Preparation process of high trans o-tert-butyl cyclohexanol

Abstract

The invention relates to the technical field of organic synthesis, and discloses a preparation process of high trans o-tert-butyl cyclohexanol, which is characterized in that o-tert-butyl phenol is used as a raw material, palladium on carbon is used as a catalyst, and o-tert-butyl cyclohexanol is prepared through catalytic hydrogenation reaction; the method specifically comprises the steps of raw material input, catalyst addition, reaction condition control, sampling detection and the like, the content of trans-o-tert-butyl cyclohexanol in the product reaches 45% or above by precisely regulating and controlling the reaction temperature, the hydrogen pressure and the reaction time, and the total purity of the product reaches 99.9%. According to the invention, palladium on carbon is used as a core catalyst, the catalytic activity is high, the selectivity is strong, the generation proportion of trans-isomers is effectively improved, the process steps are simple, the operation is controllable, and the method is suitable for industrial large-scale production.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a process for preparing high-trans-o-tert-butylcyclohexanol. Background Technology

[0002] o-tert-butylcyclohexanol is an important organic chemical intermediate widely used in fragrances, coatings, rubber additives, and other fields. It exists in cis and trans isomers, with trans-o-tert-butylcyclohexanol exhibiting superior performance in specific applications (such as high-end fragrance synthesis and high-performance coating preparation) due to its more stable spatial structure. Therefore, there is an urgent market demand for o-tert-butylcyclohexanol with high trans content.

[0003] In existing technologies, the preparation of o-tert-butylcyclohexanol is mostly achieved through catalytic hydrogenation of o-tert-butylphenol as a raw material. However, traditional processes suffer from poor catalyst selectivity, low trans isomer content (usually below 40%), and insufficient product purity. Furthermore, some processes require complex reaction systems or harsh reaction conditions to increase the trans isomer content, leading to increased production costs and difficulties in industrialization. Therefore, developing a preparation method with strong catalyst selectivity, high trans isomer content, and simple process is of significant practical importance. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a preparation process for high trans-tert-butylcyclohexanol, which solves the problems of low trans isomer content and poor catalyst performance in the existing process, and achieves efficient preparation of high trans content and high purity of o-tert-butylcyclohexanol.

[0005] To achieve the above objectives, the present invention employs the following technical solution: To achieve the above objectives, the present invention provides the following technical solution: a preparation process for high trans-o-tert-butylcyclohexanol, comprising the following steps: (1) Raw material input: Turn on the o-tert-butylphenol transfer pump and put 3 tons of metered o-tert-butylphenol into the reactor; accurately measure 3 tons with the metering pump, turn on the o-tert-butylphenol transfer pump and put it into the clean and dry reactor at a uniform speed; the reactor has been purged with nitrogen beforehand to remove the internal air and avoid oxygen from interfering with the reaction. (2) Catalyst addition: The pre-prepared palladium-on-carbon catalyst is added into the reactor. The palladium-on-carbon catalyst has extremely high catalytic hydrogenation activity and special selectivity for the formation of trans isomers, which is the core of this process to achieve high trans content. (3) Reaction start-up: Turn on the stirring device of the reactor, introduce steam for heating, and control the temperature inside the reactor; close the feed port of the reactor, turn on the stirring device, and control the stirring rate at 100-300 r / min to ensure that the raw materials and catalyst are in full contact; at the same time, introduce steam to heat the reactor, and stabilize the temperature inside the reactor at 150-170℃ through the temperature control system. This temperature range can ensure that the reaction proceeds efficiently and promote the formation of trans isomers. (4) Hydrogenation reaction: Hydrogen gas is introduced into the reactor to maintain the reaction system pressure at 0.4 MPa and the reaction continues; when the temperature in the reactor reaches the set value, high-purity hydrogen gas (purity ≥99.9%) is introduced into the reactor at a rate of 0.5-1.0 m³ / h to maintain the reaction system pressure at 0.4 MPa; under the action of palladium on carbon catalyst, o-tert-butylphenol undergoes catalytic hydrogenation reaction, the benzene ring is reduced to cyclohexane ring, and o-tert-butylcyclohexanol is generated; during the reaction, the mixture is continuously stirred to ensure that the hydrogen gas and the reaction liquid are in full contact and to avoid incomplete local reaction; (5) Product detection and termination: After the reaction is completed, samples are taken for testing. When the total content of o-tert-butylcyclohexanol is ≥99.9% and the content of trans-o-tert-butylcyclohexanol is ≥45%, the reaction is stopped to obtain a high trans-o-tert-butylcyclohexanol product. After the reaction continues for 9-10 hours, hydrogen flow and heating are stopped, and samples are taken for detection by gas chromatography. When the test results show that the total content of o-tert-butylcyclohexanol is ≥99.9% and the content of trans-o-tert-butylcyclohexanol is ≥45%, the reaction is deemed qualified, stirring is stopped, the reaction product is exported, and the finished product is obtained after subsequent separation and purification (such as filtration to recover the catalyst, distillation purification). If the test results do not meet the standards, the reaction time can be appropriately extended by 1-2 hours until the test results are qualified.

