A method for determining the crystalline content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and application thereof

Abstract

This invention discloses a method and application for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals, belonging to the technical field of determining the content of different crystals in BPEF. The method uses differential scanning calorimetry to determine the quantitative relationship between the enthalpy of the melting absorption peak of low-melting-point and high-melting-point 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals and the content of low-melting-point or high-melting-point crystals in the product, and plots a standard curve. Based on this, a simple quantitative formula for accurately determining the content of low-melting-point and high-melting-point crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples can be established. According to the established quantitative formula, the content of different crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples can be effectively and rapidly determined. This is of great significance and value for BPEF production, product quality control, and sales.

Description

Technical Field

[0001] This invention discloses a method and application for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene (BPEF) crystals, belonging to the technical field of determining the content of different BPEF crystals. Background Technology

[0002] Bisphenol A (BPA) is an important intermediate and modifier in the synthesis of polymers such as polycarbonate and epoxy resins. It was once widely used in the manufacture of baby bottles, sippy cups for toddlers, beverage and mineral water bottles, medical devices, and food packaging. However, contact with leached BPA residues can lead to endocrine disorders, induce precocious puberty, and threaten the health and development of fetuses and children. Therefore, most countries have banned the production and sale of baby and children's products containing BPA. 9,9-Bisphenoxyethanolfluorene (BPEF), a compound with a unique Cardo molecular skeleton (I), is the ideal polymer monomer to replace traditional BPA in the manufacture of safe baby bottles, sippy cups, and other healthy and safe toddler products.

[0003] The unique chemical molecular structure of BPEF endows it with excellent dielectric properties, resistance to damp heat, mechanical properties, chemical resistance, as well as excellent transparency and high refractive index. At the same time, BPEF is also an ideal monomer and modifier for synthesizing high-heat-resistant and safe polycarbonate, epoxy resin, polyurethane, acrylic resin, polyester resin or polyether and other polymer materials. Therefore, it is not difficult to find that polymer materials prepared by BPEF have been widely used in high-end precision optical lens resin materials required in aerospace, missile warheads, optical imaging, electronics, automobile manufacturing and other fields.

[0004] The synthesis of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene products mainly involves a condensation reaction mechanism between 9-fluorenone and 2-phenoxyethanol in the presence of strong acid catalysts such as sulfuric acid or methanesulfonic acid, as reported in publications such as CN112142574A, Japanese Patent Application Publication No. 10-45656, Japanese Patent Application Publication No. 2009-256342, and CN104144904A. Published literature also reports the use of heterogeneous solid acids as catalysts for the synthesis of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene products, such as montmorillonite titanium (Synth. Commun. 2007, 37:4407-4413; Green Chem. 2000, 2, 157-160).

[0005] Quantitative calculations show that the alkoxy group on the aromatic ring of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene (I) can form crystals with different molecular configurations through different intramolecular and intermolecular hydrogen bonding interactions (J. Chem. Soc., Perkin Trans. 2, 2001, 1212). Furthermore, these crystals exhibit different melting points, packing densities, and other macroscopic physical properties (CN104144904A). Compounds with different crystal structures will have different physicochemical properties, naturally leading to different application characteristics. For example, low-melting-point crystal structures can be used and reacted at lower temperatures, significantly reducing the time and energy required for processing or reaction; while correspondingly, high-packing-density crystal structures offer advantages such as significantly reduced storage, transportation, and usage costs.

[0006] Publicly available literature indicates that recrystallization of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene using alcohols, ketones, and esters primarily yields a mixture of high-melting-point and low-melting-point products. However, recrystallization with toluene mainly yields high-melting-point crystals (CN101657406B). No methods for determining the content of different crystal forms of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene have been reported in the published literature. Summary of the Invention

[0007] The first objective of this invention is to provide a method and application for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals.

[0008] The present invention adopts the following technical solution:

[0009] A method for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals, characterized by comprising the following steps:

[0010] Step 1: Using a 0.01 mg-grade balance, accurately weigh samples of low-melting-point BPEF crystals and high-melting-point BPEF crystals with different contents, and ensure that the two crystals are accurately weighed and thoroughly mixed.

