Digital saponification kinetic parameter measuring device and use method thereof

Abstract

The invention provides a digital saponification reaction kinetic parameter measuring device and a use method thereof. The digital saponification reaction kinetic parameter measuring device comprises a constant-temperature reaction system, a digital sampling system and a digital automatic acquisition and detection control system, the constant-temperature reaction system comprises a jacketed beaker saponification tank, a polytetrafluoroethylene plug, a magnetic stirrer and a low-temperature constant-temperature tank; the jacketed beaker saponification pool is arranged above the magnetic stirrer; the polytetrafluoroethylene plug is arranged in the jacketed beaker saponification pool; the digital sampling system comprises an injection pump and a communication module; the detection control system comprises a computer and a conductivity meter; the communication module is connected with the injection pump and the computer; the computer is connected with the conductivity meter and the injection pump, and the detection end of the conductivity meter goes deep into the jacketed beaker saponification pool; by applying the technical scheme, remote control can be realized, the contact of drugs is reduced, especially toxic and harmful chemical reagents, and the danger is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of teaching experiments, in particular to a digital saponification reaction kinetic parameter determination device and a use method thereof. Background Art

[0002] At present, most universities use double-tube saponification pipes as saponification tanks, such as Figure 2 As shown, ethyl acetate (CH3COOC2H5) and sodium hydroxide (NaOH) solutions of equal concentration and volume are placed in two tubes of the saponification tank, respectively, and placed in a glass thermostat for constant temperature and then mixed to conduct the saponification reaction experiment. This method is troublesome for students who are doing experiments for the first time, and the start time of the saponification reaction cannot be accurately defined. Usually, the experimental data can only be recorded after 5-6 minutes of reaction, and stirring cannot be performed during the reaction. In particular, the conductivity values ​​measured in the early stage fluctuate greatly, so the experimental data before 10 minutes are often discarded due to poor linearity. For kinetic experiments, the early experimental data are very important but are discarded, and the reliability of the experimental results is very poor. In addition, due to the influence of the glass thermostat, the rate constant at a temperature below room temperature cannot be measured.

[0003] Usually the solution in the textbook requires the preparation of 0.01 mol·L -1 NaOH, 0.02 mol·L -1 NaOH and 0.02 mol·L - 1 CH3COOC2H5 three solutions, first 0.02mol·L -1 The conductivity (denoted as κ) of the NaOH solution and CH3COOC2H5 solution was measured at different times by mixing equal volumes of the solution. t ), and then take 0.01 mol·L -1 The conductivity (denoted as κ0) was measured using NaOH solution, but the experiment was cumbersome and had poor reproducibility. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a digital saponification reaction kinetic parameter determination device and a method of using the same, so as to achieve remote control and reduce the contact with drugs, especially when encountering toxic and harmful chemical reagents, to reduce the danger.

[0005] To achieve the above object, the present invention adopts the following technical scheme: a digital saponification reaction kinetic parameter determination device, comprising a constant temperature reaction system, a digital sampling system and a digital automatic acquisition detection control system; the constant temperature reaction system comprises a jacketed beaker saponification tank, a polytetrafluoroethylene plug, a magnetic stirrer and a low-temperature constant temperature bath; the jacketed beaker saponification tank is arranged above the magnetic stirrer, the jacketed beaker saponification tank has an upper opening and a lower opening, the upper opening is connected to the inlet of the low-temperature constant temperature bath, and the lower opening is connected to the outlet of the low-temperature constant temperature bath; the polytetrafluoroethylene plug is arranged in the jacketed beaker saponification tank; the digital sampling system comprises a syringe pump and a communication module; the detection control system comprises a computer and a conductivity meter; the communication module is connected to the syringe pump and the computer; the computer is connected to the conductivity meter and the syringe pump, and the detection end of the conductivity meter penetrates into the jacketed beaker saponification tank.

[0006] The present invention also provides a method for using a digital saponification reaction kinetic parameter determination device, using the digital saponification reaction kinetic parameter determination device to prepare 0.01 mol·L -1 NaOH solution, take a certain volume of 0.01mol·L -1 The NaOH solution is placed in the jacketed beaker saponification tank, and the computer controls the conductivity meter to start recording data. After constant temperature, the conductivity value read tends to a platform value, which is recorded as κ0. Then, the digital injection system controls the injection pump to quickly inject an equal number of moles of pure CH3COOC2H5 into the NaOH solution. The computer-controlled conductivity meter in the detection and control system simultaneously captures the reaction start signal and continues to read and record the conductivity data of the saponification reaction process, which is recorded as κ t .

