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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: rleung on October 18, 2005, 09:14:26 PM

Title: polarity of diols
Post by: rleung on October 18, 2005, 09:14:26 PM

I have a quick question.  For lab, we did a TLC chromatography with two diols, and the Rf value of the trans diol was lower than the Rf of the cis diol, which indicates that the trans diol adsorbed more strongly to the polar silica gel (stationary phase).  I am not sure how to explain this.  I would've thought that the cis would've been more polar (hence, had the lower Rf) since the cis diol would have a greater dipole moment than a trans diol would (the dipoles would cancel each other out in a trans, no?).  Our teacher did not give us the structures or names of the diols.  What possible explanation do you think would explain why the trans seems to be more polar?  Thanks.

Title: Re:polarity of diols
Post by: Garneck on October 19, 2005, 12:20:07 PM
Are you sure you didn't get anything mixed up? Because you got me puzzled here, too.. what kind of eluent did you use? Methanol?  ::)
Title: Re:polarity of diols
Post by: Mitch on October 19, 2005, 12:26:17 PM
Its hard to know anything, with any level of confidence, without viewing the structures.