Why many aromatic hydrocarbons do not have any odor while compounds that have a pleasant odor do not have aromatic rings?

Answer 1

when aromatic compounds were first discovered they were called aromatic due to their plesant odours but as you have rightly pointed out compouns such as diatomic hydrogen have pleasant smells its is becuase of this that the meaning of aromaticity changed as aromatic compounds are saturated stable compounds its the notion of delocalised electrons that defines a aromatic compound now as this enhances the stabilty of the compound so chemically aromatic and aromatic are not particularly synoynymous any more in fact chemical aromacity has very little to do with aromacity and ewhat it does to the oliafactory centres that gives us the perception of smell

Answer 2

Aromatic hydrocarbons like benzene have very weak intermolecular forces and do not easily evaporate to release a smell. Compounds with pleasant odors often have functional groups like alcohols, aldehydes, or esters, rather than aromatic rings, that easily interact with olfactory receptors in our nose to detect a smell.