[0007] In a preferred embodiment, under the premise of controlling the initial concentrations of ethyl acetate and sodium hydroxide to be the same at a constant temperature, by observing the change in the conductivity of the reaction system, the reaction rate constant can be calculated according to formula (1):

[0008]

[0009] In the formula, c0 represents the initial concentration of the reactant, k0 and k ∞ are the conductivity of the solution at the beginning and the end of the reaction, respectively; κ t is the conductivity of the solution at time t; According to formula (1), is the vertical axis, The linear regression relationship can reflect the characteristics of the secondary reaction, and the slope of the straight line can be used to calculate the rate constant k. On this basis, the reaction rate constants at different temperatures can be measured. right The apparent activation energy E of the reaction is calculated according to formula (2). aand pre-exponential factor (A)

[0010]

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. Use a jacketed beaker instead of a double-tube saponification tube or fork tube as a saponification reactor, use a magnetic stirrer to stir, and mix the solution evenly; use a high and low temperature constant temperature bath instead of an ordinary constant temperature bath, and the measured temperature is not limited by room temperature;

[0013] 2. Use a digital sampling pump sampler to quickly and accurately add an equal amount (trace amount) of pure ethyl acetate to the NaOH solution to avoid the volatilization and contamination of organic reagents. The experiment is simple, the data is accurate, and the reproducibility is very good;

[0014] 3. Use a digital injection pump for micro-precise injection, without the need to prepare ester solution, to avoid volatilization and reduce waste;

[0015] 4. The introduction of an automated data acquisition system can monitor the experiment in real time, quickly record the change in conductivity during the reaction process, monitor the progress of the reaction, and reduce the phenomenon of untimely, wrong, and missed data recording. The introduction of this system makes the device not only suitable for the ethyl acetate system with slow saponification reaction (the half-life of the saponification reaction of ethyl acetate at 25°C is 18 minutes), but also can be used to measure the ethyl formate system with fast saponification reaction speed (for example: the half-life of the saponification reaction of ethyl formate at 25°C is about 10 seconds), and the rate constant measurement value is improved by two orders of magnitude;

[0016] 5. In addition to completing the determination of the rate constant of ethyl acetate in the traditional "determination of the saponification reaction rate constant of ethyl acetate" experiment, this device can also accurately obtain the measurement of apparent activation energy and pre-exponential factor, and can be conveniently used for the exploration of saponification reaction order.

[0017] 6. The device can be used to achieve remote control and reduce the contact with drugs, especially when encountering toxic and harmful chemical reagents, reducing the danger;

[0018] 7. This device can also be used for physical chemistry experiment project --- "surface adsorption experiment in solution" with appropriate modification;

[0019] 8. The sample injection system in this device can be used to prepare the solution, and the amount of solution required can be prepared, reducing the contact with the medicine and the waste of the medicine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of a digital saponification reaction kinetic parameter determination device according to a preferred embodiment of the present invention.

[0021] Figure 2It is a schematic diagram of the structure of a double-tube chemical pipe used in the prior art. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0025] A digital device for determining the kinetic parameters of saponification reactions, referring to Figure 1 , including a constant temperature reaction system, a digital sampling system and a digital automatic acquisition detection control system; the constant temperature reaction system includes a jacketed beaker saponification tank, a polytetrafluoroethylene plug, a magnetic stirrer and a low-temperature constant temperature bath; the jacketed beaker saponification tank is arranged above the magnetic stirrer, and the jacketed beaker saponification tank has an upper opening and a lower opening, the upper opening is connected to the inlet of the low-temperature constant temperature bath, and the lower opening is connected to the outlet of the low-temperature constant temperature bath; the polytetrafluoroethylene plug is arranged in the jacketed beaker saponification tank; the digital sampling system includes a syringe pump and a communication module; the detection control system includes a computer and a conductivity meter; the communication module is connected to the syringe pump and the computer; the computer is connected to the conductivity meter and the syringe pump, and the detection end of the conductivity meter goes deep into the jacketed beaker saponification tank.

