Chemical Properties
Colorless crystals. Mp 175C. Soluble
in dimethylacetamide and cyclohexanone; partially
soluble in xylene and butyl acetate.
Uses
Nonselective herbicide used to control herbaceous and woody plants on noncrop
land.
Uses
Terbacil is also absorbed by plant roots and inhibits
photosynthesis. It is used for the selective control of many
annual and some perennial weeds in apples, citrus, peaches,
and sugarcane. Application rates range from 0.5 to 8 kg/ha.
Definition
ChEBI: Terbacil is an organohalogen compound and a member of pyrimidines.
General Description
Colorless crystals. Non corrosive. Used as an herbicide.
Air & Water Reactions
Water soluble.
Reactivity Profile
A uracil derivative.
Agricultural Uses
Herbicide: Terbacil is a selective herbicide that treats a broad
spectrum of broadleaf weeds and grasses. It is formulated
as a wettable powder and is applied by aircraft or ground
equipment on terrestrial food and feed crops (e.g., apples,
mint/peppermint/spearmint, sugarcane, and ornamentals),
forestry [e.g., cottonwood (forest/shelterbelt)], terrestrialfood (e.g., asparagus, blackberry, boysenberry, dewberry,
loganberry, peach, raspberry, youngberry and strawberry),
and terrestrial feed (e.g., alfalfa, sainfoin (hay and fodder),
and forage). Not approved for use in EU countries.
Registered for use in the U.S.
Trade name
COMPOUND® 732; DuPontTM® 732;
EXPERIMENTAL HERBICIDE 732; GEONTER®;
SINBAR®; TURBSVIL®; ZOBAR®[C]
Environmental Fate
Soil. In microbially active soils, tebuthiuron is degraded via demethylation. The average
half-life in soil 12–15 months in areas receiving 60 inches of rainfall a year (Humburg et
al., 1989).
Groundwater. According to the U.S. EPA (1986) terbacil has a high potential to leach
to groundwater.
Plant. The major degradation products of [2-14C]terbacil identified in alfalfa using a
mass spectrometer were (% of applied amount): 3-tert-butyl-5-chloro-6-hydroxymethyluracil
(11.9) and 6-chloro-2,3-dihydro-7-(hydroxymethyl)-3,3-dimethyl-5H-oxa
Photolytic. Acher et al. (1981) studied the dye-sensitized photolysis of terbacil in
aerated aqueous solutions over a wide pH range. After a 2-hour exposure to sunlight,
terbacil in aqueous solution (pH range 3.0–9.2) in the presence of methylene blue (3 ppm)
or riboflavin (10 ppm), decomposed to 3-tert-5-butyl-5-acetyl-5-hydroxyhydantoin.
Deacylation was observed under alkaline conditions (pH 8.0 or 9.2) affording 3-tert-5-
hydroxyhydantoin. In neutral or acidic conditions (pH 6.8 or 3.0) containing riboflavin, a
mono-N-dealkylated terbacil dimer and an unidentified water-soluble product formed.
Product formation, the relative amounts of products formed and the rate of photolysis
were found to be all dependent upon pH, sensitizer, temperature and time (Acher et al.,
1981).
Chemical/Physical. Stable in water (Worthing and Hance, 1991).
Metabolic pathway
When rats are administered terbacil orally, the primary
biotransformation products of terbacil in the urine are
derived from hydroxylation of the 6-methyl group and
are identified as the aglycone, glucuronide, and
sulfate. The other conjugated metabolite is the
mercapturic acid conjugate of the 6-methyl substituent.
Minor metabolites are identified as sulfoxides and
sulfone at the 6-methyl substituent of terbacil.
