Question

TIC, OR ANTIAROMATIC 18.2 DETERMINING WHETHER A STRUCTURE IS AROMATIC, NONAROMATIC, OR ANTIAR LEARN the skill Determine whether the following anion is aromatic, nonaromatic, or antiaromatc SOLUTION To determine if this anion is aromatic, we must ask two questions 1. Does the compound contain a ring comprised of continuously overlapping p orbitaid 2. Is there a Huckel number of π electrons in the ring? p orbital? The answer to the first question appears to be yes, that is, the lone pair can ocopya p orbital, providing for continuous overlap of p orbitals around the ring. However, when a try to answer the second question, we discover that this anion would have which would render the anion antiaromatic. As such, the geometry of the anion will darg to avoid the instability associated with antiaromaticity. Specifically, the lone pair can ocoup an sp -hybridized orbital (rather than a p orbital), so the first criterion is no longer met. Te renders the anion nonaromatic. 。) PRACTICE the skill 18.11 oi PRACTICE the skill 18.11 Determine whether each of the following ions is aromatic, nonaromatic, or Determine whether each of the following ions is aromat antiaromatic APPLY the skill18.12 Explain the vast difference in pk, values for the following two apparently similar compounds: 18.13 Predict which compound will react more readily in an Syl process and explain your choice Br 18.14 Identify which of the following compounds is more acidic and explain your choice: acidic and explain your need more PRACTICE? Try Problems 18.34a,c,e, 18.36e, 18.52 Aromatic Heterocycles Cyclic compounds containing heteroatoms (such as S, N, or O) are calledb two examples of nitrogen-containing heterocycles. called heteroydles are called heteroycls Pyridine Pyrrole Both of these co separately and then compare chem to each other. are aromatic, but for resons. We will discus
The example is saying it's not aromatic but how come 18.11d is aromatic ?

Answer 1

18.11.d     is cyclic structure

                  planar all pi electrons are conjugated system.

                 it obeys 4n+2 pi system also.

                 (4 x2 + 2) 10 electrons so it is aromatic in nature.