For each of the species below, identify any cyclic conjugated system, then of A.
ID: 488487 • Letter: F
Question
For each of the species below, identify any cyclic conjugated system, then of A. Determine the number of electrons in a system of cyclic conjugation (zero if no cyclic conjugation). B. Specify whether the species is "a"-aromatic, "aa" atic, or na"-non-aromatic (neither aromatic nor anti-aromatic) (Presume rings to be planar unless structure obviously prevents planarity. If there is more than one conjugated ring, count electrons in the largest.) A. Electrons in a cyclic conjugated system. B. The compound is (a, aa, or na) 2. N: A. Electrons in a cyclic conjugated system. B. The compound is (a, aa, or na)Explanation / Answer
1) system 1 is only conjugated but not planner and non cyclic hence
A. 6 pie electron in this system
B. according to huckels rule the system is anti aromatic (aa) (nly conjugated but not planner and non cyclic)
2)
A. in this system system contains 6 pie electrons
B. Acccording to huckels rule the cyclic, planner and conjugated system which follows (4n+2) pie electron is aromatic
(4 x 1+2)=6 pie hence aromatic, n=1 i.e integers
1) in benimidazole system
this is cyclic, conjugated and planner system which follows (4n+2) pie electron is aromatic
where n=2, n is integers
(4 x 2 +2)= 8+2= 10 pie hence aromatic, n=2 i.e integers
this system contains 10 pie electrons
2. this system is cyclic, conjugated and planner system which follows (4n+2) pie electron is aromatic and every atom in the ring must be able to participate in delocalizing the electrons by having a p-orbital (unshared pair of electrons).
About Aromaticity , we consider the electrons inside the ring. styrene has 8 pi electrons but when checking for Huckel's rule, we only consider the electrons inside the ring. The alkenyl group is just an attachment to the stable aromatic compound which might take part in resonance but wouldn't affect the compound's aromaticity
Hence styrine is aromatic
4n+2 pie electron rule
it is aromatic
2)
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