Preparation method of 2-amino-4-fluorobenzoic acid
A technology of fluorobenzoic acid and benzoic acid, which is applied in the field of preparation of 2-amino-4-fluorobenzoic acid, can solve the problems of high impurity content in the final synthetic product and expensive intermediates, and achieve easy industrial production and short reaction route , the effect of high yield
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Embodiment 1
[0031] The present embodiment provides a kind of preparation method of 2-amino-4-fluorobenzoic acid, and the reaction process is as follows:
[0032]
[0033] Specifically include the following steps:
[0034] (1) Add 4-fluorobenzyl alcohol into the reaction flask, add 5 times the volume of concentrated sulfuric acid, cool down and stir to dissolve, cool down to 10°C, add concentrated nitric acid to react for 4 hours under the condition of heat preservation and stirring, and detect 4-fluorobenzyl alcohol by TLC Benzyl alcohol disappears, slowly added to water under cooling and stirring, suction filtration, air drying at 50°C, and brown-yellow solid intermediate 4-fluoro-2-nitrobenzyl alcohol (see Figure 1A-Figure 1C ), molar yield 81%;
[0035] (2) Add the 4-fluoro-2-nitrobenzyl alcohol described in step (1) into the reaction flask, add 5 times the volume of dimethyl sulfoxide, heat up to 50°C, and slowly add hydrogen peroxide under stirring conditions , reacted for 5h u...
Embodiment 2
[0038] The present embodiment provides a kind of preparation method of 2-amino-4-fluorobenzoic acid, and concrete steps are as follows:
[0039] (1) Add 4-fluorobenzyl alcohol into the reaction flask, add 5 times the volume of concentrated sulfuric acid, cool down and stir to dissolve, cool down to -20°C, add fuming nitric acid to react for 6 hours under the condition of heat preservation and stirring, TLC detects 4 -Fluorobenzyl alcohol disappeared, slowly added to water under cooling and stirring, suction filtered, air-dried at 50°C to obtain a brownish-yellow solid intermediate 4-fluoro-2-nitrobenzyl alcohol, the molar yield was 75%;
[0040] (2) Add the 4-fluoro-2-nitrobenzyl alcohol described in step (1) into the reaction flask, add 5 times the volume of DMF, heat up to 20°C, slowly add sodium hypochlorite under stirring conditions, and keep stirring The reaction was carried out under low temperature for 12 hours, TLC detected that 4-fluoro-2-nitrobenzyl alcohol disappear...
Embodiment 3
[0043] The present embodiment provides a kind of preparation method of 2-amino-4-fluorobenzoic acid, and concrete steps are as follows:
[0044] (1) Add 4-fluorobenzyl alcohol into the reaction flask, add 5 times the volume of concentrated sulfuric acid, cool down and stir to dissolve, cool down to 40°C, add potassium nitrate to react for 1h under the condition of heat preservation and stirring, and detect 4-fluorobenzyl alcohol by TLC The benzyl alcohol disappeared, slowly added to water under cooling and stirring, suction filtered, air-dried at 50°C to obtain a brownish-yellow solid intermediate 4-fluoro-2-nitrobenzyl alcohol, and the molar yield was 73%;
[0045](2) Add 4-fluoro-2-nitrobenzyl alcohol described in step (1) into the reaction flask, add 5 times the volume of DMF, heat up to 60°C, slowly add TEMPO under stirring conditions, and keep stirring The reaction was carried out for 2 hours, TLC detected that 4-fluoro-2-nitrobenzyl alcohol disappeared, stirred to cool d...
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