Catechol violet oily acid-base indicator for judging reaction endpoint of silicone oil

Abstract

The invention provides a catechol violet oily acid-base indicator for judging the reaction endpoint of silicone oil. The invention discloses a yellow color in an acidic environment and a red purple color in an alkaline environment, and the color range is that the pH value is 1.5-7, the color range is yellow, the pH value is 7-9, and the color range is red purple, and the pH value is 9-11. The oily acid-base indicator has important application value in chemical production, catechol violet is used as a raw material, an ethanol-acetone-aqueous solution is used as a solvent, the silicone oil acid-base indicator is successfully synthesized, and the silicone oil acid-base indicator has the advantages of being simple in preparation, clear in color development, sensitive in color change and good in indication performance and has very good practical performance.

Description

Technical Field

[0001] The invention relates to the preparation and application fields of oily acid-base indicators, and in particular to a catechol violet oily acid-base indicator for judging the end point of a silicone oil reaction. Background Art

[0002] In the field of chemical production, acid-base indicators are important chemical reagents used to detect and control the pH value of chemical reactions. Due to structural changes, their molecules and ions have different colors, and therefore present different colors in solutions with different pH values. These indicators undergo obvious color changes within a certain pH range, making it easy to judge the extent of the reaction and the end point of the reaction. In the production of silicone oil, potassium hydroxide is a commonly used catalyst. When the reaction reaches the end point, phosphoric acid needs to be used for neutralization to terminate the reaction and adjust the pH value of the product. This process usually needs to be achieved by monitoring the pH value of the reaction mixture in order to accurately control the progress of the reaction.

[0003] Existing acid-base indicators are widely used in water-based systems, and usually acidic or basic dyes such as phenolphthalein, methyl orange, and bromocresol green are used as acid-base indicators. However, such acid-base indicators in water-based systems are difficult to apply to oily systems. They are not very sensitive in oily solutions, and do not change color in silicone oil or require a long time to observe obvious color changes. This affects the efficiency of judging the reaction endpoint to a certain extent, and has a serious impact on production.

[0004] The color change range of existing acid-base indicators is relatively narrow, and they can only show color changes within a specific acid-base range. For the special environment of silicone oil production, existing acid-base indicators may not meet the needs. Existing acid-base indicators may interfere with the reaction system during use. Some indicators may react chemically with the reactants, or affect the physical properties of the reactants, thereby affecting the progress and results of the reaction. Existing acid-base indicators also have problems with post-use treatment and environmental protection. Some indicators may pollute the environment or are difficult to recycle and reuse.

[0005] Oily acid-base indicators have important application value in chemical production. This application uses catechol violet as raw material and ethanol-acetone-water solution as solvent to successfully synthesize a silicone oil acid-base indicator, which has the advantages of simple preparation, clear color development, sensitive color change, and good indication performance, and has good practicality. Summary of the invention

[0006] The invention provides a catechol violet oily acid-base indicator for judging the end point of a silicone oil reaction. The indicator is prepared by dissolving a catechol violet solid in an ethanol-acetone-water three-phase system.

[0007] The catechol violet oily acid-base indicator comprises the following raw materials by weight: 20-75 parts of ethanol, 10-40 parts of acetone, 5-30 parts of deionized water, 0.1-1.0 parts of catechol violet, and 0.1-0.2 parts of a water retaining agent.

[0008] The ethanol has a purity of ≥99%, and the impurities of methanol and isopropanol are ≤0.1%; the acetone has a purity of ≥99.5%; and the deionized water has soluble impurities of ≤0.1%.

[0009] The catechol violet has a purity of ≥95% and a soluble impurity content of ≤1.5%.

[0010] The water retaining agent is dimethyl silicone oil with a viscosity of 5 to 50 cp.

[0011] The acid-base indicator is yellow in an acidic environment and red-purple in an alkaline environment, and the color characteristics are yellow at pH values ​​of 1.5 to 7, purple at pH values ​​of 7 to 9, and red-purple at pH values ​​of 9 to 11.

