Method for determining trace components in dimethyldichlorosilane hydrolysate
Quantitative determination by head air chromatography combined with internal standard substances was solved, and the problem of analysis of trace components in dimethyldichlorosilane hydrolysate was achieved, and the accuracy of components such as methylhexane and hexamethylcyclotrisiloxane was achieved, which improved the quality control of silicone ring production.
Patent Information
- Application Number
- CN202411609871.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-03-14
AI Technical Summary
The prior art is difficult to effectively analyze the content of trace components such as methylhexane and hexamethylcyclotrisiloxane in dimethyldichlorosilane hydrolysate, which affects the quality of the silicone ring.
The head air chromatography was used to combine the internal standard for quantitative determination, and the samples were neutralized by sodium hydroxide solution, and gas chromatography was directly tested after adding the internal standard, avoiding extraction and separation operations.
Accurate measurement of trace components such as methylhexane and hexamethylcyclotrisiloxane in dimethyldichlorosilane hydrolysate is achieved, which has good operability, stability and safety, and is suitable for samples with different acid values and compositions.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of organic silicon, and in particular to a quantitative determination method of trace components in dimethyldichlorosilane hydrolyzate. Background Art In the production process of organosilicon polymers, dimethyldichlorosilane hydrolysate is an important intermediate product, and its quality affects the subsequent loop separation process control and the quality of organosilicon ring bodies. Dimethyldichlorosilane hydrolysate is produced by hydrolysis of dimethyldichlorosilane in hydrochloric acid. During the hydrolysis process, a certain amount of methylhexane needs to be added, and a certain amount of hexamethylcyclotrisiloxane ring body is produced during the hydrolysis process. Determining the content of these components has a great guiding significance for the production of organosilicon ring bodies. Summary of the invention
[0002] The main component of dimethyldichlorosilane hydrolysate is siloxane linear body, which has high viscosity and boiling point, and a certain amount of hydrochloric acid remains. There is currently no method to analyze methylhexane and hexamethylcyclotrisiloxane in dimethyldichlorosilane hydrolysate.
[0003] The present invention provides a quantitative determination method for trace components in dimethyldichlorosilane hydrolysate, which not only solves the analysis problem of organic components in dimethyldichlorosilane hydrolysate, but also can simultaneously determine the contents of methylhexane, low-polymerization linear bodies and ring bodies in the system. The method has good operability, stability and safety.
[0004] In order to achieve the above object, the present invention adopts the following technical solutions: The invention discloses a quantitative determination method of trace components in dimethyldichlorosilane hydrolyzate, which adopts headspace gas chromatography and uses an internal standard substance for quantitative determination.
[0005] The method comprises the following steps: (1) Pretreatment of dimethyldichlorosilane hydrolyzate: neutralize dimethyldichlorosilane hydrolyzate with sodium hydroxide solution; (2) Weigh the sample in step (1), add the internal standard reagent, and mix well; (3) Take the sample added with the internal standard in step (2) and perform headspace injection gas chromatography detection to obtain the corresponding peak area, and calculate the content of the trace component based on the peak area.
[0006] Trace components in the hydrolyzate of dimethyldichlorosilane include hexamethylcyclotrisiloxane, methylhexane and octamethylcyclotetrasiloxane.
[0007] In some embodiments, in step (1), water and sodium hydroxide solution are added to the dimethyldichlorosilane hydrolyzate, and the mixture is stirred in a magnetic stirrer at a speed of 500-1200 rpm for 15 min-90 min.
[0008] In the step (1), the dimethyldichlorosilane hydrolyzate is neutralized with a sodium hydroxide solution to a pH of 6.5-8; the concentration of the sodium hydroxide solution is 0.1-1.0 mol / L.
[0009] In step (2), the internal standard is n-hexane, cyclohexane, or n-dodecane, and the amount of the internal standard added is 1-10 wt % of the sample mass.
