Methyl iodide → Trimethyl(3,5-dimethyl-4-hydroxybenzyl)ammonium iodide salt

Participants

Reaction Steps

2,6-dimethylphenol (112.5 g, 0.92 mol) dissolved in 250 ml ethanol was added dropwise to a mixture of formaldehyde (139 ml of a 36.5% aqueous solution, 1.84 mol) and dimethylamine (300 ml of a 40% aqueous solution, 2.03 mol) and the resulting mixture was refluxed for 4 h. Ethanol was evaporated, the residue was partitioned between water and dichloromethane, the organic phase was dried over MgSO4 and evaporated to yield 165 g (100%) of an oil. To a dioxane solution (900 ml) of the dimethyl(3,5-dimethyl-4-hydroxybenzyl)amine thus obtained (165 g, 0.92 mol) was added methyl iodide (126 ml, 2.03 mol) and the resulting mixture was refluxed for 2 h. The solid formed was filtered and washed with dioxane to yield 296 g (100%) of the trimethyl(3,5-dimethyl-4-hydroxybenzyl)ammonium iodide salt. This latter (148 g, 0.46 mol) was suspended in 300 ml xylene, triethyl phosphite (120 ml, 0.69 mol) was added dropwise and the resulting mixture was refluxed for 16 h. The solid formed was filtered and the solvent and excess of phosphite were evaporated under vacuum to yield diethyl (3,5-dimethyl-4-hydroxybenzyl)phosphonate as a viscous oil (117 g, 93%).

Provenance & Evidence