Novel cyclic dihydric alcohol as well as preparation method and application thereof

Abstract

The invention discloses a novel cyclic dihydric alcohol as well as a preparation method and application thereof, cyclohexanone is used as a raw material, a dialdehyde monomer is obtained through electrophilic addition, and then a dihydric alcohol monomer is prepared through reduction hydrogenation. The unique advantages of the cyclohexanone structure are fully played, a new way is opened up for application of cyclohexanone, the prepared dihydric alcohol can be used as a polymeric monomer for preparing a polyurethane material, and the tensile property of the prepared polyurethane material is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane, more particularly, to a novel cyclic diol and its preparation method and application. BACKGROUND

[0002] Polyurethane is a material with excellent performance and rich functions, which has a wide range of raw material sources, excellent chemical stability, diverse structural design, good plasticity and other characteristics. After decades of development, it has been widely used in various fields and has become one of the indispensable materials in modern industry and daily life.

[0003] However, the performance of polyurethane is heavily dependent on the molecular structure, especially the molecular structure of the chain extender. The chain extender has a great influence on the mechanical properties, thermal properties, chemical resistance and processing properties of the material. Most of the alcohol chain extenders used at present are chain structures, such as ethylene glycol, 1,4-butanediol, neopentyl glycol, etc. They have high reactivity, good processing performance and low cost, but have the disadvantages of low elongation at break, poor impact resistance and too fast reaction speed. Common cyclic diol chain extenders include cyclohexanediol, bisphenol A derivatives and isosorbide, etc. The polyurethane prepared therefrom has the disadvantages of poor flexibility, high glass transition temperature and poor reactivity. Therefore, introducing a diol chain extender with both chain and cyclic structures into the polyurethane structure can help improve the overall performance of the polyurethane material.

[0004] Cyclohexanone is an important organic chemical raw material, and in recent years its development in the chemical industry has shown the characteristics of capacity expansion and diversified applications. Secondly, cyclohexanone is mainly used in the production of solvents, coatings, inks, caprolactam and adipic acid. Its application field is relatively narrow, and it is necessary to expand the downstream emerging demand to solve the problem of overcapacity.

[0005] Cyclohexanedimethanol is a compound with excellent structure and has potential in the field of polyurethane. The commonly used cyclohexanedimethanol is 1,4-cyclohexanedimethanol, while 1,3-cyclohexanedimethanol has application limitations due to the harsh reaction conditions required for its preparation, such as high temperature and high pressure or esterification reduction, and low yield. At present, the preparation conditions need to be optimized to improve the yield of 1,3-cyclohexanedimethanol and reduce the cost. SUMMARY

[0006] The present application aims to overcome the above-mentioned defects in the prior art and provide a novel cyclic diol and its preparation method and application. The present application uses cyclohexanone as a raw material to prepare a cyclic structure diol monomer, which is applied in the field of polyurethane, thereby widening the application field of cyclohexanone and alleviating the problem of cyclohexanone overcapacity.

[0007] To achieve the above-mentioned purpose, the technical solution of the present application is as follows:

[0008] A novel cyclic diol, the structural formula of which is shown in formula (1):

[0009]

[0010] The application further discloses a preparation method of the novel cyclic diol.

[0011] S1, cyclohexanone is added into a mixed solution containing phosphorus oxychloride (POCl3) and N,N-dimethylformamide (DMF), and a nitrogen atmosphere is applied to protect and perform a heating reaction, after the reaction is completed, the solution is cooled to room temperature, and then frozen and filtered to obtain an intermediate product in the form of a yellow solid;

[0012] S2, the intermediate product obtained in step 1 is added into a methanol (CH3OH) solution in which sodium acetate (CH3COONa) is dissolved, sodium borohydride (NaBH4) is added in batches under the condition of 0 DEG C to perform an ice bath reaction, the ice bath is removed and the reaction is continued at room temperature, then saturated ammonium chloride (NH4Cl) solution is added to terminate the reaction, and the obtained reaction solution is sequentially subjected to extraction, washing, drying, filtration and concentration to obtain the novel cyclic diol in the form of a white solid shown in formula (1).

[0013] Optionally, in S1, the phosphorus oxychloride and the N,N-dimethylformamide are reacted at 0 DEG C for 0.2 h to 1 h, preferably for 0.4 h to 0.8 h, to obtain the mixed solution containing the phosphorus oxychloride and the N,N-dimethylformamide.