[0010] The composition of dimethyldichlorosilane hydrolyzate is complex, and there are methylhexane, hexamethylcyclotrisiloxane, and a small amount of octamethylcyclotetrasiloxane and other substances that are easy to gasify, and there are also hydroxyl-terminated polydimethylsiloxane linear substances that are difficult to gasify. Analysis of the content of substances such as methylhexane and hexamethylcyclotrisiloxane in dimethyldichlorosilane hydrolyzate cannot be directly adopted by gas chromatography, and it is necessary to enrich and remove the difficult gasification substances through operations such as extraction and separation before gas chromatography analysis can be performed. The present invention adds internal standard in order to simplify the pretreatment process. After the sample is added with internal standard, it is analyzed without pretreatment by operations such as extraction and separation.
[0011] In some embodiments, the sample is accurately weighed and added to the headspace bottle in the step (3) of hydrolyzing dimethyldichlorosilane, and the added amount is 0.01 g to 0.5 g. The added amount of the sample is determined based on the volatile matter of the hydrolyzate at 150°C.
[0012] In the step (3), during the headspace injection process, the headspace parameters are as follows: a heating box temperature of 140-150°C, a quantitative loop temperature of 150-180°C, a transfer line temperature of 160-180°C, a sample bottle equilibration time of 15 min-60 min, a filling pressure of 10-30 psi, a final quantitative loop pressure of 1-5 psi, and a quantitative loop equilibration time of 0.01-0.1 min.
[0013] In some preferred cases, during the headspace injection process in step (3), the headspace parameters are as follows: a heating box temperature of 150°C, a quantitative loop temperature of 160°C, a transfer line temperature of 170°C, a sample bottle equilibration time of 15 minutes, a filling pressure of 15 psi, a final quantitative loop pressure of 2 psi, and a quantitative loop equilibration time of 0.05 minutes.
[0014] The composition of dimethyldichlorosilane hydrolysate is complex, and there are methylhexane, hexamethylcyclotrisiloxane and a small amount of octamethylcyclotetrasiloxane and other materials that are easy to gasify, and there are also hydroxyl-terminated polydimethylsiloxane linear bodies that are difficult to gasify. Analyzing the material contents such as methylhexane and hexamethylcyclotrisiloxane in dimethyldichlorosilane hydrolysate, it is impossible to directly adopt gas chromatography, and it is necessary to enrich and remove the difficult gasification materials through operations such as extraction and separation before gas chromatography analysis can be performed. The present invention adopts the method of headspace injection, combined with the addition of internal standard substances, effectively avoiding the operations such as extraction and separation, and also avoiding the analysis deviation caused by the loss of the component to be measured during operation.
[0015] The composition of dimethyldichlorosilane hydrolyzate varies greatly, and the content of substances that are more easily vaporized fluctuates between 20% and 80%. When injecting samples in the headspace, dimethyldichlorosilane hydrolyzate of different compositions has different gas phase compositions at the same temperature, which leads to deviations in the test results. Therefore, when selecting the temperature of the headspace heating box, select the temperature at which the component to be tested is completely vaporized, and adjust the injection volume according to the content of substances that are more easily vaporized.
[0016] In the step (3), the chromatographic detection conditions in step (3) are: 100% dimethyl polysiloxane capillary chromatographic column, 30m*0.25mm*0.25μm; injection port temperature 260°C, split ratio 50:1; program heating: temperature 90°C, hold 2min, run 2mi, heating rate 10°C / min, final temperature 190°C, hold 4min.
[0017] The case of the present application also includes the detection of standard samples, which are detected by the above-mentioned headspace injection and liquid chromatography detection methods, and a standard curve is drawn after the detection.
[0018] In the preparation process of the standard sample, 5 g of hydroxyl-terminated polydimethylsiloxane linear body was added into 3 parts, and 5 μl of methylhexane and about 0.005 g of hexamethylcyclotrisiloxane, 10 μl of methylhexane and about 0.010 g of hexamethylcyclotrisiloxane, and 20 μl of methylhexane and about 0.0015 g of hexamethylcyclotrisiloxane were added respectively, and then accurately weighed.
