Prallethrin is a chemical compound, a terminal acetylenic compound belonging to the cyclopranes, cyclic hydrocarbons, a structural derivative of naturally occurring pyrethrins. 

The name describes the structure of the molecule:

• Pralle- is a prefix used in the naming of various synthetic pyrethroids. It has no specific chemical significance in this context.
• -thrin is common in the names of pyrethroid insecticides and is derived from "pyrethrin", the natural insecticide that pyrethroids mimic.

The raw materials for the production of prallethrin include:

• Chloroethanoic acid - This is an organic compound used as a building block in the synthesis of prallethrin.
• 2,4-Dimethyl-3-methylcyclopent-2-enone - This is another key building block used in the synthesis of prallethrin.
• Allyl bromide - This compound is used as an alkylating agent in the synthesis of prallethrin.

It is composed of:

• Carbon (C): 19 atoms, 39.6% mol, 75.46% mass
• Hydrogen (H): 26 atoms, 54.2% mol, 8.666% mass
• Oxygen (O): 3 atoms, 6.25% mol, 15.87% mass

The synthesis process takes place in different steps:

• Preparation. The ingredients are cyclopentadiene, propargyl chloride, and a chrysanthemic acid derivative.
• Diels-Alder reaction. Cyclopentadiene is reacted with the chrysanthemic acid derivative in a Diels-Alder reaction, a type of cycloaddition reaction that forms a six-membered ring.
• Esterification. The product of the Diels-Alder reaction is reacted with propargyl chloride in an esterification reaction, forming pralletrine.
• Purification. All unreacted materials and by-products are removed from the mixture to obtain pure pralletrine.

It appears as a yellowish, stable liquid, incompatible with strong oxidizing agents.

What it is used for and where

Insecticides

It is a synthetic insecticide based on pyrethrin, a pyrethroid, that is, derived from pyrethrum, a component that is obtained from chrysanthemum (Chrysanthemum cinerarilifolium) , commonly used against household insects such as flies, mosquitoes, and cockroaches.

The synthesis of prallethrin, like other pyrethroids, involves a series of complex chemical reactions. The exact process may vary, but generally involves the esterification of a specific alcohol with a specific acid, both of which have complex structures. The alcohol and acid precursors are themselves synthesised through a series of reactions.

It is important to note that the synthesis of prallethrin is typically carried out in a controlled laboratory or industrial environment by trained chemists, due to the complexity of the reactions and the need for precise control of conditions.

Pyrethrins and pyrethroids are obtained from the chrysanthemum.

• Pyrethrins are commonly used in household insecticides and products for controlling insect pests of domestic and other animals.
• Pyrethroids are more potent as insecticidal action and persist in the environment longer than pyrethrins. but they pose a danger to bees.
• The class of pyrethroids includes about 42 chemical compounds

Do not take citrus fruits or fruits or vegetables after any spraying with Pralletrin for at least 14 days. The time varies depending on the eventual dose sprayed. Read the instructions in the leaflet.

Safety

In this 2008 study, it was explained that both humans and mammals are able to metabolize pyrethroid compounds into substances without toxicity, however, cases of both accidental and intentional intoxication have occurred (1). In this 2020 study, neurotoxicity of inhaled Pralletrin particulates was detected with complex metabolisms within the body, in this case laboratory animals (2).

The most relevant studies on this chemical compound have been selected with a summary of their contents:

Prallethrin  studies

Typical commercial product characteristics Prallethrin 

Appearance	Yellow brown to red brown liquid
Boiling Point	389.8ºC at 760 mmHg
Flash Point	167.9ºC
Density	1.08 g/cm3
PSA	43.37000
LogP	3.44920
Loss on drying	≤2.0%
Water	≤1.0%
Heavy metals	≤10 ppm
Sulphated ash	≤0.5%/g
Residue on ignition
Total Impurity	≤0.5%
Storage	2-8°C
Safety

Price

100 g     $202.00

• Molecular Formula     C₁₉H₂₄O₃
• Molecular Weight    300.398 g/mol
• Exact Mass    300.17300
• CAS: 23031-36-9
• EC Number: 245-387-9
• PubChem Substance ID 329754385
• MDL number MFCD03792792
• DSSTox Substance ID  DTXSID0032572
• UNII  2X67A9B2Z7
• IUPAC  (2-methyl-4-oxo-3-prop-2-ynylcyclopent-2-en-1-yl) 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylate
• InChI=1S/C19H24O3/c1-7-8-13-12(4)16(10-15(13)20)22-18(21)17-14(9-11(2)3)19(17,5)6/h1,9,14,16-17H,8,10H2,2-6H3 
• InChl Key      SMKRKQBMYOFFMU-UHFFFAOYSA-N
• SMILES   CC1=C(C(=O)CC1OC(=O)C2C(C2(C)C)C=C(C)C)CC#C
• ChEBI  39391
• RIDADR     UN2811 6.1/PG 2
• HS Code        2916209027
• RTECS   GZ1725300

Synonyms: 

• D-Prallethrin
• Prallethrin
• ETOC
• Cyclopropanecarboxylic acid, 2,2-dimethyl-3-(2-methyl-1-propenyl)-, 2-methyl-4-oxo-3-(2-propynyl)-2-cyclopenten-1-yl ester
• d,d-T80-Prallethrin
• (RS)-2-Methyl-4-oxo-3-prop-2-ynylcyclopent-2-enyl (1RS,3RS;1RS,3SR)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate
• 2,2-Dimethyl-3-(2-methyl-1-propen-1-yl)cyclopropanecarboxylic Acid 2-Methyl-4-oxo-3-(2-propyn-1-yl)-2-cyclopenten-1-yl Ester
• Cyclopropanecarboxylic acid, 2,2-dimethyl-3-(2-methylpropenyl)-, ester with 4-hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one, trans-(.+/-.)-
• trans-( inverted exclamation markA)-4-Hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one 2,2-Dimethyl-3-(2-methylpropenyl)cyclopropanecarboxylate, (8CI)
• 2-methyl-4-oxo-3-prop-2-yn-1-ylcyclopent-2-en-1-yl 2,2-dimethyl-3-(2-methylprop-1-en-1-yl)cyclopropanecarboxylate
• (2-methyl-4-oxo-3-prop-2-ynylcyclopent-2-en-1-yl) 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylate

References________________________________________________________________________

(1) Safety of pyrethroid for public health use. World Health Organization. Geneva 2005. Available at libdoc.who.int/hq/2005/ WHO_CDS_WHOPES_GCDPP_2005.10.pdf. Accessed 17 May 2008

(2) Santiasih I, Titah HS, Hermana J. The effects of particulate matters inhalation exposures of prallethrin and d-phenothrin mixture in mice (Mus musculus) against exhaled carbon dioxide concentration. Toxicol Res. 2019 Dec 2;36(1):59-67. doi: 10.1007/s43188-019-00002-8.