In the preparation of tertiary butyl alcohol and a linear C.sub.3 -C.sub.12 mono epoxide by the epoxidation reaction of a linear C.sub.3 -C.sub.12 alpha mono olefin with tertiary butyl hydroperoxide in solution in tertiary butyl alcohol in the presence of a catalytic amount of a soluble complex of molybdenum with ethylene glycol, a portion of the catalyst that is used is a recycle (final) ethylene glycol solution of a complex of ethylene glycol with ammonium-containing molybdenum compounds prepared from ethylene glycol and a precipitate of solid ammonium-containing molybdenum compounds formed by saturating a heavy distillation fraction with ammonia to thereby form a liquid amination product containing a precipitate of solid ammonium-containing molybdenum compounds; the heavy distillation fraction being obtained by distillation of the epoxidation reaction product.