R1 and R2 may be identical or different and must be chosen from substituted or unsubstituted alkyl or aryl groups. They may also form part of a ring system. R3 must be chosen from hydrogen, substituted or unsubstituted alkyl, aryl, alkoxy groups or halogens. R3 is typically a methyl or chloro group.
Online Language Learning Tool SkELL allows users to search for phrases in sentences, collocates and similar words. These examples have been automatically selected and may contain errors.