[0026] like Figure 1 As shown in the constant temperature reaction system section, a jacketed beaker is used instead of a double-tube saponification tube or a fork tube as a saponification reaction tank, and a magnetic stirrer is used for stirring so that the solution is mixed evenly; a high and low temperature constant temperature bath is used instead of an ordinary constant temperature bath, and the measured temperature is no longer limited to room temperature.

[0027] In the experiment, only 0.01 mol·L -1 NaOH solution, take a certain volume of 0.01mol·L -1The NaOH solution is placed in a jacketed beaker. The computer-controlled conductivity meter in the detection and control system starts recording data. After constant temperature, the conductivity value read tends to a platform value (recorded as κ0). Then, the computer program precisely controls the syringe to quickly inject an equal number of moles of pure CH3COOC2H5 into the NaOH solution through the injection system. The computer-controlled conductivity meter in the detection and control system can simultaneously capture the reaction start signal and continue to read and record the conductivity of the saponification reaction process (recorded as κ t )data.

[0028] Determining the rate constant of the saponification reaction of ethyl acetate by conductivity method is a classic experimental project in the kinetics part of physical chemistry experiments.

[0029] The saponification reaction of ethyl acetate is a secondary reaction. Under the premise of controlling the initial concentrations of ethyl acetate and sodium hydroxide to be the same at a constant temperature, the rate constant of the reaction can be calculated according to the following rate equation (Formula 1) by observing the change in the conductivity of the reaction system.

[0030]

[0031] In the formula, c0 represents the initial concentration of the reactant, κ0 and κ ∞ are the conductivity of the solution at the beginning and the end of the reaction, respectively; κ t is the conductivity of the solution at time t. According to formula (1), is the vertical axis, The linear regression relationship can reflect the characteristics of the secondary reaction, and the slope of the line can be used to calculate the rate constant k. On this basis, by measuring the reaction rate constants at different temperatures, right The apparent activation energy (E a ) and the pre-exponential factor (A).

[0032]

Claims

1. A digital saponification reaction kinetic parameter determination device, characterized in that: It includes a constant temperature reaction system, a digital sampling system and a digital automatic acquisition detection control system; the constant temperature reaction system includes a jacketed beaker saponification tank, a polytetrafluoroethylene plug, a magnetic stirrer and a low-temperature constant temperature tank; the jacketed beaker saponification tank is arranged above the magnetic stirrer, and the jacketed beaker saponification tank has an upper opening and a lower opening, the upper opening is connected to the inlet of the low-temperature constant temperature tank, and the lower opening is connected to the outlet of the low-temperature constant temperature tank; the polytetrafluoroethylene plug is arranged above the jacketed beaker saponification tank; the digital sampling system includes a syringe pump and a communication module; the detection control system includes a computer and a conductivity meter; The communication module is connected to the injection pump and the computer; the computer is connected to the conductivity meter and the injection pump, and the detection end of the conductivity meter is deeply inserted into the jacketed beaker saponification tank.

2. A method for using a digital saponification reaction kinetic parameter determination device, characterized in that: The digital saponification reaction kinetic parameter determination device according to claim 1 was used to prepare 0.01 mol·L -1 NaOH solution, take a certain volume of 0.01mol·L -1 The NaOH solution is placed in the jacketed beaker saponification tank, and the computer controls the conductivity meter to start recording data. After constant temperature, the conductivity value read tends to a platform value, which is recorded as κ0. Then, the digital injection system controls the injection pump to quickly inject an equal number of moles of pure CH3COOC2H5 into the NaOH solution. The computer-controlled conductivity meter in the detection and control system simultaneously captures the reaction start signal and continues to read and record the conductivity data of the saponification reaction process, which is recorded as κ t .

3. The method for using a digital saponification reaction kinetic parameter determination device according to claim 2, characterized in that: Under the premise of keeping the initial concentrations of ethyl acetate and sodium hydroxide the same at a constant temperature, by observing the change in the conductivity of the reaction system, the reaction rate constant ref can be calculated according to formula (1): In the formula, c0 represents the initial concentration of the reactant, κ0 and κ ∞ are the conductivity of the solution at the beginning and the end of the reaction, respectively; κ t is the conductivity of the solution at time t; According to formula (1), is the vertical axis, The linear regression relationship can reflect the characteristics of the secondary reaction, and the slope of the straight line can be used to calculate the rate constant k. On this basis, the reaction rate constants at different temperatures can be measured. right The apparent activation energy (E a ) and pre-exponential factor (A)

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