Unit 11: Comprehensive Summary

Alcohols (-OH): Classified as primary ($1^\circ$), secondary ($2^\circ$), or tertiary ($3^\circ$). They have high boiling points due to hydrogen bonding.

• Oxidation: $1^\circ$ alcohols oxidise to aldehydes then carboxylic acids; $2^\circ$ alcohols oxidise to ketones; $3^\circ$ alcohols are resistant to oxidation.
• Other Reactions: Dehydration to form alkenes; reaction with sodium to form alkoxides and $H_2$.

Carboxylic Acids (-COOH): Weak acids with high boiling points. They react with bases and carbonates.

• Esterification: React with alcohols in the presence of an acid catalyst to form esters (-COO-), which have fruity smells.
• Ester Hydrolysis: The reverse of esterification, breaking an ester into a carboxylic acid and an alcohol. Alkaline hydrolysis (saponification) is irreversible.

Amines (-$NH_2$): Organic derivatives of ammonia that act as weak bases.

Polymers are large molecules made of repeating monomer units.

• Addition Polymers: Formed from unsaturated monomers (alkenes) with no loss of atoms (e.g., poly(ethene)). Thermoplastics soften on heating, while thermosets are rigid due to cross-links.
• Condensation Polymers: Formed when monomers join with the elimination of a small molecule (like water). Examples include polyesters (from dicarboxylic acids and diols) and polyamides (from dicarboxylic acids and diamines).

Biochemistry is the chemistry of life.

• Lipids (Fats/Oils): Triglycerides, which are esters of glycerol and three fatty acids.
• Carbohydrates: Include monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), and polysaccharides (e.g., starch, cellulose).
• Proteins: Polymers of amino acid monomers joined by peptide bonds (amide links).

Soaps are sodium/potassium salts of fatty acids, made by the saponification of fats. They work by emulsifying grease. Soaps form scum in hard water. Soapless detergents do not form scum but are often derived from non-renewable resources.

Qualitative Analysis involves simple tests to identify functional groups:

• Alkene: Decolourises bromine water.
• Carboxylic Acid: Fizzes with sodium carbonate.
• Alcohol ($1^\circ/2^\circ$): Turns acidified dichromate(VI) from orange to green.
• $CH_3CH(OH)-$ group: Gives a yellow precipitate in the iodoform test.

Separation & Purification: Techniques like distillation (for liquids with different boiling points), crystallisation (for soluble solids), and chromatography are used to isolate and purify organic compounds.