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Oxonium ion

physical science Maturity 5-7 Next article →

An oxonium ion is a special group of atoms in chemistry. It is a cation, which means it has a positive electrical charge of +1. This group always includes an oxygen atom. This oxygen atom forms three bonds to other parts.

Oxonium-ion-2D
Oxonium-ion-2D

The shape of the oxygen is usually a pyramid. This happens because of a way atoms arrange themselves called sp3 hybridization. These ions are very important for making new things in science. They help scientists change one substance into another.

There are different ways these ions can work. The simplest type is the hydronium ion. Scientists also group them by how many parts join the oxygen. Primary oxonium ions have one part joined to the oxygen. An example is methyloxonium, which comes from protonated methanol. Secondary oxonium ions have two parts joined. Dimethyloxonium is an example of this type. Tertiary oxonium ions have three parts joined. Trimethyloxonium is a well-known example of a tertiary ion.

Trimethyloxonium-3D-balls
Trimethyloxonium-3D-balls

Some of these ions are very steady and do not change easily. Scientists first described two very stable ones in 2008. They are called oxatriquinane and oxatriquinacene. Oxatriquinane is so steady it does not react with boiling water. It also does not react with alcohols or amines. However, it will react with stronger things like cyanide or azide.

Trimethyloxonium-3D-vdW
Trimethyloxonium-3D-vdW

There is even a very stable version that uses gold. This gold complex is called tris[triphenylphosphinegold(I)]oxonium tetrafluoroborate. It stays steady because of how the gold atoms interact with each other.

Triphenylphosphinegoldoxonium
Triphenylphosphinegoldoxonium

Scientists use these ions for many tasks in the lab. Tertiary salts like triethyloxonium tetrafluoroborate are useful tools. This substance is a white crystalline solid. It can help make ethyl esters when other methods do not work. It is also used to make enol ethers.

Trimethyloxonium-2D-skeletal
Trimethyloxonium-2D-skeletal

Another type is the oxocarbenium ion. These are made by adding a proton to a carbonyl group. These ions are especially stable because of a special structure. This structure allows the charge to move around.

Nature also uses these special groups in amazing ways. Red algae from the genus Laurencia use them to grow. These tiny plants use oxonium ions as middle steps to make natural products. Scientists can make these same ions in a lab to study them. They use a special salt called Krossing's anion to keep them steady. They often study them at very cold temperatures like −78 °C.

Oxoniumionlaurencia2
Oxoniumionlaurencia2

This helps them see how the ions turn into different natural things. It shows us how much chemistry is happening in the ocean.

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🖼️ Images & Media (9)
File:Oxonium-ion-2D.png
Oxonium-ion-2D.png
File:Trimethyloxonium-2D-skeletal.png
Trimethyloxonium-2D-skeletal.png
File:Trimethyloxonium-3D-balls.png
Trimethyloxonium-3D-balls.png
File:Trimethyloxonium-3D-vdW.png
Trimethyloxonium-3D-vdW.png
File:Carbonyl-oxonium-resonance-2D-skeletal.png
Carbonyl-oxonium-resonance-2D-skeletal.png
File:Triphenylphosphinegoldoxonium.png
Triphenylphosphinegoldoxonium.png
File:Oxoniumionlaurencia2.png
Oxoniumionlaurencia2.png
File:Wiki fig 2.png
Wiki fig 2.png
File:Wiki fig 3.png
Wiki fig 3.png
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