# Why does the rate of the E1 reaction depend only on the substrate?

Sep 19, 2015

Step 1 is the rate determining step (slow step) and therefore, we have only one reactant which is $R - X$ and the $R a t e = k \left[R - X\right]$.

#### Explanation:

The elimination reaction E1 from its name, the 1 means that it is a unimolecular reaction.

E1 reactions happen in two consecutive steps:

Step 1: Formation of the carbocation ($R - X$ is the alkyl halide).
$\text{ " " " " }$$R - X \to {R}^{+} + {X}^{-}$

Step 2: Attack of the nucleophile.
$\text{ " " " " }$${R}^{+} + N {u}^{-} \to R ' + H N u$ where $R '$ is an alkene.

Since the first step is bond breaking (needs energy) and the second step is bond formation (releases energy), therefore, step 1 is the rate determining step (slow step) and therefore, we have only one reactant which is $R - X$ and the $R a t e = k \left[R - X\right]$.

Here is a video about E1 and E2.