Organic Chemistry Structures

Key Elements and Their Bonds

• Carbon (C)
  • 4 valence electrons
  • Forms 4 bonds
• Nitrogen (N)
  • 5 valence electrons
  • Forms 3 bonds (has 1 lone pair)
• Oxygen (O)
  • 6 valence electrons
  • Forms 2 bonds (has 2 lone pairs)
• Fluorine (F)
  • 7 valence electrons
  • Forms 1 bond (has 3 lone pairs)
• Other Halogens (Cl, Br, I)
  • Typically form 1 bond
• Sulfur (S) and Selenium (Se)
  • Typically form 2 bonds

Drawing Lewis Structures

Example 1: Ethane (C2H6)

• Condensed Structure: CH3-CH3
• Each carbon (C) has 4 bonds, hydrogen (H) has 1 bond.

Example 2: Ethene (C2H4)

• General formula for Alkenes: CnH2n
• Contains one double bond between carbon atoms.

Example 3: Ethyne (C2H2)

• Alkynes have triple bonds.

Example 4: Propane (C3H8)

• Lewis Structure: CH3-CH2-CH3

Example 5: Butane and Its Variants

• Condensed structures can be expanded into Lewis structures.

Functional Groups and Structures

Ether (Dimethyl Ether, CH3OCH3)

• General formula: R-O-R
• Each carbon has three hydrogens and oxygen has two lone pairs.

Ketone (Propanone, CH3COCH3)

• Contains a carbonyl group (C=O).

Alcohol (Methanol, CH3OH)

• Contains an -OH group (hydroxyl).

Aldehyde (Ethanol, CH3CHO)

• Carbonyl group at the end of the molecule.

Carboxylic Acid (Acetic Acid, CH3COOH)

• Contains carbonyl and hydroxyl groups.

Ester (Methyl Ethanoate, CH3COOCH3)

• Composed of two parts: acetate and methyl.

Amine (Ethyl Amine, CH3CH2NH2)

• Contains an amino group (-NH2).

Amide (Acetamide, CH3CONH2)

• Contains both carbonyl and amine groups.

Nitrile (Acetonitrile, CH3CN)

• Contains a C≡N group.

Alkyl Halides (Ethyl Fluoride, CH3CH2F)

• Contains a halogen (F, Cl, Br, I) attached to a carbon.

Naming and Drawing Structures

Example: 3-Ethyl-2,4-Dimethylhexane

• Parent chain: Hexane (6 carbons)
• Substituents: Ethyl (C2H5), Dimethyl (C1H3) attached accordingly.

Identifying Types of Carbons

Primary, Secondary, Tertiary Carbons

• Primary Carbon: Attached to one other carbon (3 H)
• Secondary Carbon: Attached to two other carbons (2 H)
• Tertiary Carbon: Attached to three other carbons (1 H)

Example Structures for Complex Names

• 2-Pentene: Alkene with five carbons and a double bond between 2 and 3.
• 3-Chloro-2-Methyl-1-Hexene: Contains a double bond and specified substituents.

Cis and Trans Isomerism

• Cis: Groups on the same side.
• Trans: Groups on opposite sides.

Concluding Remarks

• Familiarize with common substituents: amino, ethoxy, hydroxy, methoxy, oxo.

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