[0012] The present invention also provides a method for preparing a catechol violet oily acid-base indicator, the steps of which are as follows: S1: Weigh the formulated amount of ethanol, acetone and deionized water to prepare a mixed solution; S2: Weigh the formulated amount of catechol violet and dissolve it in a mixed solution of ethanol-acetone-deionized water; S3: Add an appropriate amount of water retaining agent to the solution obtained in S2, mix well, and obtain catechol violet oily acid-base indicator.

[0013] The application of catechol violet oily acid-base indicator is used to determine the end point of silicone oil reaction.

[0014] The method of use is: add the catechol violet oily acid-base indicator dropwise into the silicone oil reaction system, stir evenly, let stand for 0.5 to 3 minutes to observe the color, and judge the reaction endpoint according to the color change; The mass ratio of the indicator to the silicone oil reaction system material is 1:1000; the indicator is yellow when the pH value is 1.5-7, purple when the pH value is 7-9, and red-purple when the pH value is 9-11.

[0015] The beneficial effects of the present invention are as follows: 1. The present invention uses catechol violet as a basic raw material, and the application of the indicator prepared in the silicone oil synthesis process can quickly and effectively determine the reaction endpoint, thereby improving production efficiency and also improving product quality and output.

[0016] 2. The indicator prepared by the present invention has a wider color change range and can undergo obvious color changes in a wider pH value range, thereby more accurately controlling the reaction endpoint and reducing errors.

[0017] 3. The novel acid-base indicator of the present invention does not interfere with the reaction system during use and does not chemically react with the reactants, thereby not affecting the results of the reaction, thereby ensuring the stability and reliability of the reaction.

[0018] 4. The novel acid-base indicator of the present invention is easy to recycle and reuse after use, which greatly reduces production costs and environmental pressure and conforms to the development trend of green chemistry.

[0019] 5. The new acid-base indicator has a simple production process, low energy consumption, performance and price advantages, and has broad application prospects. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the examples. However, these examples shall not be interpreted as limiting the scope of protection of the present invention. The experimental methods in the following examples without specifying specific conditions are selected according to conventional methods and conditions, or according to the instructions for use of the products.

[0021] The ethanol in the embodiment of the present application is anhydrous ethanol produced by Xilong Science Co., Ltd., the acetone is acetone produced by Xilong Science Co., Ltd., the deionized water is homemade by a laboratory water purifier, the catechol purple is catechol purple produced by Shanghai MacLean Biochemical Technology Co., Ltd., and the water retaining agent is 10cp dimethyl silicone oil produced by Yichang Kelin Silicon Materials Co., Ltd.

[0022] The preparation method of the catechol violet oily acid-base indicator comprises the following steps: weighing a formula amount of ethanol, acetone and deionized water to prepare a mixed solution of a certain concentration, weighing a certain amount of catechol violet to dissolve it in an ethanol-acetone-deionized water mixed solution, adding a proper amount of a water retaining agent to the mixed solution, and mixing the mixed solution uniformly to obtain the acid-base indicator.

[0023] Example 1 Step 1: Prepare a new type of oily acid-base indicator. The proportion of each raw material component is 62 parts of ethanol, 16 parts of acetone, 21.62 parts of deionized water, 0.23 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of each component above, stir them evenly with a glass rod in a beaker, and then divide them into reagent bottles to prepare acid-base indicator 1, which is stored in a dry and closed environment. The indicator does not interfere with the reaction system during use and does not affect the reaction results.

