Organic Functional Groups Overview

Overview

This lecture covers key organic chemistry functional groups, their general structures, classification systems (like primary, secondary, tertiary), and basic identification skills necessary for future topics.

Alcohols

• Alcohols have the general structure R–OH, where R is an alkyl group.
• Classification:
  • Primary (1°): OH is attached to a carbon bonded to one other carbon.
  • Secondary (2°): OH is attached to a carbon bonded to two other carbons.
  • Tertiary (3°): OH is attached to a carbon bonded to three other carbons.
• Degree affects chemical reactivity.

Ethers and Related Compounds

• Ethers: R–O–R', with both R groups being alkyl (not hydrogen).
• Symmetrical ethers have identical R groups; unsymmetrical ethers have different R groups.
• Epoxides: three-membered cyclic ethers.
• Sulfides: like ethers but with sulfur (R–S–R').
• Thiols: R–SH; like alcohols but with sulfur instead of oxygen.

Aromatics

• Aromatic compounds feature ring structures with alternating single and double bonds.
• Benzene is the main example of an aromatic compound.

Carbonyl-Containing Compounds

• Carbonyl group: carbon double-bonded to oxygen (C=O).
• Ketones: R–CO–R', both R's are alkyl.
• Aldehydes: R–CO–H, at least one R is hydrogen.
• Carboxylic acids: R–COOH, with a carbonyl and an OH on the same carbon.
• Acyl halides: R–CO–X, with X as a halogen (Cl, Br, I, etc.).
• Anhydrides: two acyl groups bonded to the same oxygen atom.
• Esters: R–COOR', R1 (on the carbonyl) must be alkyl.
• Lactones: cyclic esters.

Amines and Amides

• Amines: nitrogen atom bonded to alkyl/hydrogen groups; no carbonyl.
  • Degree based on number of carbons directly attached to nitrogen: primary (1°), secondary (2°), tertiary (3°), quaternary (4°).
• Amides: nitrogen atom directly attached to a carbonyl carbon (R–CO–NR'R'').
• Amides can have varying substitution by alkyl or hydrogen.

Key Terms & Definitions

• Alkyl group — carbon and hydrogen chains or branches.
• Alcohol — R–OH, organic compound with a hydroxyl group.
• Ether — R–O–R', oxygen linking two alkyl groups.
• Epoxide — three-membered cyclic ether.
• Sulfide — sulfur analog of ether, R–S–R'.
• Thiol — sulfur analog of alcohol, R–SH.
• Aromatic compound — ring with alternating single and double bonds, e.g., benzene.
• Carbonyl group — C=O functional group.
• Ketone — carbonyl with two alkyl groups attached.
• Aldehyde — carbonyl with at least one hydrogen attached.
• Carboxylic acid — carbonyl with hydroxyl group (R–COOH).
• Acyl halide — carbonyl plus a halogen atom.
• Anhydride — two acyl groups bonded to one oxygen.
• Ester — carbonyl with an alkoxy group (R–COOR').
• Lactone — cyclic ester.
• Amine — nitrogen attached to alkyl/hydrogen groups, no carbonyl.
• Amide — nitrogen attached to a carbonyl carbon.

Action Items / Next Steps

• Practice identifying and drawing each functional group.
• Prepare for future lessons on the nomenclature of these groups.
• Review degree classification for alcohols and amines.