A method for converting β-phellandrene into α-terpinene

Abstract

The present invention discloses a method for converting β-phellandrene into α-terpinene. The method comprises adding β-phellandrene or turpentine containing β-phellandrene, a catalyst trimethylsilyl bromide, and an auxiliary agent H2O2 or H2O in a certain proportion to a reaction apparatus, heating and stirring the reaction, washing with water to remove unreacted trimethylsilyl bromide and H2O2, and separating the water layer to obtain α-terpinene or turpentine containing α-terpinene. When H2O2 is used as the reaction auxiliary agent, the β-phellandrene conversion rate is 88.4% and the α-terpinene selectivity is 94.0%. When H2O is used as the reaction auxiliary agent, the β-phellandrene conversion rate is 78.6% and the α-terpinene selectivity is 85.5%.

Description

Technical Field

[0001] The present invention relates to a method for converting the structure of monoterpene, in particular to a method for converting beta-phellandrene into alpha-terpinene. Background Art

[0002] β-Phellandrene is a monocyclic monoterpene olefin with the chemical name 1-methylene-4-isopropyl-2-cyclohexene. Its structural formula is shown below. β-Phellandrene is found in several natural plants, such as water fennel, Canada balsam, slash pine, Simao pine, Caribbean pine, wet pine, and slat pine. Its content in slat pine turpentine can reach over 70%, while its content in some Simao pine and slash pine turpentines is approximately 3%. Since turpentine is the most abundant natural essential oil, β-phellandrene is abundant in natural reserves. Isolating it from turpentine is an important method for its preparation. With its peppermint-like and light citrus aromas, β-phellandrene is an important spice and also a highly effective natural insecticide.

[0003] α-Terpinene is also a monocyclic monoterpene olefin, chemically known as 1-methyl-4-isopropyl-1,3-cyclohexadiene, with the structural formula shown below. α-Terpinene is also found naturally in plants such as cardamom, oregano, and coriander. However, due to the relatively low planting area of ​​these plants and their widespread use as edible herbs, natural reserves of α-terpinene are relatively low. α-Terpinene for industrial applications is primarily derived from chemical synthesis. The most common process involves catalytic isomerization of α-pinene using catalysts such as concentrated sulfuric acid, heteropolyacids, and solid superacids. The product is typically a mixture of various dipentene products. α-Terpinene selectivity is relatively low, typically exceeding 40%, and production efficiency needs to be further improved. α-Terpinene has a citrus aroma and is used as a fragrance. Furthermore, due to its excellent reactivity, it is also a key raw material for the synthesis of other chemical products, such as ascaridole and terpene resins, and holds broad application prospects.

[0004] In summary, the conversion of β-phellandrene, which has relatively more abundant natural reserves, into α-terpinene has important research and application value.

[0005] Summary of the Invention

[0006] The present invention provides a method for converting β-phellandrene into α-terpinene, which is also applicable to the conversion of β-phellandrene in turpentine products containing β-phellandrene components.

[0007] The specific embodiment of the present invention is as follows: β-phellandrene or turpentine containing β-phellandrene, a catalyst and an auxiliary agent are added to a reaction device, stirred at a certain temperature for sufficient reaction, and post-processed to remove unreacted catalyst and auxiliary agent to obtain α-terpinene or turpentine containing α-terpinene.

[0008] The turpentine containing β-phellandrene includes turpentine with β-phellandrene as the main component, such as pine turpentine, and turpentine with β-phellandrene as a minor component, such as Simao pine turpentine, slash pine turpentine, Caribbean pine turpentine, wet-added pine turpentine, etc.

[0009] The catalyst is a water-soluble acidic compound, such as trimethylsilyl bromide, p-toluenesulfonic acid, sulfuric acid, etc.; the auxiliary agent is hydrogen peroxide or water.

[0010] The amount of the catalyst is 1% to 5% of the amount of the raw material, and the amount of the auxiliary agent is 1 to 3 times the amount of the raw material.

[0011] The reaction temperature is 60-100°C.

[0012] The reaction time is 1 to 16 hours.

[0013] The post-treatment refers to a water washing method.

[0014] Beneficial effects

[0015] 1. The present invention provides a novel process for preparing α-terpinene. Compared with existing processes, it offers advantages such as low raw material costs, high reaction efficiency, and simple operation. Furthermore, the addition of a reaction aid suppresses the side reactions that can easily occur when acidic compounds are directly catalyzed, thereby improving the selectivity of α-terpinene in the product. When H₂O₂ is used as the reaction aid, the β-phellandrene conversion rate is 88.4% and the α-terpinene selectivity is 94.0%. When H₂O is used as the reaction aid, the β-phellandrene conversion rate is 78.6% and the α-terpinene selectivity is 85.5%.

