Читать книгу The Handy Chemistry Answer Book - Justin P. Lomont - Страница 33

It was first seen in a chemistry publication in 1855. The paper was written by August Wilhelm von Hofmann, but he gives no indication why he chose this term. It’s an unusual case since only a few aromatic compounds are actually smelly, while many nonaromatic compounds in chemistry labs do truly stink.

What is aromaticity?

Aromaticity is a special kind of resonance delocalization, one we’ve actually already seen. Delocalization of electrons always makes molecules more stable (compared to imaginary molecules where the electrons cannot spread out). If this delocalization takes place in a flat ring of n carbons, and the number of electrons involved is 4n + 2 (i.e., 2, 6, 10, 14, etc.), then the system is called aromatic.

What is a functional group in organic chemistry?

Functional groups are groups of atoms that tend to show similar reactivity in different molecules. Chemists use these groupings to help understand and predict how different molecules react with each other, and they’re also used for naming compounds.

Some examples of functional groups.

What is a carbocation and what is a carbanion?

A carbocation is a positively charged compound in which a carbon atom takes on a significant fraction of the positive charge. The definition for a carbanion is probably easy to guess, then—it’s a negatively charged compound in which a carbon atom bears a significant fraction of the negative charge.