[0019] Add internal standard to the above three solutions respectively, accurately weigh the mass of internal standard added, and shake to mix evenly.
[0020] The above method is used for headspace feeding and chromatographic detection for chromatographic analysis, and a standard curve is drawn.
[0021] Analyze and record the peak areas of internal standard, methylhexane and hexamethylcyclotrisiloxane, and calculate the contents of methylhexane and hexamethylcyclotrisiloxane according to the following formula:
[0022]
[0023] W methylhexane means: the mass fraction of methylhexane.
[0024] WD3 refers to: the mass fraction of hexamethylcyclotrisiloxane.
[0025] fMethylhexane means: the correction factor of methylhexane relative to the internal standard.
[0026] fD3 refers to the correction factor of hexamethylcyclotrisiloxane relative to the internal standard.
[0027] mInternal standard refers to: the mass of the internal standard added.
[0028] A Methylhexane means: the peak area of methylhexane.
[0029] AD3 refers to the peak area of hexamethylcyclotrisiloxane.
[0030] AInternal standard refers to: the peak area of the internal standard.
[0031] Msample means: the quality of the sample.
[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention realizes the determination of methylhexane and hexamethylcyclotrisiloxane ring bodies in dimethyldichlorosilane hydrolyzate.
[0033] (2) The present invention is applicable to dimethyldichlorosilane hydrolyzates having different acid values and different contents of methylhexane and hexamethylcyclotrisiloxane ring bodies.
[0034] (3) It has good operability and low cost.
[0035] (4) High safety, suitable for chemical production field. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Figure 1 This is the gas chromatogram of Example 2.
[0037] Figure 2 This is the gas chromatogram of Example 4.
[0038] Figure 3 This is the gas chromatogram of Example 5.
[0039] Figure 4 This is the gas chromatogram of Example 6. DETAILED DESCRIPTION
[0040] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0041] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.
[0042] Example 1 (1) Place the hydroxyl-terminated polydimethylsiloxane linear solid in an oven at 150°C for 24 hours to remove the residual low-boiling point components.
[0043] (2) Weigh 3 parts of 5 g of hydroxyl-terminated polydimethylsiloxane linear solid, add 5 μl of methylhexane and about 0.005 g of hexamethylcyclotrisiloxane, 10 μl of methylhexane and about 0.010 g of hexamethylcyclotrisiloxane, and 20 μl of methylhexane and about 0.0015 g of hexamethylcyclotrisiloxane, respectively, and weigh them accurately.
[0044] (3) Add 50 μl of cyclohexane internal standard to each of the three solutions above, accurately weigh the amount of internal standard added, and shake to mix evenly.
[0045] (4) Take about 0.3 g of sample from each bottle, add it to the headspace bottle, and cap it for later use.
[0046] (5) Set two different headspace parameters as follows: 1. Heating box temperature 150℃, quantitative loop temperature 160℃, transfer line temperature 170℃, sample bottle equilibration time 15min, filling pressure 15psi, final quantitative loop pressure 2psi, quantitative loop equilibration time 0.05min; 2. Heating box temperature 100℃, quantitative loop temperature 110℃, transfer line temperature 120℃, sample bottle equilibration time 30min, filling pressure 15psi, final quantitative loop pressure 2psi, quantitative loop equilibration time 0.05min. Set the test sequence.
[0047] The above three solutions were subjected to gasification process respectively using the above two different headspace parameters.
