Difference in Properties

[aommaster]

What properties would be different (other than the structure itself) of let's say, propan-1-ol and propan-2-ol? 

[wolfson]

Well the two alcohol's that you just gave are positional isomers, this is where a substituent occupies different positions on the carbon chain. The boiling point of Pro 1 is 370K, and pro 2 is 355K, the boiling points (and other physical properties) of the two compounds are different. Although the chemical properties are the same, the reactivities will be different due to the different envirenments of the OH group.

[aommaster]

oh, ok. Thanx man

[apathy]

What properties would be different (other than the structure itself) of let's say, propan-1-ol and propan-2-ol? 

 

the dipole moment

[aommaster]

Could you please explain further?

[JustinM.Dragna]

This is an odd question. I wouldn't expect any great difference between them. The different boiling point is one. There would probably be a small difference in the acidity of the hydrogen on the oxygen too. I think you could account for that by the difference in the dipole moment. 1-prop would probably be a little bit more acidic than 2-prop because the extra methly group next to the carbon with the hydroxyl group(what's that carbon called? alpha or beta?) on it destabilizes the conjugate base by "pushing" electrons onto the already negatively charged oxygen atom through sigma bonds. Of course it's not that much of a difference considering that 1-prop has an ethyl group donating electrons as well, but then there isn't that much of a difference between the two compounds. Another difference would be that 2-prop has more symmetry elements than 1-prop. For instance 2-propanol has an obvious sigma or mirror plane. This would make the NMR spectra for them differ a good deal. I can't really think of too much more to say, but i feel like i gave a pretty good rant. I hope this helps you out.

[aommaster]

Thanx! What is meant by the dipole moment? Acidity?

[Skye]

The dipole moment is the difference in charge across a molecule, or across a bond. If you have a C-OH bond, the OH group is slightly more negatively charged and the C is slightly more positively charged. The difference between the two charges as a function of the distance is the dipole moment. With the 1- or 2-propanol, the two molecules have the OH in a different position, so the distance the difference in charge occurs over, averaged over the whole molecule, will be different. In the 1-propanol, these distances are larger, as the OH is at the end of the molecule, and so the dipole moment will be larger.

[aommaster]

oh, ok. Thanx for clarifying that to me!