[0014] Optionally, in S1, the heating reaction is performed for 3 h to 6 h, preferably for 4 h to 5 h, and the heating reaction is performed at a temperature of 50 DEG C to 80 DEG C, preferably at a temperature of 55 DEG C to 70 DEG C.

[0015] Optionally, in S1, the volume ratio of the cyclohexanone, the phosphorus oxychloride and the N,N-dimethylformamide is 1:4:4.

[0016] Optionally, in S2, after the reaction solution is extracted with ethyl acetate (CH3COOCH2CH3), the solution is washed with saturated NH4Cl solution for 3 times, the organic layer solution is dried with anhydrous magnesium sulfate (MgSO4), and then filtered and concentrated to obtain the novel cyclic diol shown in formula (1).

[0017] Optionally, in S2, the molar ratio of the intermediate product, the sodium borohydride and the sodium acetate is 1:(2.0-2.4):(2.0-2.4), preferably 1:(2.1-2.3):(2.1-2.3).

[0018] Optionally, in S2, the ice bath reaction time is 1h-2h, preferably 1.2h-1.8h; the room temperature reaction time is 1h-2h, preferably 1.4h-1.6h.

[0019] Optionally, in S2, the molar ratio of sodium borohydride to methanol is 1:(15-20).

[0020] Optionally, in S2, the amount of sodium borohydride added in each batch is 10% of the total mass of sodium borohydride.

[0021] The application also discloses a preparation method of a cyclic diol, which utilizes the novel cyclic diol as described above to prepare, and the preparation method comprises the following steps:

[0022] (1) adding the novel cyclic diol in claim 1 into a methanol (CH3OH) solution in which sodium acetate (CH3COONa) is dissolved, and adding Pd / C catalyst to react under the conditions of a hydrogen pressure of 0.20 MPa-0.25 MPa and a temperature of 20-30°C;

[0023] (2) after removing the Pd / C catalyst from the reaction solution obtained in step (1), placing the reaction solution in ice water, adding sodium borohydride (NaBH4) in batches to react, removing the ice bath to continue the reaction at room temperature, then adding saturated NH4Cl solution to terminate the reaction, and sequentially extracting, washing, drying, filtering and concentrating the obtained reaction solution, and obtaining the white liquid cyclic diol shown in formula (2) through column chromatography;

[0024]

[0025] Optionally, in step (1), the mass ratio of the novel cyclic diol to the Pd / C catalyst is 1:(0.05-0.1), preferably 1:0.1.

[0026] Optionally, in step (1), the reaction temperature is preferably 20-25°C.

[0027] Optionally, in step (1), the reaction time is 0.5-1.5h, based on 1g of the novel cyclic diol.

[0028] Optionally, in step (1), the mass content of Pd in the Pd / C catalyst is 10%.

[0029] Optionally, in step (2), after the reaction solution is extracted with ethyl acetate (CH3COOCH2CH3), the solution is washed with saturated NH4Cl solution for 3 times, the organic layer solution is dried with anhydrous magnesium sulfate (MgSO4), and then filtered, concentrated and obtained through column chromatography to obtain the white liquid diol monomer shown in formula II.

[0030] Optionally, in step (2), the molar ratio of the novel cyclic diol, sodium borohydride and sodium acetate is 1: (2.0-2.4): (2.0-2.4), preferably 1: (2.1-2.4): (2.1-2.4).

[0031] Optionally, in step (2), the normal silica gel column is used in column chromatography, and the eluent is ethyl acetate: n-hexane with a volume ratio of (1-3): 1, preferably (1-2): 1.

[0032] Optionally, in step (2), the molar ratio of sodium borohydride and methanol is 1: (15-20).

[0033] Optionally, in step (2), the amount of sodium borohydride added in each batch is 10% of the total mass of sodium borohydride.

[0034] Optionally, in the present application, the reaction process is as shown in the following formula:

[0035]

[0036] The present application also discloses a novel cyclic diol as described above, or a cyclic diol prepared by the preparation method as described above, and application of the novel cyclic diol as described above or the cyclic diol prepared by the preparation method as described above in preparation of polyurethane as a chain extender.

[0037] Optionally, the application comprises the following steps: the novel cyclic diol as described above or the cyclic diol prepared by the preparation method as described above is respectively reacted with a polyurethane prepolymer, and a polyurethane material is prepared through curing.

