November 02, 2020
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Image of 4-Vinylanisole 3D Image of 4-Vinylanisole

4-Vinylanisole (4VA)—frequently also called 4-methoxystyrene—is a naturally occurring aroma compound. Among other sources, it is one of the volatile components of the French brandy Mirabelle, which is obtained by fermenting the juice of the mirabelle plum (Prunus domestica subsp. syriaca).

Beyond the brandy connection, 4VA is the center of a more spectacular natural phenomenon. This year, Xianhui Wang, Le Kang, and six collaborators at the Chinese Academy of Sciences (Beijing) reported that 4VA is the culprit responsible for locust swarms, such as those that recently devastated large portions of East Africa.

When solitary migratory locusts (Locusta migratoria) form small groups, they begin to emit 4VA, attracting additional insects. As the locusts aggregate, the 4VA signal becomes stronger, and the swarm grows exponentially. This year’s swarm—some call it a “Biblical plague”—covered thousands of square kilometers, mostly in Kenya and Ethiopia, but also in other African and Middle Eastern countries.

4VA’s aggregation pheromone property might have a positive side. Instead of using pesticides to control the locusts, 4VA could potentially be used as a bait to trap the insects before they begin the swarming process, according to Wang, Kang, et al. The researchers also found that a genetic modification prevented locusts from detecting 4VA signals; but others in the field warn against unintended consequences from this sort of alteration.

4-Vinylanisole hazard information

Hazard class* Hazard statement
Flammable liquids, category 4 H227—Combustible liquid  Chemical Safety Warning
Skin corrosion/irritation, category 2 H315—Causes skin irritation Chemical Safety Warning
Serious eye damage/eye irritation, category 2  H319—Causes serious eye irritation Chemical Safety Warning

* Globally Harmonized System of Classification and Labeling of Chemicals.
Explanation of pictograms.

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4-Vinylanisole fast facts

CAS Reg. No. 637-69-4
Benzene, 1-ethenyl-4-methoxy-
Empirical formula C9H10O
Molar mass 134.18 g/mol
Appearance Colorless liquid
Boiling Point 205 ºC
Water solubility  Insoluble

A question for readers

Fun fact: 4VA and water have essentially the same density under ambient conditions. What, if anything, are we to make of this? Please send your thoughts to motw@acs.org.

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