[0006] Furthermore, in step (2), the palladium loading in the palladium-on-carbon catalyst is 5-10 wt%.

[0007] Furthermore, in step (2), the amount of catalyst used is 0.5-1.0% of the mass of o-tert-butylphenol.

[0008] Furthermore, in step (3), the stirring rate is 100-300 r / min, and the stirring process continues until the reaction is complete.

[0009] Furthermore, in step (3), the temperature inside the reactor is controlled to be 150-170℃.

[0010] Furthermore, in step (4), the hydrogen purity is ≥99.9%, and the hydrogen introduction rate is 0.5-1.0 m / s. 3 / h.

[0011] Furthermore, in step (4), the reaction time is 9-10 hours.

[0012] Furthermore, in step (5), gas chromatography is used to detect the product content.

[0013] Compared with the prior art, the present invention has the following beneficial technical effects: In this technical solution, palladium on carbon is used as the core catalyst. Combined with a reaction temperature of 150-170℃ and a hydrogen pressure of 0.4MPa, the content of trans-tert-butylcyclohexanol is stably maintained at over 45%, and can be increased to a maximum of 50%, far exceeding the trans-content level of traditional processes, meeting the needs of high-end applications. By precisely controlling the reaction conditions and raw material purity, the total content of trans-tert-butylcyclohexanol in the product reaches 99.9%, with extremely low impurity content, eliminating the need for complex subsequent purification processes, thus reducing production energy consumption and costs. The selected palladium on carbon catalyst has high catalytic activity and strong selectivity, and can efficiently catalyze the hydrogenation reaction of trans-tert-butylphenol. Moreover, the catalyst is easy to recover and reuse, further reducing production costs and conforming to the development concept of green chemistry. This process is simple, with mild reaction conditions, convenient operation, and easy to realize large-scale industrial production. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1 A process for preparing high-trans-o-tert-butylcyclohexanol includes the following steps: Raw material input: o-tert-butylphenol was selected, and 3 tons were metered by a metering pump. The transfer pump was turned on and the 3 tons were fed into the reaction vessel after nitrogen purging at a uniform speed. Catalyst addition: Palladium on carbon catalyst with a palladium loading of 5 wt% was added to the reactor. The amount of catalyst used was 0.5% of the mass of o-tert-butylphenol. Reaction start-up: Turn on the stirring device at a stirring rate of 100 r / min, introduce steam for heating, and stabilize the temperature inside the reactor at 150℃; Hydrogenation reaction: 99.9% pure hydrogen gas is introduced at a rate of 0.5 m³ / h, the reaction system pressure is maintained at 0.4 MPa, and the reaction is continued for 9 hours; Product detection and termination: After the reaction was completed, samples were taken and detected by gas chromatography. The results showed that the total content of o-tert-butylcyclohexanol was 99.9%, of which the content of trans-o-tert-butylcyclohexanol was 45.0% and the content of cis-butylcyclohexanol was 54.9%. The reaction was qualified. The product was filtered and the catalyst was recovered to obtain the finished product.

[0016] Example 2 A process for preparing high-trans-o-tert-butylcyclohexanol includes the following steps: Raw material input: o-tert-butylphenol was selected, and 3 tons were metered by a metering pump. The transfer pump was turned on and the 3 tons were fed into the reaction vessel after nitrogen purging at a uniform speed. Catalyst addition: Palladium on carbon catalyst with a palladium loading of 8 wt% was added to the reactor. The amount of catalyst used was 0.8% of the mass of o-tert-butylphenol. Reaction start-up: Turn on the stirring device at a stirring rate of 200 r / min, introduce steam for heating, and stabilize the temperature inside the reactor at 160℃; Hydrogenation reaction: 99.9% pure hydrogen gas is introduced at a rate of 0.8 m³ / h, the reaction system pressure is maintained at 0.4 MPa, and the reaction is continued for 9.5 hours; Product detection and termination: After the reaction was completed, samples were taken and detected by gas chromatography. The results showed that the total content of o-tert-butylcyclohexanol was 99.9%, of which the content of trans-o-tert-butylcyclohexanol was 48.5% and the content of cis-butylcyclohexanol was 51.4%. The reaction was qualified. The product was filtered and the catalyst was recovered to obtain the finished product.

