Dehydrohalogenation ($$E_2$$ Elimination)

$$\begin{aligned}\text{R--CH}_2\text{--CH}_2\text{X} + \text{Alc. KOH} \xrightarrow{\Delta} \text{R--CH=CH}_2 + \text{KX} + \text{H}_2\text{O}\end{aligned}$$

Saytzeff's Rule: Major product is the more substituted, more stable alkene.}

Hofmann's Rule: Major product is the less substituted alkene when using bulky bases (-BuOK) or poor leaving groups ($$\text{F}^-$$).