阅读说明：本技术 一种电化学原位自由基在线检测装置 (Electrochemical in-situ free radical on-line detection device ) 是由 汪一 邓伟 熊哲 汪雪棚 陈元静 向军 胡松 苏胜 江龙 徐俊 于 2020-11-30 设计创作，主要内容包括：本发明属于有机电化学合成中的自由基检测领域,公开了一种电化学原位自由基在线检测装置,该检测装置用于配合电子自旋共振波谱仪(ESR)使用,包括管式反应器(1)、工作电极(2)、辅助电极(3)及参比电极(4),其中,管式反应器(1)用于容纳待测溶液；工作电极(2)、辅助电极(3)及参比电极(4)均用于与管式反应器(1)内容纳的待测溶液相接触,能够构成三电极体系,向待测溶液提供电能使待测溶液发生电化学反应。本发明通过对装置细节组件的构成及它们的配合工作方式等进行改进,与现有技术相比能够有效解决自由基寿命短、难以准确测定的问题,可实现有机电化学合成过程中的自由基的原位在线检测。(The invention belongs to the field of free radical detection in organic electrochemical synthesis, and discloses an electrochemical in-situ free radical online detection device, which is used for being matched with an electron spin resonance spectrometer (ESR) for use and comprises a tubular reactor (1), a working electrode (2), an auxiliary electrode (3) and a reference electrode (4), wherein the tubular reactor (1) is used for containing a solution to be detected; the working electrode (2), the auxiliary electrode (3) and the reference electrode (4) are all used for being in contact with a solution to be detected contained in the tubular reactor (1), a three-electrode system can be formed, and electric energy is provided for the solution to be detected to enable the solution to be detected to generate electrochemical reaction. By improving the structure of the detail components of the device, the matching working mode of the detail components and the like, compared with the prior art, the invention can effectively solve the problems of short service life of free radicals and difficult accurate determination, and can realize the in-situ on-line detection of the free radicals in the organic electrochemical synthesis process.)

1. An electrochemical in-situ free radical on-line detection device, which is used for matching with an electron spin resonance spectrometer (ESR), is characterized by comprising a tubular reactor (1), a working electrode (2), an auxiliary electrode (3) and a reference electrode (4), wherein,

the tubular reactor (1) is used for containing a solution to be tested, and when electrochemical in-situ free radical online detection is carried out, the tubular reactor (1) is placed in a testing chamber of an electron spin resonance spectrometer (ESR);

the working electrode (2), the auxiliary electrode (3) and the reference electrode (4) are all used for being in contact with the solution to be detected contained in the tubular reactor (1), a three-electrode system can be formed, and electric energy is provided for the solution to be detected to enable the solution to be detected to generate electrochemical reaction; wherein, when electrochemical in-situ free radical on-line detection is carried out, the tail end of the working electrode (2) is used for being placed in an electron spin resonance spectrometer (ESR) effective test area.

2. The electrochemical in-situ free radical on-line detection device as claimed in claim 1, further comprising a circulating liquid sleeve (8) and a thermocouple (12), wherein the circulating liquid sleeve (8) is located outside the tubular reactor (1) and is integrally formed with the tubular reactor (1), and the circulating liquid sleeve (8) is used as a flow passage for cooling circulating liquid or heating circulating liquid; the thermocouple (12) is used for being inserted into a solution to be tested in the tubular reactor (1) to monitor the temperature of the solution to be tested;

the circulating liquid sleeve (8) and the thermocouple (12) also form a temperature control unit together with a heating module and a refrigerating module, and when electrochemical in-situ free radical online detection is carried out, an ESR effective test area of an electron spin resonance spectrometer (ESR) can be cooled or heated through cooling circulating liquid or heating circulating liquid provided by the refrigerating module or the heating module, so that electrochemical free radical in-situ detection at different temperatures is realized;

preferably, the circulating liquid adopted by the heating circulating liquid is water; the circulating liquid adopted by the cooling circulating liquid is an alcohol solvent, and ethanol is more preferable.

3. The electrochemical in-situ free radical on-line detection device as claimed in claim 1, wherein the tubular reactor (1) is made of quartz material;

preferably, the tubular reactor (1) is a quartz tube with an inner diameter not greater than 2mm and openings at the upper end and the lower end; the upper end of the quartz tube is tightly connected with the upper end cover (5), and the lower end of the quartz tube is tightly connected with the lower end cover (6);

or the tubular reactor (1) is a quartz tube with a closed lower end and an open upper end, the upper end of the quartz tube is tightly connected with the upper end cover (5), and the inner diameter of the lower end is not more than 2 mm.

