A method for measuring the hydroxyl value of polyether polyols using nuclear magnetic resonance phosphorus spectroscopy

Abstract

The present invention discloses a method for measuring the hydroxyl value of a polyether polyol using nuclear magnetic resonance phosphorus spectroscopy, comprising: 1) adding a polyether polyol sample to be tested and an internal standard bisphenol A to a deuterated reagent and dissolving them by ultrasonication; 2) adding a phosphorus oxychloride compound and an acid binding agent to the mixture and allowing them to react fully to obtain corresponding different derivatized phosphorus-containing products; 3) performing a phosphorus spectroscopy test in a nuclear magnetic resonance analyzer to obtain nuclear magnetic resonance phosphorus spectroscopy data, processing and analyzing the data, integrating the nuclear magnetic resonance characteristic peak areas of the phosphorus-containing products after derivatization of the polyether polyol sample and the internal standard bisphenol A, and normalizing them to 100%, and calculating the hydroxyl value of the sample to be tested based on the molar ratio relationship between the products. The hydroxyl value result obtained by the present method has a relative deviation of less than 5% from the result obtained by the phthalic anhydride acylation method in the national standard GB / T 12008.3-2009, and the two results are close and highly accurate. The analytical testing method of the present invention is simple, has low pollution, and is short in time.

Description

Technical Field

[0001] The invention relates to a method for measuring the hydroxyl value of polyether polyol by utilizing nuclear magnetic resonance phosphorus spectrum. Background Art

[0002] Polyether polyol is an important chemical raw material. Its main application is the synthesis of polyurethane (PU) resin products, such as polyurethane foam, polyurethane adhesives, polyurethane adhesives, polyurethane elastomers, etc. In addition, it can also be used as a non-ionic surfactant, lubricant, liquid fluid, heat exchange fluid, etc.

[0003] The hydroxyl value of polyether polyols is an important indicator in the application process of polyurethane synthesis. The detection method in the current national standard GB / T12008.3-2009 is to use phthalic anhydride acylation and pyridine as an acid-binding agent for acid-base titration. The measurement time is generally about 1.5 hours, and the pyridine odor is strong, making the operation relatively cumbersome. The method of the present invention uses phosphorus oxychloride compounds for derivatization, adds an internal standard, and uses the internal standard method for quantification based on the chemical shift difference between the sample and the internal standard in the nuclear magnetic resonance phosphorus spectrum. The experimental process has the advantages of short experimental time, simple operation, and accurate quantitative determination. Summary of the Invention

[0004] In view of the above technical problems existing in the prior art, the object of the present invention is to provide a method for measuring the hydroxyl value of polyether polyols using nuclear magnetic resonance phosphorus spectroscopy.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A method for measuring the hydroxyl value of a polyether polyol using nuclear magnetic resonance phosphorus spectroscopy comprises:

[0007] 1) Add the polyether polyol sample to be tested and the internal standard bisphenol A into the deuterated reagent and dissolve them by ultrasonication;

[0008] 2) adding a phosphorus oxychloride compound and an acid binding agent to the mixture obtained in step 1) to allow them to react fully, and reacting the polyether polyol sample to be tested and the internal standard bisphenol A with the phosphonic chloride or phosphorus oxychloride compound to obtain corresponding different derivatized phosphorus-containing products;

[0009] 3) The reaction solution after the complete reaction in step 2) is transferred to a nuclear magnetic resonance tube, and the nuclear magnetic resonance tube is placed in a nuclear magnetic resonance analyzer for nuclear magnetic resonance phosphorus spectrum testing. The nuclear magnetic resonance phosphorus spectrum data is obtained and processed and analyzed. The characteristic peak areas of the nuclear magnetic resonance phosphorus spectrum of the phosphorus-containing products after derivatization of the polyether polyol sample and the internal standard bisphenol A are integrated and normalized to 100% (normalization to 100% facilitates the calculation of the content of hydroxyl functional groups of the internal standard bisphenol A and the polyether polyol sample). The hydroxyl value of the sample to be tested is calculated based on the relationship between the molar ratios of the products.

[0010] In the method for measuring the hydroxyl value of polyether polyols using nuclear magnetic resonance phosphorus spectroscopy of the present invention, the internal standard bisphenol A derivatized product has one phosphorus spectrum peak, while the derivatized product of the polyether polyol sample may have multiple phosphorus spectrum peaks because the chemical structures around their hydroxyl groups are different.

[0011] Furthermore, in step 1), the mass ratio of the polyether polyol sample to the internal standard bisphenol A is 0.5 to 5:1.

