GB1344850A - Production and purification of light-coloured piperonyl butoxide - Google Patents

Abstract

1344850 Light-coloured chloromethyl dihydrosafrole and piperonyl butoxide FMC CORP 17 Nov 1971 [19 Nov 1970 (3)] 53376/71 Heading C2C Light-coloured piperonyl butoxide is produced by reacting a light-coloured alkali metal 2-(2- butoxyethoxy)ethoxide with light - coloured chloromethyl dihydrosafrole at temperatures up to 50 degrees in an inert atmosphere of nitrogen, neutralizing and washing the alkali metal chloride from the condensed product, vacuumdistilling the product (at temperatures sufficiently low so that tar formation is avoided) to remove 2-(2-butoxyethoxy)ethanol overhead, and recovering piperonyl butoxide as a bottom product. The light-coloured alkali metal 2-(2- butoxyethoxy)ethoxide is prepared by reaction of 2-(2-butoxyethoxy)ethanol with strong aqueous alkali metal hydroxide at elevated temperatures up to 90‹ C. either in the presence of 1-5% of an organic amine or out of contact with oxygen. The light-coloured chloromethylated dihydrosafrole is produced either by chloromethylating dihydrosafrole freed of impurities of lower volatility by reacting the dihydrosafrole freed of impurities of lower volatility in an aqueous medium with a slight excess of formaldehyde and a sufficient excess of hydrogen chloride to yield a molar concentration of hydrogen chloride of 7À5 to 9À5 at 40-65‹ C. while maintaining an inert atmosphere around the reaction mixture and separating product from the aqueous medium, or (ii) by mixing crude chloromethyl dihydrosafrole with at least three times its volume of a liquid alkane or cycloalkane having a boiling point sufficiently below that of the chloromethylated dihydrosafrole to be readily distilled away from it whereby the chloromethylated dihydrosafrole is dissolved and tarry impurities are precipitated, separating the solution from the tars, and distilling the added liquid from the solution to obtain a residue of decolorized chloromethylated dihydrosafrole.