Kinetics of phenolic resol resin formation by HPLC. III: Zinc acetate

Zinc acetate was used as catalyst in the synthesis of a phenolic resol resi n. The evolution of the addition and condensation reactions was quantitativ ely followed by high performance liquid chromatography. The addition of for maldehyde to phenol was almost exclusively ortho directed. Very low advance ment in polymerization was observed, and diaryl compounds were only slightl y formed. C-13 NMR studies did not show pam, para methylene bridges as a re sult of the poor addition of hydroxymethyl groups onto the pam phenolic sit es. The change in concentration of free phenol as a parameter of the evolut ion of the resin during storage was followed by gas chromatography. Disappe arance of free phenol did not stop at any of the analysed storing temperatu res (room temperature, 4 degrees C, and -20 degrees C). (C) 1999 Elsevier S cience Ltd. All rights reserved.