Simazine

Simazine is an herbicide of the triazine class. The compound is used to control broad-leaved weeds and annual grasses.

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Physical properties

Water Solubility: 5 mg/L @ 20 C

Solubility in Other Solvents: s. in methanol, chloroform, and diethyl ether [6]; s.s. in pentane

Vapor Pressure: 0.000810 mPa @ 20 C

Partition Coefficient: 1.9600

Adsorption Coefficient: 130

Preparation

Simazine may be prepared in the laboratory from cyanuric chloride crystals and a strong solution of ethyl amine (at least 50 per-cent by number in water). The reaction is highly exothermic and is therefore best carried out in an ice bath below 10 C. It is also essential to carry out the synthesis in a fume hood since cyanuric chloride decomposes at high temperatures into hydrogen chloride and hydrogen cyanide both of which are highly toxic by inhalation.

Properties and Uses

Simazine is an off-white crystalline compound which is sparingly soluble in water. It is a member of the triazine-derivative herbicides (see also atrazine) and was widely used as a residual non-selective herbicide but is now banned in European Union states (EU directive 91/414/EEC). Like atrazine, it acts by inhibiting photosynthesis. It remains active in the soil for 2-7 months after application.