4. The electrochemical in-situ free radical online detection device according to claim 1, wherein the upper end cap (5) is further provided with a vent hole for balancing internal and external air pressures of the tubular reactor (1).

5. The electrochemical in-situ free radical on-line detection device as claimed in claim 1, wherein the inner side of the lower end cap (6) is further provided with a sealing gasket (9).

6. The electrochemical in-situ free radical online detection device according to claim 1, wherein the upper end cap (5) and the lower end cap (6) are made of polytetrafluoroethylene.

7. The electrochemical in-situ free radical on-line detection device as claimed in claim 1, wherein the outer wall of the tubular reactor (1) is further provided with scale marks.

8. The electrochemical in-situ free radical online detection device according to claim 1, wherein the working electrode (2) is a wire metal electrode or a wire carbon-based electrode; the auxiliary electrode (3) is a wire-shaped metal electrode or a wire-shaped carbon-based electrode, the tail end of the auxiliary electrode (3) is spiral, and the tail end of the working electrode (2) penetrates through the spiral area of the auxiliary electrode (3);

the reference electrode (4) is a filiform silver electrode.

9. The electrochemical in-situ free radical online detection device according to claim 1, further comprising a positioning sleeve (7), wherein the positioning sleeve (7) is used to be nested outside the tubular reactor (1), and can fix the tubular reactor (1) and position the relative positions of the tubular reactor (1) and the ESR effective test area of the electron spin resonance spectrometer (ESR).

Technical Field

The invention belongs to the field of free radical detection in organic electrochemical synthesis, and particularly relates to an electrochemical in-situ free radical online detection device.

Background

The organic electrochemical synthesis method can quickly and accurately regulate and control the reaction process and the product selectivity through the change of potential and current, the process is easy to control, the efficiency is high, and more attention and application are paid in the fields of fine chemical engineering, drug synthesis, agricultural chemistry, material preparation and other related fields in recent years. Free radicals play an important role in organic electrochemical reactions as active intermediates. Free radicals participate in the processes of coupling, substitution, oxidation reduction, addition polymerization, cyclization and fragmentation in organic electrochemical synthesis. Therefore, it is very important to detect free radicals in the organic electrochemical synthesis process. The data related to the change of free radicals in the electrochemical synthesis conversion process is directly obtained through free radical test analysis, the influence of the free radicals on the distribution of the electrochemical synthesis products is researched, and the reaction mechanism of the organic electrochemical synthesis process can be more comprehensively understood. The common free radical measuring method is to treat the sample to be measured with specific free radical trapping agent and to measure in an electron spin resonance spectrometer (ESR). However, the free radicals are extremely active reaction intermediates, have short life span and can only exist instantaneously, and the traditional method cannot accurately measure the instantaneous free radical concentration in the reaction process. The development of an in-situ detection method for realizing the on-line detection of free radicals in the organic electrochemical synthesis process is urgently needed.

Disclosure of Invention

In view of the above defects or improvement needs of the prior art, an object of the present invention is to provide an electrochemical in-situ radical on-line detection device, wherein by improving the structure of the device detail components and their cooperating working modes, the problems of short lifetime and difficulty in accurate determination of radicals can be effectively solved, and the in-situ on-line detection of radicals in the organic electrochemical synthesis process can be realized.

In order to achieve the above object, according to the present invention, there is provided an electrochemical in-situ free radical on-line detection device for use with an electron spin resonance spectrometer (ESR), comprising a tubular reactor (1), a working electrode (2), an auxiliary electrode (3), and a reference electrode (4), wherein,

the tubular reactor (1) is used for containing a solution to be tested, and when electrochemical in-situ free radical online detection is carried out, the tubular reactor (1) is placed in a testing chamber of an electron spin resonance spectrometer (ESR);

the working electrode (2), the auxiliary electrode (3) and the reference electrode (4) are all used for being in contact with the solution to be detected contained in the tubular reactor (1), a three-electrode system can be formed, and electric energy is provided for the solution to be detected to enable the solution to be detected to generate electrochemical reaction; wherein, when electrochemical in-situ free radical on-line detection is carried out, the tail end of the working electrode (2) is used for being placed in an electron spin resonance spectrometer (ESR) effective test area.

