Markovnikov's Rule & Primary, Secondary & Tertiary Carbons

Markovnikov’s Rule

used to predict the major product of an addition reaction involving an unsymmetrical alkene or alkyne. Markovnikov’s rule is a famous shortcut in organic chemistry used to predict the products of chemical reactions. In simple terms, it states that "the rich get richer." When you add a molecule to an asymmetrical alkene (a carbon-carbon double bond), the hydrogen atom attaches to the carbon that already has the most hydrogens

Major product

Markovnikov’s product. It is the most substituted, and therefore forms more product; the product that forms most of the time. Favor the major product, it is the most stable intermediate and requires less activation energy.

The most substituted

Will be the one with more Carbons attached

Minor Product

Anti Markovnikov’s Product. the product that forms less often (you get a smaller amount).

Stability increases

with more alkyl groups

Methyl Cation

A methyl with a positively charged Carbon (and missing a Hydrogen, making it a methyl). It is least stable

Primary Carbon

A Carbon attached to ONE other Carbon, more stable than a methyl cation but less stable than a secondary Carbon.

Secondary Carbon

A Carbon attached to TWO other Carbons. More stable than a primary Carbon but less stable then a Tertiary Carbon.

Tertiary Carbon

A Carbon attached to THREE other Carbons. The most stable out of all 4.

If you can draw out multiple mechanisms for a reaction, pick the one

with the most stable intermediate. So, if you have a secondary and a tertiary carbon as an intermediate in a mechanism, pick the mechanism with the tertiary Carbon as the intermediate as that will be the most stable.

If you have two mechanisms and both are symmetrical…

(meaning both with have the same amount of Carbons attached) both are major products.