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Preparation method of o-fluorotobuene

A technology of o-fluorotoluene and o-toluidine, applied in the field of preparation of fluorine-containing compounds, can solve the problems of long production cycle and low content of fluorination, and achieve the effects of high degree of automation, reduction of side reactions and short reaction cycle.

Inactive Publication Date: 2017-12-08
山东福尔有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] According to the deficiencies of existing technology, the present invention provides a method for preparing o-fluorotoluene, which adopts a tubular reactor for thermal decomposition reaction, realizes continuous production, solves the problems of long production cycle and low content of fluorination, and prepares high-purity The o-fluorotoluene laid a good foundation

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  • Preparation method of o-fluorotobuene

Examples

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Embodiment 1

[0029] The preparation method of o-fluorotoluene of the present invention comprises the following steps:

[0030] 1. Reaction steps for generating nitrous acid: Add 80kg of anhydrous hydrogen fluoride to the reactor, turn on the tail gas absorption system, keep the reactor at a slight negative pressure, add 135kg of sodium nitrite for reaction, and the addition rate is about 40kg / h, continue after adding React for 1 hour; the reaction between anhydrous hydrogen fluoride and sodium nitrite is exothermic violently, and cooling liquid needs to be passed through during the reaction, and the temperature in this step should be controlled at -3~0°C.

[0031] 2. Diazotization reaction step: Add 200kg of o-toluidine dropwise into the reaction kettle, the dropping rate is about 70kg / h, stir at 63r / min, raise the temperature to -1~1°C, after the dropwise addition, keep the temperature for 1 hour, Obtain diazo solution.

[0032] 3. Thermal decomposition reaction step: the diazo solution ...

Embodiment 2

[0036] Prepare according to the preparation method of o-fluorotoluene in embodiment 1, only change the following parameters of the following steps of embodiment 1:

[0037] 1. Reaction steps for generating nitrous acid: Add 80kg of anhydrous hydrogen fluoride to the reactor, turn on the tail gas absorption system, keep the reactor at a slight negative pressure, add 135kg of sodium nitrite for reaction, and the addition rate is about 45kg / h, continue after adding React for 1 hour; the reaction between anhydrous hydrogen fluoride and sodium nitrite is exothermic violently, and cooling liquid needs to be passed through during the reaction, and the temperature in this step should be controlled at -1~1°C.

[0038] 2. Diazotization reaction step: add 206kg of o-toluidine dropwise into the reaction kettle, the dropping rate is about 90kg / h, stir at 63r / min, raise the temperature to 0~3°C, after the dropwise addition, keep warm for 1 hour to get Diazo solution.

[0039] 3. Thermal de...

Embodiment 3

[0043] 1. Reaction steps for generating nitrous acid: Add 80kg of anhydrous hydrogen fluoride to the reactor, turn on the tail gas absorption system, keep the reactor at a slight negative pressure, add 140kg of sodium nitrite for reaction, and the addition rate is about 50kg / h, continue after adding React for 1 hour; the reaction between anhydrous hydrogen fluoride and sodium nitrite is exothermic violently, during the reaction process, cooling liquid needs to be passed through, and the temperature in this step should be controlled at 0-3°C.

[0044]2. Diazotization reaction step: Add 210kg of o-toluidine dropwise into the reaction kettle, the dropping rate is about 100kg / h, stir at 63r / min, and raise the temperature to 3~5°C. Diazo liquid.

[0045] 3. Thermal decomposition reaction step: the diazo solution generated by the reaction is injected into the tubular reactor by compressed nitrogen gas for thermal decomposition reaction. After adding the diazo solution, the temperatu...

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Abstract

The invention discloses a preparation method of o-fluorotobuene. The method comprises the following steps: (1) acid formation reaction: adding an anhydrous hydrogen fluoride raw material into a reaction kettle and stirring; adding sodium nitrite into the reaction kettle, introducing frozen salt water to cool and carrying out reaction to obtain a nitrous acid; (2) diazotization reaction: adding o-toluidine into the reaction kettle containing the nitrous acid, stirring and carrying out the diazotization reaction; (3) thermal decomposition reaction: transferring diazonium liquid obtained in the step (2) into a tubular reactor; heating and carrying out the thermal decomposition reaction to obtain an o-fluorotobuene crude product; (4) post-treatment: carrying out washing and steam distillation on the o-fluorotobuene crude product obtained in the step (3), regulating a pH value, pressing into a rectifying tower for distillation to obtain the qualified o-fluorotobuene. The preparation method disclosed by the invention has the beneficial effects that energy consumption is low, continuous production is realized, the problems of long production period of fluorination reaction and low yield of products are solved, the occurrence of side reaction is reduced, and a good foundation is laid for preparing high-purity o-fluorotobuene.

Description

technical field [0001] The invention belongs to the technical field of preparation of fluorine-containing compounds, and in particular relates to a preparation method of o-fluorotoluene. Background technique [0002] O-fluorotoluene is an important fluorine-containing compound, which has been widely used in the pharmaceutical and pesticide industries. The existing preparation method generally takes o-toluidine, hydrogen fluoride, and sodium nitrite as raw materials, and produces qualified o-fluorotoluene through steps such as salt formation, diazotization, thermal decomposition, water washing, and distillation; hydrogen fluoride and by-product waste sulfuric acid; the tail gas is discharged at high altitude after being washed with water, and dilute hydrofluoric acid is by-product. The by-product hydrogen fluoride produced in the reaction process is absorbed by falling film water and alkali. [0003] At present, there are many patent reports about o-fluorotoluene. For examp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C17/093C07C17/383C07C25/13C01B21/50C07C245/20
CPCC07C17/093C01B21/50C07C17/383C07C245/20C07C25/13
Inventor 于俊田张玲
Owner 山东福尔有限公司
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