[0048] (6) Set the chromatographic parameters: 100% dimethyl polysiloxane capillary column, 30m*0.25mm*0.25μm; injection port temperature 260℃, split ratio 50:1; program heating: temperature 90℃, hold for 2min, run for 2mi, heating rate 10℃ / min, final temperature 190℃, hold for 4min: (7) Analyze and record the peak areas of internal standard, methylhexane, and hexamethylcyclotrisiloxane. Calculate the correction factor according to the formula: when the oven temperature is 150°C and the equilibrium time is 15 minutes (i.e., the first headspace parameter is vaporized), the methylhexane correction factor is 1.04 and the hexamethylcyclotrisiloxane correction factor is 2.31; when the oven temperature is 100°C and the equilibrium time is 30 minutes (i.e., the second headspace parameter is vaporized), the methylhexane correction factor is 1.11 and the hexamethylcyclotrisiloxane correction factor is 2.78.
[0049] Example 2 (1) Place the hydroxyl-terminated polydimethylsiloxane linear solid in an oven at 150°C for 24 hours to remove the residual low-boiling point components.
[0050] (2) Weigh 3 parts of 5 g of hydroxyl-terminated polydimethylsiloxane linear solid, add 5 μl of methylhexane and about 0.005 g of hexamethylcyclotrisiloxane, 10 μl of methylhexane and about 0.010 g of hexamethylcyclotrisiloxane, and 20 μl of methylhexane and about 0.0015 g of hexamethylcyclotrisiloxane, respectively, and weigh them accurately.
[0051] (3) Add 50 μl of n-dodecane as internal standard to each of the three solutions above, accurately weigh the amount of internal standard added, and vortex to mix evenly.
[0052] (4) Take about 0.3 g of sample from each bottle, add it to the headspace bottle, and cap it for later use.
[0053] (5) Set the headspace parameters: heating box temperature 150°C, quantitative loop temperature 160°C, transfer line temperature 170°C, sample bottle equilibration time 15 min, filling pressure 15 psi, final quantitative loop pressure 2 psi, quantitative loop equilibration time 0.05 min. Set the test sequence.
[0054] (6) Set the chromatographic parameters: 100% dimethyl polysiloxane capillary column, 30m*0.25mm*0.25μm; injection port temperature 260℃, split ratio 50:1; program heating: temperature 90℃, hold for 2min, run for 2mi, heating rate 10℃ / min, final temperature 190℃, hold for 4min: (7) Analyze and record the peak areas of internal standard, methylhexane, and hexamethylcyclotrisiloxane. Calculate the correction factor according to the formula: methylhexane correction factor is 0.86, and hexamethylcyclotrisiloxane correction factor is 1.55. The chromatogram is shown in Figure 2 As shown, from Figure 1 It can be seen that the peak shape is complete and the detected data is highly accurate.
[0055] Example 3 (1) Place the hydroxyl-terminated polydimethylsiloxane linear solid in an oven at 150°C for 24 hours to remove the residual low-boiling point components.
[0056] (2) Preparation of sample 1: Weigh 5 g of hydroxyl-terminated polydimethylsiloxane linear solid, add 10 μl of methylhexane and about 0.010 g of hexamethylcyclotrisiloxane, and weigh accurately; Preparation of sample 2: Weigh 2.5 g of hydroxyl-terminated polydimethylsiloxane linear solid, add 2.5 g of octamethylcyclotetrasiloxane, 10 μl of methylhexane and about 0.010 g of hexamethylcyclotrisiloxane, and weigh accurately.
[0057] (3) Add 50 μl of cyclohexane to each of the above samples 1 and 2, and add 50 μl of n-dodecane as internal standard to sample 2. Accurately weigh the amount of internal standard added and shake to mix evenly.
[0058] (4) Take about 0.3 g of sample from each bottle, add it to the headspace bottle, and cap it for later use.
[0059] (5) Headspace parameters 1: oven temperature 150°C, quantitative loop temperature 160°C, transfer line temperature 170°C, sample bottle equilibration time 15 min, filling pressure 15 psi, final quantitative loop pressure 2 psi, quantitative loop equilibration time 0.05 min; Headspace parameters 2: oven temperature 100°C, quantitative loop temperature 110°C, transfer line temperature 120°C, sample bottle equilibration time 30 min, filling pressure 15 psi, final quantitative loop pressure 2 psi, quantitative loop equilibration time 0.05 min. Set the test sequence.
