Aromatic methyl ethers are converted to aryl benzoates in excellent yield when treated with benzoyl chloride in the presence of a "naked chloride" catalyst at $\rm 185\sp\circ C.$ The catalysts of choice are hexabutylguanidinium chloride (HBGCl) and its HCl adduct $\rm (HBGCl{\cdot}HCl),$ and the reactions are best performed neat or in o-dichlorobenzene. When coupled with the facile saponification of the ester to the phenol, this process constitutes a new scheme for the synthetically important O-demethylation of an aryl methyl ether to a phenol. Polymethoxy aromatics are efficiently per-O-demethylated. For example, when $2,2\sp\prime ,4,4\sp\prime$-tetramethoxybenzophenone was heated with 0.1 equiv. of $\rm HBGCl{\cdot}HCl$ and 6 equiv. of $\rm PhCOCl,\ 2,2\sp\prime ,4,4\sp\prime$-tetrahydroxybenzophenone was obtained in 94% overall yield after hydrolysis with NaOH. Other acid chlorides, RCOCl, where R = substituted aryl, alkyl, or alkenyl, also efficiently yielded a variety of aryl esters. Aromatic polyesters and new esters with liquid crystalline properties have been prepared. Useful extensions of this methodology also are described. When electron deficient aryl methyl ethers are heated with sulfonyl chlorides and $\rm Cl\sp-,$ aryl sulfonate esters are formed in good yield. The analogous reaction with more electron rich aromatic systems affords tars. Similar treatment of aryl methyl ethers with $\rm Cl\sp-$ and benzyl chlorides gives the transetherified, aryl benzyl ethers. Again, product yields are best with electron-deficient anisole ring systems. Finally, a one-step transesterification of aryl acetates to other aryl esters is reported. When aryl acetates are treated with the $\rm Cl\sp-$ catalyst and a high boiling $\rm ({\ge}180\sp\circ C)$ acid chloride at $\rm 185\sp\circ C,$ acetyl chloride distills from the medium and the transesterified product is isolated in high yield.