A kind of preparation method of 2,3-dichloropyridine
A technology of dichloropyridine and chloropyridine, which is applied in the field of compound preparation, can solve problems such as difficult separation, high cost, and low conversion rate, and achieve the effects of simple reaction operation, low equipment requirements, and few side reactions
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Embodiment 1
[0025] Synthesis of 3-chloro-2-pyridinesulfonic acid
[0026] Dissolve 113.5g of 3-chloropyridine in 300g of anhydrous-treated 1,2,3-trichloropropane, add 1.0g of cuprous chloride, and slowly add 128g of chlorosulfonic acid dropwise under stirring at a temperature of 40°C. Heat up to 155°C and reflux and stir for 10 hours. Control the temperature at 40°C and slowly add 110 g of triethylamine dropwise. After dropping, raise the temperature again to 150°C and reflux and stir for 10 hours. The central control detects that the remaining raw materials are <10%. Pour slowly into 300g of ice water, add 30g of 31% hydrochloric acid, stir and separate the liquids, wash the organic layer with water, concentrate to dryness under reduced pressure, and add methanol to the residue for purification to obtain 125g of 3-chloro-2-pyridinesulfonic acid with a yield of 64.6%.
Embodiment 2
[0028] Synthesis of 2,3-Dichloropyridine
[0029] Add 96.8 g of 3-chloro-2-pyridinesulfonic acid and 200 g of water in Example 1 into the reactor, slowly add 30 g of 31% hydrochloric acid under stirring, heat up to 103 ° C and reflux for 5 h, add alkali to the tail gas for absorption, slowly add 20 % sodium chlorate aqueous solution 140g, keep reflux reaction for 5h after dripping, after the reaction is over, cool down to room temperature, add dichloromethane for extraction, add 100g of dichloromethane each time, extract 3 times, after extraction, the organic layer is distilled under normal pressure to remove the solvent Distilled under high vacuum and reduced pressure to obtain 59.4 g of the product 2,3-dichloropyridine with a yield of 80.3%.
[0030] image 3 It is the mass spectrum of 2,3-dichloropyridine of the present embodiment. image 3 Middle m / z: 147 is the molecular ion peak [M] + , m / z: 149 and 151 are isotopic peaks, consistent with the molecular weight of the p...
Embodiment 3
[0032] Synthesis of 3-chloro-2-pyridinesulfonic acid
[0033] Dissolve 113.5 g of 3-chloropyridine in 300 g of anhydrous 1,1,2-trichloroethane, add 1.0 g of cuprous chloride, and slowly add 110 g of chlorosulfonic acid dropwise under stirring at a controlled temperature of 40°C. After dropping, raise the temperature to 112°C to reflux and stir for 20 hours, cool down to room temperature, and slowly add 110 g of triethylamine dropwise at a controlled temperature of 40°C, then raise the temperature to 112°C to reflux and stir for 15 hours after dropping, the central control detects that the remaining raw materials are less than 10%, and then lower the temperature After reaching room temperature, the material was slowly poured into 300 g of ice water, 30 g of 31% hydrochloric acid was added, stirred and separated, the organic layer was washed with water, concentrated to dryness under reduced pressure, and the residue was refined by adding methanol to obtain 107 g of 3-chloro-2-pyr...
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Abstract
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