[0012] Furthermore, in step 1), the deuterated reagent is deuterated chloroform, and the ratio of the mass of the polyether polyol sample to be tested to the volume of the deuterated reagent is 0.02 to 0.1:1, the mass unit is g, and the volume unit is mL.

[0013] Furthermore, in step 2), the chemical formula of the phosphonyl chloride or phosphorus oxychloride compound is as shown in general formula (1), (2), (3) or (4):

[0014]

[0015] In the general formula (1), (2), (3) or (4), the substituents R1 and R2 may form a ring or not, and R1 and R2 are each independently selected from a C1-C4 alkyl group or an aryl group, and the aryl group may be a benzene ring.

[0016] Furthermore, the phosphonyl chloride or phosphorus oxychloride compound is diphenylphosphinyl chloride or 2-chloro-1,3,2-dioxaphospholane.

[0017] Furthermore, the ratio of the volume of the derivatization reagent (i.e., phosphonyl chloride or phosphorus oxychloride compound) in step 2) to the mass of the polyether polyol sample in step 1) is 1:0.1-0.5, the volume unit is mL, and the mass unit is g.

[0018] Furthermore, in step 2), the acid binding agent is triethylamine, 4-dimethylaminopyridine, 1,8-diazabicycloundec-7-ene or pyridine, preferably pyridine, and the ratio of the volume of the acid binding agent to the mass of the polyether polyol sample in step 1) is 1:0.1 to 0.5, the volume unit is mL, and the mass unit is g.

[0019] Furthermore, in step 3), the hydroxyl value of the sample to be tested is calculated as follows:

[0020]

[0021] Where: OHV-hydroxyl value of the sample to be tested (mgKOH / g);

[0022] M-bisphenol A relative molecular mass, 228.286;

[0023] R-the number of hydroxyl groups in the bisphenol A molecule;

[0024] m1-actual sample mass of bisphenol A (g);

[0025] m2-actual weighing mass of the sample to be tested (g);

[0026] A1-integrated area of ​​the phosphorus peak of the NMR spectrum of the product after the test sample is derivatized with phosphonyl chloride or phosphorus oxychloride compounds;

[0027] The integrated area of ​​the NMR spectrum of the phosphorus peak of the product after derivatization of A2-bisphenol A with phosphonyl chloride or phosphorus oxychloride compounds.

[0028] Furthermore, the test conditions of the nuclear magnetic resonance phosphorus spectrum in step 3) include: sampling width (SW) 506.0467 ppm, number of scans (NS) 32, frequency offset (O1P) 0 ppm, and duration (D1) 2.0 s; in the nuclear magnetic resonance phosphorus spectrum obtained by the test, the peak at the chemical shift of 128 ppm is the phosphorus spectrum peak of the product after derivatization of bisphenol A with phosphonyl chloride or a phosphorus oxychloride compound.

[0029] Furthermore, in step 2), the reaction temperature is room temperature and the reaction time is 30 seconds to 10 minutes. The rate of the derivatization reaction in step 2) of the present invention is relatively fast, and detection can be performed after the mixture is prepared at room temperature.

[0030] Compared to existing technologies, the present invention achieves the following advantages: The method utilizes derivatization with a phosphorus oxychloride compound, the addition of an internal standard, and quantification using the internal standard method based on the chemical shift differences in the nuclear magnetic resonance spectra of the sample and the internal standard. The results are characterized by a relative standard deviation of less than 5%, high precision, and a simple analytical testing method with minimal pollution and a short testing time. The hydroxyl value results obtained by this method are less than 5% relative to those obtained by the phthalic anhydride acylation method specified in the national standard GB / T 12008.3–2009, resulting in similar results and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the nuclear magnetic resonance phosphorus spectrum of the final reaction product when PEG1000 is selected as the sample to be tested in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] Example 1:

[0034] 1.1) Experimental Principle

[0035] Taking commonly used polyether polyols as an example, under the condition of pyridine as an acid-binding agent, bisphenol A (BPA) as an internal standard and the sample to be tested react with phosphorus oxychloride compounds to generate corresponding different phosphorus-containing products, and the phosphorus oxychloride products are detected by nuclear magnetic resonance. 31 -NMR signal, the nuclear magnetic resonance characteristic peak area of ​​the sample to be tested and the internal standard bisphenol A is integrated, and the hydroxyl value of the sample to be tested is calculated based on the relationship between the molar ratios of the products.

[0036] Taking several common polyether polyols as examples, 2-chloro-1,3,2-dioxaphospholane was used as a derivatization reagent to derivatize polyethylene glycol (PEG), polypropylene glycol (PPG), and PEG-PPG copolymers. The equations are as follows:

[0037]

[0038] The derivatization process of the internal standard bisphenol A is as follows:

[0039]

[0040] 1.2) Instruments

[0041] Nuclear magnetic resonance spectrometer (Bruker 400M).

