Production of alkoxy phenolic compounds

Abstract

Alkoxy phenols such as o-methoxyphenol (guaiacol) and o-ethoxyphenol are prepared from substituted cycloaliphatic ketones by dehydrogenation thereof in the presence of a Group VIII noble metal catalyst, preferably palladium supported on carbon, at a temperature of 150° C., to 250° C. The reaction is carried out neat or in the liquid phase using an alicyclic ester reaction solvent having a boiling point ranging from about 150° C., to 250° C. The substituted cycloaliphatic ketone reactant, such as 2-chlorocyclohexanone is prepared by chlorination of cyclohexanone with subsequent conversion of the 2-chlorocyclohexanone to the alkoxy-cyclohexanone compound which is dehydrogenated.

The embodiments of the invention in which a particular property or privilege is claimed are defined as follows: 
     
       1. The process for the preparation of an o-alkoxyphenol in high yield and selectivity, comprising: heating 2-chlorocyclohexanone and a lower alkyl monohydric alcohol under pressure to 110° C. to 200° C., and   contacting the resulting 2-alkoxycyclohexanone in the liquid phase with a Group VIII noble metal catalyst at a temperature of about 150° C. to 250° C.   
     
     
       2. The process of claim 1 wherein the alcohol contains 1 to 2 carbon atoms. 
     
     
       3. A process for the preparation of o-methoxyphenol from 2-chlorocyclohexanone in high yield and selectivity, comprising: heating a reaction mass containing a solution of 2-chlorocyclohexanone dissolved in an excess of methanol to a temperature ranging from about 110° C. to 200° C. for conversion of the 2-chlorocyclohexanone to 2-methoxycyclohexanone,   recovering 2-methoxycyclohexanone from the reaction mass,   refluxing the recovered 2-methoxycyclohexanone substantially in the absence of a solvent therefor with a Group VIII noble metal catalyst at a temperature of from 150° C. to 250° C. for dehydrogenation of the 2-methoxycyclohexanone to o-methoxyphenol, and recovering the o-methoxyphenol.   
     
     
       4. The process of claim 3 wherein the catalyst is palladium supported on an inert carrier present in an amount ranging from 0.1 to 3.0 weight percent relative to the 2-methoxycyclohexanone. 
     
     
       5. A process for the preparation of o-ethoxyphenol from 2-chlorocyclohexanone in high yield and selectivity, comprising: heating a reaction mass containing a solution of 2-chlorocyclohexanone dissolved in an excess of ethanol to a temperature ranging from about 110° C. to 200° C. for conversion of the 2-chlorocyclohexanone to 2-ethoxycyclohexanone,   recovering 2-ethoxycyclohexanone from the reaction mass,   refluxing the recovered 2-ethoxycyclohexanone substantially in the absence of a solvent therefor with a Group VIII noble metal catalyst at a temperature of from 150°  C. to 250° C. for dehydrogenation of the 2-ethoxycyclohexanone to o-ethoxyphenol, and   recovering the o-ethoxyphenol.   
     
     
       6. A process for the production of an o-alkoxyphenol in high yield consisting of refluxing a 2-alkoxycyclohexanone with a Group VIII noble metal catalyst at a temperature of 150° C. to 250° C. 
     
     
       7. The process according to claim 6 in which it is carried out in the presence of an ester solvent. 
     
     
       8. The process according to claim 7 in which the solvent is one selected from the group consisting of ethylene glycol diacetate, trimethylene glycol diacetate, propylene glycol diacetate, 2,3 butanediol diacetate, diisopropyl succinate and dimethyl succinate. 
     
     
       9. The process of claim 7 in which the catalyst is palladium supported on carbon and the ester solvent is one selected from the group consisting of cyclohexyl acetate and cyclohexyl propionate. 
     
     
       10. The process according to claim 7 in which the reaction mass is refluxed at superatmospheric pressure. .[.11. The process for the preparation of an o-alkoxyphenol selected from the group consisting of o-methoxyphenol and o-ethoxyphenol, comprising: refluxing an alkoxycyclohexanone selected from the group consisting of 2-methoxycyclohexanone and 2-ethoxycyclohexanone substantially in the absence of a solvent for the alkoxycyclohexanone together with a Group VIII noble metal catalyst at a temperature of from about 150° C. to 250° C., and   recovering the alkoxyphenol..]..[.12. The process of claim 11 in which the catalyst is palladium supported on an inert carrier present in an amount ranging from 0.10 to 3.0 weight percent relative to the alkoxycyclohexanone..]. .[.13. The process of claim 11 in which the process is carried out at superatmospheric pressure..]. .[.14. The process of claim 11 in which the catalyst is palladium supported on an inert carrier and the reaction is refluxed at superatmospheric pressure..].