Description
Dimethipin is a plant growth regulator and defoliant. It is highly soluble in water and has a low volatility. Depending on local conditions it may be persistent in both soil and water systems. It also has potential to leach to groundwater. Dimethipin is moderately toxic to aquatic species (except algae), birds, earthworms and honeybees. This substance also has a moderate oral mammalian toxicity, is an irritant and skin sensitizer. There is also the suggestion that it is a carcinogen.
Uses
Plant growth regulator.
Uses
Dimethipin is a defoliation herbicide (1,2) which is found in pesticide formulations for protection of crops. Drinking water contaminant candidate list 3 (CCL 3) compound as per United States Environmental Protection Agency (EPA), environmental, and food contaminants.
Definition
ChEBI: Dimethipin is a sulfone.
Production Methods
The commercial production of dimethipin begins with the synthesis of the sulphide precursor, 2,3-dihydro-5,6-dimethyl-1,4-dithiin, typically via a base-catalysed cyclisation reaction of 1,2-ethanedithiol with 2,3-dibromobut-2-ene or an equivalent alpha,beta-unsaturated dihalide in an organic solvent under controlled temperature to form the dihydrodithiin ring with geminal methyl groups. The precursor is then oxidised to the tetraoxide using excess peracid, such as m-chloroperbenzoic acid or perbenzoic acid, in a biphasic solvent system like dichloromethane-water, with stirring at low temperature to selectively introduce four oxygen atoms on the sulphur atoms while minimising over-oxidation or decomposition. The reaction mixture is quenched, extracted, and the crude dimethipin purified through filtration, washing, and recrystallisation.
General Description
Colorless crystals with a mild odor. Used as a defoliant.
Air & Water Reactions
Slowly decomposes in water.
Reactivity Profile
DIMETHIPIN slowly decomposes in water to form toxic or flammable products. The decomposition is accelerated by acids. May react with aldehydes, nitrides, and hydrides to generate flammable gases. Reacts with aldehydes, nitrides, and hydrides. Incompatible with acids, peroxides, and acid halides.
Agricultural Uses
Plant growth regulator, Defoliant: Plant and harvest growth regulant. Defoliant used
on cotton crops, beans (dry), vines, plants, and trees.
Desiccant for canola seeds, flax, maize, rice, oilseed rape,
and sunflowers. Not approved for use in the U.S. or EU
countries. There are 17 global suppliers.
Agricultural Uses
Dimethipin is used as a defoliant, to aid harvesting in cotton plants and as a desiccant for potato vines. It enhances the maturation process and reduces seed moisture in the harvesting of rice, rape seed, flax and sunflower
Trade name
HARVADE®; HARVADE-25 F®;
LEAFLESS® Dimethipin; N 252®; TETRATHIIN®;
UBI-N 252®
Mechanism of action
Interferes with protein synthesis in the plant epidermis, functions by stressing the plant’s stomatal system causing it to lose water and defoliate/desiccate.
Safety Profile
Moderately toxic by ingestion. Low toxicity by inhalation and skin contact. When heated to decomposition it emits toxicvapors of SOx.
Pesticide Type
Herbicide; Plant Growth Regulator
