Alkoxy group

In chemistry, the alkoxy group is an alkyl group which is singularly bonded to oxygen; thus R−O. Denoted usually with apostrophe('). The range of alkoxy groups is vast, the simplest being methoxy (CH₃O−).¹ An ethoxy group (CH₃CH₂O−) is found in the organic compound ethyl phenyl ether (C₆H₅OCH₂CH₃, also known as ethoxybenzene).

Related to alkoxy groups are aryloxy groups, which have an aryl group singularly bonded to oxygen such as the phenoxy group (C₆H₅O−).

An alkoxy or aryloxy group bonded to an alkyl or aryl (R−O−R') is an ether. If bonded to H it is an alcohol.

The term alkoxide refers to the anionic conjugate bases of alcohols (RO⁻) or to ionic compounds containing such an anion. Alkoxide compounds are derivatives of alcohols where the hydrogen of the –OH group is replaced by a metal;² for example, the sodium salt of ethanol (CH₃CH₂OH) is sodium ethoxide, containing ethoxide anions CH₃CH₂O⁻ and sodium cations Na⁺.