[0024] Step 2: In the process of synthesizing silicone oil, potassium hydroxide is used as a catalyst. The experimental method is to add 3L of octamethylcyclotetrasiloxane and a certain amount of end-capping agent to a 5L flask, add 3ml of a new oily acid-base indicator to the flask, stir for 10 minutes to evenly disperse the acid-base indicator, add 0.1-0.2g of potassium hydroxide to the silicone oil containing the acid-base indicator, set the reaction temperature to 120-140℃, the reaction time to 5 hours, and the reaction pressure to 1.0MPa to allow potassium hydroxide to fully react with the silicone oil. When the polymerization reaction is completed, add 0.1-0.2g of phosphoric acid to the reacted silicone oil to neutralize the potassium hydroxide, and the reaction time is 1 hour.

[0025] Step 3: After the neutralization reaction is completed, observe the color change. When the solution changes from red-purple to yellow, it means that the reaction has reached the end point and the reaction can be stopped.

[0026] Through the above steps, the novel oily acid-base indicator can be used to quickly and effectively determine the reaction endpoint during the silicone oil synthesis process, thereby accurately controlling the reaction progress and improving the reaction efficiency.

[0027] Example 2 Step 1: Prepare a new type of oily acid-base indicator. The proportion of each raw material component is 50 parts of ethanol, 28 parts of acetone, 21.62 parts of deionized water, 0.23 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of each component above, stir them evenly with a glass rod in a beaker, and then divide them into reagent bottles to prepare acid-base indicator 1, which is stored in a dry and closed environment. The indicator does not interfere with the reaction system during use and does not affect the reaction results.

[0028] Step 2: In the process of synthesizing silicone oil, potassium hydroxide is used as a catalyst. The experimental method is to add 3L of octamethylcyclotetrasiloxane and a certain amount of end-capping agent to a 5L flask, add 3ml of a new oily acid-base indicator to the flask, stir for 10 minutes to evenly disperse the acid-base indicator, add 0.1-0.2g of potassium hydroxide to the silicone oil containing the acid-base indicator, set the reaction temperature to 120-140℃, the reaction time to 5 hours, and the reaction pressure to 1.0MPa to allow potassium hydroxide to fully react with the silicone oil. When the polymerization reaction is completed, add 0.1-0.2g of phosphoric acid to the reacted silicone oil to neutralize the potassium hydroxide, and the reaction time is 1 hour.

[0029] Step 3: After the neutralization reaction is completed, observe the color change. When the solution changes from red-purple to yellow, it means that the reaction has reached the end point and the reaction can be stopped.

[0030] Through the above steps, the novel oily acid-base indicator can be used to quickly and effectively determine the reaction endpoint during the silicone oil synthesis process, thereby accurately controlling the reaction progress and improving the reaction efficiency.

[0031] Example 3 Step 1: Prepare a new type of oily acid-base indicator. The proportion of each raw material component is 73 parts of ethanol, 21 parts of acetone, 5.62 parts of deionized water, 0.23 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of each component above, stir them evenly with a glass rod in a beaker, and then divide them into reagent bottles to prepare acid-base indicator 1, which is stored in a dry and closed environment. The indicator does not interfere with the reaction system during use and does not affect the reaction results.

[0032] Step 2: In the process of synthesizing silicone oil, potassium hydroxide is used as a catalyst. The experimental method is to add 3L of octamethylcyclotetrasiloxane and a certain amount of end-capping agent to a 5L flask, add 3ml of a new oily acid-base indicator to the flask, stir for 10 minutes to evenly disperse the acid-base indicator, add 0.1-0.2g of potassium hydroxide to the silicone oil containing the acid-base indicator, set the reaction temperature to 120-140℃, the reaction time to 5 hours, and the reaction pressure to 1.0MPa to allow potassium hydroxide to fully react with the silicone oil. When the polymerization reaction is completed, add 0.1-0.2g of phosphoric acid to the reacted silicone oil to neutralize the potassium hydroxide, and the reaction time is 1 hour.

[0033] Step 3: After the neutralization reaction is completed, observe the color change. When the solution changes from red-purple to yellow, it means that the reaction has reached the end point and the reaction can be stopped.

