Alcohol to Alkene

Reagents

$\mathrm{HA}+\mathrm{\Delta }$

Mechanism: E1

1. $\mathrm{HA}$ protonates $-\mathrm{OH}$ group to become $-\mathrm{OH}{}_2{}^{+}$
2. $\mathrm{OH}{}_2{}^{+}$ group leaves
3. Rearrangements may happen
4. $\beta$ carbon’s hydrogen gets picked off by an $\mathrm{A}{}^{-}$, sending electrons from the C-H bond to create a C=C between the $\beta$ and $\alpha$ carbons, causing the $\mathrm{OH}{}_2{}^{+}$ group to leave, creating an alkene