As a further preferred of the present invention, the detection device further comprises a circulating liquid sleeve (8) and a thermocouple (12), wherein the circulating liquid sleeve (8) is located outside the tubular reactor (1) and is integrally formed with the tubular reactor (1), and the circulating liquid sleeve (8) is used as a flow passage for cooling circulating liquid or heating circulating liquid; the thermocouple (12) is used for being inserted into a solution to be tested in the tubular reactor (1) to monitor the temperature of the solution to be tested;

the circulating liquid sleeve (8) and the thermocouple (12) also form a temperature control unit together with a heating module and a refrigerating module, and when electrochemical in-situ free radical online detection is carried out, an ESR effective test area of an electron spin resonance spectrometer (ESR) can be cooled or heated through cooling circulating liquid or heating circulating liquid provided by the refrigerating module or the heating module, so that electrochemical free radical in-situ detection at different temperatures is realized;

preferably, the circulating liquid adopted by the heating circulating liquid is water; the circulating liquid adopted by the cooling circulating liquid is an alcohol solvent, and ethanol is more preferable.

As a further preference of the present invention, the tubular reactor (1) is made of quartz material;

preferably, the tubular reactor (1) is a quartz tube with an inner diameter not greater than 2mm and openings at the upper end and the lower end; the upper end of the quartz tube is tightly connected with the upper end cover (5), and the lower end of the quartz tube is tightly connected with the lower end cover (6);

or the tubular reactor (1) is a quartz tube with a closed lower end and an open upper end, the upper end of the quartz tube is tightly connected with the upper end cover (5), and the inner diameter of the lower end is not more than 2 mm.

As a further optimization of the invention, the upper end cover (5) is also provided with a vent hole for balancing the internal and external air pressure of the tubular reactor (1).

As a further preferable mode of the invention, the inner side of the lower end cover (6) is also provided with a sealing gasket (9).

In a further preferred embodiment of the present invention, the upper end cap (5) and the lower end cap (6) are made of polytetrafluoroethylene.

As a further preferred aspect of the present invention, the outer wall of the tubular reactor (1) is further provided with scale marks.

As a further preference of the present invention, the working electrode (2) is a wire-shaped metal electrode or a wire-shaped carbon-based electrode; the auxiliary electrode (3) is a wire-shaped metal electrode or a wire-shaped carbon-based electrode, the tail end of the auxiliary electrode (3) is spiral, and the tail end of the working electrode (2) penetrates through the spiral area of the auxiliary electrode (3);

the reference electrode (4) is a filiform silver electrode.

As a further preferred aspect of the present invention, the detection apparatus further comprises a positioning sleeve (7), the positioning sleeve (7) is used to be nested outside the tubular reactor (1), and can fix the tubular reactor (1) and position the relative positions of the tubular reactor (1) and the ESR effective test area of the electron spin resonance spectrometer (ESR).

Through the technical scheme, compared with the prior art, the invention can obtain the following technical effects:

(1) the electrochemical in-situ free radical online detection device disclosed by the invention is compact in structure, can be placed in an ESR (equivalent series resistance) test cavity, and can realize in-situ online detection of free radicals while an electrochemical reaction is carried out. Mainly considering that free radicals are extremely active reaction intermediates, have short service life and can only exist instantaneously, the traditional method cannot accurately determine the instantaneous free radical concentration in the reaction process, and the content of the free radicals can only be accurately determined by an in-situ detection method.

(2) The tubular reactor may be of a variable diameter design, with the inner diameter of the target region preferably no greater than 2mm for placement in an electron spin resonance spectrometer (ESR) test chamber. Considering that most of liquids have the capacity of attenuating microwave power, the pipe diameter of a reactor for filling the liquid to be tested is not suitable to be too large, otherwise microwave coupling cannot be completed or is unstable, and free radical detection is influenced;

(3) the tubular reactor is preferably made of quartz, and the quartz component is mainly considered to be single (the main component is SiO)₂) The method has the advantages of low impurity content and stable physical and chemical properties, and can not generate too high impurity free radical signals to interfere the determination of the content of free radicals in the liquid to be tested in the ESR free radical testing process.

(4) The auxiliary electrode can be preferably a wire-shaped metal or carbon-based electrode, and the tail end of the auxiliary electrode can particularly adopt a spiral form, so that the working electrode is conveniently placed in the center of the spiral structure of the auxiliary electrode to form a stable electric field in a narrow reactor, the surface area of the auxiliary electrode can be increased, the polarization degree of the auxiliary electrode is reduced, and the detection accuracy is improved;

(5) the invention is also preferably provided with a temperature control unit which comprises a circulating liquid sleeve, a thermocouple, a heating module and a cooling module; considering that the temperature is continuously increased in the electrochemical reaction process and the temperature change has obvious influence on the content of free radicals, the temperature control unit can maintain the temperature of the liquid to be detected in the tubular reactor to be stable under any temperature condition within the range of 0-95 ℃, so that the electrochemical free radical in-situ detection within the temperature range of 0-95 ℃ can be realized.

