Organic Chemistry, "Change" Part 16 - Zaitsev's Rule

 Greetings,

This post is about Zaitsev's rule which states, "For an E2-type reaction, hydrogen is removed from the adjacent carbon, to the leaving group, with the lesser number of carbon atoms". When that happens, the more substituted alkene product is the main one produced. A more substituted alkene is more stable than a less substituted alkene. There are fewer hydrogen atoms connected to the double-bonded carbons of a less substituted alkene. Because hydrogen atoms are more easily removed (less energy required), fewer hydrogens, across the double bond, means more energy (activation) is required to remove any remaining hydrogens (on the double bond). This translates to lower reactivity and, consequently, greater stability of the alkene product. The result is that the main alkene product (of two possible) can be readily predicted. The following diagram shows an example of Zaitsev's rule.

The main product is the more stable compound, 2-Butene. Its formation requires removal of a Hydrogen from Carbon #3 (an interior C atom).

That's it for this post. As always, thank you for reading!