Transcript Properties of Organic Compounds

Physical
Properties of Organic
Compounds
Chem 11
Saturated vs Unsaturated:


Saturated hydrocarbons or saturated fatty acids
have all single bonds between carbon atoms
Unsaturated hydrocarbons or fatty acids have
one or more double bonds between carbon atoms
 monounsaturated
- one double bond
 polyunsaturated - more than one double bond
Alkanes:





Saturated
Non-polar
Not soluble in H2O
Intermolecular forces weak, thus alkanes have
relatively low boiling points
As the number of atoms increase, the boiling point
increases
Note: table is alphabetical!
Alkenes:



Unsaturated
Unsaturated C atoms can potentially bond to
additional atoms! Thus are more reactive.
Boiling points of alkenes are generally lower then
similar (same # C) alkanes, reflecting slightly lower
IM forces

Ex: ethane -89ºC and ethene -104ºC
Alkynes:


Similar physical properties to alkanes and alkenes
(non-polar, not soluble in water, etc.)
Boiling points of alkynes are generally slightly
higher then similar (same # C) alkanes and alkenes
Reactivity:

Predict which is most reactive:
alkanes, alkenes or alkynes
Reactivity


Alkynes > alkenes > alkanes
The presence of the triple bond makes alkynes even
more reactive than alkenes. In fact, alkynes are so
reactive that few of these compounds occur
naturally.
Alcohols:



OH bond is highly polar and creates H bonding
between molecules
Polarity makes them highly soluble in water
Higher boiling points then alkanes with the same
number of carbons
Ethers:



Bent shape around the O atom, dipoles don’t
cancel and molecules are polar
Usually soluble in water
Lower boiling point then alcohols of the same
number of carbons
Aldehydes and Ketones:




C=O bond is polar, so molecules
usually are as well
Smaller soluble in water, larger
molecules not
Smelly!
Lower boiling points than
corresponding alcohols but higher
then corresponding alkanes