Dimethenamid-P belongs to the chloroacetamide family of compounds, and is a pre-emergent herbicide. Dimethenamid-P is used for control of some grasses and broadleaved weeds used mainly beans, maize, poppies and pumpkins. It acts through inhibition of cell division. Dimethenamid-P is the more biologically active isomer of chiral dimethenamid and is used at lower rates. Dimethenamid-P is the (S)-enantiomer of 2-chloro-N-(2,4-dimethylthiophen-3-yl)-N-[(2S)-1-methoxypropan-2-yl]acetamide. It is the active enantiomer of dimethenamid, a herbicide applied to the soil to control various broad-leaved weeds and grasses. It has a role as a herbicide, an agrochemical and an antimitotic. It is an enantiomer of a (R)-dimethenamid.