Ch.11
An Introduction to Organic Molecules & Functional Groups
Tips for Organic Chemistry Success
•In
order to successfully understand the various types of Organic molecules you should
be able to identify each of the following for each type of molecule:
•Structural characteristics (know the functional group)
•Nomenclature (the rules for naming the molecules)
•Physical and Chemical properties (basic/simple)
•Occurrence and uses (common)
•Preparation (what basic reactions produce the molecules)
•Characteristic reactions of the molecules
For additional help, check out the Organic Chemistry section of the following
website:
http://www.khanacademy.org/#browse
Organic vs. Inorganic Compounds
•Inorganic compounds: cpds which are NOT hydrocarbons (~1.5 million)
•Organic compounds: cpds which contain hydrogen & carbon (thus, hydrocarbons &
derivatives) (~ 7 million)
•“Organic Chemistry” started, as a branch of chemistry, when F. Wohler
disproved the idea of “vital force.”
- previously, it was thought that there were
two types of matter (based on heating):
melting/freezing
cooking (required “vital force”)
Carbon Atoms
•Carbon atoms generally form 4 bonds (think about their electron configuration)
•In “organic” compounds these bonds are typically COVALENT.
•Carbon readily forms bonds with other carbon atoms as well as with atoms of other
elements.
•Carbons w/ H’s attached are known as alkyl groups.
-CH3
methyl
-CH2CH3
ethyl
Hydrocarbons & their Derivatives
•Hydrocarbons: H & C atoms only
•Derivatives: H, C & other elements
•Saturated Hydrocarbons: all C-C bonds are “single.”
–Alkanes and their derivatives
•Unsaturated Hydrocarbons: one or more C-C bond(s) is/are multiple.
–Alkenes, alkynes, aromatics & their derivatives
Basic Structural Features
Chains of atoms
Rings of atoms
Shapes of Organic Molecules
The # of effective e- pairs will determine the geometry of the molecule.
# e- pairs
e- pair geometry
2 pairs
linear
3 pairs
trigonal planar
4 pairs
tetrahedral
Remember, the e- pair geometry and the molecular geometry are NOT necessarily the
same!
Drawing Organic Molecules
Complete Structures: draw all atoms and all bonds, showing relative shapes
Condensed Structures: write each alkyl (CHx) group separately.
Skeletal Structures: carbon atoms at each line junction, assume enough H’s; draw all
heteroatoms & their H’s.
Naming Organic MoleculesThe number of carbons in a chain is identified according to
the following:
#C
name beginning
The end of the name is based on C-C bonding:
1
methAll single C-C bonds - end in “-ane”
2
eth3
propOne or more double C-C - bonds end in “-ene
4
but5
pentOne or more triple C-C - bonds end in “-yne”
6
hex7
hept8
oct9
non10 dec-
Functional Groups
Functional groups contain a heteroatom, a multiple bond, or both and provide
characteristic chemical & physical properties.
Abbreviating the hydrocarbon backbone:
R - fcn’l grp
ex. R - Br
alkyl halide
R - OH
alcohol (-OH is hydroxyl group)
R - COOH
carboxylic acid (-COOH is carboxyl group)
Single vs. Double bonds to Heteroatoms
•Single
Double (-C=O, carbonyl)
–Alkyl halides
- Aldehydes
–Alcohols
- Ketones
–Ethers
- Carboxylic Acids
–Amines
- Amides
- Esters
Properties of Organic Cpds
Polarity of molecule is determined by electronegativity differences and shape of
molecule.
Solubility: most are soluble in organic solvents
water solubility is based on size of molecule &
polarity.
Pollutants
Organic pollutants affect the environment depending on their solubility.
Ex.
DDT
Crude oil
Vitamins
•Water soluble:
–Lots of polar bonds
–Typically smaller molecules
–C and all the B’s
•Water insoluble:
–Lots of nonpolar bonds and few polar
fcn’l groups
–Typically larger molecules
–A, D, E, K