6 - Halo - 4 - oxo - 2 - haloalkyl - 2,3 - dihydrobenzo-1,3-oxazines, in which the alkyl group contains 1-6 carbon atoms, are prepared by reacting the corresponding 6-unsubstituted compound with a halogen in an inert organic solvent at 20-40 DEG C. The halogen is preferably chlorine or bromine, and a 5% excess of halogen is preferably used. Suitable solvents are 1,2-dichloroethane, CHCl3, CCl4, nitroethane, nitropropane and glacial acetic acid. In examples the 6-chloro-2-b -chloroethyl compound is prepared; the production of the 6-bromo-2-b -bromoethyl-, and 6-bromo- or -chloro-2-chloromethyl or -bromomethyl-compounds is also referred to. Specifications 806,729 and 809,093 are referred to.
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