2,4-Dinitrobenzeneseleninic Acid

[65252-77-9]  · C6H4N2O6Se  · 2,4-Dinitrobenzeneseleninic Acid  · (MW 279.07)

(catalyst with hydrogen peroxide for the epoxidation of alkenes1,2 and the Baeyer-Villiger oxidation of aromatic aldehydes and ketones3)

Physical Data: mp 140-143 °C (dec).

Solubility: slightly sol water; sol dioxane, ethyl acetate.

Preparative Methods: obtained from the oxidation of bis(2,4-dinitrophenyl) diselenide with 85% Hydrogen Peroxide4 or fuming Nitric Acid.5 Bis(2,4-dinitrophenyl) diselenide is prepared from the reaction of Lithium Diselenide with 2,4-dinitrochlorobenzene6 or from the base hydrolysis of 2,4-dinitrophenyl selenocyanate.5

Handling, Storage, and Precautions: both 2,4-dinitrobenzeneseleninic acid and bis(2,4-dinitrophenyl) diselenide are stable indefinitely at rt. Selenium compounds are potentially toxic and should be handled in a fume hood.

2,4-Dinitrobenzeneseleninic acid, conveniently generated in situ from bis(2,4-dinitrophenyl) diselenide (1), catalyzes the epoxidation of alkenes in CH2Cl2 under two-phase reaction conditions with 30% H2O2 (eq 1).1,2 The addition of anhydrous MgSO4 removes excess water, enhancing the reaction rate1 and inhibiting diol formation.7 Catalyst levels of 0.5-5% are effective for epoxidizing di-, tri-, and tetrasubstituted alkenes in high yields. With less reactive terminal alkenes, such as styrene, the addition of 30% H2O2 in portions over 14 h and the presence of radical inhibitor are needed to achieve good yields of epoxide.8 Allylic alcohols exhibit little, if any, stereoselectivity (eq 2) or regioselectivity (eq 3), in contrast to epoxidations with peroxycarboxylic acids or with alkyl hydroperoxides in the presence of vanadium and molybdenum catalysts.1

The use of safe and inexpensive 30% H2O2, the ease of product isolation (mild base extraction removes the traces of catalyst from the CH2Cl2 layer), and the potential for catalyst recycle3 make the in situ generation of 2,4-dinitroperoxybenzeneseleninic acid (eq 4)9 an attractive alternative to the stoichiometric use of peroxycarboxylic acids for Baeyer-Villiger oxidations.

Phenols are obtained from aromatic aldehydes via their corresponding aryl formates in high yield with 30% H2O2 (eq 5), while 90% H2O2 is needed to convert polymethoxyacetophenones to phenols in moderate yields. a,b-Unsaturated aldehydes react similarly to aromatic aldehydes to give vinyl formates (see also o-Nitrobenzeneseleninic Acid).10

A variety of other seleninic acids (see also Benzeneseleninic Acid and o-Nitrobenzeneseleninic Acid) and diselenides have been studied using the two-phase oxidation conditions. However, from an activity standpoint, 2,4-dinitrobenzeneseleninic acid is the catalyst of choice for large scale syntheses, particularly epoxidations.1,8

1. Hori, T; Sharpless, K. B. JOC 1978, 43, 1689.
2. Reich, H. J.; Chow, F.; Peake, S. L. S 1978, 299.
3. Syper, L S 1989, 167.
4. Kloc, K.; Mlochowski, J.; Syper, L. LA 1989, 811.
5. Rheinboldt, H.; Giesbrecht, E. CB 1955, 88, 666.
6. Syper, L.; Mlochowski, J. T 1988, 44, 6119.
7. Matoba, Y.; Urabe, S.; Naita, H.; Nakajima, H.; Ishii, Y.; Ogawa, M. J. Jpn. Pet. Inst. 1983, 26, 349 (CA 1984, 100, 51 373q).
8. Kubicz, E.; Mlochowski, J.; Syper, L. JPR 1991, 333, 243.
9. Syper, L.; Mlochowski, J. T 1987, 43, 207.
10. Syper, L. T 1987, 43, 2853.

James M. Renga

DowElanco, Indianapolis, IN, USA

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