Solid acid catalysts for industrial condensations of ketones and aldehydes with aromatics

The condensation reaction of ketones or aldehydes with aromatics (hydroxyalkylation) is applied in the production of many commodities and fine chemicals. Such a reaction is usually catalyzed by strong mineral acids, which have to be neutralized at the end of the reaction and the resulting salts disposed. In this review, we illustrate the results obtained by several industrial and academic research centers having as their target the substitution of mineral acids by regenerable and nonpolluting solid acid catalysts. In many cases, the results obtained have not allowed for the industrial development of the proposed alternatives, but in one case, the solid-acid-based process (BPA production) has already overcome the traditional one and in a few cases solid-acid-based processes seem to have reasonably chances to do the same in a near future.