Oxidation with chromium(VI) complexes: Difference between revisions

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===Example Procedure<ref>Guziec, F. S., Jr.; Luzzio, F. A. ''J. Org. Chem.'', '''1982''', ''47'', 1787.</ref>===

<span style="float:right;padding-right:50px;padding-top:10px;">'''''(9)'''''</span><center>[[File:ChroEx.png]]</center>

To a solution of ''p''-(3-hydroxypropyl)benzyl alcohol (165 mg, 1 mmol) in N,N-dimethylformamide (3 mL) was added imidazolium dichromate (705 mg, 2 mmol) and the mixture was stirred at room temperature (4 hours). After completion of the reaction, water (30 mL) was added to the reaction mixture and the product was extracted three times with diethyl ether. The ether extracts were washed with water and aqueous NaHCO3, dried over anhydrous MgSO4, and evaporated to dryness. The crude product was subjected to silica gel column chromatography with dichloromethane-ethyl acetate (4:1) as eluent to yield ''p''-(3-hydroxypropyl)benzaldehyde (112 mg, 68%); ¹H NMR (CDCl₃): δ1.8–2.3 (m, 2 H), 2.77 (s, 1 H), 2.93 (t, 2 H, J = 6 Hz), 3.80 (t, 2 H, J = 6 Hz), 7.4–7.98 (m, 4 H), 10.10 (s, 1 H). IR (film) 1700 cm–1. δ and 3-(4-Formylphenyl)propanal (4 mg, 3%): ¹H NMR (CDCl₃) = 2.45–3.21 (m, 4 H), 7.31–7.85 (m, 4 H), 9.81 (s, 1 H), 9.95 (s, 1 H).

To a suspension of 4-(dimethylamino)pyridinium chlorochromate (1.24 g, 4.8 mmol) in dry dichloromethane (7.0 mL) was added p-(3-hydroxypropyl)-benzyl alcohol (200 mg, 1.2 mmol). Stirring was continued (2 hours) at room temperature under a [[nitrogen]] atmosphere. The reaction mixture was diluted with [[ethyl acetate]] (10 mL) and the brown granular [[chromium]] reduction products were removed by vacuum filtration through a [[Celite]]® pad. Concentration of the solvent and [[column chromatography]] on [[silica gel]] ([[hexane]]/[[ethyl acetate]], 2:1) furnished 121 mg (62%) of p-(3-hydroxypropyl)benzaldehyde as an oil.

==References==