Question

Explain hammonds postulate using addition of hbr to propylene

Answer 1

Answer:

The proton in HBr is electrophilic; it reacts with the alkene to .... EXAMPLE: The ionic addition of HBr to propene shows protonation of the less .... Propose a mechanism for this reaction, and explain

Answer 2

Answer:

According to Hammond's postulate, the transition state of a reaction resembles either as the reactants and the products, depending on that is closer energy. The transition state in an exothermic process is closer to the reactants than to the products in terms of energy.

Explanation:

• Propene is a three-carbon alkene with an asymmetric structure. Propene reacts quickly with HBr to produce 2-bromopropane as the primary product and 1-bromopropane as a minor byproduct.

• The addition of HBr to propene is an electrophilic substitution process.

• The electrophile H+ is produced by hydrogen bromide. To produce 1° and 2° carbocations, this electrophile attacks the double bond.

• As a result, the former takes precedence because it forms at a faster rate. As a result, Br- attacks the carbocation in the next phase, forming 2 - bromopropane as the main product.

• The negative component of the addition is attached to the carbon atom with the least number of hydrogen atoms, as per Markovnikov's rule.

• An addition reaction occurs in the presence of benzoyl peroxide, which is contrary to Markovnikov's rule. A free radical chain mechanism governs the reaction:

• Primary radicals are less stable than secondary radicals. As a result, the former takes precedence because it forms at a faster rate. As a result, the main product is 1 - bromopropane.

• Br free radical behaves as an electrophile in the presence of peroxide. As a result, when HBr is added to propene in the lack or presence of peroxide, two distinct compounds are formed.

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