Question

How many benzylic hydrogens are present in the hydrocarbon shown?

A. $3$
B. $4$
C. $5$
D. $6$
E. $8$

Answer 1

In organic chemistry, Benzylic hydrogens refer to the hydrogen atoms that are attached to the carbon atom just next to or in other words the carbon atom adjacent to the benzene group. For example: In ethyl benzene carbon next to benzene has two hydrogen atoms only.

Complete step by step answer:
As we know what Benzylic hydrogens are let us try to count the benzylic hydrogens present in the given molecule, the carbon atoms next to benzene are three, now as we have identified the carbon atoms let’s count the hydrogen atoms directly attached to those carbon, the total comes out to be $2 + 1 + 2 = {\text{ }}5$ benzylic hydrogens. The carbons next to benzene atoms are encircled and the benzylic hydrogens are shown in the figure below:
So, the correct answer is Option C.
Additional information:
The benzylic hydrogens are far more very important when it comes to organic chemistry or reactions, as these being one of the most reactive sites when a functional group is present at benzylic sites as Functional groups in a benzylic position are generally more reactive than that of the isolated functional group as at the Benzylic C-H addition of halogen is easily possible via free radical path as the benzylic radical is stabilized because of the resonance (a stabilizing phenomenon occurring when three or more than three adjacent pi orbitals are present).

Note:
A student has to be careful at the time of counting the benzylic hydrogens, first of all a student should identify the adjacent carbons to the benzene ring in the case of complex structures, followed by the counting of hydrogen atoms.