[0038] Optionally, the novel cyclic diol as described above or the cyclic diol prepared by the preparation method as described above is chain-extended by using a high-speed dispersion machine, and the stirring speed is preferably 1800 r / min-2500 r / min.

[0039] Optionally, the polyurethane prepolymer is selected from one or more of polytetramethylene glycol (PTMEG1000) with a molecular weight of 1000 and diisocyanate, such as polytetramethylene glycol-toluene diisocyanate prepolymer (pre-PTMEG1000-TDI), polytetramethylene glycol-p-phenylene diisocyanate prepolymer (pre-PTMEG1000-PPDI), polytetramethylene glycol-diphenyl methane diisocyanate prepolymer (pre-PTMEG1000-MDI), polytetramethylene glycol-isophorone diisocyanate prepolymer (pre-PTMEG1000-IPDI), polytetramethylene glycol-1,3-dimethyl isocyanate cyclohexane prepolymer (pre-PTMEG1000-1,3-H6XDI), polytetramethylene glycol-1,4-dimethyl isocyanate cyclohexane prepolymer (pre-PTMEG1000-1,4-H6XDI), and other polyurethane prepolymers that can be prepared.

[0040] Optionally, the equivalent ratio of isocyanate groups of the prepolymer to active hydrogen groups of the mixed chain extender is 0.9-1.5, preferably 1-1.2, and more preferably 1.02-1.05.

[0041] Optionally, the chain extension reaction temperature is 60-160°C, preferably 60-130°C, and more preferably 70-110°C.

[0042] Optionally, the chain extension time is 1-60 min, preferably 1-30 min. Different chain extension times are selected because the chain extension speed increases with temperature.

[0043] Optionally, the aging temperature is 0-110°C, preferably 25-80°C, and the aging time is 10-30 h, preferably 15-25 h, and more preferably 20-25 h.

[0044] Optionally, aging allows the polymerization reaction to proceed more completely, and the polymer molecular weight further increases, so that the polyurethane has higher mechanical strength.

[0045] The embodiments of the present application have the following beneficial effects:

[0046] The present application provides a novel cyclic diol and a preparation method and application thereof. The present application uses cyclohexanone as a raw material, obtains a dialdehyde monomer through electrophilic addition, and then obtains a diol monomer through reduction hydrogenation. The present application fully utilizes the unique advantages of the cyclohexanone structure, opens up a new way for the application of cyclohexanone, and the prepared diol can be used as a polymerization monomer to prepare a polyurethane material. The prepared polyurethane material has excellent tensile properties. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is the mass spectrum of (2-chlorocyclohex-1 -en-1,3-diyl)dimethanol of Example 1. 1 H NMR spectrum.

[0048] Figure 2 is the mass spectrum of (2-chlorocyclohex-1 -en-1,3-diyl)dimethanol of Example 1. 13 C NMR spectrum.

[0049] Figure 3 is the mass spectrum of (2-chlorocyclohex-1 -en-1,3-diyl)dimethanol of Example 1.

[0050] Figure 4 is the tensile property spectrum of 1,3-cyclohexanedimethanol of Example 2. 1 H NMR spectrum.

[0051] Figure 5 is the mass spectrum of 1,3-cyclohexanedimethanol of Example 2. 13 C NMR spectrum.

[0052] Figure 6 is the mass spectrum of 1,3-cyclohexanedimethanol of Example 2.

[0053] Figure 7 is the FT-IR spectrum of polyurethane material prepared in Examples 3-8.

[0054] Figure 8 is the FT-IR spectrum of polyurethane material prepared in Examples 9-13.

[0055] Figure 9 is the tensile property spectrum of polyurethane material prepared in Examples 3-8.

[0056] Figure 10 is the tensile property spectrum of polyurethane material prepared in Examples 9-13. DETAILED DESCRIPTION

[0057] The application is further described in conjunction with the specific examples below, but in no way is the application limited by the examples.

[0058] Example 1

[0059] In a three-necked round bottom flask equipped with a reflux condenser, a mixture of 80 mL of DMF and 80 mL of dichloromethane (CH2Cl2) was cooled in an ice bath. Then 80 mL of POCl3dissolved in 60 mL of CH2Cl2was added dropwise under stirring, followed by the addition of 20 g of cyclohexanone. The solution was refluxed at 60 °C for 5 h, cooled, poured into 500 g of ice water and left overnight. The yellow solid was filtered and dried to give 2-chloro-3-(hydroxymethyliden)-cyclohex-1-enecarboxaldehyde 22.2 g (yield 63.4 %), which was used directly in the next step without further purification.

