Organic Chemistry and Biochemistry
Functional groups and nomenclature
Organic chemistry organizes carbon compounds by functional group: alkanes (single bonds), alkenes (C=C), alkynes (C≡C), alcohols (–OH), ethers (C–O–C), aldehydes (–CHO), ketones (C=O between carbons), carboxylic acids (–COOH), esters (–COOR), amines (–NH2), and amides (–CONH2). IUPAC names use the longest carbon chain, number to give the lowest locants, and suffix the highest-priority group. Isomers share a formula but differ in connectivity (structural), spatial arrangement (stereo), or rotation (conformers).
Reactions and biochemistry
Alkanes undergo substitution; alkenes/alkynes undergo addition. Primary alcohols oxidize to aldehydes then carboxylic acids; secondary alcohols to ketones; tertiary alcohols resist oxidation. Carboxylic acids plus alcohols form esters. Biomolecules: carbohydrates (sugars, polysaccharides), lipids (fats, phospholipids), proteins (amino acid polymers with peptide bonds), and nucleic acids (nucleotide polymers). Enzymes are biological catalysts.
Worked example
How many structural isomers does C4H10 have? Two: butane, CH3CH2CH2CH3, and 2-methylpropane, (CH3)3CH. Both have the same molecular formula but different carbon skeletons, so they are structural isomers with different boiling points.
Traps
Confusing aldehydes and ketones; numbering a chain from the wrong end; assuming all alcohols oxidize; and calling enantiomers structural isomers.