background and overview
2,4-dibromobenzoic acid is a chemical intermediate with the molecular formula c7h4br2o2. .
preparation[1-3]
method 1, cn02821215.0 discloses the two-step preparation of 2,4-dibromobenzoic acid from 2,4-dibromoaniline
the first step: 2,4-dibromobenzonitrile
at 60°c, add copper cyanide (2.32g, 25.9mmol) to stirring anhydrous dimethyl sulfoxide (50ml) to form a clear solution, then add tert-butyl nitrite (7.1ml) in one portion , 59.7mmol). to this mixture was added dropwise a solution of 2,4-dibromoaniline 21 (5.0 g, 19.9 mmol) in anhydrous dimethyl sulfoxide (30 ml) via cannula. after the addition was complete, the reaction mixture was stirred for 1 hour. after cooling to 45°c, the mixture was slowly treated with 5n hydrochloric acid (50 ml). after 5 minutes, the reaction mixture was cooled to room temperature and extracted with ethyl acetate/hexane (1:1; 2 x 300 ml). the combined organic layers were washed with water (100 ml) and brine (100 ml), dried, concentrated in vacuo, and purified by silica chromatography (0-5% ethyl acetate in hexanes) to afford the title compound (1.61g, 31% yield). fd(+)ms m/z 259, (m+) consistent with 2 br.
step 2: 2,4-dibromobenzoic acid
a stirred suspension of 2,4-dibromobenzonitrile (1.57g, 6.0mmol) in sulfuric acid (6m, 150ml) was heated to reflux for 3 days. the reaction mixture was cooled to room temperature and extracted with ethyl acetate (2 x 75 ml). the combined organic layers were washed with water (100 ml) and brine (50 ml), dried, concentrated, and then purified by silica chromatography (acetic acid/methanol/chloroform, 0.1:0.5:99.4) to obtain the title compound (0.81 g, yield 48%). mp 171-172℃; es(–)ms m/z 277, (m-h)– consistent with 2 br.
method 2
tashiro et al. reported that 2,3-dibromobenzaldehyde was oxidized with potassium permanganate to prepare 2,4-dibromobenzoic acid, with a yield of 97%.
method 3
corbett et al. reported that 2,3-dibromoiodobenzene was reacted with butyllithium and carbon dioxide at -100°c to prepare 2,4-dibromobenzoic acid, with a yield of 91%.
main reference materials
[1] cn02821215.0 thiophene and thiazolesulfonamide compounds used as antitumor agents
[2] tashiro, masashi and nakayama, kouji,from organic preparations and procedures international, 16(5), 379-83; 1984
[3] heiss, christophe et al.from european journal of organic chemistry, (23), 4625-4629; 2003