2,6-Xylenol from phenol methylation

Liquid-phase methylation of phenol with methanol at 250°C/150 bar over a selective ortho-methylation catalyst, per US Patent 3,707,569. At 50% single-pass phenol conversion the reported selectivity is 70% to o-cresol and 25% to 2,6-xylenol (the further-methylated product) — modeled here as two sequential fixed-conversion reactors (phenol -> o-cresol, then o-cresol -> 2,6-xylenol) approximating that split, followed by a distillation separating the light methanol/water from the phenolics. The five-component side-draw column sits in the same successive-substitution residual plateau documented for the light-ends-train and DME-synthesis examples — it returns a physically reasonable partial profile rather than a clean converged status.