preparation and application of 4-bromo-2,3-dimethylanisole_kain industrial additive

background and overview^[1][2]

4-bromo-2,3-dimethylanisole is an organic chemical intermediate, generally obtained by bromination of 2,3-dimethylanisole. the bromination reagent can be bromine or nbs. .

preparation^[1-2]

method 1,

add a solution of br₂ (5.3g, 33.2mmol) in ccl₄ (15ml) to the intermediate 2,3-dimethylanisole (4.1 g, 30.2 mmol) in dcm (100 ml) and the resulting solution was stirred for 1 h. the reaction mixture was concentrated and purified by chromatography to give 1.7 g (26%) of the intermediate 4-bromo-2,3-dimethylanisole. ¹hnmr (dmso-d6): 7.33 (d, j = 8hz, 1h), 6.58 (d, j = 8hz, 1h), 3.78 (s, 3h) , 2.36 (s, 3h), 2.19 (s, 3h).

method 2: add nbs (18.7g, 105mmol) to a 5ml ch₃cn solution of 2,3-dimethylanisole (13.6g, 100mmol) at 0°c. . after the reaction was stirred at room temperature for 3 hours, the solvent was evaporated under reduced pressure and ccl₄ was added. the solid was filtered, washed with ccl₄, and the solvent was removed. the yield was 98% and it was a colorless oil. ¹h nmr (cdcl₃, 400mhz) δ = 7.36 (d, j = 8.8hz, 1h), 6.61 (d, j = 8.8hz, 1h), 3.81 (s, 3h), 2.39 (s, 3h), 2.23 (s, 3h); ¹³c nmr (cdcl₃ ,100mhz) δ= 156.6,136.8,129.6,127.0,116.3,109.3,55.6,19.8,12.8; ftir (kbr, neat, cm^-1): ν3336,2935,1572 ,1460,1260,1106,796,585;hrms (esims, m/z) calculated value c9h12bro [m + h] ⁺ 215.0066, measured value 215.0062.

apply^[1]

4-bromo-2,3-dimethylanisole can be used as an intermediate to synthesize other compounds. for example, the intermediate 4-bromo-2,3-dimethylanisole (1.5g, 7mmol ) dissolved in acoh (9.2ml) and h₂o (1.6ml). after cooling at 5°c, fuming hno₃ (0.49 ml) in acoh (3.6 ml) was added dropwise. the mixture was stirred at 5°c for 15 minutes, h₂o was added, and the mixture was extracted with dcm. the organic layer was washed with h₂o, dried (na₂so₄), concentrated, and chromatographed (ea/hexane) purification yielded 1.2 g (66%) of intermediate 37c. calculated value of lc[m/z] c9h10brno3: 259.0; found value: 259.0. found 261.1 [m + h] ⁺,

main reference materials

[1] pct int. appl., 2018045246, 08 mar 2018

[2] organic letters, 16(7), 1996-1999; 2014