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Method for preparing 1,4-dimethylnaphthalene

A technology of dimethylnaphthalene and diphenylphosphine, which is applied in the field of preparation of 1,4-dimethylnaphthalene, can solve the problems of difficult separation of isomers, expensive materials, harsh reaction conditions, etc., and achieves production cost Low effect, single reaction site, short synthetic route

Active Publication Date: 2017-10-20
LIER CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the invention of the present invention is: when adopting the methylation route to synthesize 1,4-dimethylnaphthalene, the separation of isomers is difficult, industrialization is difficult, and has no industrial value, while the ring-closing route synthesizes 1,4-dimethylnaphthalene For naphthalene, some of the reaction conditions are harsh, the materials involved are expensive, highly toxic, high-risk, the total yield is not high, the cost is high, and the industrialization is difficult. A preparation method for 1,4-dimethylnaphthalene is provided

Method used

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  • Method for preparing 1,4-dimethylnaphthalene
  • Method for preparing 1,4-dimethylnaphthalene

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] First add 39.4g (0.2mol) of 1,4-dichloronaphthalene, 220mg of bis(triphenylphosphine)nickel dichloride, and 200mL of trimethylbenzene to the reaction flask in sequence; , slowly add 134 mL (0.4 mol) of methylmagnesium chloride tetrahydrofuran solution dropwise, heat up to 150 ° C for 16 hours after the drop, distill and recover the solvent, then add 100 mL of petroleum ether and 120 mL of water for extraction and phase separation; distill the organic phase obtained by extraction and separation to recover petroleum Ether, further water pump vacuum distillation to collect the fraction at 165°C, which is 1,4-dimethylnaphthalene, a total of 28.7g of the product was obtained, the content was 98%, and the yield was 90.1%. 1 H NMR (400MHz, deuterated acetone), 7.975(dd, J=6.4Hz, 3.2Hz, 2H), 7.498(dd, J=6.4Hz, 3.2Hz, 2H), 7.173(s, 2H), 2.590(s , 6H).

[0034] The content is determined by the area normalization method.

Embodiment 2

[0036]First add 57.2g of 1,4-dibromonaphthalene, 200mg of bis(triphenylphosphine)nickel dichloride, and 200mL of xylene to the reaction flask in sequence; Methylmagnesium bromide 2-methyltetrahydrofuran solution 167mL, after dripping, raise the temperature to 95°C for 18h, distill and recover the solvent, then add 100mL of petroleum ether and 120mL of water for extraction and phase separation; distill the organic phase obtained by extraction and separation to recover petroleum ether, Further, the fraction at 165°C was collected by water pump vacuum distillation, which was 1,4-dimethylnaphthalene, and a total of 30 g of the product was obtained with a content of 98% and a yield of 94.2%.

[0037] According to the method for embodiment 2, catalyst, temperature parameter have been screened, and the results are shown in table 1 below:

[0038] Table 1

[0039]

catalyst

temperature

solvent

Format reagent dosage

yield

Example 2

Bis(triphenylp...

Embodiment 10

[0044] Replace the reaction bottle with nitrogen, add NiCl to the bottle 2 ·6H 2 O 0.1g, stirred with 1mL of ethanol to obtain a green clear liquid; then added 200mL of toluene and 0.23g of triphenylphosphine, stirred to obtain a dark green liquid; then added 57.2g of 1,4-dibromonaphthalene, and slowly dropped under control at -10°C Add 167mL of methylmagnesium bromide 2-methyltetrahydrofuran solution, heat up to 105°C and react for 12h after dripping, distill to recover the solvent, then add 100mL of petroleum ether and 120mL of water for extraction and phase separation; distill the organic phase to recover petroleum ether, and further reduce the pressure of the water pump The distilled fraction at 165°C was 1,4-dimethylnaphthalene, and a total of 30.3 g of the product was obtained with a content of 98% and a yield of 95.1%.

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Abstract

The invention discloses a method for preparing 1,4-dimethylnaphthalene and belongs to the field of organic synthesis. The method aims at solving the problems during the synthesis of the 1,4-dimethylnaphthalene by a methylation route that isomers are high in separation difficulty, difficult in industrialization and free of industrialization value, and the problems during the synthesis of the 1,4-dimethylnaphthalene by a ring-closing route that partial reaction conditions are harsh, involved materials are high in price, high in toxicity and high in risk, the total yield is low, the cost is high, and the difficulty of industrialization is high. According to the method, the 1,4-dimethylnaphthalene is prepared from 1,4-dihalonaphthalene and a methyl magnesium halide Grignard reagent, which serve as main raw materials, in the presence of a nickel-phosphonium complex and a solvent. The method disclosed by the invention has the advantages of readily available raw materials, short synthesis route, mild reaction conditions and low cost, is applicable to industrial production and application and has a relatively high industrial application value. Meanwhile, the product prepared by the method is high in purity, stable in quality and high in yield and content and has a relatively high economic value.

Description

technical field [0001] The invention relates to the field of chemical industry, especially the field of organic synthesis, and specifically relates to a preparation method of 1,4-dimethylnaphthalene. Background technique [0002] 1,4-Dimethylnaphthalene is a high value-added fine chemical product, mainly used in the fields of plant growth regulators and fluorescent whitening agents. In addition, 1,4-naphthalene dicarboxylic acid obtained by oxidation of 1,4-dimethylnaphthalene is an important intermediate in the fields of pigments, resins, fuels, and medicine, and can be used as a mixed material additive for clothing materials and high-strength container materials and other materials fields (references, fuel and dyeing, Liu Bing et al., 2017, Vol. 54, p. 36). [0003] At present, there are two main synthesis routes of 1,4-dimethylnaphthalene reported in the literature: methylation route and ring closure route. Among them, for the methylation route, the content disclosed in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C15/24C07C1/32
CPCC07C1/326C07C2531/24C07C15/24
Inventor 曾柏清任杰彭启才周志成范谦
Owner LIER CHEM CO LTD
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