Alcohol Reactions (PBr3, SOCl2, HX, Sulfonate ester formation)

Condition

• Strong nucleophile

Alcohols will dehydrate in acidic, hot conditions.  When treated with a strong nucleophile, alcohols will instead react by either SN1 or SN2

SN2 –substitution nucleophilic bimolecular

Possible with both primary and secondary alcohol NOT tertiary due to steric hinderance.

Steric hinderance – the tertiary site is much too bulky to allow an SN2 mechanism.

All three examples below follow SN2.  Notice that the alcohols are each converted into a better leaving group before the substitution occurs

With PBr₃ (note that one molecule of PBr₃ can donate 3 bromines)

With SOCl₂

With sulfonate esters

Below is an example of SN1 using a generic alkyl halide

With HX