Chemistry - Does halogenation by phosphorus tribromide lead to an inverted product?

Solution 1:

Yes, the haloalkane product will have the inverse stereochemistry of the alcohol that it was produced form. $\ce{PBr3}$ does this by converting the $\ce{-OH}$ into a good leaving group and providing a nucleophile all in one. This is can be seen in the two step mechanism:

$\hspace{2.4cm}$step 1

When $\ce{Br-}$ ejects $\ce{PBr2OH}$ in an $\mathrm{S_N2}$ reaction, the stereochemistry is inverted:

$\hspace{3.1cm}$step 2

Solution 2:

Yes, halogenation by $\ce{PBr3}$ will lead to an inverted product, as it follows $\mathrm{S_N2}$ mechanism. In an $\mathrm{S_N2}$ mechanism, the product is formed through inversion as the incoming nucleophile attacks from the side opposite of the leaving group.