Summary 6 & 7: Reagents and Distinguishing Tests (Video Notes)

Vocabulary flashcards covering reagents, oxidation/elimination/substitution/addition reactions, and distinguishing tests from the notes.

Permanganate oxidation of alkenes to diols

Alkenes react with MnO4−/H+ to form vicinal diols; the purple color of MnO4− disappears as oxidation occurs.

Oxidation of primary alcohols to carboxylic acids (Cr2O7^2−/H+)

Primary alcohols are oxidized to carboxylic acids using dichromate in acidic solution; secondary alcohols oxidize to ketones.

Oxidation of alcohols to carboxylic acids (MnO4−/H+)

Alcohols (especially primaries) are oxidized to carboxylic acids with permanganate in acidic media; secondary alcohols yield ketones.

Dehydration (elimination) of alcohols to alkenes

Concentrated H2SO4 removes water from alcohols to form alkenes.

Dehydrohalogenation of haloalkanes to alkenes

Alcoholic KOH eliminates HCl from haloalkanes to give alkenes.

Halogenation of alkanes to haloalkanes

Br2 or Cl2 adds to alkanes via free-radical substitution under light to form haloalkanes.

Haloalkane to alcohol (SN2/SN1)

Haloalkanes react with KOH(aq) to produce alcohols via nucleophilic substitution.

Haloalkane to amine via ammonia

Haloalkanes react with NH3 (in alcohol) to yield amines through nucleophilic substitution.

Alcohol to haloalkane reagents

Alcohols are converted to haloalkanes using PCl3, PCl5, SOCl2, PBr3, PBr5, HBr, or Lucas reagent (conc HCl in ZnCl2).

Addition to haloalkanes from alkenes/alkynes

Alkenes or alkynes react with Br2, Cl2, HCl, or HBr to form haloalkanes via electrophilic addition.

Hydration of alkenes/alkynes to alcohols

Water in acid (H2O/H+ or dil. H2SO4) adds across C=C/C≡C bonds to form alcohols.

Br2 test for alkenes vs alkanes (distinguishing test)

Alkenes rapidly decolorize Br2 to form dibromo compounds; alkanes react slowly (often under light) to form haloalkanes.

MnO4−/H+ distinguishing test for alkenes

Alkenes are oxidized by MnO4−/H+ to diols (purple to colorless); alkanes show little or no reaction under the same conditions.

Color changes in alcohol oxidation (Cr2O7^2−/H+)

Cr2O7^2−/H+ oxidizes primary alcohols (orange to green) to carboxylic acids; MnO4−/H+ shows purple to colorless change for oxidation.

Carboxylic acids vs amines (litmus test)

Carboxylic acids are acidic and turn blue litmus red; amines are basic and can turn damp red litmus blue.

Dissociation of carboxylic acids in water

CH3COOH + H2O ⇌ CH3COO− + H3O+; carboxylate formation shows acidity in water.

Amines in water (basicity)

R–CH2–NH2 + H2O ⇌ R–CH2–NH3+ + OH−; amines act as bases in aqueous solution.