Crystal structure of a new herbicide, ethyl 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate

The crystal structure of a new grass herbicide, ethyl 2-[4-(6-chloro-2-quinoxalinyloxy)-phenoxy]propanoate (I) was investigated by the X-ray crystallographic technique. The solidstate structure and the conformation of I were confirmed and compared with those of methyl 2-[4-(2, 4-dichlorophenoxy)phenoxy]propanoate (II), (2, 4-dichlorophenoxy)acetic acid (IIIa) and 2-(2, 4, 5-trichlorophenoxy)propanoic acid (IIIb). The phenoxy propanoic acid moiety of I was similar to the equivalent moiety of II, IIIa and IIIb in preferred conformation and shape, whereas its 6-chloro-2-quinoxalinyloxy moiety was different from 2, 4-dichlorophenoxy moiety of II in preferred conformation, shape and size.