[0042] 1.3) Reagents

[0043] Bisphenol A (analytical grade);

[0044] Pyridine (analytical grade);

[0045] 2-chloro-1,3,2-dioxaphospholane;

[0046] Deuterated chloroform.

[0047] 2. Experimental Methods

[0048] 2.1 Sample testing

[0049] 1) Weigh approximately 0.05 g (accurate to 0.0001 g) of the sample to be tested and 0.15 g (accurate to 0.0001 g) of the internal standard bisphenol A, add 500 μL of deuterated chloroform, and sonicate to dissolve;

[0050] 2) Add 100 μL of a phosphoryl chloride compound (using 2-chloro-1,3,2-dioxaphospholane) and 100 μL of pyridine to the mixture, respectively, and allow them to react fully (room temperature, reaction time 1-2 min);

[0051] 3) After the reaction is complete, transfer it to an NMR tube, then place the NMR tube in an NMR analyzer, select the corresponding analysis scheme and scan it to obtain an NMR spectrum.

[0052] 2.2 NMR spectrum parameter conditions

[0053] Table 3.1 Nuclear magnetic resonance phosphorus spectrum parameters

[0054] Sampling width (SW) 506.0467ppm Number of scans (NS) 32 Frequency offset (O1P) 0ppm Duration (D1) 2.0s

[0055] 2.3 Typical NMR spectra

[0056] The derivatization reaction was carried out according to the sample test method in step 2.1. When PEG1000 was selected as the sample to be tested, the nuclear magnetic resonance phosphorus spectrum of the final reaction product was as follows: Figure 1 Among them, the peak at chemical shift of 128 ppm is the phosphorus peak of the product of derivatization of bisphenol A with phosphorus oxychloride compounds; the peak at chemical shift of 133 ppm to 139 ppm is the phosphorus peak of the product of derivatization of PEG1000 with phosphorus oxychloride compounds.

[0057] The characteristic peak area of ​​the nuclear magnetic resonance phosphorus spectrum of each product was integrated and normalized to 100% to facilitate the calculation of the content of the hydroxyl functional group of the internal standard bisphenol A and the polyether polyol sample.

[0058] 2.4 Result calculation

[0059] The hydroxyl value calculation formula is as follows:

[0060]

[0061] Where: OHV-hydroxyl value of the sample to be tested (mgKOH / g);

[0062] M-bisphenol A relative molecular mass, 228.286;

[0063] R-the number of hydroxyl groups in the bisphenol A molecule;

[0064] m1-actual sample mass of bisphenol A (g);

[0065] m2-actual weighing mass of the sample to be tested (g);

[0066] A1-integrated area of ​​the phosphorus peak of the NMR spectrum of the product after the test sample is derivatized with phosphonyl chloride or phosphorus oxychloride compounds;

[0067] The integrated area of ​​the NMR spectrum of the phosphorus peak of the product after derivatization of A2-bisphenol A with phosphonyl chloride or phosphorus oxychloride compounds.

[0068] 3.5 Sample measurement results

[0069] According to the operating procedures of steps 2.1 sample testing, 2.2 nuclear magnetic resonance spectrum parameter conditions, and 2.4 result calculation, when the samples to be tested are sample 1 (PPG), sample 2 (PEG1000), sample 3 (PEG400) and sample 4 (PEG200), the measurement results of the hydroxyl values ​​of the samples to be tested are shown in Table 3.2, Table 3.3, Table 3.4 and Table 3.5, respectively.

[0070] Table 3.2 Test results of sample 1

[0071]

[0072]

[0073] Table 3.3 Determination results of sample 2

[0074]

[0075] Table 3.4 Test results of sample 3

[0076]

[0077] Table 3.5 Test results of sample 4

[0078]

[0079] At the same time, in Tables 3.2, 3.3, 3.4 and 3.5, we used the phthalic anhydride acylation method in GB / T12008.3-2009 to determine the hydroxyl value of the samples to be tested as a control group.

[0080] Based on the above experimental results, the present method uses derivatization with a phosphorus oxychloride compound, the addition of an internal standard, and quantification using the internal standard method based on the chemical shift differences between the sample and the internal standard in the nuclear magnetic resonance spectra. The results are characterized by a relative standard deviation of less than 5%, high precision, a simple analytical test method, minimal pollution, and a short time consumption. The hydroxyl value results obtained by this method are less than 5% relative to those obtained by the phthalic anhydride acylation method specified in the national standard GB / T 12008.3–2009, resulting in similar results and high accuracy.

