Synthetic method for Laquinimod intermediate 2-amino-6-chlorobenzoic acid
A technology of chlorobenzoic acid and synthesis method, which is applied in the preparation of carbamic acid derivatives, chemical instruments and methods, preparation of organic compounds, etc., can solve the problems of unfavorable safe operation and high cost of raw materials, and achieves high reaction yield and low cost. , the effect of less by-products
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Embodiment 1
[0030] The synthetic method of 2-amino-6-chlorobenzoic acid comprises the following steps:
[0031] 1) Mix 3-chloro-2-methylaniline, di-tert-butyl dicarbonate and benzene, stir and react at 46°C for 1.5h to obtain mixture I;
[0032] 2) Mix the oxidant, water and tetrahydrofuran evenly, pass in argon, control the reaction temperature to 150°C, and the reaction pressure to 6 atmospheres to obtain mixture II, add mixture I to mixture II dropwise, and control the dropping time to 65min, Then control the temperature to 171°C and the reaction pressure to 9 atmospheres, continue the reaction for 7.5 hours and cool to obtain the mixture III;
[0033] 3) Add hydrochloric acid and dioxane with a mass fraction of 20% to mixture III, control the reaction temperature to 85° C., and the reaction pressure to normal pressure, react for 45 minutes, and cool to obtain mixture IV;
[0034] 4) Add chloroform to the mixture IV, let stand to separate layers, wash the organic phase with water, dry...
Embodiment 2
[0039] The synthetic method of 2-amino-6-chlorobenzoic acid comprises the following steps:
[0040] 1) Mix 3-chloro-2-methylaniline, di-tert-butyl dicarbonate and chlorobenzene, stir and react at 40°C for 1 hour to obtain mixture I;
[0041] 2) Mix the oxidant, water and tetrahydrofuran evenly, feed nitrogen, control the reaction temperature to 145°C, and the reaction pressure to 5 atmospheres to obtain mixture II, add mixture I dropwise to mixture II, and control the dropping time to 50min, then Control the temperature to 160°C and the reaction pressure to 8 atmospheres, continue the reaction for 6 hours and cool to obtain the mixture III;
[0042] 3) Add hydrochloric acid and dioxane with a mass fraction of 20% to mixture III, control the reaction temperature to 75°C, and the reaction pressure to normal pressure, react for 0.5h, and cool to obtain mixture IV;
[0043] 4) Add toluene to the mixture IV, let stand to separate layers, wash the organic phase with water and dry o...
Embodiment 3
[0048] The synthetic method of 2-amino-6-chlorobenzoic acid comprises the following steps:
[0049] 1) Mix 3-chloro-2-methylaniline, di-tert-butyl dicarbonate and fluorobenzene, stir and react at 50°C for 2 hours to obtain mixture I;
[0050] 2) Mix the oxidant, water and tetrahydrofuran evenly, pass in argon, control the reaction temperature to 155° C., and the reaction pressure to 7 atmospheres to obtain the mixture II. Add the mixture I to the mixture II dropwise, and control the dropping time to 70 minutes. Then control the temperature to 175° C., and the reaction pressure to 10 atmospheres, continue to react for 8 hours and cool to obtain the mixture III;
[0051] 3) Add hydrochloric acid and dioxane with a mass fraction of 20% to mixture III, control the reaction temperature to 90°C, and the reaction pressure to normal pressure, react for 1 hour, and cool to obtain mixture IV;
[0052] 4) Add chloroform to the mixture IV, let stand to separate layers, wash the organic pha...
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