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Preparation method of 3, 5-dimethylphenol

A technology of dimethylphenol and isophorone, which is applied in the field of preparation of 3,5-dimethylphenol, can solve the problem of short life, unmentioned chromium-nickel alloy steel catalyst preparation method, tubular reactor material and tube diameter and other parameters, low yield and other problems, to achieve the effect of short reaction time, easy processing and high conversion rate

Inactive Publication Date: 2015-02-18
RONGCHENG QINGMU CHEM MATERIALS
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Disadvantages: The catalyst has a short life due to deactivation due to carbon deposition
However, the preparation method of the chromium-nickel alloy steel catalyst, the material and diameter of the tubular reactor and other parameters are not mentioned in the literature.
In addition, the yield of 3,5-dimethylphenol is also low, etc.

Method used

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  • Preparation method of 3, 5-dimethylphenol

Examples

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preparation example Construction

[0017] A kind of preparation method of 3,5-xylenol, adopts stainless steel tubular reactor, with isophorone as raw material, with halogenated aliphatic hydrocarbon as homogeneous catalyst, thiophene or dimethyl sulfide or its mixture is Anti-coking agent. The halogenated aliphatic hydrocarbon contains 1 to 6 carbon atoms, and the halogen can be iodine, chlorine and bromine. such as methyl iodide (CH 3 I), ethyl iodide (C 2 h 5 I) carbon tetrachloride (CCl 4 ), 1-bromobutane (CH 3 -CH 2 -CH 2 -CH 2 -Br), allyl bromide (CH 2 =CH-CH 2 Br), ethyl bromide (CH 3 -CH 2 Br) and dibromoethane (CH 2 Br-CH 2 Br) etc. The present invention preferably uses methyl iodide and ethyl bromide.

[0018] The aromatization dehydrogenation reaction of the isophorone of the present invention is carried out in a stainless steel tubular reactor with a total length of 80m and a DN32mm. The specific operation is as follows: add a certain amount of catalysts methyl iodide and ethyl bromid...

Embodiment 1

[0027] Example 1: Press figure 1 The route diagram for the preparation of 3,5-dimethylphenol (MX) is shown. Add 600 kg (4.35 kmol) of isophorone and 6 kg of homogeneous catalyst to the batching kettle, including 2 kg of methyl iodide, 4 kg of ethyl bromide, 3 kg of anti-coking agent dimethyl sulfide, mix and stir at room temperature for 10-15 min, the mixture flows into the stainless steel tubular reactor according to the feed flow rate of 150~200L / h, and is catalytically cracked at 550~560 ℃ for 3~4 hours. Under reduced pressure, 400 kg of the product was obtained by rectification under reduced pressure, the yield of 3,5-dimethylphenol (MX) was 75.6%, the conversion rate of isophorone was 98%, the selectivity of MX was 83.8%, and the content of MX was 98.5%.

Embodiment 2

[0028] Example 2: Proceed as shown in the roadmap for producing MX, add 600 kg (4.35 kmol) of isophorone (4.35 kmol) homogeneous catalyst 9 kg to the batching tank, including 3 kg of methyl iodide, 6 kg of ethyl bromide, and 3 kg of anti-coking agent thiophene kg, stirred at room temperature for 10-15 min, the mixture flowed into a stainless steel tubular reactor at a feed rate of 150-200 L / h, and was catalytically cracked at 550-560 °C for 3-4 h. Under the vacuum degree of -0.09~-0.098MPa, 420 kg of the product was obtained by rectification under reduced pressure, the yield of MX was 79.4%, the conversion rate of isophorone was 99%, the selectivity of MX was 85.3%, and the content of MX was 98.8%.

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Abstract

The invention provides a preparation method of 3, 5-dimethylphenol. According to the method, isophorone is taken as a raw material, halogenated aliphatic hydrocarbon is taken as a homogeneous catalyst, and a stainless steel tube reactor is used for preparing 3, 5-dimethylphenol (MX) through catalytic cracking under a high-temperature gas phase. A mixture containing isophorone, methyl iodide, a bromoethane catalyst, thiophene and a methyl disulfide anti-coking agent flows into the stainless steel tube reactor, and 3, 5-dimethylphenol is prepared through atmospheric pressure cracking at the high temperature of 550-650 DEG C. The catalyst and the anti-coking agent for the method are easy to obtain, the reaction has a few steps, and the environment is protected. Further, the conversion rate of isophorone is higher than 90%, and the yield of MX is higher than 75%.

Description

technical field [0001] The invention belongs to the field of fine chemicals, and in particular proposes a method for preparing 3,5-dimethylphenol by high-temperature aromatization of isophorone. Background technique [0002] 3,5-Dimethylphenol is an important organic synthesis intermediate and fine chemical raw material. It is mainly used to prepare various products such as antioxidants, phenolic resin adhesives, fungicides, and disinfectants. [0003] At present, there are four main production methods of 3,5-dimethylphenol: Coal tar washing oil fraction extraction method, this method requires large equipment investment and low yield; Phenol alkylation method, phenol is alkylated with methanol, the selectivity of this method is too low, and a variety of dimethylphenols are produced, which have very similar properties and are difficult to separate; m-xylene sulfonation method: the process is complicated, the equipment is corroded seriously, the three wastes are treated ...

Claims

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Application Information

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IPC IPC(8): C07C39/07C07C37/50
CPCC07C37/50
Inventor 刘玉美任相忠李维平刘晓波王芳芳孙燕超宋丽丽
Owner RONGCHENG QINGMU CHEM MATERIALS
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