SUM-Y
The reaction between dimethylphenols and formaldehyde in alkaline .medium was studied by high-performance liquid chromatography and 'H nuclear magnetic resonance spectroscopy. The course of the reaction between higher phenols and formaldehyde was established. The relative retention times of or&o-and para-substituted phenols produced by reaction with formaldehyde are given. Reactions via the para position of substituted phenols appear to be favoured.
INTRODUCI'ION
The formation of phenolic resins involves three reaction steps: the addition of formaldehyde to phenols to form hydroxymethylphenols, .the condensation of hydroxymethylphenols to methylene ether bridged di-or high-molecular compounds and disproportionation of methylene ether bridge to methylene-bridged phenols and formaldehyde. The application of the highly selective high-performance liquid chromatography permits the separation of the products of the reaction between phenols and formaldehyde, which differ in the number of hydroxyl and methyl groups in the benzene ring and in the positions of the hydroxymethyl groups linked to the benzene ring1s2.
In this paper, we report the results of studies of the separation and identikation of the products of the reaction between higher phenols and formaldehyde in alkaline medium. The technique allows the rapid ~separation of the reaction products, which can be analysed by means .of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy.
EXPERIMENTAL
The phenols were products of Fluka (Buchs, Switzerland) and Ferak @erhn, G-F-R.). These Bnd all other reagents were of analytical-reagent grade.
AR Perkin-Elmer 1220 analytical liquid chromatography was used; the c01umnS were 0:5 m x 0.2 mm LD; stainless-steel tubes Bled. with 5-pm LiChrosorb Si-60