Farnesene composite polymerization inhibitor and use method thereof

Abstract

The invention provides a farnesene composite polymerization inhibitor and a use method thereof, and the farnesene composite polymerization inhibitor comprises five components: a quinone methyl compound, a phenolic compound, substituted 2, 2, 6, 6-tetramethylpiperidine-1-oxygen free radical, citric acid and a solvent isopropyl myristate. Wherein the retarder is a quinone methyl compound and a phenolic compound, the true polymerization inhibitor is substituted 2, 2, 6, 6-tetramethylpiperidine-1-oxygen free radical, the synergist is citric acid, the solvent is isopropyl myristate, the quinone methyl compound is small in toxicity, the synergist is low in price, and the environmental protection property and economical efficiency of the polymerization inhibitor can be effectively improved. According to the invention, the induction period of the polymerization inhibitor can be effectively prolonged, farnesene oxides and dimers are reduced, the formation of high polymers is blocked, the rectification yield of farnesene is improved, and the polymerization inhibitor has good polymerization inhibition and environmental protection properties. The composite polymerization inhibitor provided by the invention is used in the rectification process of farnesene, and can be popularized to the transportation, storage and use processes of farnesene so as to improve the purity of farnesene.

Description

Technical Field

[0001] The invention belongs to the technical field of polymerization inhibitors, and particularly relates to a farnesene composite polymerization inhibitor and a use method thereof. Background Art

[0002] Most of the rubbers currently used by people, except natural rubber, are synthesized from olefin monomers extracted from petroleum. In order to reduce the dependence of synthetic rubber on unsustainable petrochemical resources, many scholars at home and abroad have focused on terpene compounds, among which farnesene belongs to chain sesquiterpenes, and its polymer is an important type of bio-based synthetic rubber that can replace natural rubber and conjugated diene rubber. In addition, farnesene is also used in many fields such as fragrances, medicine, fuel and agriculture.

[0003] As fermentation technology matures, it will become more and more convenient to obtain farnesene, and the cost will also become lower. However, there are few studies on the separation of farnesene, and how to obtain the monomer is still the focus of attention. Due to its diene structure, active chemical properties and high boiling point, farnesene is very easy to self-polymerize and copolymerize during distillation and storage. In order to reduce the polymerization loss of farnesene during the distillation process and ensure the normal operation of the distillation system, it is necessary to add an inhibitor during the distillation process to increase the yield of farnesene and realize the low-cost industrial production of farnesene.

[0004] According to the different inhibitory effects, polymerization inhibitors are divided into true polymerization inhibitors and retarders. True polymerization inhibitors can produce a long induction period, during which free radicals can be terminated and polymerization is completely stopped, so basically no polymer is produced during the induction period. Once the induction period ends, a large amount of polymer begins to be produced. Therefore, the use of true polymerization inhibitors has the potential safety hazards of being easily consumed by free radicals, having a short service life, and causing monomer explosion. The chemical properties of retarders are relatively stable, and the failure of the polymerization inhibition process is less, but only a part of the free radicals is terminated, which slows down the polymerization reaction. During use, no obvious induction period is produced, so the content of polymer has been slowly increasing. In order to overcome the shortcomings of the above two polymerization inhibitors, domestic and foreign scholars have used true polymerization inhibitors and retarders in combination, which can not only extend the polymerization induction period, but also reduce the polymerization rate after the induction period, thereby reducing the polymer and achieving a synergistic effect. The optimization of the composite polymerization inhibitor system has become the focus of polymerization inhibitor development, and the development of efficient, low-cost and easy-to-operate polymerization inhibitors has become a trend today.

[0005] Therefore, it is urgent to develop a farnesene complex polymerization inhibitor with good polymerization inhibition and environmental protection under high temperature conditions. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] The invention provides a farnesene composite polymerization inhibitor and a use method thereof, so as to solve the technical problem of effectively prolonging the induction period of the polymerization inhibitor and improving the farnesene distillation yield.

[0008] (II) Technical solution

[0009] In order to solve the above technical problems, the present invention provides a farnesene composite polymerization inhibitor, which includes five components: a quinone methide compound, a phenolic compound, a substituted 2,2,6,6-tetramethylpiperidin-1-oxyl free radical, citric acid and a solvent isopropyl myristate.

[0010] Furthermore, in parts by mass, the quinone methide compound is 5 to 50 parts, the phenolic compound is 5 to 30 parts, the substituted 2,2,6,6-tetramethylpiperidin-1-oxyl free radical is 1 to 20 parts, the citric acid is 1 to 10 parts, and the isopropyl myristate is 100 parts.

[0011] Furthermore, the quinone methide compound is one or more of 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one, 4-methylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one, and 4-methylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one-7-carboxylic acid.

