Abstract: The invention provides N-acyl-N-phenyltetrahydrophthalamic acid derivatives represented by the general formula [I], methods of producing the same, and herbicides containing the same as the effective components, ##STR1## wherein X and Y each individually represent hydrogen atoms or halogen atoms, R.sup.1 represents a hydrogen atom, a halogen atom, a lower alkoxy group, a lower alkenyloxy group, a lower alkynyloxy group, a lower alkoxyalkoxy group or a lower alkoxycarbonylalkoxy group, R.sup.2 represents a lower alkyl group, a halogenated lower alkyl group, or a substituted or unsubstituted phenyl group, and R.sup.3 represents a lower alkoxy group, a lower alkenyloxy group, a lower alkynyloxy group, a lower alkoxyalkoxy group, a benzyloxy group or a lower alkoxycarbonylalkoxy group. The herbicides which are very useful can be widely applied to upland, paddy field, orchard, turf, forest, non-crop land, etc, and are not harmful to crops.

Abstract: Trifluoromethyltoluene is obtained from a halomethylbenzotrifluoride, which is a relatively inexpensive material, by hydrogenating the halomethyl group of the starting compound to methyl group with hydrogen gas in the presence of a hydrogenation catalyst and an acid acceptor. Suitable examples of the halomethyl group to be hydrogenated are --CH.sub.2 Cl, --CH.sub.2 F, --CHClF, --CClF.sub.2 and --CF.sub.3. When the starting compound is bis(trifluromethyl)benzene, addition of either an alcohol or an alkali metal fluoride to the reaction system is effective for suppression of formation of xylene as a by-product, and xylene still contained in the reaction product can completely be removed by treatment with a sulfonating agent such as fuming sulfuric acid.