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Phenol oxidation to o-benzoquinone using Fremy's salt; 4-(Methylsulfanyl)-1,2-benzoquinone

SyntheticPage 439
DOI: 10.1039/SP439
Submitted Jul 20, 2010, published Jul 20, 2010
Christopher Cooksey (rsc@chriscooksey.demon.co.uk)
A contribution from QUINTOX group


			Reaction Scheme: Phenol oxidation to o-benzoquinone using <SPAN class=csm-chemical-name id=csm1285432823767 title="Fremy's salt">Fremy's salt</SPAN>

Chemicals Used

Potassium nitrosodisulfonate, Fremy's salt, (KSO3)2NO (Aldrich)

4-(Methylmercapto)phenol (Aldrich)

KH2PO4

Procedure

A solution of KH2PO4 (10 g) in water (200 cm3) was mechanically stirred in a 2L round bottom flask and ice (200 g) added. The flask was cooled in ice-ethanol mixture and (KSO3)2NO (6 g, 22.4 mmol) added followed by a solution of 4-(methylmercapto)phenol (1.0 g, 7.1 mmol) in diethyl ether (20 cm3). After 1 m the solution was orange and after 5 m dark red. After 1 h the mixture was rotoevaporated at 20 ºC to remove the diethyl ether and extracted with chloroform (3 x 50 cm3). Evaporation gave a crimson solid (0.95 g, 86% yield), m.p. 92 ºC.

Author's Comments

No attempt was made to optimise yields. This methylsulfanyl product was more stable than the ethers which were unstable short-lived products and which were reduced (Na2S2O4) without delay to give the corresponding catechols in 34-87% yields Page xxx

Using the same method, the following 4-substituted o-benzoquinones were prepared:

CH3O

CH3CH2CH2O

CH3CH2CH2CH2O

CH3CH2CH2S

CH3CH2CH2CH2S

HOCH2CH2S

Data

δH (CDCl3) 6.82dd (10.1, 2.4), 6.42dq (10.1, 0.5), 6.19d of qui (2.4, 0.5), 2.51d (0.5)

λmax/nm (log ε) (H2O), 330(3.77), 460 (3.42)

Lead Reference

Cooksey CJ, Land EJ, Riley PA, Org. Prep. Proced. Int., 1996, 28(4), 463-467, doi: 10.1080/00304949609356553

Other References

Teuber HJ, Chem. Rev., 1971, 71, 229

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

Keywords: oxidation, radical, sulphides

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