[0012] Furthermore, the phenolic compound is one or more of tert-butylhydroquinone, p-tert-butylcatechol, and 2,5-di-tert-butylhydroquinone.

[0013] Furthermore, the substituted 2,2,6,6-tetramethylpiperidine-1-oxyl free radical is one or more of 4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, and 4-carboxyl-2,2,6,6-tetramethylpiperidine-1-oxyl free radical.

[0014] In addition, the present invention also provides a method for preparing the farnesene composite polymerization inhibitor. The preparation method comprises the following steps: mixing the four components in proportion, adding the mixture to a solvent, and stirring the mixture to uniformly dissolve the mixture at room temperature.

[0015] In addition, the present invention also provides a method for using the farnesene composite polymerization inhibitor, which uses the farnesene composite polymerization inhibitor in the distillation process of farnesene.

[0016] Furthermore, the farnesene composite inhibitor is used in the negative pressure high temperature distillation process of farnesene.

[0017] Furthermore, during the distillation process, the amount of the farnesene composite polymerization inhibitor used is 0.002% to 1.0% of the mass of the farnesene monomer.

[0018] Furthermore, the vacuum degree during the distillation process is 0.005-0.1Mpa, and the distillation temperature is 20-180°C.

[0019] (III) Beneficial effects

[0020] The present invention proposes a farnesene composite inhibitor and a method of use, comprising five components, namely, a quinone methide compound, a phenolic compound, a substituted 2,2,6,6-tetramethylpiperidine-1-oxyl free radical, citric acid and a solvent, isopropyl myristate. Among them, the retarder is a quinone methide compound and a phenolic compound, the true inhibitor is a substituted 2,2,6,6-tetramethylpiperidine-1-oxyl free radical, the synergist is citric acid and the solvent is isopropyl myristate, the quinone methide compound has low toxicity, the synergist is low in price, and the environmental protection and economy of the inhibitor can be effectively improved. The present invention can effectively extend the induction period of the inhibitor, reduce farnesene oxide and dimer, block the formation of polymers, improve the distillation yield of farnesene, and has good inhibitory and environmental protection properties. The composite inhibitor of the present invention is used in the farnesene distillation process, and can be extended to the application of the transportation, storage and use process of farnesene to improve the purity of farnesene. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The impurity contents of farnesenol, farnesene dimer, polymer, etc. at different times in Example 2 and Comparative Example 2. DETAILED DESCRIPTION

[0022] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0023] Embodiments 1 to 5

[0024] A (quinone methide compound), B (phenolic compound), C (substituted 2,2,6,6-tetramethylpiperidin-1-oxyl free radical), D (citric acid) and E (solvent isopropyl myristate) are mixed in proportion and fully stirred and dissolved at room temperature. Then, they are added into a four-necked flask together with the farnesene extract, a condenser is added above the four-necked flask, and the air in the system is replaced with nitrogen for 5 to 10 minutes to reduce the oxygen content in the flask. Then, the system is sealed, and the four-necked flask is placed in a constant temperature heater for heating. The temperature is kept constant at 150°C for a certain period of time, and samples are taken to analyze the content of impurities such as farnesene, farnesenol, farnesene dimer, and polymer in the product.

[0025] The amount of polymer generated was determined by the weight method: using the property that the polymer is insoluble in methanol, sufficient dry methanol was added to the sample to completely precipitate the polymer, and then filtered, dried, weighed, and constant weight was obtained to obtain the mass of the generated polymer. The experimental results are shown in Table 1, where the proportion of each group of inhibitors is the mass fraction ratio; the amount of inhibitor added refers to the mass fraction of the composite inhibitor to farnesene, where the mass of farnesene is 100 parts.

[0026] The concentrations of farnesene, farnesenol and farnesene dimer in the distillate were determined by gas chromatography. A certain volume of farnesene distillate was added to n-hexane for dilution and determination. The inhibitory effects of different components and ratios of inhibitors in Examples 1 to 5 are shown in Table 1.

[0027] Table 1 Inhibition effect of different components and ratios of inhibitors in Examples 1 to 5

[0028]

[0029]

[0030] It can be seen from Table 1 that under the high-temperature distillation condition of 150°C, the composite inhibitor exhibits a good inhibitory effect and the polymer content is low.

[0031] Embodiments 6 to 11

[0032] According to the process described in Examples 1 to 5, the polymerization inhibitor was prepared and added to farnesene, and kept at 150°C for 3 hours. The content of impurities such as farnesene, farnesenol, farnesene dimer, and polymer in the product was calculated based on the following: 20 parts of 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one, 10 parts of tert-butylhydroquinone, 2 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical, 5 parts of citric acid, and 100 parts of isopropyl myristate. The change of the polymerization inhibition effect with the dosage of different polymerization inhibitors is shown in Table 2.

