Organic Chemistry I

Chem 334 - Fall 2009

Chapter 2 Notes

Professor Carl C. Wamser

Alkanes and Cycloalkanes

Molecular orbitals

Hybrid orbitals

Why hybrid orbitals?

Identifying the hybridization of carbon

  Neighboring Atoms

  Sigma Bonds

  Pi Bonds

  Hybrid

  Structure

  4

  4

  0

  sp3

  tetrahedral

  3

  3

  1

  sp2

  trigonal planar

  2

  2

  2

  sp

  linear


Hydrocarbons

only C-H and C-C single bonds (alkanes)
C=C double bond (alkenes)
C=C triple bonds (alkynes)
rings (cycloalkanes, bicycloalkanes, polycycloalkanes)
aromatic rings (arenes)

Alkane Family

Higher Alkanes

Alkane Isomers

straight-chain
branched-chain
cyclic chain

atoms connected in a different order
butane and isobutane
3 pentane isomers

Butane isomers

n-butane

isobutane

Pentane Isomers

Alkyl Groups

n-propyl alcohol

isopropyl alcohol

(constitutional isomers)

Butyl Groups

Classification of C Atoms

Identifying Carbon Classes

IUPAC Nomenclature

(substituents)-(parent alkane)-(family)

Cl-CH2CH2-OH
2-chloro ethan ol

IUPAC Rules

IUPAC Examples

IUPAC Examples

Cycloalkane nomenclature

Writing Skeletal Structures

Practice with Line Structures

methylcyclohexane

Alkanes - Source (Petroleum)

Alkanes - physical properties

nonpolar - low melting point, low boiling point, low water solubility

e.g., NaCl (ionic) bp 1413° , H2O (polar) bp 100° , CH4 (nonpolar) bp -161°

branched alkanes have lower bp than straight-chain analogs

( van der Waals forces depend on surface area)

Reactions of alkanes

Heats of combustion

Oxidation-reduction reactions