[0060] (6) Set the chromatographic parameters: 100% dimethyl polysiloxane capillary column, 30m*0.25mm*0.25μm; injection port temperature 260℃, split ratio 50:1; program heating: temperature 90℃, hold for 2min, run for 2mi, heating rate 10℃ / min, final temperature 190℃, hold for 4min: (7) Under the conditions of headspace parameter 1 and headspace parameter 2, sample 1 and sample 2 were analyzed respectively, and the peak areas of internal standard, methylhexane and hexamethylcyclotrisiloxane were recorded. The contents were calculated according to the correction factors of Example 1.
[0061]
[0062] (8) The best results were obtained using 150°C, cyclohexane as the internal standard, and dimethyldichlorosilane hydrolysates of different compositions.
[0063] Example 4 (1) Take 20g of dimethyldichlorosilane hydrolyzate with an acid value of 0.06%, add 100ml of water and 1ml of 1mol / L sodium hydroxide solution, and stir at 800 rpm in a magnetic stirrer for 30min. Then let the mixture stand in a separatory funnel to separate the layers, take the upper layer of dimethyldichlorosilane hydrolyzate, and the acid value is 0.0007%; (2) Weigh 5.00635 g of the hydrolyzate of dimethyldichlorosilane after the above treatment, add 0.03317 g of cyclohexane, and mix well; (3) Take 0.03107 g of sample, add it to the headspace bottle, and cap it for later use; (4) Set the headspace parameters: heating box temperature 150°C, quantitative loop temperature 160°C, transfer line temperature 170°C, sample bottle equilibration time 20 min, filling pressure 15 psi, final quantitative loop pressure 2 psi, quantitative loop equilibration time 0.05 min. Set the test sequence and place the sample and blank into the headspace injector in sequence; (5) Set the chromatographic parameters: 100% dimethyl polysiloxane capillary column, 30m*0.25mm*0.25μm; injection port temperature 260℃, split ratio 50:1; program temperature rise: temperature 90℃, hold for 2min, run for 2mi, heating rate 10℃ / min, final temperature 190℃, hold for 4min; (6) After the analysis, the peak area of the internal standard cyclohexane was recorded as 1851.13 mV.s, the peak area of methylhexane was recorded as 4918.40 mV.s, and the peak area of hexamethylcyclotrisiloxane was recorded as 102.428 mV.s. According to the formula, the content of methylhexane was 1.8308%, and the content of hexamethylcyclotrisiloxane was 0.0932%.
[0064] Example 5 (1) The acid value of dimethyldichlorosilane hydrolyzate was determined to be 0.0010%.
[0065] (2) Weigh 5.00673 g of dimethyldichlorosilane hydrolyzate, add 0.03733 g of internal standard cyclohexane, and mix well.
[0066] (3) Take 0.10012 g of sample, add it to the headspace bottle, and cap it for later use.
[0067] (4) Set the headspace parameters: heating box temperature 150°C, quantitative loop temperature 160°C, transfer line temperature 170°C, sample bottle equilibration time 20 min, filling pressure 15 psi, final quantitative loop pressure 2 psi, quantitative loop equilibration time 0.05 min. Set the test sequence and place the sample and blank into the headspace injector in sequence; (5) Set the chromatographic parameters: 100% dimethyl polysiloxane capillary column, 30m*0.25mm*0.25μm; injection port temperature 260℃, split ratio 50:1; program heating: temperature 90℃, hold for 2min, run for 2mi, heating rate 10℃ / min, final temperature 190℃, hold for 4min: (6) After the analysis, the peak area of the internal standard cyclohexane was recorded as 6834.60 mV.s, the peak area of methyl hexane was recorded as 23.65 mV.s, and the peak area of hexamethylcyclotrisiloxane was recorded as 19.50 mV.s. According to the formula, the content of methyl hexane was 0.0057% and the content of hexamethylcyclotrisiloxane was 0.0049%.
