Functional Groups Flashcards

Alcohol (–OH). Classified as 1°, 2°, or 3° by the number of carbons on the –OH carbon.

R–CHO. Carbonyl (C=O) bonded to at least one hydrogen, always terminal.

A ketone has the carbonyl bonded to two carbon groups (R–CO–R'), making it internal rather than terminal.

The carboxyl group (–COOH): a carbonyl and hydroxyl on the same carbon. General formula R–COOH, typical pKa 2–5.

R–COO–R'. Formed by Fischer esterification: acid-catalyzed condensation of a carboxylic acid and an alcohol, releasing water.

An oxygen bonded to two alkyl or aryl groups (R–O–R'). Relatively unreactive; commonly used as solvents.

By the number of carbon groups on nitrogen: R–NH₂ (1°), R₂NH (2°), R₃N (3°).

R–CO–NR'R''. The nitrogen lone pair delocalizes into the carbonyl, giving the C–N bond partial double-bond character.

A sulfhydryl group (–SH). Thiols have strong odors and can be oxidized to disulfide bonds (R–S–S–R).

–ol (e.g., ethanol, propan-1-ol). The position of –OH is indicated by a locant.

–al (e.g., ethanal, propanal). The aldehyde carbon is always C-1, so no locant is needed.

–one (e.g., propanone, butan-2-one). A locant indicates the carbonyl position.

–oic acid (e.g., ethanoic acid). The carboxyl carbon is always C-1.

R–CO–O–CO–R'. Essentially two carboxylic acids minus water. More reactive than esters but less than acid chlorides toward nucleophilic acyl substitution.

R–COCl. Chloride is an excellent leaving group, making acid chlorides the most reactive carboxylic acid derivatives.

R–C≡N (carbon–nitrogen triple bond). Named with the suffix –nitrile; the nitrile carbon is counted in the parent chain.

A C=C double bond. Alkenes undergo electrophilic addition because the pi electrons act as a nucleophilic site.

A C≡C triple bond (one sigma, two pi). Terminal alkynes are weakly acidic (pKa ~25) due to sp hybridization.

R₂C(OR')₂. Formed by reacting an aldehyde or ketone with two equivalents of alcohol under acid conditions. Stable under basic conditions; used as carbonyl protecting groups.

R₂C(OH)(OR'). Intermediate from adding one equivalent of alcohol to a carbonyl. Generally unstable in open-chain form but stable in cyclic sugars.

R₂C=NR'. Formed by condensation of a primary amine with an aldehyde or ketone, losing water.

Acid chloride > anhydride > ester > amide. Reactivity decreases as the leaving group worsens and heteroatom resonance stabilizes the carbonyl.

–OH bonded to a benzene ring. Phenols (pKa ~10) are more acidic than alcohols (pKa ~16–18) because the phenoxide ion is resonance-stabilized.

A three-membered cyclic ether. Severe ring strain (~60° vs. ideal ~109.5°) makes it far more reactive than typical ethers.

A cyclic ester from intramolecular esterification of a hydroxy acid. Named by ring size: β (4), γ (5), δ (6). Five- and six-membered lactones form readily.