[0016] 2. The present invention provides a new utilization method for β-phellandrene and turpentine (expanded turpentine) with β-phellandrene as the main component.

[0017] 3. The process of the present invention can efficiently convert β-phellandrene in turpentine into α-terpinene without substantially affecting other components, and then obtain a high-purity α-terpinene product while separating other components through distillation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Structural characterization of β-phellandrene, a is 1 H NMR, b is 13C NMR, c GC-MS. The purity of the compound is 93.1%. The C and H numbers are as shown in the background art. 1 H NMR (CDCl3, 500MHz): δ, 0.93 (3H, s, C -9 -H)、0.94(3H,s,C- 10 -H), 1.28 (1H, m, C -5 -H-1), 1.44 (1H, m, C -5 -H-2), 1.68 (1H, m, C -8 -H), 2.31 (1H, m, C -6 -H-1), 2.49 (1H, m, C -6 -H-2), 4.74 (1H, s, C -7 -H-1), 4.78 (1H, d, J = 10Hz, C -7 -H-2), 5.78 (1H, d, J = 10Hz, C -3 -H), 6.18 (1H, d, J = 10Hz, C -2 -H); 13 C NMR (CDCl3, 125MHz): δ, 19.50 (C -9 )、19.70(C -10 )、25.78(C -5 )、30.26(C -6 )、31.99(C -8 )、42.14(C -4 )、109.99(C -7 )、129.66(C -2 )、134.01(C -3 )、143.59(C -1 ); GC-MS: m / z calcd. 136.1, found 136.2.

[0019] Figure 2 Structural characterization of α-terpinene, a is 1 H NMR, b is 13 C NMR, c GC-MS. The purity of the compound is 95.6%. The C and H numbers are as shown in the background art. 1 H NMR (CDCl3, 500MHz): δ, 1.07 (3H, s, C -9 -H), 1.09 (3H, s, C -10 -H), 1.82 (3H, s, C -7 -H), 2.15 (2H, s, C -6 -H), 2.15 (2H, s, C -5-H), 2.33 (1H, m, C -8 -H)、5.65(1H,s,C -3 -H)、5.67(1H,s,C -2 -H); 13 C NMR (CDCl3, 125MHz): δ, 21.18 (C -9 , C -10 )、22.87(C -7 )、25.29(C -5 )、29.02(C -6 )、34.52(C -8 )、116.50(C -3 )、119.61(C -2 )、132.95(C -1 )、142.29(C -4 ); GC-MS: m / z Required: 136.1, Found: 136.1. DETAILED DESCRIPTION

[0020] The present invention relates to a method for converting β-phellandrene into α-terpinene. β-phellandrene or turpentine containing β-phellandrene, a catalyst, and an auxiliary agent are added to a reaction device, stirred at a certain temperature for sufficient reaction, washed with water to remove unreacted catalyst and auxiliary agent, and the water layer is separated to obtain α-terpinene or turpentine containing α-terpinene.

[0021] The turpentine containing β-phellandrene includes turpentine with β-phellandrene as the main component, such as pine turpentine, and turpentine with β-phellandrene as a minor component, such as Simao pine turpentine, slash pine turpentine, Caribbean pine turpentine, wet-added pine turpentine, etc.

[0022] The catalyst is a water-soluble acidic compound, such as trimethylsilyl bromide, p-toluenesulfonic acid, sulfuric acid, etc.; the auxiliary agent is hydrogen peroxide or water.

[0023] The amount of the catalyst is 1% to 5% of the amount of the raw material, the amount of the auxiliary agent is 1 to 3 times the amount of the raw material; the reaction temperature is 60 to 100° C.; and the reaction time is 1 to 16 hours.

[0024] Example 1

[0025] 650 g of spreading pine turpentine (containing 63.1% β-phellandrene) was placed in a distillation flask and subjected to vacuum distillation under nitrogen protection with a controlled vacuum degree of -0.8 to -0.4 kPa. Fractions with different boiling points were collected in batches according to the change in top temperature. Each fraction was analyzed by GC, and fractions with similar composition were combined to obtain 238.6 g of β-phellandrene with a purity of 93.1%.

[0026] Example 2

[0027] 13.6 g (0.1 mol) of β-phellandrene (the same below) obtained in Example 1 and 0.002 mol of trimethylsilyl bromide (TMSBr) were added to a reaction flask and stirred at 100°C for 3 hours. Gas chromatography analysis showed a β-phellandrene conversion rate of 88.7% and an α-terpinene selectivity of 61.2%.

