Transcript Tips for Organic Chemistry Success

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
• -CH2CH3
methyl
ethyl
Hydrocarbons & their Derivatives
Hydrocarbons: H & C atoms only (the C & H
atoms form the backbone of all organic molecules)
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 around a center
atom will determine the geometry of the
molecule.
# e- pairs
2 pairs
3 pairs
4 pairs
e- pair geometry
linear
trigonal planar
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 Molecules
The number of carbons in
a chain is identified
according to the following:
– #C
name beginning
1
meth-
2
3
4
5
6
7
8
9
10
ethpropbutpenthexheptoctnondec-
The end of the name is
based on C-C bonding:
– All single C-C bonds end in “-ane”
– One or more double C-C
bonds end in “-ene”
– One or more triple C-C
bonds end in “-yne”
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
– Alkyl halides
– Alcohols
Double (-C=O, carbonyl)
– Aldehydes
– Ketones
– Carboxylic Acids
– Ethers
– 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 (dichlorodiphenyltrichlorothane)
Crude Oil
Vitamins
Water soluble:
– Lots of polar bonds &
polar fcn’l groups
– 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