Description
Benzthiazuron is an obsolete pre-emergence herbicide that was used mainly to control annual broadleaved weeds in a variety of crops. This herbicide has a moderate aqueous solubility and is not volatile. There is some evidence that it can be moderately persistent in some soil systems. Based on its physico-chemical properties benzthiazuron also has potential to leach to groundwaters. Ecotoxicology information is scant but for aquatic organisms the risk appears to be low to moderate. The mammalian oral toxicity is moderate and the substance is a skin and eye irritant.
Uses
Benzthiazuron is an herbicide. It is generally a component of pesticide compositions.
Definition
ChEBI: Benzthiazuron is a member of benzothiazoles.
Production Methods
The commercial production of benzthiazuron begins with the preparation of 2-aminobenzothiazole, obtained by reacting aniline with sulphur and carbon disulfide in a high-pressure autoclave (the Hugerschoff reaction variant), or more commonly in modern plants via cyclisation of phenylthiourea using bromine in acetic acid, followed by neutralisation and crystallisation to yield the heterocyclic amine. This intermediate is then reacted with methyl isocyanate in an inert solvent such as toluene or acetone, where the nucleophilic amine attacks the isocyanate to form the unsymmetrical urea linkage. The resulting benzthiazuron precipitates upon cooling.
Mechanism of action
Absorbed by roots and translocated. PSII inhibitor resulting in plant cell death and plant necrosis.
