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Preparation method of 2,3-dichloropyridine
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A technology of dichloropyridine and trichloropyridine is applied in the field of preparation of 2,3-dichloropyridine, can solve unseen problems and the like, and achieve the effects of good yield, safe preparation process and simple operation steps
Inactive Publication Date: 2013-06-12
QUZHOU HENGSHUN CHEM IND +2
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[0012] However, the CTH reaction is used in the dechlorination and hydrogenation of chloropyridines, but there is no reported literature
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Embodiment 1
[0051] Add 300ml of absolute ethanol and 0.125mol of 2,3,6-trichloropyridine (23g, 99.2% GC content) into a 500ml four-necked reaction flask equipped with a stirrer, thermometer, reflux condenser and feeder, and then Add 5.55g of ammoniumformate, start stirring and heat slowly at the same time. When the temperature of the feed liquid reaches 50-55°C, start to add 2g of 5% Pd / C catalyst (containing 65% of water base), after a while, dense bubbles will escape, and continue to slowly Slowly raise the temperature to slight reflux reaction for 3 hours, then add 10.20 g of ammoniumformate in 6 batches within 6 hours, after the addition, react at the same temperature for about 1 hour, monitor the reaction by GC until the conversion rate meets the requirements, filter while hot , the filter cake is washed with water, and the catalyst recovered after desalination is used for the next reaction. GC analysis of the filtrate showed:
[0052] 3-chloropyridine: 4.95%,
[0053] 2,5-D...
Embodiment 2
[0060] Operate in the same manner as in Example 1, but change the amount of ammoniumformate added to 8 g with 2.5 g of reclaimed catalyst instead, and then add 16 g of ammonium formate evenly in 8 batches within 7 hours. GC analysis of the filtrate showed:
[0061] 3-chloropyridine: 3.55%,
[0062] 2,5-dichloropyridine: 1.12%,
[0063] 2,3-Dichloropyridine: 40.83%,
[0064] 2,6-dichloropyridine: 2.52%,
[0065] 2,3,6-trichloropyridine: 51.98%.
[0066] After vacuum distillation and comprehensive treatment, the yield of 2,3-dichloropyridine is 81.46% based on the reacted 2,3,6-trichloropyridine.
Embodiment 3
[0068] Operate in the same way as in Example 1, but use methanol as a solvent, and when the reaction finishes, the GC analysis result of the reaction mixture is:
[0069] 3-chloropyridine: 7.56%,
[0070] 2,5-Dichloropyridine: 2.01%,
[0071] 2,3-Dichloropyridine: 34.61%,
[0072] 2,6-dichloropyridine: 3.01% %,
[0073] 2,3,6-trichloropyridine: 52.76%.
[0074] After vacuum distillation and comprehensive treatment, the yield of 2,3-dichloropyridine is 69.10% based on the converted 2,3,6-trichloropyridine.
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Abstract
The invention discloses a preparation method of 2,3-dichloropyridine. The preparation method is implemented by taking 2,3,6-trichloropyridine as a starting material and dissolving the 2,3,6-trichloropyridine into an solvent, taking an organic compound as a hydrogen donor and heating the organic compound in the presence of a metal catalyst until a micro reflux reaction occurs, carrying out post-treatment on reaction liquid so as to obtain a target product 2,3-dichloropyridine, wherein the solvent is a C1-C4 alcoholsolvent; the hydrogen donor is of a structure shown in a formula (VI), wherein R refers to H<+1>, Na<+1> and NH<4+>; and the metal catalyst is a Pd / C catalyst. According to the invention, a CTH reaction is successfully applied to the dechlorination and hydrogenation of multiple chloropyridines, the catalyst can be repeatedly regenerated and continuously indiscriminately used, the hydrogen donor is relatively cheap, available and stable, nontoxic and easily removed from a system, the yield of target products is good, a small amount of by-products are extensive in use, chloropyridine raw materials with a high economic value are fully used, the operation steps are simple, and the preparation process is safe, green and environmental-friendly.
Description
[0001] technical field [0002] The invention relates to a preparation method of 2,3-dichloropyridine. Background technique [0003] 2,3-Dichloropyridine is a chloropyridine with wide application and large dosage among the 6 dichloropyridine isomers, and it is one of the important intermediates of the new insecticide chlorantraniliprole. [0004] As early as the early 1950s, 2,3-dichloropyridine was obtained by H. J. den Hertog in the laboratory through the Gatterman reaction of 3-amino-2-chloropyridine, but the yield was low and had no industrial application value. [0005] 2,3-Dichloropyridine can be obtained by liquid-phase chlorination of pyridine or pyridinehydrochloride (JP61249965), and can also be obtained by liquid-phase chlorination of 3-chloropyridine (US4515953). Due to the low yield, it is practical There is no value for industrial production. [0006] The earliest patented technology for preparing 2,3-dichloropyridine by dechlorination and hydrogenat...
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