Synthesis of¹⁴C-propoxur (o-isopropoxyphenyl N-methylcarbamate-¹⁴C) insecticide

Abstract

Propoxur (Baygon^®) is an insecticide with a broad spectrum of activity and a very low order of mammalian toxicity. Radiosynthesis of propoxur was performed by the reaction of acetyl-1¹⁴C chloride and sodium azide to produce methyl isocyanate which then reacted with o-isopropoxyphenol at 100°C. A two compartment reaction tube with a break seal was utilized. Chromatographic procedures for isolating the N-methylcarbamates from their reaction mixtures are reported. Acetyl-1−¹⁴C chloride was prepared from thionyl chloride and sodium acetate-1−¹⁴C. Grignard reaction between methyl iodide and carbon −14 dioxide yielded acetic acid −¹⁴C which was neutralized by sodium hydroxide solution to give sodium acetate 1-¹⁴C.