Barriers to CC Bond Rotation
CC ~3 kcal/mol
C=C >50 kcal/mol
Butane spins around its C2-C3 bond at room
temperature, but cis- and trans-butene cannot.
To isomerize cis and trans isomers, the bond but
must be brok
Analyze the following IR spectra and match each spectrum to the correct
molecule. Label all relevant peaks with the proper functional group. Draw
the correct molecule in the blank box (a copy of this exercise will be
provided for you to
Dehydration of Alcohols
In the presence of strong acids, alcohols lose water to
2-Methyl-2-butanol dehydrates to a mixture of two low-
boiling methylbutenes and some
Preparation of n-Butyl Iodide
Heating a Reaction
Many organic reactions do not occur quickly at room
temperature but require a period of heating.
Heating in an open container would evaporate the
solvent and other liquids.
Heating in a clo
There are four types of distillation:
1. Simple separates compounds with large
differences (>100 C) in bp
2. Fractional separates compounds with close (~25
3. Vacuum for liquids with high bps
Distillation is a very common
purification method in chemistry.
It is used to purify liquids based on
their boiling points.
It is extremely important to the
petroleum, food, pharmaceutical and
Chromatography - a physical
method of separating a
The components separate
between two phases, mobile
The stationary phase is a solid
or liquid; the mobile phas
Liquid-liquid Extraction (LLE)
LLE partitions a solute between
two liquid solvents.
The solvents must be immisible
One of the solvents is usually
water and the other a less polar
solvent like diethyl ether,
Recrystallization is a common
An impure solid is dissolved in a
hot solvent. Crystals form when
the solvent cools.
Ideally, impurities remain in
What is recrystallized?
Infrared Radiation (IR)
Infrared radiation is electromagnetic radiation with a
longer wavelength than visible light.
Its range on the electromagnetic spectrum is = 0.7
300 mm or 430 - 1 THz (1 THz = 1012 Hz).
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Molecules in a crystalline
solid are arranged in a
They dont move relative to
each other, but th