[0034] Through the above steps, the novel oily acid-base indicator can be used to quickly and effectively determine the reaction endpoint during the silicone oil synthesis process, thereby accurately controlling the reaction progress and improving the reaction efficiency.

[0035] Example 4 Step 1: Prepare a new type of oily acid-base indicator. The proportion of each raw material component is 65 parts of ethanol, 15 parts of acetone, 19.70 parts of deionized water, 0.15 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of each component above, stir them evenly with a glass rod in a beaker, and then divide them into reagent bottles to prepare acid-base indicator 1, which is stored in a dry and closed environment. The indicator does not interfere with the reaction system during use and does not affect the reaction results.

[0036] Step 2: In the process of synthesizing silicone oil, potassium hydroxide is used as a catalyst. The experimental method is to add 3L of octamethylcyclotetrasiloxane and a certain amount of end-capping agent to a 5L flask, add 3ml of a new oily acid-base indicator to the flask, stir for 10 minutes to evenly disperse the acid-base indicator, add 0.1-0.2g of potassium hydroxide to the silicone oil containing the acid-base indicator, set the reaction temperature to 120-140℃, the reaction time to 5 hours, and the reaction pressure to 1.0MPa to allow potassium hydroxide to fully react with the silicone oil. When the polymerization reaction is completed, add 0.1-0.2g of phosphoric acid to the reacted silicone oil to neutralize the potassium hydroxide, and the reaction time is 1 hour.

[0037] Step 3: After the neutralization reaction is completed, observe the color change. When the solution changes from red-purple to yellow, it means that the reaction has reached the end point and the reaction can be stopped.

[0038] Through the above steps, the novel oily acid-base indicator can be used to quickly and effectively determine the reaction endpoint during the silicone oil synthesis process, thereby accurately controlling the reaction progress and improving the reaction efficiency.

[0039] Example 5 Step 1: Prepare a new type of oily acid-base indicator. The proportion of each raw material component is 45 parts of ethanol, 32 parts of acetone, 22.55 parts of deionized water, 0.3 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of each component above, stir them evenly with a glass rod in a beaker, and then divide them into reagent bottles to prepare acid-base indicator 1, which is stored in a dry and closed environment. The indicator does not interfere with the reaction system during use and does not affect the reaction results.

[0040] Step 2: In the process of synthesizing silicone oil, potassium hydroxide is used as a catalyst. The experimental method is to add 3L of octamethylcyclotetrasiloxane and a certain amount of end-capping agent to a 5L flask, add 3ml of a new oily acid-base indicator to the flask, stir for 10 minutes to evenly disperse the acid-base indicator, add 0.1-0.2g of potassium hydroxide to the silicone oil containing the acid-base indicator, set the reaction temperature to 120-140℃, the reaction time to 5 hours, and the reaction pressure to 1.0MPa to allow potassium hydroxide to fully react with the silicone oil. When the polymerization reaction is completed, add 0.1-0.2g of phosphoric acid to the reacted silicone oil to neutralize the potassium hydroxide, and the reaction time is 1 hour.

[0041] Step 3: After the neutralization reaction is completed, observe the color change. When the solution changes from red-purple to yellow, it means that the reaction has reached the end point and the reaction can be stopped.

[0042] Through the above steps, the novel oily acid-base indicator can be used to quickly and effectively determine the reaction endpoint during the silicone oil synthesis process, thereby accurately controlling the reaction progress and improving the reaction efficiency.

[0043] In order to further verify the feasibility and effectiveness of the present invention and screen out the best solution, the inventor conducted a series of experiments, as follows: Test 1 1.1 Raw material selection test, set up 7 recipes, the specific scheme is as follows: Formula 1 - "Ethanol Single Phase System" Raw material ratio: 99.65 parts of ethanol, 0.2 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of the above components and stir them evenly in a beaker using a glass rod.