[0011] Step 2: The melting point and melting absorption enthalpy of the mixed sample were analyzed using a differential scanning calorimeter (DSC). The DSC test conditions were as follows: initial temperature 30℃, temperature increased to 200℃ at 5-20℃ / min, then held at 200℃ for six minutes. The heat and enthalpy change of the sample were analyzed using the DSC software.

[0012] Step 3: Plot a standard curve by using the content of low-melting-point crystals or high-melting-point crystals in the sample as the x-axis and the ratio of the melting absorption enthalpy of low-melting-point crystals or high-melting-point crystals to the total absorption enthalpy as the y-axis.

[0013] Step 4: Based on the standard curves of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different low-melting-point and high-melting-point ratios, a quantitative formula (1) is established to correlate the ratio of melting absorption peak enthalpy y with its crystal content x in the product:

[0014] y = 2.83 + 0.3088x + 0.0062x 2 (1)

[0015] Where: y represents the ratio of the melting absorption peak enthalpy values ​​of low-melting-point or high-melting-point crystals in the BPEF sample, and x represents the content of low-melting-point or high-melting-point crystals in the BPEF sample;

[0016] Step 5: For 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples obtained by recrystallization in different solvents, first determine whether they are low-melting-point crystals, high-melting-point crystals, or a mixture of both by differential scanning calorimetry (DSC). Then, according to the obtained quantitative formula (1), the content of low-melting-point and high-melting-point crystals in the samples is determined.

[0017] The working principle of this invention is as follows:

[0018] This invention discloses a method for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals. The method involves determining the quantitative relationship between the enthalpy of the melting absorption peak of low-melting-point and high-melting-point 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals and the crystal content in the product using differential scanning calorimetry, and plotting a standard curve. Based on this, a simple quantitative formula (Equation 1) is established for accurately determining the content of low-melting-point and high-melting-point crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples.

[0019] Further settings include:

[0020] The low-melting-point crystalline form of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene described in this invention refers to a crystalline form whose maximum endothermic temperature, determined by differential scanning calorimetry, is in the range of 110-130°C. The high-melting-point crystalline form of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene described in this invention refers to a crystalline form whose maximum endothermic temperature, determined by differential scanning calorimetry, is in the range of 150-170°C.

[0021] The preferred heating rate in step 2 is 10℃ / min;

[0022] Preferably, a method for determining the content of different crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is characterized by comprising the following steps:

[0023] Step 1: Using a 0.01 mg-grade balance, accurately weigh samples of low-melting-point BPEF crystals and high-melting-point BPEF crystals with different contents, and ensure that the two crystals are accurately weighed and thoroughly mixed.

[0024] Step 2: Differential scanning calorimetry (DSC) was used to analyze the melting point of the mixed sample and the corresponding enthalpy change of the melting absorption peak. The DSC test conditions were: initial temperature 30℃, temperature increased to 200℃ at 10℃ / min, and then held at 200℃ for six minutes. The heat absorbed and enthalpy change of the melting peak of the sample were analyzed using the software attached to the DSC.

[0025] Step 3: Plot the standard curves of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different low-melting-point crystal contents, with the content of low-melting-point crystals in the sample as the abscissa and the ratio of the enthalpy of the melting absorption peak of the low-melting-point crystals to the enthalpy of the total absorption peak as the ordinate.

[0026] Step 4: Based on the standard curves of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different low-melting-point crystal contents, a quantitative formula (1) is established to correlate the ratio of melting absorption peak enthalpy y with its content x in the sample:

[0027] y = 2.83 + 0.3088x + 0.0062x 2 (1)

[0028] Where: y represents the ratio of the enthalpy values ​​of the melting absorption peaks of low-melting-point crystals in the BPEF sample, and x represents the content of low-melting-point crystals in the BPEF sample;

[0029] Step 5: Based on the obtained quantitative formula (1), the content of low-melting-point crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples obtained by recrystallization in different solvents was tested and analyzed.

[0030] A second aspect of the present invention is to provide an application of the aforementioned determination method in the preparation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals with different contents, characterized by comprising the following steps:

[0031] (1) Preparation of crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene

[0032] 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crude product was prepared by heating and reflux dehydration under the catalysis of concentrated sulfuric acid and 3-mercaptopropionic acid using 9-fluorenone and phenoxyethanol as reactants;

[0033] (2) Recrystallization

[0034] The crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene was dissolved in a solvent and heated under reflux until completely dissolved. Then, it was naturally cooled to form a large amount of white crystals. After filtration, it was vacuum dried at room temperature to obtain the refined 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0035] The solvent is selected from any one or more organic solvents such as tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol, ethanol, benzene, toluene, or xylene.

