Monolinuron

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Monolinuron is a selective systemic herbicide that also acts as an algaecide. It is used to control broadleaf weeds and annual grasses in crops such as leeks, potatoes, and dwarf French beans. It works by inhibiting photosynthesis in treated plants, causing early leaf yellowing, die-back, and eventual weed death after the plant takes it up through roots or leaves. In aquariums, it is sometimes used to control blanket weed and hair algae.

Chemical and physical properties:
- IUPAC name: N′-(4-Chlorophenyl)-N-methoxy-N-methylurea
- Molecular formula: C9H11ClN2O2; molar mass about 214.65 g/mol
- Melting point: 80–83°C
- Solubility: soluble in water (about 0.735 g/L); very soluble in many organic solvents (acetone, methanol, toluene)
- Volatility: low
- Mobility and persistence: moderately persistent in soil and moderately mobile; degrades relatively quickly in water sediments
- Key identifiers include CAS 1746-81-2 and various registry numbers

How it behaves in the environment:
- It is fairly persistent in soil but not highly volatile.
- It tends to remain in or near treated areas and can move with water in the environment.
- Degradation in water sediments has a half-life around 22 days.

Toxicity:
- Mammals: relatively low acute toxicity; a rat oral LD50 is about 2100 mg/kg

Trade names and history:
- Marketed under names such as Monamex, Gramonol, and Aresin
- Introduced for use around the mid-1960s

Notes:
- Monolinuron is a derivative of urea and is related to certain other herbicides in its mode of action, particularly its inhibition of photosystem II.