A process for preparation of a phosphoromonochloridite in high yield, by contacting phosphorus trichloride (PCl3) with an aromatic diol, such as 2,2′-biphenol, in a slurry, which contains a portion of the aromatic diol in solid form and contains a solution phase containing the remaining portion of the aromatic diol and an organic solvent, under reaction conditions sufficient to produce the phosphoromonochloridite. The slurry comprises less than 5 mole percent of a nitrogen base, calculated on total moles of the aromatic diol, and the organic solvent is selected for its low hydrogen chloride solubility.