hich the alkyl groups can also be substituted), esters (???C(O)???OR, where R can be a group such as alkyl, aryl, etc., which can be substituted), aryl (most preferred is phenyl, which can be substituted) and arylalkyl (which can be substituted). [0466] N-oxide refers a functionality wherein an oxygen atom is bonded to the nitrogen of a tertiary amine.