5,5-DIMETHYL-1-PYRROLINE N-OXIDE

Free radicals are highly reactive, short-lived species. Spin traps react with radicals, forming stable adducts that can be further studied. DMPO is a commonly-used spin trap that reacts with O-, N-, S-, and C-centered radicals. This allows their characterization when used in association with electron spin resonance and immuno-spin trapping. DMPO is water-soluble, rapidly penetrates lipid bilayers, has low toxicity, and can be used in vitro and in vivo.

white to faintly yellow solid

5,5-Dimethyl-1-pyrroline N-oxide is a reagent generally used either as a free-radical spin-trapping agent, or electrophilic component during the synthesis of pyrrolidine derivatives. It may also be considered as 1,3-dipole in cycloaddition processes.

To a three-necked round bottom flask equipped with a condenser, addi­tion funnel, thermometer, and mechanical stirrer and containing 300 ml. 95% ethanol precooled to 2°C is added, all at once, 14.5 g (0.1 mole) 4-methyl-4-nitropentanol, and 13.1 g (1.2 mole) zinc dust. With rapid agita­tion, the glacial acetic acid (24.0 g, 0.4 mole) is added dropwise over a 1-hr period while maintaining the reaction temperature below 15°C. The mix­ture is stirred vigorously for 2 hr and then stored in the refrigerator for 2 days, at approximately 1°C. Then the zinc acetate is filtered and rinsed with 100 ml of ethanol. The combined ethanol factions are rotoevapo-rated to give the crude nitrone. The crude nitrone is dissolved in a 200 ml portion of dichloromethane and the latter washed two times with saturated sodium bicarbonate solution. The organic layer is dried over sodium sul­fate and the solvent rotoevaporated, to give 10.7 (94% yield) of the crude nitrone. The product was purified by double distillation (b.p. 53°C, 0.1 Torr), to give 6.8 g (60%) of the pure nitrone as a white hygroscopic solid. The H¹ NMR (400 MH CDC1₃, Me₄Si) is 6.80 (t, 2H, methylene bound to quaternary C, J = 7.2Hg), 1.43 (s, 6H, methyl), C¹³NMr (100 MH2, CDC13, Me₄ Si) 5=132.4 (Vinyl), 73.5 (quaternary), 34.1 (Allyl), 25.3 (methylene bound to quaternary C), 24.4 (methyls).

Water soluble nitric oxide spin trap; allows the measurement of oxygen-centered free radicals in biological systems at room temperature using electron spin resonance (ESR). Has a high reaction rate constant for superoxide and hydroxyl radicals, and distinguishes simultaneously among a variety of important biologically generated free radicals.

5,5-dimethyl-1-pyrroline N-oxide is used as a spin trap for the study of radicals formed by enzymatic acetaldehyde oxidation. It has a role as a neuroprotective agent and a spin trapping reagent.