Ethers - Non Polar

[xzk]

Why do all ethers are non polar?

Is it that because the oxygen got two non ligant pair of electrons and thus its geometry tends to be arched?

Thanks.

[pdavis68]

Ethers aren't non-polar. Most have a fairly low polarity, but THF (Tetrahydrofuran), for instance, has a dipole moment very close to water.

The carbon-oxygen bonds of of ethers are close to the same angle as the carbon-hydrogen bonds of water.

The oxygen is more electronegative than the bonded carbons, so it's always going to have some dipole moment.

Pete

[RobJim]

Pdavis is right. However, you might be interested to know that because ethers do not have an H on the O, hydrogen bonding cannot occur. This means it's useful as a solvent when alcohols for example would not be.

[wangshilei]

The ethers will be non-poler if it's symmetry at the two side of the oxygen of the function group ether.

but most ethers are unsymmetry ,so it might be poler.

[jeffy]

Originally Posted by wangshilei

The ethers will be non-poler if it's symmetry at the two side of the oxygen of the function group ether.

but most ethers are unsymmetry ,so it might be poler.

You know, I don't think that can be right. Water would be non polar if you use symmetry as the reason.

[Gary Clark]

Polar or Non Polar?

Is it that because the oxygen got two non ligant pair of electrons and thus its geometry tends to be arched?

Whether a molecule is polar or non polar doesn't depend on its shape, it depends on electron distribution. Shape and polarity both have the same fundamental cause - electron distribution.

Polar molecules arise when atoms make covalent bonds and the bonding electrons spend more time on average closer to one atom in the bond than another.

If the atoms are identical, such as with H₂ and O₂, they have identical electronegativities and are therefore non-polar.

If the atoms have widely differing electronegativities, the electrons are no longer shared in a covalent bond. One atom grabs another atom's electron(s) completely and ions are formed.

Between these extremes, you get polar molecules. C-H bonds are non-polar because the electron share is equal.

In ethers, the oxygen gets a tiny amount more of the electron distribution than carbon does, but it really is tiny. The result is that ethers dissolve completely in (non-polar) hydrocarbons but won't dissolve in water.