Preparation method for synthesizing high-purity cyclopentanol from cyclopentanone
A two-step process combining Raney nickel catalytic hydrogenation and metal borohydride reduction with distillation produces high-purity cyclopentanol, addressing inefficiencies in existing methods by achieving 99.5% purity and reducing costs.
Patent Information
- Application Number
- CN202310671441.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-08
- Publication Date
- 2024-12-10
AI Technical Summary
Existing methods for synthesizing cyclopentanol are inefficient and environmentally harmful, and current methods fail to produce high-purity cyclopentanol, with aromatic smells. The existing methods are costly, have low yield, and involve complex separation procedures, making them unsuitable for industrial-scale production.
A two-step process using Raney nickel for catalytic hydrogenation followed by metal borohydride reduction and reduced pressure distillation to produce high-purity cyclopentanol, achieving a GC normalized purity of more than 99.5%.
The method achieves high-purity cyclopentanol with a normalized purity of 99.5% through the combination of Raney nickel and metal borohydride reduction, reducing costs and simplifying the separation process.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of medicine and chemical technology, and specifically relates to a method for preparing high-purity cyclopentanol by synthesizing cyclopentanone. Background Art
[0002] Cyclopentanol is also known as cyclohexylpentanol and hydroxycyclopentane, with the molecular formula of C5H 10 O, the appearance is colorless viscous liquid, with aromatic smell. Cyclopentanol is an important solvent, and also an intermediate of medicine, pesticide and fragrance. It can be used to prepare halogenated cyclopentane, cyclopentylthiazide, a drug for treating edema and hypertension, and ketamine, a new non-barbital intravenous anesthetic. Cyclopentanol is also an important fine chemical raw material, widely used in the field of synthetic rubber. Cyclopentanol only exists in a small amount in elderberry juice and Chinese cochinchinensis oil, but it is difficult to extract, so industrial synthesis of cyclopentanol has become the main source.
[0003] The main production processes of cyclopentanol include adipic acid method, cyclopentene hydration method, cyclopentane method, etc. The adipic acid method uses adipic acid as raw material, and obtains cyclopentanone by high-temperature decarboxylation. Cyclopentanone is hydrogenated under the action of a catalyst to obtain cyclopentanol. The production process of cyclopentanol enterprises in my country mainly adopts the adipic acid method. Although this method is mature in technology, has a high yield, low product purity, and high raw material cost. The preparation of cyclopentanol by cyclopentene hydration requires the use of a large amount of acidic catalysts, the single-pass conversion rate is not high, and the subsequent separation procedures involve complex procedures. The process of preparing cyclopentanol by cyclopentane oxidation method, but the oxidation conversion rate and selectivity are poor, and the content of raw material cyclopentane in the C5 fraction (a mixture of hydrocarbons containing five carbon atoms produced as a by-product in the process of petroleum cracking to produce ethylene) is low, and the resulting oxidation product has complex composition, difficult separation, and no industrial value. In summary, it is necessary to develop an environmentally friendly, high-conversion, and high-purity process route for synthesizing high-purity cyclopentanol from cyclopentanone. Summary of the invention
[0004] Through a large number of experiments on the synthesis of cyclopentanol from cyclopentanone, it was found that expensive platinum carbon and palladium carbon do not have a good catalytic hydrogenation reduction effect on this reaction, while the reduction effect of metal borohydride alone is good, the post-processing is troublesome, and the cost is too high. The cheap Raney nickel is reversible as a catalyst, that is, it can reduce the keto group to the hydroxyl group and dehydrogenate the hydroxyl group to the keto group. The object of the present invention is to provide a preparation method for synthesizing high-purity cyclopentanol from cyclopentanone, which is achieved by combining metal catalytic hydrogenation reduction and metal borohydride-assisted reduction to obtain high-purity cyclopentanol with a GC normalized purity of more than 99.5%. The invention has the following advantages: firstly, cheap Raney nickel is used to catalytically hydrogenate and reduce more than 99% of the cyclopentanone raw material, the catalyst Raney nickel is used and circulated, and the remaining 1% of the cyclopentanone raw material is reduced by metal borohydride, so that the amount of metal borohydride used is very small, the cost is not increased, and the reverse dehydrogenation reaction of Raney nickel is inhibited; due to the thorough reaction, the GC normalized purity of the cyclopentanol is high; then, reduced pressure distillation is performed to remove the residual nickel metal impurities and trace impurities; finally, high-purity cyclopentanol with a GC normalized purity of more than 99.5% is obtained.
