Question

Question #3dd79

Answer 1

The dihedrals are `0^@` causing the hydrogens on C 2, 5, 6 to be more reactive than the in norbornane more reactive than the tertiary H atoms on C1 or 4 or the bridgehead carbons.

Explanation:

Torsional strain or eclipsing strain is the increase in potential energy of a molecule due to repulsion between electrons in bonds that do not share an atom.Therefore any dihedral angle that is `0^@` causes a sufficient Torsional strain because the electrons not involved in bonding are nearest to each other.Torsional strain causes instability in a molecule

Observe the structure of norbornane (bicyclo[2.2.1]heptane)

If you draw a newman projection of the molecule you would see that the dihedrals are `0^@` except the hydrogen bond on the bridgehead carbons.This causes the hydrogen to be more reactive than the hydrogen attached to the bridgehead carbon and the Br- tends to go that way.

On the other hand observe the structure of Bicyclo[3.3.1]nonane, 1-bromo- and imagine there's a Hydrogen atom instead of the bromine ion

https://pubchem.ncbi.nlm.nih.gov/compound/637905#section=3D-Conformer

The dihedrals are not `0^@` thus causing the hydrogens to be stable.

As the hydrogens in the norbornane are less stable the bromine ion tends to react with it instead of the tertiary H atoms on C1 or 4.This is not case in bicyclo[3.3.1]nonane.

The reaction between bromine and norbornane causes

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