Morphine, testosterone, phenylalanine, serotonin and adenine are drawn below. How many aromatic rings are there in all five compounds together ? Count only rings with a cyclic, planar, fully conjugated 4n+2 π system.
(a) morphine (b) testosterone
(c) phenylalanine (d) serotonin
(e) adenine

Question

Morphine, testosterone, phenylalanine, serotonin and adenine are drawn below. How many aromatic rings are there in all five compounds together ? Count only rings with a cyclic, planar, fully conjugated 4n+2 π system.

(a) morphine structure (b) testosterone

(c) phenylalanine structure (d) serotonin

(e) adenine structure

TestHub · Accepted Answer

(a) morphine : 1 benzene ring. (b) testosterone : no aromatic ring (the C=C-C=O ring is a cross-conjugated enone). (c) phenylalanine : 1 benzene ring. (d) serotonin : the benzene ring and the pyrrole ring of the indole system : 2. (e) adenine : the pyrimidine ring and the imidazole ring, both 6π : 2. Total = 1 + 0 + 1 + 2 + 2 = 6.

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