Silver nitrate–alumina: a chromatographic reaction medium for conversion of 5-halogenopent-2-enes into 1-cyclopropylethyl nitrate

Abstract

A chromatography column of 30% silver nitrate–neutral alumina provides a reactive surface for the ready conversion of 5-halogenopent-2-enes (1) into 1-cyclopropylethyl nitrate (2) upon elution with pentane. By this technique 5-bromopent-2-ene (1a) and 5-iodopent-2-ene (1b) are converted into (2) in 74 and 94% yield, respectively, in less than five minutes. 5-Chloropent-5-ene (1c) was unreactive under the same conditions. Reduced yields of (2) were observed when (1a) or (1b) were stirred, neat, with powdered silver nitrate. When acidic alumina was used to prepare the chromatography column and only partially dried, an efficient medium for hydrolysis to the corresponding alcohol resulted. Elution of (1a) with diethyl ether therefore gave 1-cyclopropylethanol (5) in 31% yield and elution of (2) with diethyl ether gave (5) in ca. 100% yield.