[0044] Formula 2--"Ethanol-water two-phase system" Raw material ratio: 79.65 parts of ethanol, 20 parts of deionized water, 0.2 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of the above components and stir them evenly in a beaker using a glass rod.

[0045] Formula 3 - "Ethanol-water two-phase system" Raw material ratio: 59.65 parts of ethanol, 40 parts of deionized water, 0.2 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of the above components and stir them evenly in a beaker using a glass rod.

[0046] Formula 4 - "Ethanol-water two-phase system" Raw material ratio: 39.65 parts of ethanol, 60 parts of deionized water, 0.2 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of the above components and stir them evenly in a beaker using a glass rod.

[0047] Formula 5 - "Ethanol-water two-phase system" Raw material ratio: 19.65 parts of ethanol, 80 parts of deionized water, 0.2 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of the above components and stir them evenly in a beaker using a glass rod.

[0048] Formula 6 - "Ethanol-acetone-water three-phase system" Raw material ratio: 67.65 parts of ethanol, 5 parts of acetone, 27 parts of deionized water, 0.2 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of the above components and stir them evenly in a beaker using a glass rod.

[0049] Formula 7 - "Ethanol-acetone-water three-phase system" Raw material ratio: 61.65 parts of ethanol, 15 parts of acetone, 23 parts of deionized water, 0.2 parts of catechol violet, and 0.15 parts of water retaining agent. Weigh the raw materials of the above components and stir them evenly in a beaker using a glass rod.

[0050] 1.2 Test method: (1) Observe the solubility of catechol violet and the color of the solution in different systems.

[0051] (2) Take 30 g of methyl silicone oil prepared by the alkaline method, add 1 drop of the prepared acid-base indicator into the silicone oil using a rubber-tipped dropper, stir evenly with a glass rod, let it stand for 30 seconds, and observe the color change of the silicone oil.

[0052] 1.3 Test results: The indicators prepared by formula 1-7 were tested for performance and the data obtained are shown in Table 1.

[0053] Table 1 Performance test data of indicators prepared by formula 1-7

[0054] In summary, formulation 7 is the preferred formulation.

[0055] Test 2 2.1 The optimal ratio screening test was carried out with the preferred formula 7 obtained under "Test 1", and 5 formulas were set up, as shown in Table 1.

[0056] Formulation A - Example 1 Raw material ratio: 62 parts of ethanol, 16 parts of acetone, 21.62 parts of deionized water, 0.23 parts of catechol violet, and 0.15 parts of water retaining agent.

[0057] Formulation B - Example 2 Raw material ratio: 50 parts of ethanol, 28 parts of acetone, 21.62 parts of deionized water, 0.23 parts of catechol violet, and 0.15 parts of water retaining agent.

[0058] Formulation C - Example 3 Raw material ratio: 73 parts of ethanol, 21 parts of acetone, 5.62 parts of deionized water, 0.23 parts of catechol violet, and 0.15 parts of water retaining agent.

[0059] Formulation D - Example 4 Raw material ratio: 65 parts of ethanol, 15 parts of acetone, 19.70 parts of deionized water, 0.15 parts of catechol violet, and 0.15 parts of water retaining agent.

[0060] Formulation E - Example 5 Raw material ratio: 45 parts of ethanol, 32 parts of acetone, 22.55 parts of deionized water, 0.3 parts of catechol violet, and 0.15 parts of water retaining agent.

[0061] 2.2 Test method: Potassium hydroxide is used as a catalyst in the process of synthesizing silicone oil. The experimental method is to add 3L of octamethylcyclotetrasiloxane and a certain amount of end-capping agent to a 5L flask, add 3ml of a new oily acid-base indicator to the flask, stir for 10 minutes to evenly disperse the acid-base indicator, add 0.1-0.2g of potassium hydroxide to the silicone oil containing the acid-base indicator, set the reaction temperature to 120-140℃, the reaction time to 5 hours, and the reaction pressure to 1.0MPa to allow potassium hydroxide to fully react with the silicone oil. At the end of the polymerization reaction, sample the silicone oil to test the viscosity, add 0.1-0.2g of phosphoric acid to the reacted silicone oil to neutralize potassium hydroxide, and the reaction time is 1 hour. After the neutralization reaction is completed, sample the silicone oil to test the viscosity and observe its color change. When the solution changes from red-purple to yellow, the reaction can be stopped.

