| 摘要 |
<p>New p-phenoxy-phenoxyalkanoic acid derivs. are cpds. of formula (I) in which R1 is H, Cl or 1-3C alkyl; R2 is 1-3C alkyl; and Y is cyclopropylmethyl, the group -CR3R4-C=CH or a group of formula (Ia) in which R3 and R4 are H or 1 -6C alkyl and R5 and R6 are H or CH3. (I) are pre- and post-emergence herbicides useful for combatting grassy weeds in crops such as cereals (esp. barley, oats and wheat), rice, cotton, soya, sugar beet and greens. They are particularly useful againt grassy weeds in sugar beet. Specific cpds. (I) include 2-(p-(p-chlorophenoxy)phenoxy)-propionic acid 2-propynyl ester. In an example, this is prepd. by reacting 2-propynyl 2-bromopropionate with p-(p-chlorophenoxy)phenol in hexamethylphosphortriamide in the presence of NaH.</p> |
