may be attained to a greater degree if this ratio is greater than 1 and preferably 1 2 4 0 say 2 0 presence of the excess of e g methanol facilitates purification of the desired unsymmetrical ethers and increases the life and selectivity of the catalysts used for preparation etherification may be preferably carried out in the presence of a solid resin etherification catalyst these catalysts are preferably relatively high molecular weight carbonaceous materials containing at least one so 3 h group as the functional group typical of these catalysts are the sulfonated coals 34 zeo karb h 34 34 nalcite x 34 and 34 nalcite ax 34 produced by the treatment of bituminous coals with sulfuric acid these materials are usually available in a neutralized form and in this case must be activated to the hydrogen form by treatment with a strong mineral acid such as hydrochloric acid followed by water washing to remove sodium and chloride ions prior to use the sulfonated resin type catalysts are preferred for use in the present invention these catalysts include the reaction products of phenol formaldehyde resins and sulfuric acid 34 amberlite ir 1 34 34 amberlite ir 100 34 and 34 naleite mx 34 also useful are the sulfonated resinous polymers of coumarone indene with cyclopentadiene sulfonated polymers of coumarone indene with furfural sulfonated polymers of coumarone.