Organic Chemistry
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Zaitsev Rule
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Elimination reactions often can yield multiple products. However, not all of these products will be of equal stability. Zaitsev’s Rule (also spelled Saytzeff’s Rule) helps us predict the major product.
Zaitsev vs. Hofmann Product
concept
Defining Zaitsev’s Rule
Zaitsev’s Rule predicts that in most cases, the most substituted product will be favored. This is also known as the Zaitsev product. Draw the Zaitsev product of the following reaction:
example
Zaitsev product
The exception to this rule comes with the use of bulky bases. These promote the formation of the les substituted product.
- The most common bulky bases are lithium diisopropylamide (LDA) and tert-butoxide (t-BuO-)
The less substitued product is called the Hofmann product. Let's draw the Hofmann product of the following reaction:
example
Hofmann product
Thermodynamic vs. Kinetic Product
concept
Using a Free Energy Diagram to explain thermodynamic vs. kinetic products.
- The Zaitsev product is also known as the thermodynamic product, since it is the one that releases the most free energy overall (most negative ΔG°).
- The Hofmann product is also known as the kinetic product, since it is the one that overcomes the lowest activation energy (Ea).
Practice
What is the major product of the reaction?
What is the major product of the reaction?
What is the major product of the reaction?
