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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Skybydo on September 09, 2011, 05:08:18 PM

Title: Is diethylether polar or non-polar?
Post by: Skybydo on September 09, 2011, 05:08:18 PM

In Wikipedia in the article of "solvent" (http://en.wikipedia.org/wiki/Solvent#Polar_protic_and_polar_aprotic) diethylether is listed as a non-polar solvent. However, my professor draw it like the attached image and said it is polar.
Does it have the two properties?
How should I treat it in SN₁ and SN₂ reactions?

Title: Re: Is diethylether polar or non-polar?
Post by: Dan on September 10, 2011, 06:05:02 AM

Most organic molecules are polar by definition - they have a dipole moment (ethers included).

In the context of solvents, polar refers to solvents with higher polarity, and non-polar to solvents with lower polarity. It's relative. Diethyl ether is at the lower end of the polarity scale and so is generally considered a "non-polar" solvent - though what we really mean is a low polarity solvent.

This sliding scale situation comes up a lot in chemistry. Another example is when someone asks, "is methanol acidic?". To which the answer can only be, "compared to what?". It's all relative.

Title: Re: Is diethylether polar or non-polar?
Post by: Skybydo on September 10, 2011, 09:57:03 AM

Ok, it's relative. Thank you!

Title: Re: Is diethylether polar or non-polar?
Post by: msalexanderjohn on September 20, 2011, 11:28:56 AM

any molecue having atoms of different electronegativity is polar.

Title: Re: Is diethylether polar or non-polar?
Post by: Nosterius on September 20, 2011, 11:44:25 AM

Quote from: msalexanderjohn on September 20, 2011, 11:28:56 AM

any molecue having atoms of different electronegativity is polar.

As Dan said, you need a dipole moment to define a molecule as "polar". This definition fails short in that carbon dioxide, for example, has different atoms, but no dipole moment. Same goes for methane, CBr4, ethane, benzene etc...