反应详情

The crude diamine base (3.0 g.) was then purified by dissolution in chloroform, followed by extraction of the latter solution with ice-cold 3 N aqueous hydrochloric acid. The combined acidified aqueous layers were then basified (with the aid of ice-cooling) and the resulting organic base back extracted into chloroform, using four-100 ml. portions of the latter solvent. After drying over anhydrous magnesium sulfate and filtering, there was ultimately obtained a clear chloroform solution that was subsequently concentrated in vacuo to afford 2.0 g. of pure 1,1'-[4-methoxy-1,2-phenylenebis(methylene)]bispiperidine as the free base in the form of a pale-colored residual oil. The pure diamine oil (2.0 g.) was then dissolved in diethyl ether (200 ml.) and filtered, and the filtered solution was subsequently added to a filtered solution of maleic acid (10 g.; 0.086 mole) dissolved in diethyl ether (600 ml.) to afford a pale yellow gum as the product. Recrystallization of the latter material twice from isopropyl alcohol/diethyl ether then gave analytically pure 1,1'-[4-methoxy-1,2-phenylenebis(methylene)]bispiperidine dimaleate, m.p. 124°-126° C. The yield of pure salt amounted to 1.99 g. (9.8%).

1. customThe crude diamine base (3.0 g.) was then purified by dissolution in chloroform
2. extractionfollowed by extraction of the latter solution with ice-cold 3 N aqueous hydrochloric acid
3. temperaturecooling) and the resulting organic base
4. extractionback extracted into chloroform
5. dry with materialAfter drying over anhydrous magnesium sulfate
6. filtrationfiltering
7. customthere was ultimately obtained a clear chloroform solution that
8. concentrationwas subsequently concentrated in vacuo
9. customto afford 2.0 g
10. filtrationfiltered
11. customto afford a pale yellow gum as the product
12. customRecrystallization of the latter material twice from isopropyl alcohol/diethyl ether