[0033] Table 2 Comparison of inhibition effect at different dosages

[0034]

[0035] Comparative Example 1

[0036] 4-Methylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one was used as a polymerization inhibitor for comparison.

[0037] Comparative Example 2

[0038] The polymerization inhibitor is obtained by mixing 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical and p-tert-butylcatechol in a mass ratio of 1:10.

[0039] The polymerization inhibitors in Examples 1-2 and Comparative Examples 1-2 were added into a farnesene experimental device to examine the polymerization inhibition effect.

[0040] The polymerization inhibitor was added at 0.3% of the mass of farnesene, and the temperature was kept constant at 150°C for 7 hours. The impurity contents of farnesene, farnesenol, farnesene dimer, polymer, etc. in the product were sampled and analyzed. The results are shown in Table 3.

[0041] It can be seen from Table 3 that the high-efficiency and environmentally friendly polymerization inhibitor of the present invention has a significantly better polymerization inhibition effect on farnesene than 4-methylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one at the same concentration; the polymerization inhibitor provided by the present invention has a similar polymerization inhibition effect to the polymerization inhibitor of Comparative Example 2, but has low toxicity and is relatively environmentally friendly.

[0042] Table 3 Performance of the inhibitors of Examples 1 to 2 and Comparative Examples 1 to 2

[0043]

[0044] The inhibitors in Example 2 and Comparative Example 2 were added to the farnesene experimental device to evaluate the retarding performance of the inhibitor and the effect of the inhibitor on the emergency shutdown of the farnesene distillation device. 0.1% of the inhibitor was added to 150g of farnesene, and the solution was poured into a 250mL three-necked flask and a stirring magnet was added; nitrogen was passed through, and the mixture was stirred and heated for 8h. When heated to 150°C, the timing was started and about 10mL of the sample was taken out from the mouth of the flask with a syringe. Thereafter, 10mL of the sample was taken every 1 hour to measure the impurity content of farnesenol, farnesene dimer, polymer, etc., and the results are listed in Table 4.

[0045] Table 4 Inhibition performance of the inhibitors of Example 2 and Comparative Example 2 at different times

[0046]

[0047] According to Table 4, a dotted line comparison diagram of the impurity contents of farnesenol, farnesene dimer, polymer, etc. at different times in the system containing the polymerization inhibitor of Example 2 and Comparative Example 2 is drawn, as shown in FIG. Figure 1 Combining Table 4 and Figure 1 It can be seen that the retarding performance of Example 2 is significantly better than the combined use effect of Comparative Example 2.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A farnesene composite polymerization inhibitor, characterized in that: The farnesene composite inhibitor comprises five components, namely, a quinone methyl compound, a phenolic compound, a substituted 2,2,6,6-tetramethylpiperidin-1-oxyl free radical, citric acid and a solvent, isopropyl myristate.

2. The farnesene composite polymerization inhibitor according to claim 1, characterized in that In parts by mass, the composition comprises 5 to 50 parts of quinone methide compound, 5 to 30 parts of phenolic compound, 1 to 20 parts of substituted 2,2,6,6-tetramethylpiperidin-1-oxyl free radical, 1 to 10 parts of citric acid and 100 parts of isopropyl myristate.

3. The farnesene composite polymerization inhibitor according to claim 1, characterized in that The quinone methide compound is one or more of 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one, 4-methylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one, and 4-methylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one-7-carboxylic acid.

4. The farnesene composite polymerization inhibitor according to claim 1, characterized in that The phenolic compound is one or more of tert-butylhydroquinone, p-tert-butylcatechol and 2,5-di-tert-butylhydroquinone.

5. The farnesene composite polymerization inhibitor according to claim 1, characterized in that The substituted 2,2,6,6-tetramethylpiperidine-1-oxyl free radical is one or more of a 4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, a 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, and a 4-carboxyl-2,2,6,6-tetramethylpiperidine-1-oxyl free radical.

6. A method for preparing the farnesene composite polymerization inhibitor according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: mixing the four components in proportion, adding the mixture into a solvent, and fully stirring the mixture at room temperature to uniformly dissolve the mixture.

7. A method for using the farnesene composite polymerization inhibitor according to any one of claims 1 to 5, characterized in that: The farnesene composite polymerization inhibitor is used in the distillation process of farnesene.

8. The method for using the farnesene composite polymerization inhibitor according to claim 7, characterized in that: The farnesene composite polymerization inhibitor is used in the negative pressure high temperature distillation process of farnesene.

9. The method for using the farnesene composite polymerization inhibitor according to claim 8, characterized in that: During the distillation process, the amount of the farnesene composite inhibitor used is 0.002% to 1.0% of the mass of the farnesene monomer.

10. The method for using the farnesene composite polymerization inhibitor according to claim 8, characterized in that: The vacuum degree during the distillation process is 0.005-0.1Mpa, and the distillation temperature is 20-180°C.

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