Method for preparing 2, 5-dibromo-benzene acetic acid
A technology of bromophenylacetic acid and bromination, which is applied in the field of preparation of 2,5-dibromophenylacetic acid, can solve problems such as difficult operation and control, low product yield, environmental pollution, etc., and achieve easy control, good product purity, and production good safety effect
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Embodiment 1
[0019] Step 1, the preparation of indolinone (formula II)
[0020]
[0021] In a 5L four-necked flask, add 768.0g of 5-bromoisatin, 2500ml of absolute ethanol, stir, then slowly add 250g of hydrazine hydrate (80wt%), heat up to reflux (80°C), react for 2h, and take a sample for HPLC detection , no raw materials remained, the temperature of the reaction solution was lowered to about 15°C, and after crystallization for 15 minutes, filtered, the filter cake was washed with a small amount of cold absolute ethanol or mother liquor, and then dried in a blast oven at 50°C for 12 hours to obtain the crude hydrazone.
[0022] In a 5L four-necked bottle, put the above obtained hydrazone crude product, 2500ml of ethylene glycol, stir, add 100g of sodium hydroxide, heat up to reflux, the reflux temperature gradually rises from 95°C to 115°C, after 7 hours of reaction, sample HPLC detection , no raw material remains, stop heating, lower the temperature to below 30°C, transfer the reacti...
Embodiment 2
[0029] Step 1, the preparation of indolinone (formula II)
[0030]
[0031] In a 5L four-neck flask, add 500.0g of 5-bromoisatin, 2000ml of absolute ethanol, stir, then slowly add 162.7g of hydrazine hydrate (80%), heat up to reflux (80°C), react for 2h, and sample HPLC After detection, no raw materials remained, the reaction solution was cooled to about 15°C, crystallized for 15 minutes, filtered, the filter cake was washed with a small amount of cold absolute ethanol or mother liquor, and then dried in a blast oven at 50°C for 12 hours to obtain the crude hydrazone.
[0032] In a 5L four-necked bottle, put the above obtained hydrazone crude product, 2000ml of ethylene glycol, stir, add 65.1g of sodium hydroxide, heat up to reflux, the reflux temperature gradually rises from 95°C to 115°C, after 7 hours of reaction, sample HPLC Test, if there is no raw material remaining, stop heating, lower the temperature to below 30°C, transfer the reaction solution into a 10L bottle, a...
Embodiment 3
[0039] Step 1, the preparation of indolinone (formula II)
[0040]
[0041]In a 5L four-neck flask, add 250.0g of 5-bromoisatin, 1000ml of absolute ethanol, stir, then slowly add 81.4g of hydrazine hydrate (80%), heat up to reflux (80°C), react for 2h, and sample HPLC After detection, no raw materials remained, the reaction solution was cooled to about 15°C, crystallized for 15 minutes, filtered, the filter cake was washed with a small amount of cold absolute ethanol or mother liquor, and then dried in a blast oven at 50°C for 12 hours to obtain the crude hydrazone.
[0042] In a 5L four-necked bottle, put the above obtained hydrazone crude product, 1000ml of ethylene glycol, stir, add 32.5g of sodium hydroxide, heat up to reflux, the reflux temperature gradually rises from 95°C to 115°C, after 7 hours of reaction, sample HPLC Test, if there is no raw material remaining, stop heating, lower the temperature to below 30°C, transfer the reaction solution into a 10L bottle, add...
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