反应详情

To a stirred, cooled (-5° C. solution of 2-bromo-4-methyl-aniline (50.54 g, 0.272 mol) in concentrated HCl solution (200 mL) was added sodium nitrite (18.9 g, 0.274 mol) in water (200 mL) dropwise at such a rate as to maintain temperature below 5° C. After complete addition, the mixture was further stirred[at 5° C. for 30 minutes. A solution of tin chloride monohydrate (185.4 g, 0.822 mol) in concentrated HCl (total volume 400 mL) was added dropwise again maintaining temperature below 5° C. After complete addition and 30 minutes of further stirring, the mixture was placed in the freezer overnight. The light brown solid which precipitated was isolated by filtration and washed with cold brine followed by a solution of petroleum ether/diethyl ether (2/1 by volume). This solid was slowly added to an ice cooled mixture of 50% sodium hydroxide solution/ethyl acetate. The mixture was extracted with ethyl acetate and the organic phase dried over magnesium sulfate. After filtration, the solution was concentrated to 400 mL total volume, diluted with diethyl ether (1.5 L) and treated with dry HCl. The product, 2-bromo-4-methyl-phenylhydrazine hydrochloride (52.4 g) was isolated as a light brown solid and used without further purification. ##STR37##

1. temperatureto maintain temperature below 5° C
2. additionAfter complete addition
3. temperaturemaintaining temperature below 5° C
4. additionAfter complete addition and 30 minutes of further stirring
5. customwas placed in the freezer overnight
6. customThe light brown solid which precipitated
7. customwas isolated by filtration
8. washwashed with cold brine
9. additionThis solid was slowly added to an ice
10. temperaturecooled
11. additionmixture of 50% sodium hydroxide solution/ethyl acetate
12. extractionThe mixture was extracted with ethyl acetate
13. dry with materialthe organic phase dried over magnesium sulfate
14. filtrationAfter filtration
15. concentrationthe solution was concentrated to 400 mL total volume
16. additiondiluted with diethyl ether (1.5 L)
17. additiontreated with dry HCl