Реакция #551417

Уравнение реакции

tetramethylammonium hydroxide

CDCA

→

UDCA

Выход 37.6%

Растворители

dimethylsulfoxide

methanol

Условия реакции

Обработка

1. 1
   Сушкаdried over 3A molecular sieves
2. 2
   workup.DISSOLUTION2.0 g of 7-ketolithocholic acid was dissolved
3. 3
   ДругоеThe filtrate was evaporated under high vacuum
4. 4
   workup.DISSOLUTIONThe crude product was dissolved in 30 mL of methanol
5. 5
   workup.ADDITION30 mL of 2N sodium hydroxide added
6. 6
   Другоеthe methanol evaporated
7. 7
   ДругоеThe product was precipitated with hydrochloric acid at pH 4.0
8. 8
   Другоеyielding 1.79 g
9. 9
   Другоеafter drying

Методика

The cell was assembled with a lead-plated monel electrode as cathode and a ruthenized titanium anode. The cell was undivided and contained just one Telfon gasket. A stock solution of electrolyte was made up from 25 mL of 1.94 M tetramethylammonium hydroxide in methanol and 475 mL of dimethylsulfoxide dried over 3A molecular sieves. The entire solution was stored over 3A molecular sieves and then 60 mL of electrolyte placed in the reservoir. 2.0 g of 7-ketolithocholic acid was dissolved therein, the flow was adjusted to a steady stream, and a constant current of 200 ma was established. 3960 coulombs were accumulated. When the cell was opened it could be seen that the monel sub-surface of the electrode was exposed. There were fine flakes of lead in the reservoir and pump. The filtrate was evaporated under high vacuum. The crude product was dissolved in 30 mL of methanol and 30 mL of 2N sodium hydroxide added. The solution was left at room temperature for five minutes and then the methanol evaporated. The product was precipitated with hydrochloric acid at pH 4.0 yielding 1.79 g after drying. The HPLC analysis indicated 45% reduction with a 37.6% yield of UDCA and 7.4% CDCA. The UDCA/CDCA ratio is 5.08. Analysis by C13 nmr was qualitatively consistent with this ratio.

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