DIMETHENAMID-P/RACEMIC DIMETHENAMID

Explanation Dimethenamid-P is the International Standardization Organization (ISO) approved common name for S-2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-acetamide. This compound belongs to the chemical family of chloroacetamides and is used as a pre-emergent or early post-emergent herbicide with a broad spectrum of activity against most annual grasses and some important broad leaf weeds. It is taken up through the coleoptiles (grass seedlings) or the roots and emerging shoots (dicotyledonous seedlings) and reduces cell division and plant growth. Dimethenamid is a racemic mixture of the M (or R) and P (or S) stereoisomers. When this compound was originally registered in various countries, all studies of toxicity were conducted with the racemic mixture. Later, it was discovered that only the P (or S) enantiomer has useful