Nomenclature danh phap

Organic Chemistry
4th Edition
Paula Yurkanis Bruice

Chapter 2

An Introduction to
Organic Compounds

Nomenclature,
Physical Properties,
and
Representation of
Structure

Irene Lee
Case Western Reserve University
Cleveland, OH
©2004, Prentice Hall
Alkanes are hydrogen carbons containing only single
bonds
General formula: CnH2n+2
Constitutional isomers have the same molecular
formula, but their atoms are linked differently
Nomenclature of Alkyl Substituents

A compound can have more than one name, but a
name must specify only one compound
A C7H16 compound can be any one of the following:
Different Kinds of Carbons and Hydrogens
Nomenclature of Alkanes
Nomenclature of Cycloalkanes
3. If there are more than two substituents,
Nomenclature of Alkyl Halides
In the IUPAC system, alkyl halides are named as substituted
alkanes
Different Kinds of Alkyl Halides
Nomenclature of Ethers
Nomenclature of Alcohols
4. If there is more than one substituent, the substituents are cited
in alphabetical order
Nomenclature of Amines
Naming Quaternary Ammonium Salts
Structures of Alkyl Halides
Structures of Alcohol and Ether
Structures of Amines
The greater the attractive forces between molecules,
the higher is the boiling point of the compound
Attractive Forces
van der Waals force
Dipole–dipole interaction
Hydrogen bonds
van der Waals Forces
The boiling point of a compound increases with the
increase in van der Waals force
Dipole–Dipole Interaction
Dipole–dipole interactions are stronger than van der
Waals force but weaker than ionic or covalent bonds
A hydrogen bond is a special kind of dipole–dipole
interaction
Like Dissolves Like
Polar compound dissolves in polar solvent
Nonpolar compound dissolves in nonpolar solvent
Conformations of Alkanes:
Rotation about Carbon–Carbon Bonds
Torsional strain: repulsion between pairs of bonding
electrons
A staggered conformer is more stable than an eclipsed
conformer
Different Conformations of Ethane
Conformations of n-Butane
Steric strain: repulsion between the electron clouds of
atoms or groups
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Cycloalkanes: Ring Strain
Angle strain results when bond angles deviate from the
ideal 109.5° bond angle
The chair conformation of cyclohexane is free of strain
Ring Flipping in Cyclohexane
Drawing Cyclohexane
The Conformations of Cyclohexane
and Their Energies
Conformations of Monosubstituted Cyclohexanes
Steric Strain of 1,3-Diaxial Interaction in Methylcyclohexane
Keq = [equatorial conformer]/[axial conformer]
The larger the substituent on a cyclohexane ring, the
more the equatorial substituted conformer will be
favored
The Chair Conformers of cis-1,4-Dimethylcyclohexane
The Chair Conformers of trans-1,4-Dimethylcyclohexane
1-tert-Butyl-3-Methylcyclohexane
Conformations of Fused Rings
Trans-fused cyclohexane ring is more stable than
cis-fused cyclohexane ring