The problem of determination of hydroxy groups in poly(oxyethylene) diols by using the phenylisocyanate method

Traces of potassium acetate present in commercial poly(oxyethylene) diols (Fluka) were shown to catalyze the cyclotrimerization reaction of isocyanates. This reaction interferes with the determination of hydroxy groups by using the phenylisocyanate method. After the removal of potasium acetate (e. g. by means of ion exchangers) the phenylisocyanate method gives reproducible results which can be compared with those obtained by other methods. Reaction conditions suitable for the determination of OH groups in poly(oxyethylene) diols were found.