Patent ID: 7847097

Claim:
A process for preparing a 1-alkyl-3-phenyluracil of the formula I or a herbicidally acceptable salt thereof, where the variables are as defined below: R 1 is C 1 -C 6 -alkyl; R 2 and R 3 independently of one another are hydrogen, C 1 -C 6 -alkyl or C 1 -C 6 -haloalkyl; R 4 and R 5 independently of one another are hydrogen, halogen, cyano, C 1 -C 6 -alkyl or C 1 -C 6 -haloalkyl; R 6 and R 7 independently of one another are hydrogen, C 1 -C 6 -alkyl, C 1 -C 6 -alkoxy, C 3 -C 6 -alkenyl, C 3 -C 6 -alkynyl, C 3 -C 6 -cycloalkyl, C 3 -C 6 -cycloalkenyl, phenyl or benzyl; comprising reacting a 3-phenyluracil of the formula II or a herbicidally acceptable salt thereof, where the variables R 2 to R 7 are as defined above with an alkylating agent of the formula III R 1 -L 1 III, where R 1 is as defined above and L 1 is halogen, hydrogensulfate, C 1 -C 6 -alkyl sulfate, C 1 -C 6 -alkyl carbonate, C 1 -C 6 -alkylsulfonyloxy, C 1 -C 6 -haloalkylsulfonyloxy or phenylsulfonyloxy, where the phenyl ring may carry one or more substituents selected from the group consisting of halogen, nitro, C 1 -C 6 -alkyl and C 1 -C 6 -haloalkyl, wherein during the entire reaction the pH is kept in a range from 1 to 6 by adding base a little at a time.