Introduction to Organic Chemistry

Organic chemistry is the study of carbon compounds -- and carbon is everywhere! From the food you eat (carbohydrates, proteins, fats) to the fuels that power vehicles, from medicines to plastics, organic compounds form the foundation of life and modern technology.

Why Carbon is Special

Carbon has four valence electrons and can form four covalent bonds. This gives it unique abilities:

• Catenation: Carbon atoms can bond with each other to form long chains, branched chains, and rings
• Tetravalency: Carbon can bond with H, O, N, S, halogens, and other elements
• Carbon forms strong, stable bonds with many elements

These properties allow millions of different organic compounds to exist.

Hydrocarbons

Hydrocarbons are compounds containing only carbon and hydrogen.

| Type | General Formula | Bond Type | Example | |------|----------------|-----------|---------| | Alkanes | CnH₂n+₂ | Single bonds only (saturated) | CH₄ (methane), C₂H₆ (ethane) | | Alkenes | CnH₂n | One double bond (unsaturated) | C₂H₄ (ethene), C₃H₆ (propene) | | Alkynes | CnH₂n-₂ | One triple bond (unsaturated) | C₂H₂ (ethyne), C₃H₄ (propyne) |

IUPAC Nomenclature

The International Union of Pure and Applied Chemistry (IUPAC) provides systematic naming rules:

Steps to name an organic compound:

1. Find the longest carbon chain (parent chain)
2. Number carbons from the end nearest to the first substituent
3. Name substituents (methyl, ethyl, etc.) with position numbers
4. Use prefixes: meth- (1C), eth- (2C), prop- (3C), but- (4C), pent- (5C), hex- (6C)
5. Use suffixes: -ane (single bond), -ene (double bond), -yne (triple bond)

Example: CH₃-CH(CH₃)-CH₂-CH₃ is 2-methylbutane (4C parent chain with a methyl group at position 2).

Functional Groups

A functional group is a specific atom or group of atoms that determines the chemical properties of an organic compound.

| Functional Group | Name | Suffix | Example | |-----------------|------|--------|---------| | -OH | Hydroxyl | -ol (alcohol) | CH₃OH (methanol) | | -CHO | Aldehyde | -al | CH₃CHO (ethanal) | | -COOH | Carboxyl | -oic acid | CH₃COOH (ethanoic acid) | | -CO- | Ketone | -one | CH₃COCH₃ (propanone) | | -NH₂ | Amino | -amine | CH₃NH₂ (methanamine) |

Nepal Connection

Biogas plants across rural Nepal produce methane (CH₄) from organic waste. Ethanol is produced from sugarcane in the Terai region. Understanding organic chemistry helps improve these processes.

Key Takeaways

• Carbon's tetravalency and catenation allow millions of organic compounds
• Hydrocarbons are classified as alkanes, alkenes, and alkynes
• IUPAC nomenclature provides systematic, unambiguous names
• Functional groups determine the chemical behaviour of organic molecules