Chemistry behind mosquito repellent products. Mosquito repellents contain active ingredients that repel mosquitoes like pyrethrum, pyrethroids (allethrin, esbiothrin), and meperfluthrin. Products include coils, liquid repellents, creams, and sprays. Coils use pyrethrum and synthetic pyrethroids which are neurotoxins that paralyze mosquitoes. Liquid repellents use transfluthrin, BHT, and perfume. Creams contain DEET, picaridin, and IR3535 which form a barrier to interfere with mosquito sensing. Natural alternatives include lemon eucalyptus oil, neem oil, and cit

1. Chemistry behind the
mosquito repellent
products
Presented by-
Sanjeev Ranjan
Ajinkya Patil

3. WHAT IS MOSQUITO REPELLENT?
A mosquito repellent is a substance designed to keep away
mosquitoes, thereby preventing them from biting humans and
feeding on human blood.
It typically contains an active ingredient that repels mosquitoes
and secondary ingredients that, among other things, dilute the
active ingredient to a desired concentration and help in releasing
the active ingredient when needed.

4. The products that are currently available in the
market is in the form of followings.
1)mosquito coils
2)liquid repellent(Plug-in mosquito repellents )
3)creams, lotions, oils
4)spray

5. Coils

6. COILS
A mosquito coil is a mosquito-repelling incense, usually made into a spiral, and
typically made using dried paste of pyrethrum powder as active ingredient.
->Pyrethrum(plant name) have potent insecticidal activity by targeting the nervous
systems of insects
Active ingredients found in mosquito coils may include
● Pyrethrum – a natural, powdered material from a kind of chrysanthemum plant.
● Pyrethrins – an extract of the insecticidal chemicals in pyrethrum.
● Allethrin(synthetic pyrethroids) – sometimes d-trans-allethrin(isomer of allethrin is more
toxic to insects), the first synthetic pyrethroid.
● Esbiothrin – a form of allethrin.
● Meperfluthrin - a pyrethroid ester

7. Pyrethrin Allethrin Meperfluthrin

8. Active ingredients of coil continued....
● Butylated hydroxytoluene (BHT) – an optional additive used to prevent
pyrethroid from oxidizing during burning.
● Piperonyl butoxide (PBO) – an optional additive to improve the effectiveness
of pyrethroid.
● N-Octyl bicycloheptene dicarboximide (MGK 264) – an optional additive to
improve the effectiveness of a pyrethroid.
● Dimefluthrin - a pyrethroid pesticide.

9. Butylated hydroxytoluene
(BHT)
Piperonyl butoxide (PBO)
N-Octyl
bicycloheptene
dicarboximide (MGK
264)
Dimefluthrin

10. BHT(Butylated hydroxytoluene)
->primarily act as a terminating agent in oxidation of unsaturated (usually) organic
compounds that are attacked by atmospheric oxygen.
->BHT stops this autocatalytic reaction by converting peroxy radicals to
hydroperoxides. It effects this function by donating a hydrogen atom:
RO2• + ArOH → ROOH + ArO•
RO2• + ArO• → non radical products
where R is alkyl or aryl, and where ArOH is BHT or related phenolic antioxidants.
Each BHT consumes two peroxy radicals.

11. These chemical vapors are neurotoxins that attack the nervous systems of all
mosquito,and paralyses their body and they eventually die.The chemical
repellents used as mosquito repellents are toxic substances.

12. Disadvantages
1)Mosquito coils can be fire hazards
2)the amount of exposure poses a health risk, but there is a lack of clear evidence
that the long-term exposure to mosquito coil smoke increases the risk of more
serious health impacts such as lung cancer.
3)Coils sold in China and Malaysia were found to produce as much smoke PM2.5
as 75-137 burning cigarettes and formaldehyde emission levels in line with 51
burning cigarettes.

