Functional Group Chemistry
Functional groups are the reactive substructures that define the chemistry of organic molecules, allowing reactivity to be organized and predicted by the groups a molecule contains.
Definition
Functional group chemistry is the organization of organic reactivity around the structural motifs (functional groups) that confer characteristic chemical behavior on the molecules that bear them.
Scope
This area surveys the principal functional groups — alcohols, ethers, amines, aldehydes and ketones, carboxylic acids and their derivatives, and aromatic systems — along with their characteristic preparations, reactions, and interconversions.
Sub-topics
Core questions
- How does each functional group confer a characteristic pattern of reactivity?
- How are functional groups interconverted in synthesis?
- Why does the same nucleophile or electrophile react differently with different groups?
Key theories
- Functional-group concept
- Organic reactivity is localized in functional groups, so molecules with the same group display analogous reactions regardless of the rest of the carbon skeleton.
- Functional-group interconversion
- Synthesis is organized as a network of transformations that convert one functional group into another, enabling target molecules to be assembled by sequential interconversions.
Mechanisms
The reactivity of a functional group is governed by its electronic structure — bond polarity, the availability of lone pairs or pi systems, acidity or basicity, and the stability of any intermediates it forms. These properties dictate whether a group acts as a nucleophile, electrophile, acid, base, or leaving group.
Clinical relevance
Recognizing functional groups is the basis for predicting a compound's solubility, metabolism, and biological activity, and for designing drugs whose functional groups present the right hydrogen-bond donors, acceptors, and reactive handles to their targets.
History
The functional-group concept grew out of nineteenth-century radical and type theories of organic compounds, which recognized that certain groupings of atoms behaved as coherent reactive units, providing the organizing principle that still structures organic chemistry teaching.
Key figures
- August Kekulé
- Justus von Liebig
- Christopher Kelk Ingold
Related topics
Seminal works
- march2007
- clayden2012
Frequently asked questions
- Why organize organic chemistry by functional group?
- Because reactivity is concentrated in functional groups, learning the behavior of each group lets a chemist predict how an unfamiliar molecule will react simply by identifying the groups it contains.
- Can one molecule contain several functional groups?
- Yes; most complex and biologically active molecules are polyfunctional, and a central skill is judging which group will react first under given conditions and how to protect the others.