[0036] (3) Using the aforementioned test methods and quantitative formulas, the contents of low-melting-point and high-melting-point crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene prepared by recrystallization in different solvents in step (2) were detected, and the correspondence between solvent selection and the contents of low-melting-point and high-melting-point crystals was established.

[0037] (4) Based on actual production needs, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different contents of low-melting-point and high-melting-point crystals was prepared by controlling the recrystallization solvent.

[0038] Further settings include:

[0039] In step (1):

[0040] The preparation method of crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is as follows: 9-fluorenone, 3-mercaptopropionic acid, phenoxyethanol, and cyclohexane are added to a reaction vessel, and concentrated sulfuric acid is added under stirring. Then, the mixture is refluxed to separate water. After the reaction is completed, water is added to cool and crystallize. The mixture is filtered and rinsed until neutral, and then dried to obtain crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0041] In step (3):

[0042] When the recrystallization solvent is selected from any one of tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol or ethanol, recrystallization of BPEF yields a low-melting-point crystal.

[0043] When the recrystallization solvent is any one of benzene, toluene, p-xylene, or o-xylene, recrystallizing BPEF yields a high-melting-point crystal.

[0044] When the recrystallization solvent is selected as either tetrahydrofuran / toluene (volume ratio 2:3) or butanol / toluene (volume ratio 1:1), recrystallization of BPEF yields a mixed crystal of low melting point and high melting point.

[0045] In step (4):

[0046] The method for preparing low-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is as follows: 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is dissolved in an organic solvent such as tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol, or ethanol, preferably tetrahydrofuran or methanol. The solution is then heated under reflux until completely dissolved, followed by natural cooling to form a large amount of white crystals. After filtration, the solution is vacuum dried at room temperature to obtain low-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene. Drying at room temperature can prevent the low-melting-point BPEF crystals from transforming into high-melting-point crystals.

[0047] The method for preparing high-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is as follows: 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample is dissolved in organic solvents such as benzene, toluene, and xylene, preferably toluene, and heated under reflux until completely dissolved. Then, it is allowed to cool naturally to form a large amount of white crystals. After filtration, it is dried under vacuum at room temperature to obtain high-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0048] The method for preparing a mixture of low-melting-point and high-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is as follows: 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample is dissolved in a mixed solvent of n-butanol / toluene and tetrahydrofuran / toluene, heated under reflux until completely dissolved, and then allowed to cool naturally to form a large amount of white crystals; after filtration, it is vacuum dried at room temperature to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene containing a mixture of low-melting-point and high-melting-point crystals.

[0049] The beneficial effects of this invention are as follows:

[0050] (1) Through extensive research, we found that: 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples purified by recrystallization with organic solvents such as tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol, or ethanol all yielded low-melting-point crystals, while 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples purified by recrystallization with organic solvents such as toluene or xylene yielded high-melting-point crystals. Furthermore, many solvents, such as n-butanol / toluene and tetrahydrofuran / toluene, also yielded 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples purified by recrystallization. The 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample is a mixture of two different crystals with different melting points: low melting point and high melting point. Therefore, the applicant used differential scanning calorimetry to determine the quantitative relationship between the enthalpy of the melting absorption peak of the low-melting-point and high-melting-point 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals and the content of low-melting-point or high-melting-point crystals in the product, and plotted a standard curve to establish a simple quantitative formula for determining the accurate content of low-melting-point and high-melting-point crystals in the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample.

[0051] (2) Based on the aforementioned simple test method for effectively and rapidly determining the content of different crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples, the applicant tested the content of low-melting-point and high-melting-point crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene prepared by recrystallization in different solvents, and established the correspondence between solvent selection and the content of low-melting-point and high-melting-point crystals. Thus, according to actual production needs, by controlling the recrystallization solvent, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different contents of low-melting-point and high-melting-point crystals can be prepared. This is of great significance and value for BPEF production, product quality control, and sales.