[0081] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A method for measuring the hydroxyl value of polyether polyols using nuclear magnetic resonance phosphorus spectroscopy, characterized in that include: 1) Add the polyether polyol sample to be tested and the internal standard bisphenol A into the deuterated reagent and dissolve them by ultrasonication; 2) adding a phosphorus oxychloride compound and an acid binding agent to the mixture obtained in step 1) to allow them to react fully, and reacting the polyether polyol sample to be tested and the internal standard bisphenol A with the phosphonic chloride or phosphorus oxychloride compound to obtain corresponding different derivatized phosphorus-containing products; 3) The reaction solution after the complete reaction in step 2) is transferred to a nuclear magnetic resonance tube, and the nuclear magnetic resonance tube is placed in a nuclear magnetic resonance analyzer for nuclear magnetic resonance phosphorus spectrum testing. The nuclear magnetic resonance phosphorus spectrum data is obtained and processed and analyzed. The characteristic peak areas of the nuclear magnetic resonance phosphorus spectrum of the phosphorus-containing products after derivatization of the polyether polyol sample with the internal standard bisphenol A are integrated and normalized to 100%. The hydroxyl value of the sample to be tested is calculated based on the molar ratio relationship between the products; In step 3), the hydroxyl value of the sample to be tested is calculated as follows: Where: OHV-hydroxyl value of the sample to be tested, mgKOH / g; M-bisphenol A relative molecular mass, 228.286; R-the number of hydroxyl groups in the bisphenol A molecule; m1-actual sample mass of bisphenol A, g; m2-actual mass of the sample to be tested, g; A1-integrated area of ​​the phosphorus peak of the NMR spectrum of the product after the test sample is derivatized with phosphonyl chloride or phosphorus oxychloride compounds; The integrated area of ​​the NMR spectrum of the phosphorus peak of the product after derivatization of A2-bisphenol A with phosphonyl chloride or phosphorus oxychloride compounds.

2. The method for measuring the hydroxyl value of polyether polyols by using nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 1, wherein In step 1), the mass ratio of the polyether polyol sample to the internal standard bisphenol A is 0.5 to 5:

1.

3. The method for measuring the hydroxyl value of polyether polyols by utilizing nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 1, wherein In step 1), the deuterated reagent is deuterated chloroform, and the ratio of the mass of the polyether polyol sample to be tested to the volume of the deuterated reagent is 0.02 to 0.1:1, the mass unit is g, and the volume unit is mL.

4. The method for measuring the hydroxyl value of polyether polyols by utilizing nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 1, wherein In step 2), the chemical formula of the phosphonyl chloride or phosphorus oxychloride compound is as shown in general formula (1), (2), (3) or (4): In the general formula (1), (2), (3) or (4), the substituents R1 and R2 may form a ring or not, and R1 and R2 are each independently selected from a C1-C4 alkyl group or an aryl group.

5. A method for measuring the hydroxyl value of polyether polyols by utilizing nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 4, characterized in that The phosphonyl chloride or phosphorus oxychloride compound is diphenylphosphinyl chloride or 2-chloro-1,3,2-dioxaphospholane.

6. The method for measuring the hydroxyl value of polyether polyols by utilizing nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 1, wherein The ratio of the volume of the phosphonyl chloride or phosphorus oxychloride compound in step 2) to the mass of the polyether polyol sample in step 1) is 1:0.1-0.5, the volume unit is mL, and the mass unit is g.

7. The method for measuring the hydroxyl value of polyether polyols by utilizing nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 1, wherein In step 2), the acid binding agent is triethylamine, 4-dimethylaminopyridine, 1,8-diazabicycloundec-7-ene or pyridine, and the ratio of the volume of the acid binding agent to the mass of the polyether polyol sample in step 1) is 1:0.1-0.5, the volume unit is mL, and the mass unit is g.

8. The method for measuring the hydroxyl value of polyether polyols by utilizing nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 7, wherein In step 2), the acid binding agent is pyridine.

9. The method for measuring the hydroxyl value of polyether polyols by utilizing nuclear magnetic resonance phosphorus spectroscopy as claimed in claim 1, wherein The test conditions of the nuclear magnetic resonance phosphorus spectrum in step 3) include: sampling width SW 506.0467 ppm, number of scans NS32, frequency offset O1P 0 ppm, and duration D12.0 s; In the nuclear magnetic resonance phosphorus spectrum obtained by the test, the peak at the chemical shift of 128 ppm is the phosphorus spectrum peak of the product after bisphenol A is derivatized with phosphonyl chloride or phosphorus oxychloride compounds.

10. The method for measuring the hydroxyl value of polyether polyols by using nuclear magnetic resonance phosphorus spectroscopy according to claim 1, wherein In step 2), the reaction temperature is room temperature and the reaction time is 30s-10min.

Images