Efficient demethylation of aromatic methyl ethers with HCl in water

A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as a catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols, catechols, pyrogallols) in high yield. 4-Propylguaiacol was chosen as a model, given the various applications of the 4-propylcatechol reaction product. This demethylation reaction could be easily scaled and biorenewable 4-propylguaiacol from wood and clove oil could also be applied as a feedstock. Greenness of the developed method versus state-of-the-art demethylation reactions was assessed by performing a quantitative and qualitative Green Metrics analysis. Versatility of the method was shown on a variety of aromatic methyl ethers containing (biorenewable) substrates, yielding up to 99% of the corresponding aromatic alcohols, in most cases just requiring simple extraction as work-up.

Automated summary

The demethylation reaction of aromatic methyl ethers using mineral acid as a catalyst in high temperature pressurized water provides high yields of aromatic alcohols. Versatility of the method was demonstrated on various substrates, with up to 99% yield of aromatic alcohols in most cases. The method is scalable and can utilize biorenewable feedstock like wood and clove oil.