[0005] In order to solve the above technical problems, the technical solution of the present invention is: a method for preparing high-purity cyclopentanol with a GC normalized purity of more than 99.5% by synthesizing cyclopentanone, comprising the following steps: 1) Add reaction solvent, cyclopentanone and metal catalyst into the autoclave, replace with nitrogen, then introduce hydrogen and control the hydrogen pressure at 7-10 kg, maintain the temperature at 30-70°C for reaction, and use Raney nickel to catalyze hydrogenation to reduce ≥99% of cyclopentanone; 2) After the hydrogen pressure stops decreasing, the reaction is maintained for 30 minutes, the temperature is lowered to 10°C to 30°C, the material is discharged, and the catalyst is filtered out; 3) Add a certain amount of potassium borohydride or sodium borohydride to the filtrate, keep it at 50℃~90℃ for a period of time, and use sodium borohydride or potassium borohydride to completely reduce the remaining small amount of cyclopentanone; 4) The reaction liquid is distilled under reduced pressure to obtain cyclopentanol with a GC normalized purity of more than 99.5%.
[0006] The cyclopentanone used in the present invention is an industrial bulk raw material that can be purchased from the market; Raney nickel is a solid heterogeneous catalyst composed of fine grains of nickel-aluminum alloy with a porous structure, which is usually used as a hydrogenation catalyst for organic compounds and can be used for hydrogenation reduction reactions of compounds containing unsaturated bonds such as aldehydes and ketones. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figure 1 It is the GC spectrum of the cyclopentanone raw material used in the present invention.
[0008] Figure 2 , 3 , 4 are GC spectra of cyclopentanol prepared by the present invention. DETAILED DESCRIPTION
[0009] In order to make the purpose, technical scheme and advantages of the present invention clearer, the preferred embodiments of the present invention are described in detail below. It should be understood that the embodiments are only for illustrating the present invention, not for limiting the protection scope of the present invention. GC is the abbreviation of gas chromatography; FID is the full name of flame ionization detector, which is a high-sensitivity universal detector. It responds to almost all organic substances, but has no response or very small response to inorganic substances, inert gases or substances that do not dissociate in flames.
[0010] Example 1: 42.0 g of cyclopentanone (GC normalized content 99.95%, see Figure 1 ), 3.3g of Raney nickel, 100g of methanol, nitrogen was introduced to replace air 3 times, and then hydrogen was introduced, the hydrogen pressure was controlled to 7 kg, the reaction temperature was controlled at 30°C, and the reaction was maintained for 30 minutes until the hydrogen pressure no longer decreased, and Raney nickel was first used for catalytic hydrogenation to reduce ≥99% of cyclopentanone; after nitrogen replacement, the temperature was lowered to 10°C to 30°C, and the catalyst was filtered out; 0.4g of sodium borohydride was added to the filtrate to control the reaction temperature at 50°C for 2 hours to reduce the remaining small amount of cyclopentanone; the reaction solution was vacuum distilled to obtain 41.2g of cyclopentanol, 99.755% purity by GC normalization method, 0.07% residual cyclopentanone, and a molar yield of 95.6%, see Figure 2 .
