Iodine → HCID 54081156, compound

Participants

Reaction Steps

The alcohol required for the preparation of the pyrethroid is prepared as follows: ##STR12## A reaction vessel is charged with 14.6 g of magnesium filings together with a trace of iodine crystals. 73.6 g of ethyl bromide in 25 ml of tetrahydrofuran are then added dropwise such that the tetrahydrofuran boils gently under reflux. The Grignard solution formed is added dropwise at 0°-5° C. to a solution of 62.1 g of phenylacetylene in 250 ml of tetrahydrofuran and the mixture is stirred until the evolution of gas ceases. The resultant solution is cooled to 0° C. and 99 g of 3-phenoxybenzaldehyde are added dropwise such that the temperature does no exceed +5° C. The reaction mixture is stirred overnight at room temperature and then cooled to a temperature in the range from 0° to +5° C. About 100 g of ice are added, whereupon a precipitate forms which is dissolved in 100 ml of concentrated HCl. The aqueous solution is extracted with three 150 ml portions of ether and the extracts are washed with NaHCO3 solution and then dried over Na2SO4. The ether is distilled off by rotary evaporation, affording as residue 148 g of 3-phenoxy-α-phenylethynylbenzyl alcohol with a refractive index of nD23 =1.6238 and with an NMR spectrum as shown in FIG. 2. The yield is 98.8 % of theory.

Provenance & Evidence