[0017] Example 3 A process for preparing high-trans-o-tert-butylcyclohexanol includes the following steps: Raw material input: o-tert-butylphenol was selected, and 3 tons were metered by a metering pump. The transfer pump was turned on and the 3 tons were fed into the reaction vessel after nitrogen purging at a uniform speed. Catalyst addition: Palladium on carbon catalyst with a palladium loading of 10 wt% was added to the reactor. The amount of catalyst used was 1.0% of the mass of o-tert-butylphenol. Reaction start-up: Turn on the stirring device at a stirring rate of 300 r / min, introduce steam for heating, and stabilize the temperature inside the reactor at 170℃; Hydrogenation reaction: 99.9% pure hydrogen gas is introduced at a rate of 1.0 m³ / h, the reaction system pressure is maintained at 0.4 MPa, and the reaction is continued for 10 hours; Product detection and termination: After the reaction was completed, samples were taken and detected by gas chromatography. The results showed that the total content of o-tert-butylcyclohexanol was 99.9%, of which the content of trans-o-tert-butylcyclohexanol was 50.0% and the content of cis-butylcyclohexanol was 49.9%. The reaction was qualified. The product was filtered and the catalyst was recovered to obtain the finished product.

[0018] Comparative Example 1 (using a conventional nickel-based catalyst) Raw material input: Same as in Example 1, 3 tons of o-tert-butylphenol were selected and added to the reaction vessel after nitrogen purging; Catalyst addition: Add nickel-based catalyst (nickel loading 20 wt%), the amount of catalyst being 2.0% of the mass of o-tert-butylphenol; Reaction start-up: Turn on the stirring device, stir at a speed of 200 r / min, introduce steam to heat to 190℃ and stabilize the temperature; Hydrogenation reaction: 99.5% pure hydrogen gas is introduced, the reaction pressure is maintained at 0.8 MPa, and the reaction continues for 14 hours; Product testing: Samples were taken after the reaction was completed and tested. The total content of o-tert-butylcyclohexanol was 98.3%, of which the content of trans-o-tert-butylcyclohexanol was 35.7% and the content of cis-butylcyclohexanol was 62.6%. The product contained 0.8% residual o-tert-butylphenol and a small amount of byproducts such as cyclohexane and cyclohexanol (total impurity content 1.7%).

[0019] Comparative Example 2 (using a low-load palladium-on-carbon catalyst) Raw material input: Same as in Example 2, 3 tons of o-tert-butylphenol were selected and added to the reaction vessel after nitrogen purging; Catalyst addition: A conventional palladium-on-carbon catalyst with a palladium loading of 2 wt% was added, and the amount of catalyst was 1.5% of the mass of o-tert-butylphenol; Reaction start-up: Turn on the stirring device, stir at a speed of 200 r / min, heat to 160℃ and stabilize the temperature; Hydrogenation reaction: 99.9% pure hydrogen gas is introduced, the reaction pressure is maintained at 0.4 MPa, and the reaction is continued for 15 hours; Product testing: Samples were taken after the reaction was completed and tested. The total content of o-tert-butylcyclohexanol was 99.2%, of which the content of trans-o-tert-butylcyclohexanol was 38.2% and the content of cis-butylcyclohexanol was 61.0%. The catalyst could not be recycled and reused due to severe carbon buildup.

[0020] Comparative Example 3 (using conventional reaction conditions) Raw material input: Same as in Example 3, 3 tons of o-tert-butylphenol were used and put into the reactor (without nitrogen purging). Catalyst addition: Palladium on carbon catalyst with a palladium loading of 8 wt% was added, and the amount of catalyst was 0.8% of the mass of o-tert-butylphenol; Reaction start-up: Turn on the stirring device, stir at 80 r / min, heat to 180℃ and stabilize the temperature; Hydrogenation reaction: 99.9% pure hydrogen gas is introduced at a rate of 0.3 m³ / h, the reaction pressure is maintained at 0.3 MPa, and the reaction is continued for 12 hours; Product testing: Samples were taken after the reaction was completed and tested. The total content of o-tert-butylcyclohexanol was 98.7%, of which the content of trans-o-tert-butylcyclohexanol was 36.5% and the content of cis-butylcyclohexanol was 62.2%. A small amount of oxidized impurities (1.3%) were generated in the product due to oxygen interference, which required additional distillation purification, reducing the yield to 85%.