13. liquid repellent

14. Liquid repellents are now widely used to repel mosquitoes.
The Liquidator mosquito repellent has a graphite rod in the middle and the bottle
is filled with the repellent. There is a heater coil in the liquidator. The repellent
chemical when comes in to contact with the heated rod turns into fume which
attack the nervous systems of mosquitoes.

15. Liquid repellents
This mosquito repellant consists of a liquid mix, that gets converted into vapors on
moderate heating.
The liquid inside the refill is a mixture of mostly 3 types of chemicals
1. Insecticide - this makes the mosquitoes fly away
2. Stabiliser / anti-oxidant - to prevent the insecticide getting oxidised due to heat.
3. A perfume - to prevent the humans from running away!

16. A typical liquid contains followings;
1)transfluthrin 0.888%(w/w)(as insecticide)
2)butylated hydroxytoluene 1%(w/W)( Stabilizer / anti-oxidant)
3)perfume drakkar 1%(w/w)(perfume)
4)deodorised kerosene 97.120%(w/w)(solvent)

17. Transfluthrin
Transfluthrin is a fast-acting pyrethroid insecticide .
Transfluthrin is neurotoxins that attack the nervous systems of all insects. ... They
affect the flow of sodium out of the nerve cells in insects, resulting in repeated and
extended firings of the nerves, causing the insects to die.

18. How insecticide works?

20. Pyrethroids are axonic excitoxins, the toxic effects of which are mediated through
preventing the closure of the voltage-gated sodium channels in the axonal
membranes. The sodium channel is a membrane protein with a hydrophilic
interior. This interior is a tiny hole which is shaped precisely to strip away the
partially charged water molecules from a sodium ion and create a favorable way
for sodium ions to pass through the membrane, enter the axon, and propagate an
action potential. When the toxin keeps the channels in their open state, the nerves
cannot repolarize, leaving the axonal membrane permanently depolarized, thereby
paralyzing the organism.As to why they don’t stay there and die? Will you stay in a
closed space with toxic gas surrounding you? well , the insect also want to escape
to open environments but the chemical has already entered through its spiracles
and shows its effect as paralysis and death!

21. Disadvantages
1. Exposure to it’s smoke can cause headaches, coughs, sore throats, nausea
and dizziness.
2. Long-term exposure side-effects can include allergies, asthma and
persistent wheeze in children, as well as respiratory irritation.

22. Creams, lotions, oils ,spray

23. Creams, lotions, oils
These mosquito repellents work by interfering with the insect's homing system. This
homing system, located in the antennae, consists of chemical receptors. The
chemical receptors are stimulated by lactic acid that naturally evaporates from the
skin of warm-blooded animals. When a repellent ingredient, such as DEET(N,N-
Diethyl-m-toluamide), is applied to the skin, it evaporates, forming a barrier around
the skin. The mosquito, therefore, is unable to "find" the person to bite.

24. DEET: is available in multiple formulations, including solutions, lotions, creams, gels,
aerosol and pump sprays, and impregnated towelettes
Picaridin: Sprays, Pump, Lotion, Creams, Liquids
PMD(para-Menthane-3,8-diol): Spray and a Lotion
Ethyl butylacetylaminopropionate (trade name IR3535): Lotions, Creams, Gels,
Sprays.
Permethrin: Sprays (Only for Cloths)
Oil of Citronella: Sprays, Lotions,Creams, Arosoles

25. DEET
PICARIDIN
IR3535
Permethrin

26. NATURAL MOSQUITO REPELLANT
1. Lemon Eucalyptus (Corymbia Citriodora) essential oil and its active ingredient
p-menthane‐3,8‐ diol (PMD)
2. Neem Oil (Azadirachta Indica) (Repels or kills mosquitoes, their larvae and a
plethora of other insects including those in agriculture)
3. Catnip oil
4. cedar oil
5. citronella oil

27. NATURAL MOSQUITO REPELLANT
-Eucalyptus oil
-Lemongrass oil
-Fennel oil
-castor oil
-Achillea alpina
-Alpha Terpinene
-Carvacrol

28. THANK YOU