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but is not limited to the following embodiments. Various substitutions or modifications made based on ordinary technical knowledge and conventional methods in the art under the above-described technical concept should be included within the scope of protection of the present invention. Attached image description:

[0053] Figure 1 Standard curves for 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different ratios of low-melting-point and high-melting-point compounds.

[0054] Figure 2 The DSC spectrum of the low-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene prepared in Example 3 (instrument: PerkinElmer, DSC6000).

[0055] Figure 3 The DSC spectrum of the high-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene prepared in Example 4 (instrument: PerkinElmer, DSC6000).

[0056] Figure 4 The DSC spectrum of the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene mixed crystal sample prepared in Example 5 (instrument: PerkinElmer, DSC6000).

[0057] Figure 5 The DSC spectrum of the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene mixed crystal sample prepared in Example 6 (instrument: PerkinElmer, DSC6000). Detailed implementation method:

[0058] Example 1: Plotting the standard curve of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and establishing a quantitative formula

[0059] Step 1: Using a 0.01 mg balance, accurately weigh samples of low-melting-point BPEF crystals and high-melting-point BPEF crystals with different contents, and ensure that the two crystals are accurately weighed and thoroughly mixed.

[0060] Step 2: Differential scanning calorimetry (DSC) was used to analyze the melting point of the mixed sample and the corresponding enthalpy change of the melting absorption peak. The DSC test conditions were: initial temperature 30℃, temperature increased to 200℃ at 10℃ / min, and then held at 200℃ for six minutes. The heat absorbed and enthalpy change of the sample melting peak were analyzed using the software provided with the DSC.

[0061] Step 3: Plot a standard curve for 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different contents of low-melting-point crystals, using the content of low-melting-point crystals in the sample as the x-axis and the ratio of the enthalpy of the melting absorption peak of the low-melting-point crystals to the enthalpy of the total absorption peak as the y-axis. Figure 1 As shown, there is a quantitative correlation between the enthalpy of the melting absorption peak of different low-melting-point crystal contents and their content in the sample.

[0062] Step 4: Based on the standard curves of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different contents of low-melting-point crystals, a quantitative formula (1) is established to correlate the ratio of the enthalpy values ​​of the melting absorption peaks of low-melting-point crystals, y, with their content x in the sample:

[0063] y = 2.83 + 0.3088x + 0.0062x 2 (1)

[0064] Where: y represents the ratio of the enthalpy values ​​of the melting absorption peaks of low-melting-point crystals in the BPEF sample, and x represents the content of low-melting-point crystals in the BPEF mixed sample.

[0065] Step 5: For 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples obtained by recrystallization in different solvents, first determine whether they are low-melting-point crystals, high-melting-point crystals, or a mixture of both by differential scanning calorimetry (DSC). Then, according to the obtained quantitative formula (1), the content of low-melting-point and high-melting-point crystals in the samples is determined.

[0066] The following analysis of products obtained by recrystallization in different solvents is performed using the method of the present invention.

[0067] Example 2: Preparation of crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene

[0068] 9,9-Bis(4-(2-hydroxyethoxy)phenyl)fluorene was prepared by heating and reflux dehydration of 9-fluorenone and phenoxyethanol as reactants under the catalysis of concentrated sulfuric acid and 3-mercaptopropionic acid. The specific steps are as follows: In a 2-liter reactor, 180 g of 9-fluorenone, 1.8 g of 3-mercaptopropionic acid, 415 g of phenoxyethanol, and 540 g of cyclohexane were added. Under stirring, 27 g of concentrated sulfuric acid was added, followed by reflux to separate the water. After the reaction was complete, 360 g of water was added to cool and crystallize. The crystals were filtered, washed until neutral, and dried to obtain 412 g of crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, with a yield of 94%.

[0069] Example 3: Preparation of low-melting-point crystalline samples of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene

[0070] 10 g of the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample prepared in Example 2 was dissolved in 10 mL of tetrahydrofuran solvent, heated under reflux until completely dissolved, and then allowed to cool naturally to form a large amount of white crystals. After filtration, the crystals were dried under vacuum at room temperature to obtain 9.0 g of low-melting-point 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals, with a yield of 90%. Drying at room temperature can prevent some of the sample from transforming into high-melting-point crystals.

