A new efficient catalytic method of naphthols ring alkylation Original Research Article

The attempts carried out so far concerning catalytic ring alkylation of naphthols with alcohols have, as a rule, brought about a complex mixture of products from which the separation of individual compounds with the aim of their practical utilization has been proved to be impossible. We have found that naphthols and some of their derivatives could be easily alkylated with methanol or higher alcohols in the presence of iron oxide catalyst by a gas-phase continuous process. As a result of alkylation the alkyl group enters into the ortho-position to the hydroxyl group. The yields of alkylnaphthols are approximately about 90%, which simplifies their separation and purification considerably. The advantage of the newly developed method of alkylation is that it leads to high degree of raw materials utilization: it is practically wasteless, thus it is well suited to the requirements of modern process technologies. Its application may contribute to the increase of the demand for naphthol derivatives as potential raw materials for many new syntheses of pharmaceuticals, plant protection agents, dyes, etc.