Polarity of Propan-1-ol and Propan-2-ol

  • #1
Summary:
Dipole moment of propan-2-ol is higher but based on the molecular structure, I think propan-2-ol should be less polar.
Based on the two structures, I think Propan-1-ol is more polar because the electrons are drawn to the end of the molecule while propan-2-ol has electrons drawn to the center of the molecule (less of an unequal electron distribution in the molecule). However when looking at the dipole moment I see that propan-1-ol has a dipole moment of 1.487022 debye while propan-2-ol has a dipole moment of 1.555496. Can someone explain this to me.
 

Answers and Replies

  • #2
TeethWhitener
Science Advisor
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With such a tiny difference in dipole moments, the answer is going to come down to a detailed examination of the electronic structures of the two molecules. (Not sure where you got the values from; CCCBDB gives slightly different experimental values—1.55D and 1.58D) The lion’s share of the dipole moment will come from the charge separation in the O-H bond, and the hydrocarbon chain is a relatively small perturbation on that.
 

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