Kinetics of the hydroxymethylation of phenol - I: Rate equation and methodof analysis

Seven reactions take place consecutively and competitively during the hydro xymethylation of phenol in aqueous alkaline media. This hydroxymethylation is the first step in the formation of phenolic resins and has long been stu died. However, the rate equation, which can describe the seven reactions in those reaction systems where the alkali/phenol molar ratios are < 1.0, has not yet been obtained. The authors present a rate equation (in a different ial form) for a computer simulation. This equation involves the concentrati on of hydroxide ion, [OH-], which changes with the change in the compositio n of the reaction system and cannot be expressed as a function of reaction time. However, the value of [OH-] can be obtained by numerical calculation. In the computer simulation the reactions occur for an infinitesimal unit o f time, and the changes in the concentrations of formaldehyde, phenols, and hydroxide ion are calculated. The next step of the reaction takes place ac cording to the reaction conditions that result from the previous step. In t his manner the reactions progress step by step in a computer. Using this me thod we can describe the reaction time course, (i.e., the changes in the co ncentrations of phenol, formaldehyde, and five species of hydroxymethylphen ols with the reaction time).