Preparation of 6-bromo-1-hexanol
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.