Markovnikov Rule vs. Anti Markovnikov Rule

Main Difference

The main difference between Markovnikov Rule and Anti Markovnikov Rule is that Markovnikov Rule specifies that hydrogen atoms present in an addition reaction involved by having many hydrogen substituents with a carbon atom, whereas Anti Markovnikov Rule specifies that hydrogen atoms present in an addition reaction are involved by having minimum hydrogen substituents with a carbon atom.

Difference Between Markovnikov Rule and Anti Markovnikov Rule

Comparison Chart

Markovnikov Rule vs. Anti Markovnikov Rule

Markovnikov rule usually explains that when the addition of protic acid of an alkene, the H attaches to double bonds with a more significant number of substituted hydrogen atoms attached to the carbon atom. In contrast, anti markovnikov rule explains when HBr added to alkene in the occurrence of catalyst peroxide, the H atom bonded to C that contains less substituted H whereas Br bonded to C having more H. The hydrogen atom will always get attached to that carbon atom that has maximum number of hydrogen substituents attached to carbon atom by according to markovnikov rule; on the contrary, the hydrogen atom will always attach to that carbon atom having least number of hydrogen substituents by according to anti markovnikov rule.

The part of addendum that is negative (such as X^– or Cl^–/Br^–) usually goes to the carbon which consists of least number of hydrogen atoms attached to carbon atom in markovnikov rule; on the contrary, the part of addendum that is negative attaches to the carbon atom that consists of highest number of hydrogen atoms attached to the carbon atom in anti markovnikov rule. The mechanism of markovnikov rule is an ionic mechanism in chemistry; on the flip side, the mechanism of anti markovnikov rule is a free radical mechanism. The reactants which are used in markovnikov rule are HBr, HI, HCL, and H₂O; on the other hand, the free reactant, which is used in anti markovnikov rule, is only HBr and not HCl, or HI underwent in this type of addition reaction.

No medium or catalyst is generally required in markovnikov rule; on the flip side, the medium/ catalyst is required that is peroxide or ultraviolet, which must be present to carry out the anti-markovnikov rule. The markovnikov accumulation of hydrogen halide to olefin results in the production of carbocation as the reaction intermediary; on the other hand, the creation of carbon-free radical as the reaction intermediary in anti markovnikov rule. The attack on the carbon-carbon double bond is started by hydrogen ion from reactant HX in markovnikov rule; on the contrary, the attack on carbon-carbon double bond is usually started by halogen-free radicals X which is produced by the communication in between HX and the radical peroxide in anti markovnikov rule.

The major product is given by HBr from (CH₃) 2C = CHCH₃ will produce (CH₃) 2CBrCH₂CH₃ in markovnikov rule; on the contrary, in the presence of peroxide, the main product will be given as (CH₃) 2CHCH(Br)CH₃ in an anti markovnikov addition reaction. In markovnikov addition reaction, the intermediary which is formed is carbocation, then undergoes a rearrangement, and the stability of carbocation becomes increases. In contrast, in anti markovnikov rule, the produced intermediary does not undergo rearrangement of products.

What is the Markovnikov Rule?

The rule of markovnikov explains that some addition reactions of alkenes or alkynes, the proton gets attached to that carbon atom that has a maximum number of hydrogen substituents attached to a carbon atom — the markovnikov rule assists in calculating the end products of certain chemical reactions.

The following of markovnikov rule is because of the most stable product, i.e., carbocation, which is the intermediary product of markovnikov rule. The stability of carbocation become increases when it undergoes rearrangements in the chemical reactions. The involvement of hydrogen atom to the carbon atom forms the double bond in carbon, which provides other vinyl carbon atom a positive charge. For producing the stable end product, the carbocation must be a stable intermediary carbocation product. After the production of the precise carbocation, the Cl^– then attaches to the positively charged carbon atom.

Though, after the completion of the reaction, a mixture of products is produced, which is formed of products given by stable carbocation or unstable carbocation.

What is Anti Markovnikov Rule?

The rule of anti markovnikov explains that in various addition reactions of alkenes and alkynes, the proton gets attached to that carbon atom that has a minimum number of hydrogen atoms. The end product obtained from this rule is known as an anti markovnikov product. The carbocation is not formed in anti markovnikov rule as an intermediary product. The chemical reaction of anti markovnikov could be obtained into reactions that produce anti markovnikov product is by adding the catalyst peroxide like HOOH in the reaction mixture, which will then give carbon free radicals as products of anti markovnikov rule.

A peroxide could alter the regioselectivity (the production of bonds at a specific atom above all other possible atoms) of an anti markovnikov’s addition reaction. The effect of peroxide takes a long time. That’s why the peroxide acts as a catalyst/ medium in anti markovnikov rule reactions.

Conclusion

Above discussion concludes that the both markovnikov and anti markovnikov rules are important in predicting the products of chemical reactions in which markovnikov rule describes that proton is convoluted to that carbon atom that has the maximum number of hydrogen atoms attached to it; on the other hand, anti markovnikov rule give details that proton is involved to that carbon atom that has minimum number of hydrogen atoms attached to it.