How to Predict where a Substitution May Occur in a Ring Compound – Part 1

A radical-substitution reaction is a substitution reaction involving free-radicals as a reactive intermediate.


A free-radical substitution reaction is usually initiated by peroxide, light, heat or a radical initiator.

On the other hand, an electrophilic aromatic substitution (SEAr or EAS) is an organic reaction in which an atom attached to an aromatic system (usually hydrogen) is replaced by an electrophile.

The substitution can be in the ring or in the side-chain depending on the reagent used.

The bond dissociation energy (BDE, D0, or DH°) is the standard enthalpy change when a chemical bond A−B is cleaved by homolysis to produce radical fragments A & B. BDE is one measure of the bond strength & temperature-dependent.

The BDE differs from the bond energy (BE aka mean bond, bond enthalpy, average bond enthalpy, or bond strength) except for diatomic molecules. While the BDE is the energy of a single bond, the BE is the average of all the BDEs of the bonds of the same type for a given molecule. IUPAC (international union of pure and applied chemistry) defines BE in the gas-phase usually at a temperature of 298.15 K.

Question:

Predict the major product(s) of the following reaction and explain it step-by-step.



Click/tap to enlarge the image

Solution infographic:



Click/tap to enlarge the image

ΔGѲ = Standard change in Gibbs free energy

NOTE: Post modified since published

Rendezvous with radicals❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com❗

References:

(‌1)    Wikipedia Contributors. Radical substitution. Wikipedia.

‌(2)    Ncert. Chemistry : Textbook for Class XI - Part.II; National Council Of Educational Research And Training: New Delhi.

(3)    Brown, C.; Ford, M. Higher Level Chemistry, 2nd ed.; Pearson Education: Harlow, Essex, 2014.

(4)    Graham, T. W.; Fryhle, C. B.; Snyder, S. A. Organic Chemistry.; Hoboken, Nj John Wiley Et Sons, Inc, 2016.

‌(5)    Chouhan, M. S. Advanced Problems in Organic Chemistry for JEE, 11th Ed.

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