🧪 Introduction to Organic Chemistry
Organic chemistry is the study of carbon compounds. The term "organic" means life - these are compounds derived from living
sources like plants and animals.
📚 Historical Development
Early Classification (≈200 years ago)
Scientists initially classified compounds into two categories:
Type Source Examples
Organic compounds Living sources Plants, animals
Inorganic compounds Non-living sources Minerals, gases
Vital Force Theory (1815)
Berzelius proposed that organic compounds contain a mysterious "vital force" that cannot be recreated in laboratories. This
phenomenon was called vitalism.
⚗️ Breakthrough Discoveries
Wöhler's Synthesis (1828)
Friedrich Wöhler (Berzelius's student) disproved the vital force theory by synthesizing urea from ammonium cyanate:
N H4 CNO → CO(N H2 )2
This demonstrated that organic compounds can be synthesized in laboratories.
Subsequent Syntheses
1. Kolbe (1845): Synthesized acetic acid from elements
2. Berthelot (1856): Synthesized methane from carbon and hydrogen
🔬 Carbon's Unique Properties
Catenation Property
Carbon exhibits self-linking ability, forming long chains:
Catenation: The ability of carbon atoms to bond with other carbon atoms, creating chains and rings.
This property allows carbon to form:
Long chains
Branched structures
Ring structures
📝 Representation Methods
1. Molecular Formula
Shows number and type of atoms only
No connectivity information
Examples: C 2 H6 O
,C 3 H6 ,C
4 H10
, 2. Lewis Structure
Shows:
All atoms
All bonds
Lone pairs (if any)
3. Condensed Formula
Shows atoms and their connectivity
No bonds or lone pairs
Example: C H 3 C H2 C H2 N
H2
4. Partially Condensed Structure
Shows some bonds and lone pairs
5. Bond-Line Structure (Most Important)
Key features:
Only C-C bonds are shown
Heteroatoms (O, N, halogens) always represented
Longest carbon chain in zigzag pattern
Double bonds: 2 lines
Triple bonds: 3 lines
Example conversion:
From Lewis structure to bond-line structure
Carbon atoms at chain ends and junctions are implied## 🧪 Bond-Line Representation Rules
Bond-line structures show carbon chains as zig-zag lines where:
Each vertex or end = carbon atom
Hydrogens are never drawn but must be “seen with the mind’s eye”
Heteroatoms (O, N, Cl, etc.) must be written explicitly
A carbon with one bond drawn ⇒ 3 H
A carbon with two bonds drawn ⇒ 2 H
A carbon with three bonds drawn ⇒ 1 H
A carbon with four bonds drawn ⇒ 0 H
Quick Examples
Condensed Formula Bond-Line Drawing Rule
CH₃CH₂CH₃ Zig-zag of 3 C’s, no H
CH₃CH₂CH₂OH 3 C zig-zag, last C bonded to O-H
CH₃CH₂CHO 3 C zig-zag, last C double-bonded to O
🎯 Degree of Carbon (1°, 2°, 3°, 4°)
Degree = number of other carbon atoms directly bonded to that carbon.
Degree Name Visual H Count
1° Primary 3H
2° Secondary 2H
Organic chemistry is the study of carbon compounds. The term "organic" means life - these are compounds derived from living
sources like plants and animals.
📚 Historical Development
Early Classification (≈200 years ago)
Scientists initially classified compounds into two categories:
Type Source Examples
Organic compounds Living sources Plants, animals
Inorganic compounds Non-living sources Minerals, gases
Vital Force Theory (1815)
Berzelius proposed that organic compounds contain a mysterious "vital force" that cannot be recreated in laboratories. This
phenomenon was called vitalism.
⚗️ Breakthrough Discoveries
Wöhler's Synthesis (1828)
Friedrich Wöhler (Berzelius's student) disproved the vital force theory by synthesizing urea from ammonium cyanate:
N H4 CNO → CO(N H2 )2
This demonstrated that organic compounds can be synthesized in laboratories.
Subsequent Syntheses
1. Kolbe (1845): Synthesized acetic acid from elements
2. Berthelot (1856): Synthesized methane from carbon and hydrogen
🔬 Carbon's Unique Properties
Catenation Property
Carbon exhibits self-linking ability, forming long chains:
Catenation: The ability of carbon atoms to bond with other carbon atoms, creating chains and rings.
This property allows carbon to form:
Long chains
Branched structures
Ring structures
📝 Representation Methods
1. Molecular Formula
Shows number and type of atoms only
No connectivity information
Examples: C 2 H6 O
,C 3 H6 ,C
4 H10
, 2. Lewis Structure
Shows:
All atoms
All bonds
Lone pairs (if any)
3. Condensed Formula
Shows atoms and their connectivity
No bonds or lone pairs
Example: C H 3 C H2 C H2 N
H2
4. Partially Condensed Structure
Shows some bonds and lone pairs
5. Bond-Line Structure (Most Important)
Key features:
Only C-C bonds are shown
Heteroatoms (O, N, halogens) always represented
Longest carbon chain in zigzag pattern
Double bonds: 2 lines
Triple bonds: 3 lines
Example conversion:
From Lewis structure to bond-line structure
Carbon atoms at chain ends and junctions are implied## 🧪 Bond-Line Representation Rules
Bond-line structures show carbon chains as zig-zag lines where:
Each vertex or end = carbon atom
Hydrogens are never drawn but must be “seen with the mind’s eye”
Heteroatoms (O, N, Cl, etc.) must be written explicitly
A carbon with one bond drawn ⇒ 3 H
A carbon with two bonds drawn ⇒ 2 H
A carbon with three bonds drawn ⇒ 1 H
A carbon with four bonds drawn ⇒ 0 H
Quick Examples
Condensed Formula Bond-Line Drawing Rule
CH₃CH₂CH₃ Zig-zag of 3 C’s, no H
CH₃CH₂CH₂OH 3 C zig-zag, last C bonded to O-H
CH₃CH₂CHO 3 C zig-zag, last C double-bonded to O
🎯 Degree of Carbon (1°, 2°, 3°, 4°)
Degree = number of other carbon atoms directly bonded to that carbon.
Degree Name Visual H Count
1° Primary 3H
2° Secondary 2H
