Cyhalothrin acid

Cyhalothrin acid

Cyhalothric Acid (Chemical Name: *(RS)-α-Cyano-3-phenoxybenzyl (1R,3R)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclopropanecarboxylate acid*) is the carboxylic acid metabolite and precursor of cyhalothrin, a potent synthetic pyrethroid insecticide. It is not typically isolated but is a key intermediate in the synthesis of lambda-cyhalothrin, one of the most widely used agricultural and public health insecticides.

Key Properties

Chemical Formula: C₂₃H₁₉ClF₃NO₃

Molecular Weight: 449.85 g/mol

Appearance: Likely a white to off-white crystalline solid (pure form).

Solubility:

Insoluble in water (hydrophobic due to aromatic and cyclopropyl groups).

Soluble in organic solvents (e.g., acetone, ethanol, DCM).

Stability:

Sensitive to UV light and alkaline conditions (may degrade under hydrolysis).

Role in Pyrethroid Chemistry

Insecticide Synthesis:

Cyhalothric acid is esterified with alcohols (e.g., α-cyano-3-phenoxybenzyl alcohol) to produce cyhalothrin and its enantiomerically pure form, lambda-cyhalothrin.

The cyclopropane carboxylate core contributes to the insecticidal activity by disrupting sodium channels in pests.

Mode of Action:

Acts as a neurotoxin in insects, causing paralysis and death (similar to natural pyrethrins but more stable).

Applications

Agriculture: Used in crops (cotton, cereals, vegetables) to control lepidopteran and coleopteran pests.

Public Health: Found in mosquito control formulations (indoor residual sprays, bed nets).

Veterinary: Occasionally used in ectoparasite treatments.

Safety & Environmental Notes

Toxicity:

Highly toxic to aquatic life and bees (restricted near water bodies).

Low mammalian toxicity (but irritant to eyes/skin).

Degradation: Forms less toxic metabolites in soil (half-life ~30–60 days).

Synthesis Pathway

Cyclopropanation:

Derived from chrysanthemic acid derivatives (e.g., dichlorovinyl-dimethylcyclopropane carboxylate).

Esterification:

Reacted with α-cyano-3-phenoxybenzyl alcohol to form cyhalothrin.

Regulatory Status

Approved by EPA, WHO, and EU (with usage restrictions).

Requires protective gear (gloves, masks) during handling.