[0071] Product confirmation:

[0072] The 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample prepared in Example 3 was analyzed by DSC, and the results were as follows: Figure 2 As shown: This indicates that all the obtained samples are low-melting-point crystals. Since all the samples tested by DSC analysis are low-melting-point crystals, there is no need to further detect the specific content of crystals using the quantitative formula (1).

[0073] Example 4: Preparation of high-melting-point crystalline samples of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene

[0074] 10 g of the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample prepared in Example 2 was dissolved in 50 mL of toluene and heated under reflux until completely dissolved. After natural cooling, a large amount of white crystals formed. After filtration, the crystals were vacuum dried at room temperature to obtain 9.20 g of high-melting-point 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals, with a yield of 92%.

[0075] Product confirmation:

[0076] The 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample prepared in Example 4 was analyzed by DSC, and the results were as follows: Figure 3As shown: This indicates that all the obtained samples are high-melting-point crystals. Since all the samples tested by DSC are high-melting-point crystals, there is no need to further detect the specific content of crystals using the quantitative formula (1).

[0077] Example 5: Preparation of a mixed crystalline sample of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with low and high melting points

[0078] 10 g of the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample prepared in Example 2 was dissolved in a mixed solvent of 10 mL tetrahydrofuran and 15 mL toluene. The solution was heated under reflux until completely dissolved, and then allowed to cool naturally to form a large amount of white crystals. After filtration, the solution was vacuum dried at room temperature to obtain a 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample containing both low-melting-point and high-melting-point crystals.

[0079] Product confirmation:

[0080] The prepared 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples containing mixed crystals of different low and high melting points were subjected to DSC analysis. Figure 4 As shown, Figure 4 It is clearly shown that the obtained 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample contains both low-melting-point and high-melting-point crystals.

[0081] according to Figure 4 The DSC spectrum, combined with Figure 1 Based on the standard curve and quantitative formula (1), the content of low-melting-point crystals in the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample was calculated to be 84.05%, and the content of high-melting-point crystals was 15.95%.

[0082] The specific calculation process is as follows:

[0083] y = 2.83 + 0.3088x + 0.0062x 2 (1)

[0084] As shown in Table 1: In Example 5, the y value, which is the ratio (percentage) of the melting absorption peak of low-melting-point crystals in the BPEF sample, is 72.58. According to the above formula, the x value is calculated to be 84.05, that is, the content of low-melting-point crystals in the BPEF sample is 84.05%, and the content of high-melting-point crystals is 15.95%.

[0085] Example 6: Preparation of a mixed crystalline sample of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with low and high melting points

[0086] 10 g of the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample prepared in Example 2 was dissolved in a mixed solvent of 15 mL n-butanol and 15 mL toluene. The solution was heated under reflux until completely dissolved, and then allowed to cool naturally to form a large amount of white crystals. After filtration, the solution was vacuum dried at room temperature to obtain a 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample containing both low-melting-point and high-melting-point crystals.

[0087] Product confirmation:

[0088] The prepared 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples containing mixed crystals of different low and high melting points were subjected to DSC analysis. Figure 5 As shown, Figure 5 It is clearly shown that the obtained 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample contains both low-melting-point and high-melting-point crystals.

[0089] according to Figure 5 The DSC spectrum, combined with Figure 1 Based on the standard curve and quantitative formula (1), the content of low-melting-point crystals in the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample was calculated to be 96.52%, and the content of high-melting-point crystals was 4.48%.

[0090] The specific calculation process is as follows:

[0091] y = 2.83 + 0.3088x + 0.0062x 2 (1)

[0092] As shown in Table 1: In Example 6, the y-value, i.e., the ratio of the enthalpy of the melting absorption peak of the low-melting-point crystals in the BPEF sample, is 90.39. According to the above formula, the x-value is 96.52, that is, the content of low-melting-point crystals in the BPEF sample is 96.52%, and the content of high-melting-point crystals is 4.48%.

[0093] Statistical analysis:

[0094] The experimental method was the same as in Example 3, except that the choice of recrystallization solvent was adjusted, and the prepared samples were subjected to DSC analysis. Then, combined with... Figure 1 The standard curve and quantitative formula were used to calculate the content of low-melting-point crystals and low-melting-point crystals in the BPEF sample, as shown in Table 1.

