Introduction to Biochemistry
COURSE TITLE: INTRODUCTION TO BIOCHEMISTRY
COURSE CODE: BC 120
LECTURE 6
Organic Compounds
- Organic Chemistry (Chemistry of Carbon compounds):
• The study of carbon-containing compounds and their properties.
• The vast majority of organic compounds contain chains and rings of carbon atoms,
and are held together by covalent bonds.
Organic compounds and the atomic properties of carbon:
• Carbon can form 4 covalent bonds (Carbon with 4 electrons in its outer energy
level). This allows it to make millions of different compounds.
• Each carbon forms a maximum of four single bonds, OR two single and one double
bond, OR one single and triple bond.
Organic Compounds
• Many organic compounds contain heteroatoms ‘atoms other than C and H’. The most
common of these are O, N, S, the halogens (Cl, F, Br, and I), and P.
Organic Compounds
Isolation from nature (animal and plant)
(extract-isolate-purify)
Obtained by:
Compounds in living systems are organic
Synthesis in lab
- Classification of organic compounds:
- Hydrocarbons [Aliphatic & Aromatic hydrocarbons].
• Functional groups
Hydrocarbons
Large family of organic compounds
Composed of only carbon and hydrogen
Saturated hydrocarbons
Unsaturated hydrocarbons
Alkanes
Alkenes, Alkynes & Benzene compounds
C-C
C=C
C C
Alkanes
Saturated compounds (alkanes): Have the maximum number of hydrogen atoms
attached to each carbon atom.
Methane
Tetrahedral
Molecular formula
CH4
Expanded structural formula:
showing each bond line.
Naming of Alkanes
Using the IUPAC alkane names: -ane
Prefix + ane
CnH2n+2
Line-angle Formula
Propane
CH3-CH2-CH3
Butane
CH3-CH2-CH2-CH3
Pentane
CH3-CH2-CH2-CH2-CH3
Cyclic Hydrocarbon - Cycloalkane
=
Cyclobutane
=
Cyclopentane
=
Cyclohexane
Alkenes and Alkynes
Unsaturated compounds:
Have fewer hydrogen atoms attached to
the carbon chain than alkanes.
• Containing double bond are alkenes.
CnH2n
• Containing triple bonds are alkynes.
CnH2n-2
Naming Alkenes & Alkynes
Using the IUPAC names:
Alkene names change the end to -ene.
Alkyne names change the end to -yne
Naming Substituents
In the IUPAC system:
• Removing a H from an
alkane is called alkyl
group.
-ane
-yl
• Halogen atoms are named
as halo.
-ine
-O
-OH
-NO2
Hydroxyl
Nitro
Benzene: 3π bonds x 2e¯= 6e π
4n+2=6 →n=1 aromatic
Cyclobutadiene: 2π bonds x 2e¯= 4e π
4n+2=4 → n=0.5
4n=4 → n=1 antiaromatic
Aromatic Compounds or Aromatic Hydrocarbons
Benzene has:
• 6 C atoms and 6 H atoms.
• Two possible ring structures.
H
Resonance hybrid
H
C
C
H
C
C
H
C
C
H
H
H
H
C
C
H
C
C
H
C
C
H
H
Benzene Compounds
Arene: A compound
H containing one or more benzene rings.
H
C
C
C
C
H
C
H
C
H
Naphthalene
Aromatic compounds H
are named:
A Kek ulé structure
A Keku lé structu re
show ing all atoms as a line-angle formula
• With benzene as the parent chain.
• Name of substituent comes in front of the “benzene”.
CH
CH32 CH3
methylbenzene
Eth ylb enzene
CH2 CH3
Cl
CH
3
Eth ylbeenzene
chlorobenzene
Toluen
CH
CH -CH
CH33
CH=CHCH
2 3 22
Anthracene
CH=CHCH
2 3
Toluen
Eth ylb
e enzene Styrene
Toluen e
ethylbenzene
Styrene
Naming of Aromatic Compounds
Some substituted benzenes have common names.
CH
OH3
Toluene
Phen ol
OH
Phen ol
OCH3
A nisole
NH2
A niline
OH
OCH
3
NHOCH
2 3
O
NH
2
C-H
OO
C-H
C-OH
Phen ol A niline
A nisoleBenAzaldehyde
niline BenBenzoic
zaldehyde
A nisole
aci
O
C-H
Ben zaldehyde
O
C-OH
Benzoic acid
Functional groups
An atom or group of
atoms within a
molecule that shows a
characteristic set of
physical and chemical
properties.
General structures of amines
the amine functional group
primary (1o) amine
secondary( 2o) amine
C N
tertiary (3o) amine
The formation of
carboxylic,
phosphoric, and
sulfuric acid
anhydrides
The carbonyl group
π
σ
δ
δ
Some common aldehydes and ketones
methanal
(formaldehyde)
used as
biological
preservative
ethanal
(acetaldehyde)
benzaldehyde
2-propanone
(acetone)
2-butanone
(ethyl methyl
ketone)
Carboxylic acid