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Phase transfer catalysed permanganate oxidation of hydroxymethyl to carboxylic acid; 1,3,4-Trimethoxy-9,10-dioxo-9,10-dihydro-anthracene-2-carboxylic acid

SyntheticPage 458
DOI: 10.1039/SP458
Submitted Aug 06, 2010, published Aug 10, 2010
Christopher Cooksey (rsc@chriscooksey.demon.co.uk)
A contribution from R J H Clark Group, UCL


			Reaction Scheme: Phase transfer catalysed permanganate oxidation of hydroxymethyl to carboxylic acid

Chemicals Used

2-Hydroxymethyl-1,3,4-trimethoxyanthraquinone Page 457

KMnO4

Tetrabutylammonium chloride

KOH

Procedure

2-hydroxymethyl-1,3,4-trimethoxyanthraquinone (1.39 g, 4.22 mmol) was dissolved in benzene (100 cm3) and water (50 cm3) added, tetrabutylammonium chloride (360 mg) was added, followed by powdered KMnO4 (1 g, 6.3 mmol) and finally KOH (2.8 g).   The mixture was stirred for 3 d then the phases were separated and the organic phase extracted with water (25 cm3). The combined aqueous phases were stirred and cooled, adding Na2SO3 (3 g) and H2SO4 to acidify. The bright lemon yellow precipitate of 1,3,4-trimethoxy-9,10-dioxo-9,10-dihydro-anthracene-2-carboxylic acid was filtered and dried to give 1.20 g (83% yield).

Author's Comments

The hydroxymethyl starting material was obtained Page 457 as a minor product from the nitrite reaction of the bromomethyl compound which gave the carboxylic acid as the major product.

Data

δH (CDCl3) 8.21m (2H), 7.78m (2H), 4.13s (3H), 4.06s (3H), 4.03s (3H)

EI-MS m/z (%), 342 (97), 312 (41), 310 (11), 309 (50), 298 (17), 297 (98)

Lead Reference

Rosenau T, Habicher WD, Synlett, 1997(2), 208-210

DOI: 10.1055/s-1997-730

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Get structure file (.cdx, .sk2, .mol)

Keywords: carboxylic acids, oxidation, phase transfer

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