[0095] Table 1. Samples of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene obtained by recrystallization with different solvents

[0096]

[0097]

[0098] As shown in Table 1:

[0099] 1. The detection method of this invention can be used to detect the content of low-melting-point and high-melting-point crystals in the prepared 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene (BPEF) sample. Statistical analysis revealed that the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene (BPEF) product, after recrystallization in different solvents, had its melting point determined using differential scanning calorimetry (DSC). We found that when the recrystallization solvent was any one of tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol, or ethanol, the recrystallized BPEF yielded low-melting-point crystals; when the recrystallization solvent was any one of benzene, toluene, p-xylene, or o-xylene, the recrystallized BPEF yielded high-melting-point crystals; and when the recrystallization solvent was any one of tetrahydrofuran / toluene (volume ratio 2:3) or butanol / toluene (volume ratio 1:1), the recrystallized BPEF yielded a mixture of low-melting-point and high-melting-point crystals.

[0100] 2. Based on the above detection method, this application statistically analyzes the content of low-melting-point or high-melting-point BPEF crystals in mixed crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene obtained by recrystallization in different solvents. In this way, by controlling the selection and amount of recrystallization solvent, the product composition of BPEF can be accurately controlled, which is very important for product quality monitoring and sales.

Claims

1. A method for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals, characterized in that... This includes the following steps: Step 1: Using a 0.01 mg-level balance, accurately weigh samples of low-melting-point BPEF crystals and high-melting-point BPEF crystals with different contents, and ensure that the two crystals are accurately weighed and thoroughly mixed. The low-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene refer to crystals whose maximum endothermic temperature is in the range of 110-130℃ as determined by differential scanning calorimetry. The high-melting-point crystals of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene refer to crystals whose maximum endothermic temperature is in the range of 150-170℃ as determined by differential scanning calorimetry. Step 2: The melting point and melting absorption enthalpy of the mixed sample were analyzed using a differential scanning calorimeter (DSC). The DSC test conditions were as follows: initial temperature 30 ℃, temperature increased to 200 ℃ at 5-20 ℃ / min, then held at 200 ℃ for six minutes. The heat and enthalpy change of the sample were analyzed using the DSC software. Step 3: Plot a standard curve by using the content of low-melting-point crystals or high-melting-point crystals in the sample as the x-axis and the ratio of the melting absorption enthalpy of low-melting-point crystals or high-melting-point crystals to the total absorption enthalpy as the y-axis. Step 4: Based on the standard curves of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different low-melting-point and high-melting-point ratios, a quantitative formula (1) is established to correlate the ratio of melting absorption peak enthalpy y with its crystal content x in the product: y = 2.83 + 0.3088 x + 0.0062 x 2 (1) Where: y represents the ratio of the melting absorption peak enthalpy values ​​of low-melting-point or high-melting-point crystals in the BPEF sample, and x represents the content of low-melting-point or high-melting-point crystals in the BPEF sample; Step 5: For 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples obtained by recrystallization in different solvents, first determine whether they are low-melting-point crystals, high-melting-point crystals, or a mixture of both by differential scanning calorimetry (DSC). Then, according to the obtained quantitative formula (1), the content of low-melting-point and high-melting-point crystals in the samples is determined.

2. The method for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals according to claim 1, characterized in that: The heating rate in step 2 is 10℃ / min.

3. The method for determining the content of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals according to claim 1, characterized in that: Includes the following steps: Step 1: Using a 0.01 mg-level balance, accurately weigh samples of low-melting-point BPEF crystals and high-melting-point BPEF crystals with different contents, and ensure that the two crystals are accurately weighed and thoroughly mixed. Step 2: The melting point of the mixed sample and the corresponding enthalpy change of the melting absorption peak were analyzed using a differential scanning calorimeter (DSC). The DSC test conditions were: initial temperature 30℃, temperature increased to 200℃ at 10℃ / min, and then held at 200℃ for six minutes. The heat absorbed and enthalpy change of the melting peak of the sample were analyzed using the software attached to the DSC. Step 3: Plot the standard curves of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different low-melting-point crystal contents, with the content of low-melting-point crystals in the sample as the abscissa and the ratio of the enthalpy of the melting absorption peak of the low-melting-point crystals to the enthalpy of the total absorption peak as the ordinate. Step 4: Based on the standard curves of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different low-melting-point crystal contents, a quantitative formula (1) is established to correlate the ratio of melting absorption peak enthalpy y with its content x in the sample: y = 2.83 + 0.3088 x + 0.0062 x 2 (1) Where: y represents the ratio of the enthalpy values ​​of the melting absorption peaks of low-melting-point crystals in the BPEF sample, and x represents the content of low-melting-point crystals in the BPEF sample; Step 5: Based on the obtained quantitative formula (1), the content of low-melting-point crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene samples obtained by recrystallization in different solvents was tested and analyzed.