(6) The electrochemical in-situ free radical online detection device disclosed by the invention is simple in structure, convenient to assemble and disassemble and easy to clean.

Drawings

FIG. 1 is a schematic structural diagram of an electrochemical in-situ free radical on-line detection device according to the present invention.

FIG. 2 shows the results of the electrochemical in-situ free radical on-line detection in example 1 of the present invention.

FIG. 3 shows the results of the on-line detection of the electrochemical in-situ free radicals in example 2 of the present invention.

FIG. 4 is a schematic structural diagram of an electrochemical in-situ free radical on-line detection device in embodiment 3 of the present invention.

FIG. 5 is a schematic view of a positioning sleeve according to the present invention; fig. 5 (a) corresponds to a front view, and fig. 5 (b) corresponds to a three-dimensional perspective view.

FIG. 6 is a logic flow diagram of a temperature control unit in accordance with the present invention.

The meanings of the attached symbols in the drawings are as follows: the device comprises a tubular reactor (namely, a reaction tube) 1, a working electrode 2, an auxiliary electrode 3, a reference electrode 4, an upper end cover 5, a lower end cover 6, a positioning clamping sleeve 7, a circulating liquid sleeve 8, a sealing washer 9, a circulating liquid inlet 10, a circulating liquid outlet 11 and a thermocouple 12.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

In general, the electrochemical in-situ free radical online detection device of the present invention is used in cooperation with an electron spin resonance spectrometer (ESR), as shown in fig. 1, and mainly comprises a tubular reactor 1, a working electrode 2, an auxiliary electrode 3, and a reference electrode 4; it is also preferable to provide: the device comprises an upper end cover 5, a lower end cover 6, a positioning clamping sleeve 7, a circulating liquid sleeve 8 and a sealing gasket 9.

Specifically, tubular reactor can be for the internal diameter be not more than 2mm, both ends open-ended quartz capsule, and external diameter and length are confirmed according to the test chamber size of ESR, and tubular reactor both ends outer wall adopts dull polish technology to handle, and the suit upper end cover of being convenient for, bottom end cover guarantee that the reactor is sealed. The outer wall of the upper end of the tubular reactor can be provided with scale marks, so that the reactants can be conveniently and quantitatively filled, and the accuracy of measuring the free radicals can be ensured.

A circulating liquid sleeve 8 and a thermocouple 12, wherein the circulating liquid sleeve 8 is positioned outside the tubular reactor 1 and is integrated with the tubular reactor 1, and the thermocouple 12 is used for being inserted into the solution in the tubular reactor. Furthermore, the circulating liquid sleeve 8, the thermocouple 12, the heating module and the refrigeration module form a temperature control unit, a logic flow schematic diagram of the temperature control unit is shown in fig. 6, when electrochemical in-situ free radical online detection is performed, a cooling circulating liquid (or a heating circulating liquid; the cooling circulating liquid can adopt alcohol solvents such as ethanol, and the heating circulating liquid can adopt water) provided by the cooling module or the heating module is used for cooling (or heating) an ESR effective test area of an electron spin resonance spectrometer (ESR), the temperature of the liquid to be detected in the tubular reactor can be kept stable under any temperature condition within a range of 0-95 ℃, and electrochemical free radical in-situ level detection within the range of 0-95 ℃ can be realized.

The working electrode is a wire metal or carbon-based electrode, can penetrate through the central position of the upper end cover along the axial direction of the upper end cover and is processed into a whole with the upper end cover through an injection molding process.

The auxiliary electrode is a wire-shaped metal or carbon-based electrode, and the auxiliary electrode can penetrate along the axial direction of the upper end cover along the inner wall surface of the tubular reactor and is processed into a whole with the upper end cover through an injection molding process. The tail end of the auxiliary electrode is spiral. The working electrode tip passes through the auxiliary electrode helical region.

The reference electrode is a filiform silver electrode, can penetrate through the central position of the lower end cover along the axial direction of the lower end cover and is processed into a whole with the lower end cover through an injection molding process.

