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I am refluxing $\ce{HBr}$ with 1,6-hexanediol for 16 hours at $80\ ^\circ\mathrm{C}$ in toluene. How can I be sure that more than $90\,\%$ of the product is brominated only at one terminal? If the amount of double brominated product is in more than $10\,\%$ of the total yield, then the product mixture will be useless for me.

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    $\begingroup$ Would having unreacted 1,6-hexanediol be acceptable? If so, use it in excess. $\endgroup$ – jerepierre May 21 '15 at 15:55
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    $\begingroup$ @ringo the ° is not typeset well in math equations in mathjax, it's probably better to use ${}^\circ$. $\endgroup$ – Martin - マーチン May 22 '15 at 4:12
  • $\begingroup$ jerepierre what I am concerned about is the by product 1,6-dibromohexane which I can't allow to be there. $\endgroup$ – Punarbasu Roy May 22 '15 at 4:33
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In an article by Katharina C. Kress, Martin Kaller, Kirill V. Axenov, Stefan Tussetschläger, and Sabine Laschat, published in Beilstein J. Org. Chem., 2012, 8, 371-378 (DOI), this procedure is described. From the Supporting Information, I read that the authors obtained the product in 72% yield after

column chromatography on silica gel (hexanes/EtOAc, 1:1)

I wouldn't be astonished if that's as good as it can get.

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