[0028] Example 3

[0029] 0.1 mol of β-phellandrene, 0.002 mol of TMSBr, and 0.1 mol of H2O2 (30%, the same below) were added to a reaction flask and stirred at 100°C for 1 hour. Gas chromatography analysis showed that the conversion rate of β-phellandrene was 64.3% and the selectivity of α-terpinene was 78.3%.

[0030] Example 4

[0031] The reaction time was 6 hours, and the other processes were the same as in Example 3. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 91.6%, and the selectivity of α-terpinene was 80.4%.

[0032] Example 5

[0033] The amount of TMSBr used was 0.005 mol, and the other processes were the same as in Example 4. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 93.8%, and the selectivity of α-terpinene was 74.0%.

[0034] Example 6

[0035] The amount of H2O2 used was 0.3 mol, and the other processes were the same as in Example 4. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 88.4%, and the selectivity of α-terpinene was 94.0%.

[0036] Example 7

[0037] The reaction temperature was 60° C., the amount of H 2 O 2 was 0.3 mol, and the other processes were the same as in Example 4. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 40.6%, and the selectivity of α-terpinene was 84.4%.

[0038] Example 8

[0039] The catalyst was p-toluenesulfonic acid in an amount of 0.001 mol, and the other processes were the same as in Example 6. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 70.9%, and the selectivity of α-terpinene was 73.7%.

[0040] Example 9

[0041] The reaction time was 12 h, and the other processes were the same as in Example 8. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 93.2%, and the selectivity of α-terpinene was 60.9%.

[0042] Example 10

[0043] The catalyst was concentrated sulfuric acid in an amount of 0.005 mol, the reaction temperature was 100°C, and the reaction time was 16 hours. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 78.5% and the selectivity of α-terpinene was 47.3%.

[0044] Example 11

[0045] The reaction auxiliary agent was H2O in an amount of 0.3 mol, the reaction temperature was 100°C, and the reaction time was 6 h. Gas chromatography analysis results showed that the conversion rate of β-phellandrene was 78.6% and the selectivity of α-terpinene was 85.5%.

[0046] Example 12

[0047] The reaction was carried out without a catalyst, with 0.3 mol of H2O2, a temperature of 100°C, and a reaction time of 3 h. Gas chromatography analysis showed that the conversion of β-phellandrene was 2.3%, and no α-terpinene was detected.

[0048] Example 13

[0049] The raw material was pine turpentine, in which the β-phellandrene content was 63.1%, the feed amount was 13.6 g (0.1 mol), and the other reaction processes were the same as in Example 6. Gas chromatography analysis results showed that the β-phellandrene conversion rate was 85.7% and the α-terpinene selectivity was 80.1%.

[0050] Example 14

[0051] The raw material is Simao pine turpentine, wherein the β-phellandrene content is 3.2%, the feed amount is 13.6 g (0.1 mol), and the other reaction processes are the same as those in Example 6. The gas chromatography analysis results show that the β-phellandrene conversion rate is 78.2% and the α-terpinene selectivity is 76.0%.

[0052] Example 15

[0053] The raw material was slash pine turpentine, wherein the β-phellandrene content was 3.5%, the feed amount was 13.6 g (0.1 mol), and the other reaction processes were the same as in Example 6. Gas chromatography analysis results showed that the β-phellandrene conversion rate was 77.6% and the α-terpinene selectivity was 74.9%.

Claims

1. A method for converting β-phellandrene into α-terpinene, characterized by: β-phellandrene or turpentine containing β-phellandrene, a catalyst and an auxiliary agent are added to a reaction device, stirred at a certain temperature for sufficient reaction, and post-processed to remove unreacted catalyst and auxiliary agent to obtain α-terpinene or turpentine containing α-terpinene; the catalyst is any one or more of trimethylsilyl bromide and p-toluenesulfonic acid, and the auxiliary agent is hydrogen peroxide or water.

2. The method for converting β-phellandrene into α-terpinene according to claim 1, wherein The turpentine containing β-phellandrene includes any one or more of pine turpentine, Simao pine turpentine, slash pine turpentine, Caribbean pine turpentine and wet-added pine turpentine.

3. The method for converting β-phellandrene into α-terpinene according to claim 1, wherein The amount of the catalyst is 1% to 5% of the amount of the raw material, and the amount of the auxiliary agent is 1 to 3 times the amount of the raw material.

4. The method for converting β-phellandrene into α-terpinene according to claim 1, wherein The reaction temperature is 60-100°C.

5. The method for converting β-phellandrene into α-terpinene according to claim 1, wherein The reaction time is 1 to 16 hours.

6. The method for converting β-phellandrene into α-terpinene according to claim 1, wherein Post-processing refers to water washing.

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