Alpha-carbon: The carbon directly adjacent to the carbonyl carbon (C=O) in an aldehyde or ketone. Hydrogens on this carbon are called alpha-hydrogens.

Alpha-hydrogen: A hydrogen atom bonded to the alpha-carbon (adjacent to C=O). Alpha-H atoms are weakly acidic (pKa ~20) because the resulting carbanion (enolate) is resonance-stabilized by the carbonyl group.

Aldehyde: A carbonyl compound with at least one H directly attached to the carbonyl carbon (R-CHO or HCHO). Aldehydes are reducing agents.

Aldol condensation: A reaction between two carbonyl compounds (with at least one bearing an alpha-H), catalyzed by dilute NaOH or acid, giving a beta-hydroxy carbonyl compound (aldol product).

Cannizzaro reaction: Disproportionation (self-redox) of an aldehyde WITHOUT alpha-hydrogen in the presence of concentrated NaOH. One molecule is oxidized (to carboxylate salt) and one is reduced (to alcohol).

Carbonyl group: The functional group C=O (carbon doubly bonded to oxygen). Present in aldehydes (R-CHO), ketones (R-CO-R'), carboxylic acids (R-COOH), and derivatives.

Clemmensen reduction: Reduction of C=O to CH2 using zinc amalgam (Zn-Hg) and concentrated HCl under acidic, reflux conditions. Completely removes oxygen.

Condensation reaction: A reaction in which two molecules combine with the loss of a small molecule (usually water). NH3 derivative reactions with C=O are condensation reactions.

Enolate: The resonance-stabilized carbanion formed by removal of an alpha-hydrogen from a carbonyl compound. Key nucleophile in aldol condensation.

Haloform reaction: The reaction of a methyl ketone (CH3COR) with I2/NaOH to give CHI3 (iodoform, yellow precipitate) and the sodium carboxylate salt (RCOONa).

Iodoform: CHI3, a yellow crystalline solid with characteristic smell. Product of the iodoform/haloform reaction. SMILES: IC(I)I

Ketone: A carbonyl compound with two carbon substituents on the carbonyl carbon (R-CO-R'). Ketones are not easily oxidized and do not give positive Tollens'/Fehling's tests.

Nucleophilic addition: Addition of a nucleophile (electron-rich species, Nu-) to the electrophilic carbonyl carbon. Characteristic reaction of aldehydes and ketones (contrasts with electrophilic addition of alkenes).

Oxime: Product of reaction between a carbonyl compound and hydroxylamine (NH2OH). Contains the C=NOH group. Used for characterization.

Semicarbazone: Product of reaction between a carbonyl compound and semicarbazide (H2NCONHNH2). Contains C=NNHCONH2. Crystalline solid used for characterization.

Tollens' reagent: Ammoniacal silver nitrate ([Ag(NH3)2]+ in alkaline solution). Selective oxidizing agent for aldehydes; gives silver mirror. Does not react with ketones.

Wolff-Kishner reduction: Reduction of C=O to CH2 using hydrazine (NH2NH2) and strong base (KOH) in ethylene glycol at high temperature. Basic conditions. Completely removes oxygen.