KINETICS ON COCONDENSATION BETWEEN PHENOL AND UREA THROUGH FORMALDEHYDE .1. PSEUDO-FIRST-ORDER REACTION OF MONOMETHYLOLPHENOL AND UREA

The kinetics of the reactions of methylolphenols and urea were investi gated using 2- and 4-hydroxybenzyl alcohols. The high-performance liqu id chromatography (HPLC) using a reverse phase column gave a clear sep aration between methylolphenols and hydroxybenzylureas. The molar rati os of hydroxybenzylureas to the corresponding methylolphenols in react ion mixtures were obtained from the ratios of peak areas of the chroma tograms by using transfer factors corrected by quantitative C-13-NMR ( carbon 13 nuclear magnetic resonance) measurements. The reactions of 2 - and 4-hydroxybenzyl alcohols with excessive amounts of urea were fou nd to follow the pseudo-first-order reaction. It was found that the ps eudo-first-order rate constant for the formation of 4-hydroxybenzylure a is at least ten times greater than that of 2-hydroxybenzylurea. The reactivities of the two hydroxybenzyl alcohols also were investigated in terms of pH and kinds of acids used as catalysts. The pH dependenci es of the pseudo-first-order rate constants were represented by linear equations in terms of hydrogen ion concentrations. It was found that the reactivity of 2-hydroxybenzyl alcohol is enhanced considerably by a zinc acetate/sulfuric acid system.