Chemistry: Organic Synthesis

Test between carboxylic acids and phenols/esters

Add CO₃^2- and observe effervescence in carboxylic acid but not phenol

Test for carbonyl compound

Add excess 2,4-DNPH and observe yellow solid precipiate

Test for aldehyde

Add Tollen’s reagent and observe formation of silver mirror

Method: place boiling tube in beaker of hot water (60 degrees C) for 5-10 mins

Test for alkene

Decolourisation of bromine water, Br₂ (aq) at RTP

Test for acyl chloride

Add H₂O (l) and observe steamy (HCl) fumes (fume cupboard)

Reduction of carbonyls (aldehydes and ketones) to form alcohols

R: NaBH₄ (aq)

C: Warm

Reaction of carbonyls with HCN

R: NaCN and H₂SO₄ (HCN in situ)

C: (aq), fume cupboard as HCN is toxic

Preparation of an ester from carboxylic acid and alcohol

C: conc H₂SO₄ catalyst and heat

Preparation of ester from acid anhydride and alcohol

C: heat under anhydrous conditions

Preparation of ester from acyl chloride and alcohol

C: Under anhydrous conditions

Preparation of acyl chloride from carboxylic acid

Carboxylic acid + SOCl₂ → acyl chloride + sulphur dioxide + HCl (g)

Acid or base catalysed hydrolysis of esters

C: heat under reflux

Test for phenol

Bromine water is decolourised and forms white precipitate

Reaction of phenol and Na₂CO₃

No reaction takes place

Neutralisation reaction of phenol

Phenol + NaOH → sodium phenoxide (salt) + H₂O

Esterification of Phenol

phenol + acyl chloride → ester + HCl

Reaction of phenol and carboxylic acid

No reaction

Hydrogenation (alkene to alkane)

R: Alkene + H₂

C: Nickel catalyst, 150 degrees C

Hydration (alkene to alcohol)

R: H₂O (g)

C: Conc H₃PO₄ (aq), temp >100 degrees C, high pressure

Hydrolysis of haloalkanes (aq alkali)

R: NaOH (aq)/KOH (aq)

C: Heat under reflux

Hydrolysis of haloalkanes (water)

R: AgNO₃ (aq)

C: Ethanol solvent and heat in water bath

Method to test rate of hydrolysis of primary haloalkanes

1) Inclubate haloalkane in water bath at 50 degrees C 2) Mix ethanol and AgNO₃ and also heat at 50 degrees C 3) Mix both test tubes together and heat at 50 4) Measure the time taken for precipitate to form and rate by 1/time

Why is hydrolysis of iodo- faster than bromo- ?

Rate of hydrolysis depends on carbon-halogen bond. C-I bond weaker than C-Br so less energy is needed to break C-I so hydrolysis reaction is faster.

Condensation of alcohol to form alkene

C: Conc H₂SO₄/H₃PO₄, heat under reflux

Substitution of halide ions to form haloalkane from alcohol

R: HBr made in situ (NaBr + H₂SO₄)

C: Heat under reflux

Nitration of benzene

R: conc HNO₃, conc H₂SO₄

C: Heat under reflux (50 degrees C)

Bromination of benzene

R: Br₂ and halogen carrier catalyst (AlCl₃)

Alkylation of benzene (haloalkane)

R: Haloalkane and halogen carrier catalyst

Acylation of benzene

R: Acyl chloride and halogen carrier catalyst

Neutralisation reaction of phenol (phenol as an acid)

R: NaOH (aq)

Nitration of nitrobenzene (3 directing affect)

R: conc HNO₃, conc H₂SO₄

C: heat under reflux at 100 degrees C

Formation of acyl chlorides from carboxylic acids

R: SOCl₂

C: Anhydrous conditions

Formation of ester from acyl chlorides

R: Alcohol

C: Anhydrous

Formation of carboxylic acids from acyl chlorides

R: H₂O

Formation of primary amides (H₂N-C=O) from acyl chlorides

R: x2 Ammonia (forms NH₄Cl)

C: Anhydrous

Formation of secondary amides (O=C-NH-C) from acyl chlorides

R: Primary amine (CH₃NH₂)

C: Anhydrous

Formation of salts from amines

R: Dilute acids (HCl (aq))

Preparation of aliphatic amines from haloalkanes

R+C: Excess ethanolic ammonia

Preparation of aliphatic amines from reduction of nitriles

R: Nitrile (R-C-=N), H₂

C: Nickel catalyst

Production of aromatic amines by reduction

R: Nitroarene (e.g. nitrobenzene), tin(s), conc HCl (aq)

C: Heat under reflux

Amino acid and alkali

Carboxylate group will react to form a salt and water

Esterification of amino acid (COOH and NH₂)

R: Alcohol, conc H₂SO₄ (aq)

C: Heat, acidic conditions

P: Ester and NH₂ protonated to form NH₃⁺

Formation of nitriles from haloalkanes

R: Haloalkane, NaCN/KCN

C: dissolved in ethanol

Acid hydrolysis of nitriles to form carboxylic acids

R: Nitrile and aq acid

C: Heat with dilute aq acid

Acid hydrolysis of polyesters

R: Acid e.g. HCl (aq)

C: Heat

P: carboxylic acid and alcohol

Alkaline hydrolysis of polyesters

R: Alkali e.g. NaOH (aq)

C: Heat

P: dicarboxylate salt and alcohol

Acid hydrolysis of polyamides

R: aq acid

C: heat

P: dicarboxylic acid and ammonium salt of diamine

Alkaline hydrolysis of polyamide

R: aq alkali

C: heat

P: dicarboxylate salt and amine