Chemistry- the subject of fascination and excitement. With many rules and concepts, it is common to get confused between them. For instance, the Markovnikov and Zaitsev rule. These rules are related to the concept of elimination reactions. Although both these scientists formulated a rule in the same concept, they both are better known as rivals, as both of them had conflicting opinions on the same topic.
Markovnikov vs Zaitsev
The main difference between Markovnikov and Zaitsev is that Markovnikov is a scientist who put forth the rule that said that in an elimination reaction, the least substituted alkene would be the stable product. On the other hand, Zaitsev was a scientist who contradicted this statement and stated that the most substituted alkene would be the favored product.
Markovnikov was a Russian Chemist who is popularly known for his Markovnikov rule in chemistry. After extensively studying and researching addition and elimination reactions, he put forward his rule. He stated that when a halogen (X) is added to an alkene with two or more carbons, the halogen gets attached to that carbon, which is less substituted.
Zaitsev was a Russian Chemist also known for his rule opposing Markovnikov’s rule- Zaitsev or Saytzeff rule. This rule states that during the addition of a halogen reaction, the halogen often gets attached to the carbon, which is highly substituted. He believed the product formed after this reaction is the most stable and favored. But Zaitsev’s rule also has many exceptions.
Comparison Table Between Markovnikov and Zaitsev
|Parameters of Comparison||Markovnikov||Zaitsev|
|Born in||25 December 1837||2 July 1841|
|Popular/ Known for||Markovnikov/ Markownikoff’s Rule||Zaitsev/ Saytzeff’s Rule|
|Published the rule on||1869||1875|
|Statement of the rule||In an elimination reaction, the least substituted alkene will form the most stable product||In an elimination reaction, the most substituted alkene will form the most stable product|
|Exceptions||Anti-Markovnikov’s rule||Conjugation, Bulky base addition, Steric hindrance, etc.|
Who is Markovnikov?
As mentioned above, Vladimir Markovnikov is a Russian scientist born on 25 December 1837 who actively pursued a career in organic chemistry and contributed to this field by publishing his Markovnikov’s rule, also spelled as Markownikoff’s rule in the year 1869.
Markovnikov completed his early education at the University of Kazan and thereon pursued a scientific career. His career got a boost and recognition after the publication of his rule.
He was the first one to observe a pattern in the addition and elimination reactions and later on introduced a rule that aided in simplifying and understanding the elimination reactions. He stated that while adding a halogen as a compound (for instance, HCl) to an alkene, the halogen part gets attached to the less substituted carbon. The proton part gets attached to the more substituted carbon. If we take the example of HCl and propene, after breaking the double bond, the chlorine part gets attached to the mid-carbon, while the hydrogen gets attached to the end carbon (Final product- 2-chloropropane)
This rule boosted Markovnikov’s career in Russia, but he did not get enough recognition globally until other scientists translated his statement into other languages. This rule has some exceptions that are stated in the Anti-Markovnikov Rule. The contribution of Markovnikov in organic chemistry is tremendous and inspiring. To date, this rule is followed extensively.
Who is Zaitsev?
Aforementioned, Alexander Zaitsev is a Russian chemist who was born on 2 July 1841 and followed his passion for pursuing organic chemistry. He gained fame because of Zaitsev Rule (also called Saytzeff Rule), published in 1875.
He also completed his early education at the University of Kazan by pursuing a degree in economics. Because of the Cameral system (any student pursuing a degree in economics should study chemistry for two years), Zaitsev also pursued a career in chemistry. He has worked as an assistant to many renowned scientists like Kolbe and Wurtz, which granted him colossal experience.
While studying at the University of Kazan, Zaitsev also observed some reactions and inscribed them. After Markovnikov’s rule, Zaitsev published his version of it, contradicting Markovnikov’s statement. He stated that when a halogen reacts with an alkene, after the double bond breaks, the halogen part gets attached to the more substituted carbon, the proton gets attached to the least substituted carbon.
Zaitsev actively researched addition and elimination reactions to argue and disprove his rival, Markovnikov. Zaitsev’s rule was successful but had many exceptions with Bulky bases, conjugations, Steric activity, etc.
This rule is highly acknowledged in the world of chemistry. Zaitsev even received numerous awards for his discovery and was highly appreciated in the 18th and 19th centuries.
Main Differences Between Markovnikov and Zaitsev
- Markovnikov was a Russian chemist born on 25 December 1837 and is known for his Markovnikov/Markownikoff rule. Whereas Zaitsev was a Russian chemist born on 2 July 1841 who is famous for his Zaitsev/ Saytzeff rule.
- According to the Markovnikov rule, in an alkene elimination reaction, the functional group gets attached to the least substituted carbon. According to the Zaitsev rule, the functional group gets attached to the most substituted carbon.
- According to the Markovnikov rule, the proton part in the functional group gets attached to the more substituted carbon. According to the Zaitsev rule, the proton part gets attached to the least substituted carbon.
- Markovnikov believed that the least substituted alkene is the most stable product, whereas Zaitsev defended that the most substituted alkene is the balanced product.
- Markovnikov’s rule has exceptions- Anti-Markovnikov’s rule, whereas Zaitsev rule has exceptions based on conjugation, stereochemistry, steric hindrance, etc.
From the above points, it is evident that although both Markovnikov and Zaitsev are well-known/ renowned scientists of that era known for their contribution to organic chemistry, their rules differ completely, yet these rules are first taught to the chemistry students as basic rules.
Back then, Markovnikov and Zaitsev were aggressive rivals, as both contradicted each other’s opinions. Both these scientists have pursued chemistry from the same university, yet they are extremely passionate about the subject that is seen in their work. Both of them have received praises and appreciation for their work and they honored both of them with some dignified awards for their contribution.