Hydrochloric Acid → 4-Piperidinol, 1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethyl-

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Reaction Steps

A solution of 34.5 g (200 mmol) of 4-hydroxy-1-oxyl-2,2,6,6-tetramethylpiperidine dissolved in 75 mL of water and a solution of 49.5 g (0.73 mol) of 50% aqueous hydrogen peroxide are added simultaneously over seven hours at 40° C. to a mixture of 1.61 g (8.1 mmol) of ferrous chloride tetrahydrate, 50 mL of water, 1.6 mL of 37% hydrochloric acid and 390 mL of tert-butyl alcohol. About four hours into the addition, a solution of 0.22 g (1.1 mmol) of ferrous chloride tetrahydrate, 0.2 mL of 37% hydrochloric acid and 1-2 mL of water are added to the reaction mixture. The reaction mixture is stirred overnight at room temperature. The reaction is then completed by adding a solution of 0.11 g (0.55 mmol) of ferrous chloride tetrahydrate, 0.1 mL of 37% hydrochloric acid and 1-2 mL of water and a solution of 5.8 g (85 mmol) of 50% aqueous hydrogen peroxide while heating the reaction mixture at 40° C. The reaction mixture is filtered to remove solids, quenched with sodium sulfite, treated with sodium hydroxide and sodium borohydride and concentrated. The residue is dissolved in ethyl acetate and passed through silica gel to afford 42.6 g (87% yield) of the title compound as a white solid.

Provenance & Evidence