反应详情

温度

15 °C

Substituted nitrobenzenes, not hitherto described in the chemical literature, used in the preparation of substituted anilines as hereinbefore described in Reference Example 2, were prepared as follows: (a) 2,3-Dichloro-6-nitroaniline [29 g; prepared by a modification (reaction at 125° C.) of the procedure described by Beilstein and Kurbatow, Ann., 192, 235 (1878)] was dissolved with stirring at 55°-60° C. in glacial acetic acid (350 ml). A solution of sodium nitrite (11 g) in concentrated sulphuric acid (80 ml) was then added to the solution thus obtained with stirring over 15 minutes at a temperature of 55°-60° C. maintained by intermittent cooling with water. The red solution obtained was cooled to 15° C. and poured, with stirring, into a solution of cuprous bromide (20 g) in concentrated hydrobromic acid (200 ml) and ice (500 g). The mixture was allowed to attain laboratory temperature, heated for one hour at 60° C. and then steam-distilled. The distillate obtained was extracted with diethyl ether (6×500 ml). The combined ethereal extracts were washed successively with aqueous sodium hydroxide solution (2N; 3×750 ml and water (2×500 ml), dried over anhydrous sodium sulphate and filtered. The filtrate was evaporated to dryness to give a yellow powder, which was then crystallised from hexane (125 ml) to give 2-bromo-3,4-dichloronitrobenzene (26.7 g), m.p. 73° C., in the form of yellow crystals.

1. customwere prepared
2. customprepared by a modification (reaction at 125° C.) of the procedure
3. dissolution, 192, 235 (1878)] was dissolved
4. customthus obtained
5. temperaturemaintained
6. customThe red solution obtained
7. additionpoured
8. temperatureheated for one hour at 60° C.
9. distillationsteam-distilled
10. customThe distillate obtained
11. extractionwas extracted with diethyl ether (6×500 ml)
12. washThe combined ethereal extracts were washed successively with aqueous sodium hydroxide solution (2N
13. dry with material3×750 ml and water (2×500 ml), dried over anhydrous sodium sulphate
14. filtrationfiltered
15. customThe filtrate was evaporated to dryness
16. customto give a yellow powder, which
17. customwas then crystallised from hexane (125 ml)