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Nguyên văn bởi LessThanPerfect
I know very little about organic chemistry but my book at home contradicts what you said earlier. Could you please check your reference again? According to my book, the nucleophilic reactivity increases in the order benzene << thiophene < furan < pyrrole.
(K. Peter, C. Vollhardt and Neil E. Schore, Organic Chemistry 2nd ed., p. 998.)
This may explain why NO2+ attacks the furan side of the initial compound during the electrophilic aromatic substitution.
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Hi !
Maybe you have misunderstood ! The nucleophilic reactivity and the aromatic stability are separate, they are different in both agurments and practical results.
As zero said earlier, it's very difficult to estimate the aromatic stability order, and normally, base on the practical reports, compare the endothermal energy of breaking aromatic system (e.g by hydrogenation reaction) to accord which systems are more stablility. Of course, if you want to agurment with theory aspect, you should makd exception for thiophene. Don't estimate the aromatic stability order base on the ability of conjugating of atoms.
But, the nucleophilic reactivity can estimate by the ability of conjugating of heteroatom, exception for benzene system since it's prefect aromatic system.
It's is my opinion !