Thin-layer chromatography of phenol-formaldehyde resole resins

Abstract

The determination of isomers of mononuclear methylol phenols in phenol-formaldehyde resole resins was studied by two-dimensional thin-layer chromatographic separation and ultraviolet spectroscopy with phlorogrucin dihydrate as an internal standard.
The optimum thickness of cellulose plates used were 0.6 mm. The first developing solvent was water and the second one was a mixture of benzene-acetic acidwater (5 : 5 : 1). The sum of the first and second developing time in thin-layer chromatography was about one fifth as long as that in paper chromatography for the qualitative analysis.
The extracts of each spots with methyl alcohol were determined by the key band at 269 nm for phlorogrucin dihydrate, and at about 280 nm for mononuclear isomers.
The reproducibility of the determination of 2-methylol phenol was about 10 per cent by the coefficient of variance. However, 4-methylol phenol, 2, 4-and 2, 6-dimethylol phenols and 2, 4, 6-trimethylol phenol were determined semi-quantitatively; the correction coefficients used were obtained by using standards in which cresols, ethyl phenols, dimethyl phenols, trimethyl phenol, dimethylol cresols, and monomethylol xylenol were substituted to these materials except 2-, and 4-methylol phenols, respectively.