Beflubutamid

Beflubutamid is used on arable land to protect common wheat, barley, triticale and rye crops. The herbicide protects these cultigens from annual dicotyledon weeds.^[2]

Beflubuitamid has two stereoisomers.^[3] The substance as used in agriculture is typically a racemic mixture, a 1:1-mixture of the (S)- and (R)-form:^[4][5]

Enantiomers of beflubutamid
(S)-Beflubutamid	(R)-Beflubutamid

Beflybutamid is placed in the HRAC classification group F1 based on its mode of action. Herbicides in HRAC group F1 influence the biosynthesis of carotenoids.^[6] The molecular characteristic relevant to this group is the partial tetrafluorocarbon-phenyl structure.^[7]

Beflubutamid inhibits the enzyme phytoene desaturase (PDS) in carotenoid biosynthesis. PDS catalyzes the dehydrogenation of phytoene in the synthesis reaction, which is necessary for the final carotenoid synthesis to take place in further reaction steps.^[8]

Plants unable to complete carotenoid synthesis will die, as reactive oxygen compounds will build up in the absence of carotenoids. These reactive oxygen compounds cause the oxidation of cholorphylls and a decrease in green colorants. As such, carotenoid synthesis-inhibiting herbicides like beflubutamid are known as "bleaching herbicides".^[7]

Beflubutamid has been approved in the European Union since 1 December 2007. Plant protection products containing beflubutamid are sold in Austria and Germany, but not Switzerland.^[9]

Beflubutamid has a low vapor pressure of 1.1·10-5 Pa at 25 °C. As such, it does not evaporate under standard conditions. The compound will decompose by reaction with tropospheric hydroxyl radical with a half-life of 3.5 hours (predicted using the Atkinson method),^[6][10][11] and is unlikely to disperse greatly on its own in air. In soil, beflubutamid decomposes to amide and azide forms, as well as other bound residues and CO₂. These degradation products are classified as harmless.^[12]