[0021] Comparing the experimental data of the above examples and comparative examples, it can be seen that the trans-o-tert-butylcyclohexanol content in Examples 1-3 of the present invention reaches more than 45%, with a maximum of 50.0%, while the trans content in Comparative Examples 1-3 is only 35.7%-38.2%, significantly lower than the level of the present invention. This indicates that the high-load palladium-on-carbon catalyst and optimized reaction conditions selected in the present invention can effectively improve the selectivity of the trans isomer. The total purity of the products in the examples is ≥99.9%, with no obvious by-products generated. In contrast, due to insufficient catalyst performance or improper reaction conditions, the purity of the products in the comparative examples is only 98.3%-99.2%, and there are residual raw materials, oxidation impurities, or ring-opening by-products, requiring additional purification and increasing production costs. The reaction cycle of the present invention is only 9-10 hours, and the reaction temperature (150-170℃) and pressure (0.4MPa) are mild, resulting in low energy consumption. In contrast, the reaction cycle of the comparative examples is as long as 12-15 hours, and Comparative Example 1 requires reaction at a higher temperature (190℃) and pressure (0.8MPa), significantly increasing energy consumption. The palladium-on-carbon catalyst used in this invention is only 0.5%-1.0% of the mass of o-tert-butylphenol; while the low-load palladium-on-carbon catalyst in Comparative Example 2 cannot be recovered, and the nickel-based catalyst in Comparative Example 1 is 2-4 times that of this invention, resulting in significantly higher catalyst costs. In summary, this invention, by optimizing the catalyst system (high-load palladium-on-carbon catalyst), precisely controlling reaction conditions and raw material pretreatment processes, solves the problems of low trans-content, insufficient product purity, high energy consumption, and poor catalyst economy in existing technologies. It achieves efficient and low-cost preparation of high-trans-content, high-purity o-tert-butylcyclohexanol, making it more suitable for large-scale industrial applications.

[0022] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0023] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0024] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A process for the preparation of high trans-ortho-tert-butylcyclohexanol, characterized in that, The method comprises the following steps: (1) raw material feeding: open the o-t-butyl phenol delivery pump, and feed 3 tons of metered o-t-butyl phenol into a reaction kettle; (2) catalyst adding: feed the prepared palladium-carbon catalyst into the reaction kettle; (3) reaction starting: open the stirring device of the reaction kettle, and pass steam to heat and control the temperature in the reaction kettle; (4) hydrogenation reaction: pass hydrogen into the reaction kettle, maintain the pressure of the reaction system at 0.4 MPa, and continuously react; (5) product detection and termination: after the reaction is completed, sample detection is performed, when the total content of o-t-butyl cyclohexanol is greater than or equal to 99.9% and the content of trans-o-t-butyl cyclohexanol is greater than or equal to 45%, the reaction is stopped, and the high-trans o-t-butyl cyclohexanol product is obtained.

2. The process for the preparation of high trans-ortho-tert-butylcyclohexanol according to claim 1, characterized in that, In the step (2), the loading amount of palladium in the palladium-carbon catalyst is 5-10 wt%.

3. The process for the preparation of high trans-ortho-tert-butylcyclohexanol according to claim 1, characterized in that, In the step (2), the catalyst dosage is 0.5-1.0% of the mass of the o-t-butyl phenol.

4. The process for the preparation of high trans-ortho-tert-butylcyclohexanol according to claim 1, characterized in that, In the step (3), the stirring rate is 100-300 r / min, and the stirring process is continuously performed until the reaction is completed.

5. The process for the preparation of high trans-ortho-tert-butylcyclohexanol according to claim 1, characterized in that, In the step (3), the temperature in the reaction kettle is controlled at 150-170 °C.

6. The process for the preparation of high trans-ortho-tert-butylcyclohexanol according to claim 1, characterized in that, The purity of hydrogen is ≥99.9% and the rate of hydrogen flow is 0.5-1.0 m 3 / h.

7. The process for the preparation of high trans-ortho-tert-butylcyclohexanol according to claim 1, characterized in that, In the step (4), the continuous reaction time is 9-10 hours.

8. The process for the preparation of high trans-ortho-tert-butylcyclohexanol according to claim 1, characterized in that, In the step (5), the product content is detected by using gas chromatography.