The upper end cover and the lower end cover can be respectively processed into a whole with the working electrode, the auxiliary electrode and the reference working electrode through an injection molding process, the functions of the upper end cover and the lower end cover are that the working electrode, the auxiliary electrode and the reference working electrode are fixed and the tubular reactor is sealed, and the side surface of the upper end cover can be provided with a vent hole so as to facilitate the discharge of gas generated in the reaction process. The inner side of the lower end cover is provided with a sealing gasket. The upper end cover and the lower end cover can be made of polytetrafluoroethylene materials.

The electrode joints outside the upper end cover and the lower end cover can be wrapped by copper columns, so that wiring is facilitated.

The positioning clamping sleeve is used for fixing and positioning the tubular reactor. The positioning clamping sleeve can be made of polytetrafluoroethylene materials and is sleeved on the outer wall of the tubular reactor, and the tubular reactor can be clamped tightly. The locating cutting sleeve can be an oval arc surface at the outer side, can be embedded into an entrance of an ESR testing chamber, and can be used for adjusting the position of the locating cutting sleeve to enable the liquid to be tested to be located in an effective ESR testing area in the tubular reactor.

The electrochemical in-situ free radical on-line detection device can be assembled and used for on-line detection of free radicals according to the following steps:

(1) sleeving the reference electrode and the lower end cover into the lower port of the tubular reactor, and ensuring that the reference electrode is positioned at the central position of the tubular reactor as much as possible;

(2) dripping the liquid to be detected from the upper end of the tubular reactor, and adding the liquid level to the graduation line of the upper port;

(3) and sleeving the working electrode, the auxiliary electrode and the upper end cover into the upper port of the tubular reactor, ensuring that the spiral tail end of the auxiliary electrode is positioned around the working electrode, and ensuring that the tail end of the working electrode is 1cm away from the tail end of the reference electrode, so that the working electrode, the auxiliary electrode and the reference electrode are not contacted with each other.

(4) Sleeving a positioning clamping sleeve on the outer wall of the tubular reactor, placing the tubular reactor in an ESR (equivalent series resistance) testing cavity, and adjusting the positioning clamping sleeve to ensure that the part to be tested of the liquid is positioned in an effective ESR testing area;

(5) and after the electrode is connected, carrying out electrochemical in-situ free radical online detection.

The following are specific examples:

example 1

(a) Assembling the detection device according to the method provided by the invention, wherein the working electrode and the auxiliary electrode are made of platinum metal;

(b) adding a straw pyrolysis oil methanol solution into a reaction tube of a detection device, wherein the quality concentration of the pyrolysis oil is 5%, placing the detection device in an ESR detection cavity, fixing and connecting wires;

(c) electrolyzing the pyrolysis oil solution under the condition of constant current of 100mA for 1h, and simultaneously carrying out in-situ on-line detection on the free radicals every 10min, wherein the result is shown in figure 2, and the concentration of the free radicals in the pyrolysis oil is continuously increased along with the increase of the electrochemical reaction time.

Example 2

(a) Assembling the detection device according to the method provided by the invention, wherein the working electrode and the auxiliary electrode are made of platinum metal;

(b) adding a straw pyrolysis oil methanol solution into a reaction tube of a detection device, wherein the quality concentration of the pyrolysis oil is 5%, placing the detection device in an ESR detection cavity, fixing and connecting wires;

(c) the pyrolysis oil solution is electrolyzed under the conditions of constant current of 100mA and 150mA respectively, and meanwhile, the in-situ online detection of the free radicals is carried out, and the result is shown in figure 3, wherein the concentration of the free radicals in the pyrolysis oil increases along with the increase of the current.

Example 3

The tubular reactor in the electrochemical in-situ free radical detection device proposed by the present invention can be deformed into the form shown in fig. 4. The tubular reactor 1 can be divided into an upper half and a lower half, the upper end of the tubular reactor is open, and the lower end of the tubular reactor is closed. The upper half part is a quartz tube with the inner diameter of 5mm, a working electrode 2, an auxiliary electrode 3 and a reference electrode 4 are arranged from an opening at the upper end, and the three electrodes and an upper end cover 5 are integrated. The lower half part is a quartz tube with the inner diameter not more than 2mm, and the lower end is a free radical test area. The tail end of the auxiliary electrode is spiral, and the working electrode and the reference electrode penetrate through the middle of the spiral tail end of the auxiliary electrode. A positioning clamping sleeve 7 is arranged for fixing and positioning the tubular reactor. The circulating liquid casing pipe 8 is positioned on the outer wall surface of the tubular reactor and is integrated with the tubular reactor.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.