Compounds were classified as being either aliphatic or aromatic in the latter part of the nineteenth century. To be classified as aliphatic meant then that the chemical behavior of a compound was “fatlike”. To be classified as aromatic meant then that the compound had a low hydrogen/carbon ratio and that it was “fragrant

A ring that contains at least one heteroatom (an atom other than carbon) is called a heterocycle, and a substance based on a heterocyclic ring is a heterocyclic compound. Heterocyclic compounds containing N, O or S are by far the most common

Many other pairs of reagents that form cabocations (orcarbocationlike species) may be used as well

Aldehydes are named by replacing the terminal –e of the corresponding alkane name with –al. The longest chain selected as the base name must contain the –CHO group, and the –CHO carbon is always numbered as carbon 1

If a chiral atom attached to the carbonyl group, the stereoselectivity of nucleophilic addition follows the Cram’s rule

The aldols formed in aldol additions can be easily dehydrated to yield conjugated enals (enones)

Phenols are like alcohols in being able to form strong intermolecular hydrogen bonds. Phenols have higher boiling points than hydrocarbons of the same molecular weight. A modest solubility in water

21.11 Aryl Halide and Nucleophilic Aromatic Substitution 21.12 Spectroscopic Analysis of Phenols and Aryl Halides

Carbon’s ability to form strong covalent bonds to other carbon atoms is the single property of the carbon atom that — more than any other—accounts for the existence of a field of study called organic chemistry. Carbon’s ability to form as many as four strong bonds to other carbon atoms, and to form strong bonds to hydrogen, oxygen, sulfur, and nitrogen atoms as well

Infrared Spectroscopy: An Instrumental Method for detecting Functional Groups