Fundamentals of Organic
Chemistry
1 2 3 4 bonds
HONC
What is organic chemistry?
• study of carbon, the compounds it makes, and
the reactions it undergoes
• over 16 million carbon-containing compounds
are known
• because the C-C single bond (348 kJ/mol) and
the C-H bond (412 kJ/mol) are strong, carbon
compounds are stable
• carbon can form chains and rings
Empirical, molecular & structural formulas
2
• empirical formula
– simplest ratio of
atoms in a
molecule
• molecular formula
– actual numbers
of atoms in a
molecule
Empirical
Formula
Molecular
Formula
CH4
CH4
CH3
C2H6
CH2O
C6H12O6
CH2
C4H8
CH2
C8H16
structural formula
• unambiguously shows how the atoms are
bonded together
• can use condensed structural formulas
– bonds are omitted, repeated groups put
together, side chains put in brackets
• CH3CH2CH2CH2CH2CH3
–or even CH3(CH2)4CH3
• CH3CH(CH3) CH2CH3
condensed
skeletal formula
– every “corner” or “end” represents a carbon
unless a different element is there
– hydrogens are implied
Isomers
• (structural) isomers: compounds with the
same molecular formula but different structure
(arrangement of atoms)
• different isomers can have different chemical
properties
• and different physical properties such as melting
point and boiling point
Structural
Formulas
for C4H10O
Isomers
Alkanes
Structural formulas for the isomers of noncyclic alkanes up to C6
• hydrocarbon chains where all the bonds between
carbons are SINGLE bonds
• draw out and write the structural formulas for
all isomers that can be formed by:
–
–
–
–
–
–
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
Richard Thornley
2:54
Naming the isomers (IUPAC) of non-cyclic
alkanes up to C6
1. determine the longest carbon chain
–
–
1
2
3
4
5
6
use the prefix to denote the number carbons
ending is -ane
MethEthPropButPentHex-
Monkeys
Eat
Peeled
Bananas
Alkenes
Structural formulas for the isomers of the straight
chain alkenes up to C6
• alkenes have a double bond between two or
more of the carbons
• suffix changes to -ene
• when there are 4 or more carbon atoms in a
chain, the location of the double bond is
indicated by a number
• begin counting the carbons closest to the end
with the C=C bond
• draw the structural formulas for all isomers that
can be formed by each
– C2H4
– C3H6
Richard Thornley 10.1.7 (1:37)
– C4H8
These are only straight chain isomers.
– C5H10
– C6H12
pent – 1 – ene
pent – 2 – ene
Functional Groups
• a part of the molecule that stands out as an unusual
or unique part of the molecule
• add these somewhere on alkanes and alkenes
• the molecule often has certain characteristics based
on a functional group
• the entire class of compounds is often named
according to the functional group they contain
• “R” in a structural formula of a molecule just stands
for any other atoms other than the functional group
website on functional groups click here
carboxyl
- found in carboxylic acids
- putrid smelling
ester
- found in esters
- sweet smelling
carbonyl
- found in ketones
- sweet, minty, camphor smelling
hydroxyl
- found in alcohols
- sweet, camphor smelling
amino
- found in amines
- fishy smelling
- look for N, doesn’t matter how many H’s
Smells
• humans can tell the difference between
10,000 different odors
• a more distant sense allowing us to detect
small concentrations of airborne substances
– must be a gas
• therefore cannot smell ionic compounds since they are
normally solids at room temperature
• molecules fit into certain receptors sites in the
human body as a result of their shape
– signals are then sent to the brain
• compounds that have similar smells have
similar structural formulas
• polar molecules may “stick” to receptor sites
better than non-polar
Amino Acids/Proteins
• the molecular subunits/building blocks of proteins
(the essential building blocks for living organisms)
• 20 different amino acids are used to synthesize
almost all the proteins in almost all living cells
• protein formation
– link is between carboxyl group on one a.a.
and the amino group on the other.
– water is formed and remaining N and C link
together called a peptide bond
Protein movie