Abstract: 4-Ethyl-3-(phenyl)-1-(3-trifluoromethylphenyl)-2-pyrrolidinones and corresponding compounds bearing a p-substituent on the 1-position phenyl group and/or a substituent on the 3-position phenyl group exhibit selective herbicidal activities against various weeds which cause problems in rice or upland fields, even at extremely low application rates. They can be prepared by reductive dehalogenation of a corresponding .alpha.-haloethyl substituted pyrrolidinone or reductive cyclization of a corresponding N-2-butenyl-N-(substituted phenyl)-haloacetyl-3-trifluoromethylaniline.

Abstract: 1-(3-Substituted benzyl)-3-halogeno-4-(1-halogenoalkyl)-2-pyrrolidinones of the general formula (I): ##STR1## where X represents a hydrogen atom or halogen atom, Y and Z each represents a chlorine atom or bromine atom, and R represents an alkyl group with 2 to 4 carbon atoms, are herbicides useful in rice paddy fields to control weeds therein, especially Echinochloa crusgalli and can be produced subjecting the corresponding 3-dihalogeno compounds to dehalogenation to remove one of the halogen atoms or by cyclizing a 2,2-dihalogenoacetamide derivative represented by the general formula (II) under the presence of an appropriate catalyst; ##STR2## in which X, Y, Z and R respectively have the same meanings as described above.