[0068] Example 6 (1) The acid value of polydimethylsiloxane linear is determined to be 0.0001%.
[0069] (2) Weigh 5.00230 g of polydimethylsiloxane linear solid, add 0.03661 g of internal standard cyclohexane, and mix well.
[0070] (3) Take about 0.20236 g of sample, add it to the headspace bottle, and cap it for later use.
[0071] (4) Set the headspace parameters: heating box temperature 150°C, quantitative loop temperature 160°C, transfer line temperature 170°C, sample bottle equilibration time 20 min, filling pressure 15 psi, final quantitative loop pressure 2 psi, quantitative loop equilibration time 0.05 min. Set the test sequence and place the sample and blank into the headspace injector in sequence; (5) Set the chromatographic parameters: 100% dimethyl polysiloxane capillary column, 30m*0.25mm*0.25μm; injection port temperature 260℃, split ratio 50:1; program heating: temperature 90℃, hold for 2min, run for 2mi, heating rate 10℃ / min, final temperature 190℃, hold for 4min: (6) After the analysis, the peak area of the internal standard cyclohexane was recorded as 11424.89 mV.s, the peak area of methyl hexane was recorded as 6.72 mV.s, and the peak area of hexamethylcyclotrisiloxane was recorded as 42.28 mV.s. According to the formula, the content of methyl hexane was 0.0004% and the content of hexamethylcyclotrisiloxane was 0.0049%.
[0072] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.
Claims
1. A method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate, characterized in that: The method comprises the following steps: (1) Pretreatment of dimethyldichlorosilane hydrolyzate: neutralize dimethyldichlorosilane hydrolyzate with sodium hydroxide solution; (2) Weigh the sample in step (1), add the internal standard reagent, and mix well; (3) Take the sample added with the internal standard in step (2) and perform headspace injection gas chromatography detection to obtain the corresponding peak area, and calculate the content of the trace component based on the peak area.
2. The method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate according to claim 1, characterized in that: Trace components in the hydrolyzate of dimethyldichlorosilane include hexamethylcyclotrisiloxane, methylhexane and octamethylcyclotetrasiloxane.
3. The method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate according to claim 1, characterized in that: In the step (1), the dimethyldichlorosilane hydrolyzate is neutralized with a sodium hydroxide solution to a pH of 6.5-8; the concentration of the sodium hydroxide solution is 0.1-1.0 mol / L.
4. The method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate according to claim 1, characterized in that: In step (2), the internal standard is n-hexane, cyclohexane, or n-dodecane, and the amount of the internal standard added is 1-10 wt % of the sample mass.
5. The method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate according to claim 1, characterized in that: In the step (3), the sample is added into the headspace bottle, and the added amount is 0.01 g to 0.5 g.
6. The method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate according to claim 1, characterized in that: During the headspace injection process, the headspace parameters are: heating box temperature 140-150°C, quantitative loop temperature 150-180°C, transfer line temperature 160-180°C, sample bottle equilibration time 15min-60min, filling pressure 10-30psi, final quantitative loop pressure 1-5psi, and quantitative loop equilibration time 0.01-0.1min.
7. The method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate according to claim 6, characterized in that: During the headspace injection process in step (3), the headspace parameters are as follows: a heating box temperature of 150°C, a quantitative loop temperature of 160°C, a transfer line temperature of 170°C, a sample bottle equilibration time of 15 min, a filling pressure of 15 psi, a final quantitative loop pressure of 2 psi, and a quantitative loop equilibration time of 0.05 min.
8. The method for quantitative determination of trace components in dimethyldichlorosilane hydrolyzate according to claim 1, characterized in that: The chromatographic detection conditions in step (3) are: 100% dimethyl polysiloxane capillary column, 30m*0.25mm*0.25μm; injection port temperature 260°C, split ratio 50:1; programmed temperature rise: temperature 90°C, hold for 2min, run for 2mi, heating rate 10°C / min, final temperature 190°C, hold for 4min.