Organic Compound Classification 🌿

1. Acyclic (Open-Chain) Compounds

Also called aliphatic compounds. They have straight or branched carbon chains. Examples:

  • Ethane: CH3CH3
  • Isobutane: (CH3)2CHCH3
  • Acetaldehyde: CH3CHO

2. Cyclic (Closed-Chain) Compounds 🔄

Atoms form rings! Two main types:

A. Alicyclic Compounds

Carbon-only rings (homocyclic) or rings with other atoms (heterocyclic). Examples:

  • Cyclopropane, Cyclohexane
  • Tetrahydrofuran (heterocyclic)

They behave like aliphatic compounds!

B. Aromatic Compounds

Special ring structures with unique properties. Three sub-types:

  • Benzenoid (contain benzene ring):
    Benzene (C6H6), Aniline, Naphthalene
  • Non-benzenoid:
    Tropone
  • Heterocyclic aromatic (ring has non-carbon atoms):
    Furan, Thiophene, Pyridine

Functional Groups & Homologous Series ⚗️

Functional Group

An atom/group of atoms that gives organic compounds their characteristic properties. Key examples:

  • Hydroxyl (–OH)
  • Aldehyde (–CHO)
  • Carboxylic acid (–COOH)

Homologous Series

A family of compounds with the same functional group! Members:

  • Can be represented by a general formula (e.g., alkanes: CnH2n+2)
  • Differ by –CH2 between successive members
  • Examples: Alkanes, Alkenes, Alkynes, Haloalkanes, Alcohols, Carboxylic acids

Compounds with ≥2 functional groups are called polyfunctional.

Organic Compound Naming ✍️

Common Names (Trivial Names)

Based on origin/properties (still used today!):

CompoundCommon Name
CH4Methane
CH3COOHAcetic acid
C6H6Benzene
CHCl3Chloroform
HCHOFormaldehyde

IUPAC System

Systematic names based on:

  1. Parent hydrocarbon chain (longest carbon chain)
  2. Functional groups attached
  3. Branches/substituents

Example structure:
CH3–CH–CH2–CH–CH–CH3
(Here, identify parent chain, branches & functional groups!)

NEET Must-Knows! 🎯

Top 5 high-yield concepts:

  1. Classification types: Acyclic vs. Cyclic (Alicyclic/Aromatic)
  2. Aromatic subtypes: Benzenoid (benzene rings) vs. Non-benzenoid vs. Heterocyclic aromatic
  3. Functional groups: Identify –OH, –CHO, –COOH in compounds
  4. Homologous series: Members differ by –CH2; know general formulas (e.g., alkanes: CnH2n+2)
  5. Naming: Common names (Table 8.1) + IUPAC rules (parent chain + functional group priority)

Happy studying! You’ve got this! 💪