C – H bond energy is about 101 kcal/mol for methane, ethane and other alkanes but is only 77 kcal/mol for C – H bond of CH₃ in toluene. This is because :
(a) of inductive effect due to – CH₃ in toluene
(b) of the presence of benzene ring in toluene.
(c) of resonance among the structures of benzyl radical in toluene
(d) of aromaticity of toluene
Answers
Hi there !
The answer is (C) .
Answer:
Because the bond between carbon and hydrogen is covalent, up to four hydrogen atoms share the outer valence electrons of carbon. Both of their outer shells are now complete, stabilizing them.
Explanation:
Due to resonance, the C-H bond in toluene exhibits partial double bond characteristics. Toluene's C-H bond has a lower energy level than other C-H bonds.
Resonance is not possible in methane, ethane, and other alkanes because they do not have pi-bond or unsaturated bonds, or hetero atoms that contain lone pair of electrons.
In toluene, there are three Pi bonds that form an aromatic ring and they are capable of showing resonance and generating a partial double bond character.
The other reasons are incorrect for the lower carbon-hydrogen bond energy in toluene.
Hence, the correct option is (c) of resonance among the structures of benzyl radical in toluene.
#SPJ3