[0011] Example 2: 42.0 g of cyclopentanone (GC normalized content 99.95%, see Figure 1 ), 3.3g of Raney nickel, 110g of ethanol, nitrogen was introduced to replace air 3 times, and then hydrogen was introduced, the hydrogen pressure was controlled to 10 kg, the reaction temperature was controlled at 60°C, and the reaction was maintained for 30 minutes until the hydrogen pressure no longer decreased, and Raney nickel was first used for catalytic hydrogenation to reduce ≥99% of cyclopentanone; after nitrogen replacement, the temperature was lowered to 10°C to 30°C, and the catalyst was filtered out; 0.4g of sodium borohydride was added to the filtrate to control the reaction temperature at 80°C for 2 hours to reduce the remaining small amount of cyclopentanone; the reaction solution was vacuum distilled to obtain 41.0g of cyclopentanol, 99.61% purity by GC normalization method, 0.104% residual cyclopentanone, and a molar yield of 95.1%. Figure 3 .
[0012] Example 3: 42.0 g of cyclopentanone (GC normalized content 99.95%, see Figure 1), 3.4g of Raney nickel, nitrogen was introduced to replace air 3 times, and then hydrogen was introduced, the hydrogen pressure was controlled to 9 kg, the reaction temperature was controlled at 70°C, and the reaction was maintained for 45 minutes until the hydrogen pressure no longer decreased, and Raney nickel was first used for catalytic hydrogenation to reduce ≥99% of cyclopentanone; after nitrogen replacement, the temperature was lowered to 10°C to 30°C, and the catalyst was filtered out; 0.5g of potassium borohydride was added to the filtrate to control the reaction temperature at 90°C for 2.5 hours to reduce the remaining small amount of cyclopentanone; the reaction solution was vacuum distilled to obtain 40.9g of cyclopentanol, 99.529% purity by GC normalization method, 0.224% residual cyclopentanone, and a molar yield of 94.7%. Figure 4 .
[0013] As can be seen from the above embodiments, the preparation method of synthesizing cyclopentanol from cyclopentanone disclosed in the present invention can produce high-purity cyclopentanol with a gas phase normalization purity of more than 99.5%. The above preferred embodiments are only used to illustrate the technical scheme of the present invention but not to limit it. Although the present invention has been described in detail through the above preferred embodiments, it should be understood by those skilled in the art that any various changes made to it in form and detail are within the scope defined by the claims of the present invention.
Claims
1. A method for preparing high-purity cyclopentanol from cyclopentanone, characterized in that The keto reduction reaction is carried out by combining Raney nickel catalytic hydrogenation and metal borohydride-assisted reduction, and then vacuum distillation is performed to obtain high-purity cyclopentanol with a GC normalized purity of more than 99.5%.
2. The method according to claim 1, characterized in that The following steps are used to synthesize high-purity cyclopentanol with a purity of more than 99.5% by GC normalization method: 1) Add the reaction solvent and cyclopentanone into the autoclave, replace with nitrogen, then introduce hydrogen and control the hydrogen pressure at 7-10 kg, maintain the temperature at 30-70°C for reaction, and use Raney nickel to catalyze hydrogenation to reduce ≥99% of the cyclopentanone; 2) After the hydrogen pressure stops decreasing, the reaction is maintained for 30 minutes, the temperature is lowered to 10°C to 30°C, the material is discharged, and the catalyst is filtered out; 3) Add a certain amount of metal borohydride to the filtrate, keep it at 50℃~90℃ for a period of time, and use the metal borohydride to completely reduce the remaining small amount of cyclopentanone; 4) The reaction liquid is distilled under reduced pressure to obtain high-purity cyclopentanol with a purity of more than 99.5% according to GC normalization method.
3. The method according to claim 1, 2, characterized in that The solvent used in the metal catalytic hydrogenation process is ethanol, methanol or the reaction system itself.
4. The method according to claim 1, 2, characterized in that The metal borohydrides used are sodium borohydride and potassium borohydride.
5. The method according to claim 1, 2, characterized in that GC column: Hp-1 (30m*320um*1.0um) or column with equivalent column efficiency, injection volume: 0.2ul, injection port: 300℃, column flow rate: 1.0ml / min, split ratio 100:1; column box: initial temperature 40℃, retain for 5min, increase to 130℃ at 5℃ / min, maintain for 0min, then increase to 250℃ at 30℃ / min, maintain for 4min, detector (FID): 300℃.