Process for synthesizing 2-chloropyridine from chlorine and pyridine

A technology for chloropyridine and pyridine, which is applied in the field of improvement of the synthetic 2-chloropyridine process, can solve the problems of difficult separation, difficult temperature control, large waste liquid discharge and the like

A technology for chloropyridine and pyridine, which is applied in the field of improvement of the synthetic 2-chloropyridine process, can solve the problems of difficult separation, difficult temperature control, large waste liquid discharge and the like

CN1110481CInactive Publication Date: 2003-06-04TIANJIN UNIV
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  • Process for synthesizing 2-chloropyridine from chlorine and pyridine
  • Process for synthesizing 2-chloropyridine from chlorine and pyridine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Pyridine: Origin: Tianjin Second Chemical Reagent Factory, purity ≥ 99%

[0014] Chlorine: Origin: Tianjin Dagu Chemical Plant, purity ≥ 99%

[0015] Using the above-mentioned equipment and process flow, mix 500g of pyridine and 340ml of water, feed 428g of chlorine gas, the reaction temperature is 142-155°C, the reaction time is 180 minutes, and 142g of NaOH is used for neutralization to obtain 640.3g of 2-chloropyridine, unreacted pyridine 24.3 g, the selectivity is 94.1%, and the yield is 89.6%.

Embodiment 2

[0017] Using the same experimental device and the same raw materials as in Example 1, add 500g of pyridine and 340g of water, feed 540g of chlorine gas, and the reaction temperature is 160-180°C. Coke appears on the inner wall of the reactor, and dark red liquid flows out from the outlet of the reactor. Even visible white crystals, obtained 534.6g 2-chloropyridine after 120 minutes of reaction, 198.0g 2.6-dichloropyridine containing a small amount of impurities, the total conversion rate of the reaction was 96.8%, and the yield of 2-chloropyridine was 74.7%. Sex is 77.2%.

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Abstract

A process for synthesizing 2-chloropyridine from pyridine and chlorine gas includes such technological steps as reaction while rectification, neutralization, and refining by rectification. It features that the liquid-phase mixture of pyridine and water in mol ratio of 1 : 3 is fed into coupled rectifying tower-reactor, the mixture containing pyridine output from tower top is partially returned back into tower, residual is fed to top of reactor while the mol raatio of chlorine gas to pyridine is ensured to be 1 : 2.5-4.0, the residual and chlorine gas take part in parallel-current reation in reactor to generate 2-chloropyridine, and after neutralized it comes to central position of coupled rectifying tower with the temp at top of 94-96 deg.C and reactor temp of 140-190 deg.C. Its advantages include short technological route, high output rate and less waste liquid drainage.

Description

technical field [0001] The invention relates to a process for synthesizing 2-chloropyridine by using pyridine and chlorine gas as raw materials, which belongs to the improvement of the process for synthesizing 2-chloropyridine. technical background [0002] 2-Chloropyridine is a raw material intermediate used in the synthesis of medicines, preservatives, fungicides and fungicides. Its downstream products have the characteristics of high efficiency and low toxicity, and are widely used in pharmaceutical, shipbuilding, construction and metal processing industries. Now It is gradually being pushed into the daily chemical market. In addition, this product can also be used to produce low-toxic pesticides and other industrial chemicals, and the future application prospects are extremely promising. [0003] There are two methods for synthesizing 2-chloropyridine from pyridine and chlorine: one is catalytic thermal chlorination, and the other is gas p...

Claims

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Application Information

Patent Timeline
04 Jun 2003
Publication
CN1110481C
IPC
C07D213/61
Inventors
辛峰; 王富民