[0060] In a single-necked round bottom flask, 60 g of 2-chloro-3-(hydroxymethyliden)- cyclohex-1-enecarboxaldehyde was dissolved in a solution containing 68.67 g of CH3COONa in 320 mL of CH3OH and cooled in an ice bath. Then 31.65 g of NaBH4was added in 10 portions under stirring. The solution was left to react in an ice bath for 1.5 h, then it was left to react at room temperature for another 1.5 h, after which the reaction was terminated by the addition of an appropriate amount of saturated NH4Cl solution. The reaction solution was extracted with CH3COOCH2CH3, washed with saturated NH4Cl solution three times and the organic layer solution was dried using anhydrous MgSO4, filtered, concentrated and finally (2-chlorocyclohex-1-en-1,3-diyl)dimethanol 35.7 g (yield 58.1 %) was obtained. Nuclear magnetic resonance 1 H, nuclear magnetic resonance 13 C spectrum, mass spectrum as shown in Figures 1-3

[0061] Example 2

[0062] In a hydrogenation autoclave with a capacity of 500 mL, 40 g of (2-chlorocyclohex-1-en-1,3-diyl)dimethanol prepared in Example 1, 250 mL of CH3OH, 37.27 g of CH3COONa and 4 g of Pd / C catalyst were added. The reaction was carried out at 25 °C under a hydrogen pressure of 0.2 MPa for 32 h.

[0063] After the Pd / C catalyst was removed from the reaction solution, it was placed in a single-necked round bottom flask and cooled in an ice bath. Then 20.62 g of NaBH4was added in 10 portions under stirring. The solution was left to react in an ice bath for 1.5 h, then it was left to react at room temperature for another 1.5 h, after which the reaction was terminated by the addition of an appropriate amount of saturated NH4Cl solution. The reaction solution was extracted with CH3COOCH2CH3, washed with saturated NH4Cl solution three times and the organic layer solution was dried using anhydrous MgSO4, filtered, concentrated and 1,3-cyclohexanedimethanol 11.8 g (yield 35.9 %) was obtained by column chromatography. Nuclear magnetic resonance 1 H, nuclear magnetic resonance 13 C spectrum, mass spectrum as shown in Figures 4-6 ​​

[0064] Example 3

[0065] Chain extension was carried out using a high speed disperser. 60 g of polytetrahydrofuran glycol-diphenylmethane diisocyanate pre-polymer (pre-PTMEG1000-MDI) with an NCO value (content of isocyanate group) of 5.48% was weighed into a fluorotetrafluoroethane beaker and chain extension was carried out by adding 6.69 g (38.01 mmol) of (2-chlorocyclohex-1-en-1,3-diyl) dimethanol prepared in Example 1 under the condition of 100°C and 2200 r / min stirring. After 25 min of stirring, the product was transferred to a flat vulcanizing machine and cured under the condition of 110°C, 25 tons of pressure, and 1 h of time. Finally, the product was transferred to a 90°C oven for 24 h of aging to obtain a polyurethane.

[0066] Example 4

[0067] Polyurethane was prepared in a similar manner to Example 3, except that the pre-polymer was polytetrahydrofuran glycol-toluene diisocyanate pre-polymer (pre-PTMEG1000-TDI) with an NCO value (content of isocyanate group) of 5.91%.

[0068] Example 5

[0069] Polyurethane was prepared in a similar manner to Example 3, except that the pre-polymer was polytetrahydrofuran glycol-p-phenylene diisocyanate pre-polymer (pre-PTMEG1000-PPDI) with an NCO value (content of isocyanate group) of 5.64%.

[0070] Example 6

[0071] Polyurethane was prepared in a similar manner to Example 3, except that the pre-polymer was polytetrahydrofuran glycol-isophorone diisocyanate pre-polymer (pre-PTMEG1000-IPDI) with an NCO value (content of isocyanate group) of 5.73%.

[0072] Example 7

[0073] Polyurethane was prepared in a similar manner to Example 3, except that the pre-polymer was polytetrahydrofuran glycol-1,3-dimethyl isocyanate cyclohexane pre-polymer (pre-PTMEG1000-1,3-H6XDI) with an NCO value (content of isocyanate group) of 6.06%.

