following examples.

Example 1

For the implementation of isomerization processes in the norbornadiene - quadricyclane system, the most promising is the implementation of reactions without the use of solvents or with a minimal amount of them. In this embodiment, no additional energy is required for pumping the liquid reaction mass.

In the photochemical module, a continuous supply of reagents is carried out at a speed of 1 l / h. The radiation wavelength is 300 nm. The average residence time of the reactants in the reactor is 15 minutes. Acetophenone in an amount of 2% of the amount of norbornadiene administered is used as a sensitizer. The isomerization reaction proceeds at 20 ° C. The conversion of norbornadiene at the output is 90%. Further, the flow is directed to separation in a distillation column operating in a continuous mode. Norbornadiene with a purity of 99.95% and a sensitizer are returned to the photochemical reactor, and a quadricyclone with a purity of 99.90% is fed to a catalytic module that uses a heterogeneous catalyst SiO ₂ (100am) /2.5MKM-CoPc (CH ₂ Cl) ₇ : carrier - aminopropylated silica gel Diaeorb-100 amine, the active phase content is 2.5 μM / g [RU 2470030 C1 (Federal State Unitary Enterprise “State Scientific Center“ Scientific Research Institute of Organic Intermediates and Dyes "”) 12/20/2012]. The average residence time of the reagents in the catalytic module is from 10 to 20 minutes depending on the process temperature, and the conversion of quadricyclane from 80 to 95%. After this, the mixture of norbornadiene and unreacted quadricyclane is sent to a distillation column for separation, as a result of which the flow of norbornadiene is fed into the photochemical module, and the unreacted quadricyclane is again fed to the catalytic module.

The conservation of the parameters of the photochemical and catalytic processes is experimentally observed for 5 days (about 120 conversion cycles). By-products are also absent in the photochemical and catalytic modules (Table 1).

The data obtained are presented in table 1.

Table 1

The conversion of quadricyclane and the selectivity of the isomerization of quadricyclane to norbornadiene in the presence of a catalyst at various temperatures after 5- and 20-fold use of the catalyst (the reaction was carried out in a mass of quadricyclane for 20 minutes and at 1 atm)

Example 2. (Comparative example)

The process is carried out as in example 1, but in the absence of a distillation column.

Under these conditions, the unreacted sensitizer and norbornadiene enter the catalytic reactor, and the unreacted quadricyclane enters the photochemical reactor. As a result of this, by-products are formed in both modules (norbornadiene dimeters, condensation products of the sensitizer with quadricyclane), and due to the cyclical nature of the process, their significant accumulation occurs, and the efficiency of the technological scheme sharply decreases (Table 2).

The data obtained are shown in table 2.

table 2

The conversion of quadricyclane and the selectivity of the isomerization of quadricyclane to norbornadiene in the presence of a catalyst at various temperatures after 5- and 20-fold use of the catalyst (time 20 minutes, 1 atm, the reaction was carried out in a mass of quadricyclane).

Claims (3)

1. A method for carrying out the process of reversible isomerization of norbornadiene into a quadricycle, characterized in that a distillation column is installed between the photochemical and catalytic modules to organize the continuous flow of the process and ensure the material and heat balance of the flows, which allows efficient separation of components, such as norbornadiene and quadricyclane, and their directing into the appropriate modules, adjusting the cyclic transformations. 2. The method according to p. 1, characterized in that it is allowed to use norbornadiene without prior purification. 3. The method according to p. 1, characterized in that the number of reagents used is reduced in connection with an increase in the selectivity of the processes.

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