4. The application of the determination method according to claim 1 in the preparation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals with different contents, characterized in that, Includes the following steps: (1) Preparation of crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crude product was prepared by heating and reflux dehydration under the catalysis of concentrated sulfuric acid and 3-mercaptopropionic acid using 9-fluorenone and phenoxyethanol as reactants; (2) recrystallization The crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene was dissolved in a solvent and heated under reflux until completely dissolved. Then, it was naturally cooled to form a large amount of white crystals. After filtration, it was vacuum dried at room temperature to obtain the refined 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene. The solvent is selected from any one or more organic solvents such as tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol, ethanol, benzene, toluene, or xylene. (3) Using the determination method and quantitative formula described in claim 1, detect the content of low-melting-point and high-melting-point crystals in 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene prepared by recrystallization in different solvents in step (2), and establish the correspondence between solvent selection and the content of low-melting-point and high-melting-point crystals; (4) Based on actual production needs, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene with different contents of low-melting-point and high-melting-point crystals was prepared by controlling the recrystallization solvent.

5. The application of the determination method according to claim 4 in the preparation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals with different contents, characterized in that, In step (1), the preparation method of crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is as follows: 9-fluorenone, 3-mercaptopropionic acid, phenoxyethanol and cyclohexane are added to a reaction vessel, concentrated sulfuric acid is added under stirring, and then the mixture is refluxed to separate water; after the reaction is completed, water is added to cool and crystallize, filtered and rinsed until neutral, and dried to obtain crude 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

6. The application of the determination method according to claim 4 in the preparation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals with different contents, characterized in that, In step (3): When the recrystallization solvent is selected from any one of tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol or ethanol, recrystallization of BPEF yields a low-melting-point crystal. When the recrystallization solvent is any one of benzene, toluene, p-xylene, or o-xylene, recrystallizing BPEF yields a high-melting-point crystal. When the recrystallization solvent is selected as either tetrahydrofuran / toluene (volume ratio 2:3) or n-butanol / toluene (volume ratio 1:1), recrystallization of BPEF yields a mixture of low-melting-point and high-melting-point crystals.

7. The application of the determination method according to claim 4 in the preparation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals with different contents, characterized in that, In step (4), the method for preparing 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene low-melting-point crystals is as follows: 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is dissolved in tetrahydrofuran, diethyl ether, chlorobenzene, petroleum ether, cyclohexane, methanol or ethanol organic solvents, and then heated under reflux until completely dissolved. After natural cooling, a large amount of white crystals are formed. After filtration, the crystals are dried under vacuum at room temperature to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene low-melting-point crystals. Drying at room temperature avoids the transformation of low-melting-point BPEF crystals into high-melting-point crystals.

8. The application of the determination method according to claim 4 in the preparation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals with different contents, characterized in that, In step (4), the method for preparing 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene high-melting-point crystals is as follows: Dissolve the 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample in benzene, toluene, or xylene organic solvents, heat under reflux until completely dissolved, and then allow to cool naturally to form a large amount of white crystals; after filtration, dry under vacuum at room temperature to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene high-melting-point crystals.

9. The application of the determination method according to claim 4 in the preparation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene crystals with different contents, characterized in that, In step (4), the method for preparing the mixed crystals of low-melting-point and high-melting-point 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is as follows: The 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene sample is dissolved in a mixed solvent of n-butanol / toluene (volume ratio 1:1) and tetrahydrofuran / toluene (volume ratio 2:3), heated and refluxed until completely dissolved, and then naturally cooled to form a large amount of white crystals; after filtration, it is vacuum dried at room temperature to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene containing mixed crystals of low-melting-point and high-melting-point 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

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