[0074] Example 8

[0075] The polyurethane was prepared in a similar manner as in Example 3, except that the prepolymer was polytetramethylene glycol-1,4-dimethyl isocyanate cyclohexane prepolymer (pre-PTMEG 1000-1,4-H6XDI) with an NCO value (content of isocyanate group) of 6.25%.

[0076] Example 9

[0077] Chain extension was performed using a high speed disperser. 60 g of polytetramethylene glycol-diphenylmethane diisocyanate prepolymer (pre-PTMEG 1000-MDI) with an NCO value (content of isocyanate group) of 5.48% was weighed into a fluorotetrafluoroethane flask and 5.48 g (38.02 mmol) of 1,3-cyclohexanedimethanol prepared in Example 2 was added at 110°C under high speed stirring at 2200 r / min. The chain extension reaction was stirred for 25 min, after which the product was transferred to a flat vulcanizing machine and cured at a temperature of 110°C, a pressure of 25 tons and a time of 1 h. Finally, the product was transferred to a 60°C oven for 24 h to obtain the polyurethane.

[0078] Example 10

[0079] The polyurethane was prepared in a similar manner as in Example 9, except that the prepolymer was polytetramethylene glycol-toluene diisocyanate prepolymer (pre-PTMEG 1000-TDI) with an NCO value (content of isocyanate group) of 5.91%.

[0080] Example 11

[0081] The polyurethane was prepared in a similar manner as in Example 9, except that the prepolymer was polytetramethylene glycol-isophorone diisocyanate prepolymer (pre-PTMEG 1000-IPDI) with an NCO value (content of isocyanate group) of 5.73%.

[0082] Example 12

[0083] The polyurethane was prepared in a similar manner as in Example 9, except that the prepolymer was polytetramethylene glycol-1,3-dimethyl isocyanate cyclohexane prepolymer (pre-PTMEG 1000-1,3-H6XDI) with an NCO value (content of isocyanate group) of 6.06%.

[0084] Example 13

[0085] The polyurethane was prepared in a similar manner as in Example 9, except that the prepolymer was polytetrahydrofuran glycol-1,4-dimethyl isocyanate cyclohexane prepolymer (pre-PTMEG1000-1,4-H6XDI) and the NCO value (content of isocyanate group) was 6.25%.

[0086] Test Example

[0087] The properties of the polyurethane prepared according to Examples 3-13 are shown in Table 1. Figures 7-8 Figure 7 The infrared spectrum of the polyurethane prepared by chain extension reaction with (2-chlorocyclohex-1-en-1,3-diyl) dimethanol as chain extender. Figure 8 The infrared spectrum of the polyurethane prepared by chain extension reaction with 1,3-cyclohexanedimethanol as chain extender. -1 at -NH characteristic vibration peak, 1720 cm -1 at C=O characteristic vibration peak, 2937 cm -1 , 2855 cm -1 at -CH2- and -CH3 characteristic vibration peak, 1531 cm -1 at C-N bending vibration absorption peak, 1238 cm -1 and 1105 cm -1 at -C-O-C- asymmetric stretching vibration absorption peak and symmetric stretching vibration absorption peak. The infrared spectrum analysis results show that the polyurethane material is successfully prepared.

[0088] The tensile strength and elongation at break of the polyurethane material sample were determined according to GB / T 528-2009, the test temperature was 20-25°C, the relative humidity was 44-50%, and the tensile rate was 200 mm / min. Figure 9 The tensile strength spectrum of the polyurethane prepared by chain extension reaction with (2-chlorocyclohex-1-en-1,3-diyl) dimethanol as chain extender. PTMEG1000-PPDI-Cl has the largest tensile strength of 32.9 MPa, lower elongation at break of 940.0%; PTMEG1000-1,4-H6XDI-Cl has the smallest tensile strength of 3.2 MPa and the largest elongation at break of 2658.9%; PTMEG1000-1,3-H6XDI-Cl has excellent tensile strength of 16.7 MPa and elongation at break of 1804.0% at the same time. Figure 10 ​The tensile strength spectrum of the polyurethane prepared by using 1,3-cyclohexanedimethanol as a chain extender for chain extension reaction. PTMEG1000-MDI-1,3-Cyclohexanedimethanol has the maximum tensile strength of 18.6 MPa and a lower elongation at break of 979.3%; PTMEG1000-1,4-H6XDI-1,3-Cyclohexanedimethanol has the minimum tensile strength of 3.2 MPa and the maximum elongation at break of 2269.2%; PTMEG1000-1,3-H6XDI-1,3-Cyclohexanedimethanol has excellent tensile strength of 14.9 MPa and elongation at break of 1797.7%.

