Chemical properties
The original medicine is an oil like liquid. At b.p.>313.5℃ , the relative density is 1.03. It is easy to dissolve in methanol and hexane. The solubility is >50% at normal temperature, The solubility in the water at 25 C is 8.03mg/L, The distribution coefficient is 30800.
Application
The product characteristics of fenvalerate are the same as those of fenpropathrin with strong contact toxicity. The knockdown and killing performance is 4 times higher than that of the right-handed trans pyrethrin, and has a prominent driving effect on cockroaches. It is mainly used for processing mosquito repellent incense, electric mosquito repellent incense, liquid mosquito repellent incense and spray to control household pests such as housefly, mosquito, louse, cockroach etc. The recommended amount of use is as follows: (with effective ingredients) mosquito repellent incense: The electric heat mosquito incense containing 0.05% of the product: Containing 10mg/ tablets of this product to control the temperature of the electric heater center at 125-135℃. Liquid mosquito repellent incense: containing 0.66% of this product, plus proper stabilizer; Sustained-release agent; Aerosols: 0.05 0.2% of this product with appropriate amount of lethal agent, synergist and emulsifier.
Chemical Properties
solid
Uses
Prallethrin ia a synthetic pyrethroid; propynyl analog of allethrin. Prallethrin is used as an insecticide.
Uses
Prallethrin is used for the control of insects in domestic and public
health situations.
Definition
ChEBI: Prallethrin is a member of cyclopropanes and a terminal acetylenic compound. It has a role as a pyrethroid ester insecticide and an agrochemical. It is functionally related to a chrysanthemic acid.
Production Methods
Prallethrin is synthesised through a multi-step chemical process rooted in pyrethroid chemistry, specifically involving the esterification of chrysanthemic acid derivatives with alcohols. The key intermediate is a cyclopropane carboxylic acid, which is reacted with a substituted cyclopentenol, often containing a propargyl group, to form the final ester compound. This reaction is carefully controlled to yield the desired cis-trans isomeric mixture, which is crucial for prallethrin’s insecticidal potency. The process emphasises high purity and precise stereochemistry, as impurities can affect both efficacy and safety.
Hazard
A poison by ingestion and inhalation. Low
toxicity by skin contact.
Mechanism of action
Contact, with rapid knock down effect, acts on the insects nervous system. Sodium channel modulator.
Pharmacology
Prallethrin is a propynyl analog of allethrin, with
2-methyl-4-oxo-3-(prop-2-ynyl)-cyclopent-2-enyl as the
secondary alcohol moiety that has been introduced against
public health pests (113–115). The ester of the (S)-alcohol
with (1R)-trans,cis-chrysanthemic acid resolved partially
is commercialized on the strength of the assessment of
insecticidal action of individual stereoisomers (116). Compared
with d-allethrin, it is approximately four, six, and
five times more effective on Musca domestica (for killing),
Blattella germanica (for killing), and Culex pipiens pallens
(for knockdown), respectively (43). A lower level of resistance
to prallethrin than to phenoxybenzyl pyrethroids
was demonstrated in a kdr-resistant housefly strain (116).
Safety Profile
A poison by ingestion
and inhalation. Low toxicity by skin contact.
When heated to decomposition it emits
acrid smoke and irritating vapors.
Metabolic pathway
Prallethrin is stable under normal room temperature storage conditions
for up to 36 months. It is labile to alkali at the ester linkage, forming 2
and 3 (Scheme 1). Analogy with the allethrins (from which it differs
only in the degree of unsaturation in the side chain - propyne rather
than propene) would suggest that the compound is very photolabile.
Degradation
The metabolism of prallethrin was studied following single oral administration
and subcutaneous injection of the cis- and trans-isomers to rats at
two dose levels and after repeated dosing. The compound was labelled in
the alcohol moiety (inferred from the results) (PSD, 1995).
Absorption was rapid with maximum tissue residues being attained
3 hours after the dosing of each isomer. Biphasic clearance of radioactivity
then occurred with half-lives of 3 and 14-23 hours (cis-isomer) and 3-5
and 7-35 hours (trans-isomer). Urinary excretion accounted for 13-32%
(cis-isomer) and 45-62% (trans-isomer) of the dose with most of the balance in the faeces. Less than 0.1% was exhaled as
14CO
2 . Residues
in tissues were very low (0.3% of the dose at 7 days). Metabolism and
disposition were independent of dose and dose route but residues in
tissues were somewhat higher for the cis-isomer.
Twenty-one metabolites were identified (taking account of stereochemistry
and conjugates). The major pathways of metabolism involved
oxidation at a methyl group of the isobutenyl group in the acid moiety
(giving 4 and 5), at the C1 and C2 positions of the propynyl group in the
alcohol moiety (giving 6 and 9) and dihydroxylation (to 7 and 8). The
resulting hydroxy derivatives were conjugated with glucuronic acid and
sulfate.
Hydrolysis of prallethrin also occurred to afford the acid 2 (presumed)
and the alcohol 3. Hydrolysis of the hydroxylated prallethrins and further
oxidation of 3 afforded 10 and 11. Further oxidation of 10 to the cyclic
tertiary alcohol (12) was observed.
When bluegill sunfish were exposed to a l4C-labelled (acid and alcohol
groups) prallethrin isomer (1Rtrans), more than 50% of the biliary
radioactivity recovered from the gall bladder was observed as one ester metabolite. This was identified as the taurine conjugate of carboxylic acid
metabolite 5 (Oshima et al., 1992).
Pesticide Type
Insecticide; Veterinary substance
