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Preparation method of 2-methyl-1,3-pentadiene

A technology of pentadiene and methyl group, applied in the field of organic synthesis, can solve the problems such as restricting the production cost and market scale of privet aldehyde, difficult to achieve recovery and application of catalysts, poor selectivity of target products, etc., achieves superior catalytic performance, and avoids equipment corrosion. , the effect of high stability

Active Publication Date: 2020-11-13
SHANDONG NHU PHARMA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the price of elemental iodine is relatively expensive, and the industrial production cost of catalytic diol dehydration to prepare mixed dienes is relatively high
[0011] In summary, the existing method for preparing 2-methyl-1,3-pentadiene has high catalyst price and poor target product selectivity, The operation process is complicated, the catalyst is highly acidic and corrosive to the equipment, and the catalyst is difficult to realize recycling and other shortcomings, which seriously restrict the production cost and market scale of privetal. Therefore, a new high selectivity, simple operation, economical and environmental protection is developed. Catalysts for the preparation of 2-methyl-1,3-pentadiene are of great significance

Method used

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  • Preparation method of 2-methyl-1,3-pentadiene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] Weigh 100g of the carrier Al-H-ZSM-5, put it into a muffle furnace, bake it at 200°C for 4 hours, and let it cool naturally for later use.

[0052] Weigh 10g of Al-H-ZSM-5, add it to 60mL deionized water, slowly add 5mL of 0.266g / mL H 2 PtCl 6 The solution was stirred at 50°C for 8 hours, dried in an oven at 70°C for 12 hours, and calcined at 600°C in air for 2 hours. Finally, 5%wt.Pt / Al-H-ZSM-5 catalyst can be obtained by sodium borohydride reduction for 3 hours at 50℃.

[0053] Using the same impregnation method as above, changing the types and ratios of active components, carriers or catalyst aids to prepare catalysts loaded with other active components or catalyst aids. In addition, the catalysts supported by HKUST-1, MIL-100, MIL-101, MIL-125, MOF-901, and Uio-66 were adsorbed and dried in an oven at 70°C for 24 hours, and then directly reduced. The results are shown in Table 1. All the other operations are the same as in Example 1, see Table 1 for details.

...

Embodiment 2

[0058] 5%wt. Pt / Al-H-ZSM-5 catalyzes the dehydration reaction of 2-methyl-2,4-pentanediol, as follows: In a 250mL three-necked flask, add 100g of 2-methyl-2,4-pentanediol Alcohol, 5g5%wt.Pt / Al-H-ZSM-5, 0.6g anhydrous ferric chloride, start stirring at 400 rpm, and heat to 130°C. Total reflux for 10 minutes, the temperature at the top of the tower is 73°C~75°C, and the extraction starts, and the reflux ratio is 5. After cumulative reaction rectification for 3 hours, the temperature was lowered to stop the reaction. The collected product was separated from water and dried and weighed 66.71g, with a purity of 99.2% and a diene yield of 95.3%. (The molar ratio of 2-methyl-1,3-pentadiene and 4-methyl-1,3-pentadiene in the product detected by gas chromatography is 9.3:0.7.) The catalyst was obtained by filtering the liquid in the tower kettle, and recovered Then continue to apply to the next batch of reactions.

Embodiment 3-10

[0060] Performance comparison of different catalysts for the dehydration of 2-methyl-2,4-pentanediol to 2-methyl-1,3-pentadiene and 4-methyl-1,3-pentadiene . Except that the reaction temperature is slightly adjusted, other operations are the same as in Example 2. The results are shown in Table 2.

[0061] Table 2 The results of the investigation of the catalytic performance of different catalysts

[0062]

[0063] Note: The yield in Table 2 is the sum of the yields of 2-methyl-1,3-pentadiene and 4-methyl-1,3-pentadiene.

[0064] It can be seen from the results in Table 2 that the catalysts with better catalytic effects are 5%wt.Pt / Al-H-ZSM-5, 5%wt.Pd / H-ZSM-5, 5%wt.Re / HKUST- 1. 3%wt.Pd / MIL-101, 3%wt.Pt / MIL-100.

[0065] The total yield is multiplied by the proportion of 2-methyl-1,3-pentadiene, which is the yield of 2-methyl-1,3-pentadiene.

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Abstract

The invention relates to a preparation method of 2-methyl-1,3-pentadiene. The preparation method comprises the following steps: in the presence of a supported metal catalyst and a catalyst assistant,carrying out a dehydration reaction on 2-methyl-2,4-pentanediol to obtain 2-methyl-1,3-pentadiene. According to the method, strong acid is not used as a catalyst, so the selectivity of a product is effectively improved, higher yield can be obtained, the problem of equipment corrosion is avoided, the service life of equipment is prolonged, environmental protection benefits are remarkable, and the method is environment-friendly. The 2-methyl-1,3-pentadiene prepared by the method is high in selectivity and high in yield, the generation of a byproduct, namely 4-methyl-1,3-pentadiene is effectivelyreduced, the cyclic application of the catalyst is realized, and the industrial large-scale production of ligustral is facilitated.

Description

technical field [0001] The invention belongs to the field of organic synthesis and relates to a method for preparing high-proportion 2-methyl-1,3-pentadiene by dehydrating 2-methyl-2,4-pentanediol. Background technique [0002] Liguinal aldehyde has a strong grassy and grassy aroma, which can be used in daily chemical fragrance formulations, especially in soaps, synthetic detergents, and cosmetic fragrance formulations, to increase the freshness and diffusion of fragrances. At present, the global demand is about 2,000 tons per year, and it is an important fragrance raw material. [0003] 2-Methyl-1,3-pentadiene is an important intermediate for the preparation of privetal, which can be prepared by Diles-Alder reaction with acrolein. Therefore, the preparation of 2-methyl-1,3-pentadiene is particularly important in the synthesis of privetal. [0004] Industrially, 2-methyl-1,3-pentadiene is mainly obtained by dehydration of 2-methyl-2,4-pentanediol, and the dehydration of 2-...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C1/24C07C11/12B01J29/48B01J31/22
CPCB01J29/48B01J31/1691C07C1/24B01J2229/18C07C11/12Y02P20/10Y02P20/584
Inventor 马慧娟马啸李庆辉宦关生于明姜晓阳黄珊珊
Owner SHANDONG NHU PHARMA
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