[0089] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A novel cyclic diol, characterized in that, The structure of the novel cyclic diol is shown in formula (1):

2. A process for the preparation of novel cyclic diols as claimed in claim 1, characterized in that, The method comprises the following steps: S1, adding cyclohexanone into a mixed solution containing phosphorus oxychloride and N,N-dimethylformamide, and performing a heating reaction under nitrogen atmosphere protection, cooling to room temperature after the reaction is completed, freezing, and filtering to obtain an intermediate product in yellow solid; S2, adding the intermediate product obtained in step 1 into a methanol solution containing sodium acetate, adding sodium borohydride in batches under the condition of 0 DEG C to perform an ice bath reaction, removing the ice bath to continue the reaction at room temperature, then adding saturated ammonium chloride solution to terminate the reaction, and sequentially performing extraction, washing, drying, filtering, and concentrating on the obtained reaction solution to obtain a novel cyclic diol in white solid shown in formula (1).

3. The production method according to claim 2, characterized by, In S1, the mixed solution containing phosphorus oxychloride and N,N-dimethylformamide is obtained by reacting phosphorus oxychloride and N,N-dimethylformamide at 0 DEG C for 0.2 h to 1 h.

4. The production method according to claim 2, characterized by, In S1, the heating reaction is performed for 3 h to 6 h at a temperature of 50 DEG C to 80 DEG C. In S1, the volume ratio of the cyclohexanone, the phosphorus oxychloride, and the N,N-dimethylformamide is 1:4:

4.

5. The preparation method according to claim 2, characterized in that, In S2, the reaction solution is extracted with ethyl acetate, washed with saturated NH4Cl solution for 3 times, dried with anhydrous magnesium sulfate, filtered, and concentrated to obtain the novel cyclic diol shown in formula (1).

6. The preparation method according to claim 2, characterized in that, In S2, the molar ratio of the intermediate product, the sodium borohydride, and the sodium acetate is 1:(2.0-2.4):(2.0-2.4). In S2, the ice bath reaction is performed for 1 h to 2 h, and the room temperature reaction is performed for 1 h to 2 h. In S2, the molar ratio of the sodium borohydride and the methanol is 1:(15-20). In S2, the amount of sodium borohydride added in each batch is 10% of the total mass of sodium borohydride.

7. A process for the preparation of a cyclic diol, characterized in that, The preparation method comprises the following steps: (1) adding the novel cyclic diol in claim 1 into a methanol solution containing sodium acetate, and adding Pd / C catalyst to react under the condition of a hydrogen pressure of 0.20 MPa to 0.25 MPa and a temperature of 20 DEG C to 30 DEG C; (2) removing the Pd / C catalyst from the reaction solution obtained in step (1), placing it in ice water, adding sodium borohydride in batches to react, removing the ice bath to continue the reaction at room temperature, then adding saturated NH4Cl solution to terminate the reaction, sequentially performing extraction, washing, drying, filtering, and concentrating on the obtained reaction solution, and obtaining a cyclic diol in white liquid shown in formula (2) through column chromatography; 8. The preparation method according to claim 7, characterized in that, In step (1), the mass ratio of the novel cyclic diol and the Pd / C catalyst is 1:(0.05-0.1). In step (1), the mass content of Pd in the Pd / C catalyst is 10%.

9. The preparation method according to claim 7, characterized in that, In step (2), the reaction solution is extracted with ethyl acetate, washed with saturated NH4Cl solution for 3 times, dried with anhydrous magnesium sulfate, filtered, and concentrated, and a diol monomer in white liquid shown in formula II is obtained through column chromatography. In step (2), the molar ratio of the novel cyclic diol, sodium borohydride and sodium acetate is 1: (2.0-2.4): (2.0-2.4); In step (2), column chromatography uses a normal phase silica gel column, and the eluent is ethyl acetate: n-hexane with a volume ratio of (1-3): 1; In step (2), the molar ratio of sodium borohydride and methanol is 1: (15-20). In step (2), the amount of sodium borohydride added in each batch is 10% of the total mass of sodium borohydride.

10. Use of the novel cyclic diol according to claim 1, or the cyclic diol prepared by the method according to any one of claims 7-9, as a chain extender for preparing polyurethane.

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