[0062] 2.3 Test data and results: The indicator prepared by formula AE was tested for performance and the data are shown in Table 2.

[0063] Table 2 Performance test data of the indicator prepared by formula AE

[0064] From the results in Table 2, it can be seen that the indicators prepared by formula AE are all uniform dark purple solutions, the indicators have good compatibility with silicone oil, the indicators can be completely dissolved in silicone oil, and the viscosity of silicone oil after polymerization is basically consistent with the viscosity after neutralization, indicating that phosphoric acid completely neutralizes the catalyst, and the color of silicone oil changes from red purple to yellow, indicating that the reaction has reached the end point, and the end point indication is accurate. The above examples show that the indicator provided by the present invention has the advantages of obvious and clear color change and good indication performance, and has good practical performance in chemical production.

[0065] Although the present invention has been described in detail above by means of general description, specific implementation methods and experiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A catechol violet oily acid-base indicator for judging the end point of silicone oil reaction, characterized in that: It is prepared by dissolving catechol violet solid in an ethanol-acetone-water three-phase system.

2. The catechol violet oily acid-base indicator for judging the end point of silicone oil reaction according to claim 1, characterized in that: The catechol violet oily acid-base indicator comprises the following raw materials by weight: 20-75 parts of ethanol, 10-40 parts of acetone, 5-30 parts of deionized water, 0.1-1.0 parts of catechol violet, and 0.1-0.2 parts of a water retaining agent.

3. The catechol violet oily acid-base indicator for judging the end point of silicone oil reaction according to claim 1, characterized in that: The purity of the ethanol is ≥99%, and the impurities methanol and isopropanol are ≤0.1%; the purity of the acetone is ≥99.5%; and the soluble impurities of the deionized water are ≤0.1%.

4. The catechol violet oily acid-base indicator for judging the end point of silicone oil reaction according to claim 1, characterized in that: The purity of the catechol violet is ≥95%, and the soluble impurities are ≤1.5%.

5. The catechol violet oily acid-base indicator for judging the end point of silicone oil reaction according to claim 2, characterized in that: The water retaining agent is dimethyl silicone oil with a viscosity of 5 to 50 cp.

6. The catechol violet oily acid-base indicator for judging the end point of silicone oil reaction according to claim 1, characterized in that: The acid-base indicator is yellow in an acidic environment and red-purple in an alkaline environment, and the color characteristics are yellow at pH values ​​of 1.5 to 7, purple at pH values ​​of 7 to 9, and red-purple at pH values ​​of 9 to 11.

7. The method for preparing the catechol violet oily acid-base indicator according to any one of claims 1 to 6, characterized in that: Here are the steps: S1: Weigh the formulated amount of ethanol, acetone and deionized water to prepare a mixed solution; S2: Weigh the formulated amount of catechol violet and dissolve it in a mixed solution of ethanol-acetone-deionized water; S3: Add a water retaining agent to the solution obtained in S2, mix well, and obtain a catechol violet oily acid-base indicator.

8. The use of the catechol violet oily acid-base indicator according to any one of claims 1 to 6, characterized in that: Used to determine the end point of silicone oil reaction; The method of use is: add the catechol violet oily acid-base indicator dropwise into the silicone oil reaction system, stir evenly, let stand for 0.5 to 3 minutes to observe the color, and judge the reaction endpoint according to the color change; pH values ​​of 1.5 to 7 are yellow, pH values ​​of 7 to 9 are purple, and pH values ​​of 9 to 11 are reddish purple.

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