反应详情

6.22 g (53.5 mmol) of maleic acid are dissolved in a glass flask in 130 ml of ethyl acetate and then added dropwise with stirring to a solution, adjusted to a temperature of 50° C., of 12.48 g (53.5 mmol) of (+)-(1R,2R)-3-[2-(dimethylamino)methyl-(cyclohex-1-yl)]-phenol in 40 ml of ethyl acetate. After the addition of 20 to 25 ml, a white precipitate forms. After addition of the entire solution, the finely crystalline white solid is filtered out of the warm solution and washed with a little cold ethyl acetate. The residue is dried by having air drawn through it. 18.38 g (98.3% of theoretical) of (+)-(1R,2R)-3-[2-(dimethylamino)methyl-(cyclohex-1-yl)]-phenol maleate are obtained as crystalline form A (according to the X-ray diffraction pattern) with a melting point of 177-179° C. DSC analysis reveals two peaks at 165.5 and 177.2° C.

1. additionadded dropwise
2. additionAfter the addition of 20 to 25 ml
3. additionAfter addition of the entire solution
4. filtrationthe finely crystalline white solid is filtered out of the warm solution
5. washwashed with a little cold ethyl acetate
6. customThe residue is dried