Organic Chemistry Exam 2

What are the two types of alkanes

acyclic and cycloalkanes

Acyclic Alkane Molecular Formula

CnH2n+2

Cycloalkane Molecular Formula

CnH2n

What kinds of bonds do alkanes have?

nonpolar C-C and C-H bonds

What are alkanes composed of?

Tetrahedral, sp3 hybridized C’s

How do you classify carbon atoms?

By the number of C’s bonded to them

How do you classify Hydrogen atoms?

By the type of Carbon atom they are bonded to

Conformations in acyckic alkanes

Eclipsed, Staggered, Anti, Guache

Eclipsed

Dihedral angle of 0

Staggered

Dihedral Angle of 60 degrees

Anti

dihedral angle of 2 CH3’s = 180 degrees

Guache

Dihedral angle of 2 CH3’s = 60 degrees

Which has lower energy: staggered or eclipsed?

Staggered conformation

Which has lower energy: anti or gauche?

Anti conformation

Torsional Strain

an increase in energy due to eclipsing conformation

Steric Strain

an increase in energy when atoms are forced too close to each other

Angle Strain

an increase in energy when tetrahedral bond angles deviate from 109.5

What are the two types of isomers?

Constitutional and Stereoisomers

Constitutional Isomers

Isomers that differ in the way the atoms are connected to each other

Stereoisomers

isomers that differ only in the way atoms are oriented in space

Cis isomer

has two groups on the same side of the ring, either both up or both down

Trans isomer

has two groups on the opposite sides of the ring, one up and one down

Results from Oxidation

Results in an increase in the number of C-Z bonds or a decrease in the number of C-H bonds

Results from Reduction

decrease in the number of C-Z bonds or an increase in the number of C-H bonds