Preparation method of m-fluorotoluene

A technology of m-fluorotoluene and fluorotoluene, which is applied in the field of preparation of fluorine-containing compounds, can solve the problems of many side reactions, product purity and yield reduction, and achieve the effects of avoiding separation and transfer, increasing yield, and reducing side reactions

Active Publication Date: 2012-11-21
山东福尔有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The above-mentioned preparation method has the following disadvantages: there are many side reactions in step 3, which reduce the purity and yield of the product. Typical side reaction products include reduction products (that is: hydrogen-substituted amino groups instead of fluorine-substituted amino groups), chlorinated aromatic Compounds, couple products (ie: biphenyl) and diazo tar, diazo tar refers to a mixture of polyaromatic compounds, in the above preparation method, sometimes diazo tar is the main product of the reaction

Method used

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  • Preparation method of m-fluorotoluene
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  • Preparation method of m-fluorotoluene

Examples

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Effect test

Embodiment 1

[0027] The preparation method of m-fluorotoluene of the present invention comprises the following steps:

[0028] 1. Salt forming step: Add 1 mol of m-toluidine dropwise to 2 mol of anhydrous hydrofluoric acid at a constant speed at 5-7°C. The dropping process is completed within 7 hours. Under the condition of insulation reaction for 1 hour, the mixture 1 was obtained;

[0029] 2. Diazotization step: Add 1 mol of sodium nitrite dropwise to mixture 1 at a constant speed under the condition of -3-0°C. The dropping process is completed within 8 hours. React for 1 hour to obtain mixture 2;

[0030] 3. Thermal decomposition step: thermally decompose the 2 mixture, and the thermal decomposition is divided into the following four stages:

[0031] The first stage is 6 hours in total, control the temperature at 0-20°C: control the temperature at 0-4°C in the first hour, control the temperature at 4-8°C in the second hour; control the temperature at 8-12°C in the third hour, and cont...

Embodiment 2

[0040] Prepare according to the preparation method of embodiment 1 mesofluorotoluene, only change the following parameters of the following steps of embodiment 1:

[0041] Salt-forming step: Add 1 mol of m-toluidine dropwise to 5 mol of anhydrous hydrofluoric acid at a constant speed at 5-7°C, the dropping process is completed within 10 hours, and keep warm at 5-7°C after the addition Reacted for 3 hours to obtain mixture 1;

[0042] Diazotization step: Add 1.5 mol of sodium nitrite dropwise to the mixture 1 at a constant speed under the condition of -3-0°C, the dropping process is completed within 10 hours, and then react under the condition of 0-3°C after the addition is completed 3 hours, to obtain mixture 2;

[0043]Recovery of waste hydrofluoric acid: Mix the waste acid with 3mol of 98% by mass sulfuric acid, distill, and the temperature in the still is from low to high, ensuring that the top temperature of the tower is at 40-45°C in the early stage, and the temperature ...

Embodiment 3

[0046] Prepare according to the preparation method of embodiment 1 mesofluorotoluene, only change the following parameters of the following steps of embodiment 1:

[0047] Salt-forming step: Add 1 mol of m-toluidine dropwise to 3.5 mol of anhydrous hydrofluoric acid at a constant speed at 5-7°C. The dropping process is completed within 9 hours. Under the insulation reaction for 2 hours, the mixture 1 was obtained;

[0048] Diazotization step: Add 1.5 mol of sodium nitrite dropwise to mixture 1 at a constant speed under the condition of -3-0°C, the dropping process is completed within 9 hours, and then react under the condition of 0-3°C after the addition is completed 2 hours, to obtain mixture 2;

[0049] Recovery of waste hydrofluoric acid: Mix the waste acid with 3mol of 98 mass% sulfuric acid, distill, and the temperature in the distillation pot is from low to high, ensuring that the top temperature of the tower is 40-45°C in the early stage, and the temperature of the top...

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Abstract

The invention relates to a preparation method of m-fluorotoluene, and the preparation method has the advantages of fewer steps, high yield and high purity of the obtained product. The preparation method of m-fluorotoluene provided by the invention comprises the following steps: (1) salt formation step: anhydrous hydrofluoric acid and m-toluidine are mixed at a mole ratio of (2-5):1 to obtain a mixture 1 through dripping the whole m-toluidine into anhydrous hydrofluoric acid within 7-10 hours at a constant rate and then reacting for 1-3 hours at 5-7 DEG C; (2) diazotization step: sodium nitrate is dripped into the mixture 1 at a mole ratio of sodium nitrate to m-toluidine in the salt formation step of (1-1.5):1 to obtain a mixture 2 through dripping the whole sodium nitrate into the mixture 1 within 8-10 hours at a constant rate and then reacting for 1-3 hours at 0-3 DEG C; and (3) thermal decomposition step: the mixture 2 is heated to decompose at 0-50 DEG C.

Description

technical field [0001] The invention relates to a preparation method of fluorine-containing compounds, in particular to a preparation method of m-fluorotoluene. Background technique [0002] m-Fluorotoluene is an important pharmaceutical industry intermediate, widely used in the fields of medicine, pesticides, dyes and fluoroplastics, etc. An important intermediate for the synthesis of the powerful sleeping agent flurazepam. The preparation method of existing m-fluorotoluene comprises the following steps: 1, carry out diazotization reaction with m-toluidine, sodium nitrite and hydrochloric acid; The insoluble diazonium fluoroborate is produced; 3. The diazonium fluoroborate is separated and decomposed by heating to obtain m-fluorotoluene. [0003] The above-mentioned preparation method has the following disadvantages: there are many side reactions in step 3, which reduce the purity and yield of the product. Typical side reaction products include reduction products (that is...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C25/13C07C17/093C01B7/19
Inventor 于俊田张玲孙志国栾秀丽
Owner 山东福尔有限公司
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