Chapter 28 - Organic Synthesis (UNFINISHED)

Question 1

What are the reactions of alkenes?

Answer 1

HALOGENATION (Electrophilic addition)
Alkene + Hydrogen halide → Haloalkane
OR
Alkene + Halogen (e.g. Br2) → Haloalkane

ADDITION
Alkene + H2 → Alkane
Nickel catalyst

HYDRATION
Alkene + H20 → Alcohol
H3PO4 catalyst

Question 2

What are the reactions of alkanes?

Answer 2

RADICAL SUBSTITUTION
Alkane + Halogen → Haloalkane
UV

COMBUSTION
Alkane + Oxygen → Carbon dioxide (complete combustion) OR Carbon monoxide (incomplete combustion) + Water

Question 3

What are the reactions of haloalkanes?

Answer 3

HYDROLYSIS (Nucleophilic substitution)
Haloalkane + NaOH → Alcohol + Halide ion
Halide ion, X + Na+ → NaX

SUBSTITUTION
Haloalkane + NH3 → Salt
Salt + Alkali (aq) (e.g. NaOH) → Primary Amine + NaX + H2O

PREPARATION OF NITRILES (Nucleophilic substitution)
Haloalkane + CN- ion source (e.g. NaCN) → Nitrile + Halide ion
Ethanol solvent

Question 4

What are the reactions of alcohols?

Answer 4

DEHYDRATION
Alcohol → Alkene
Heating under reflux
Acid catalyst (e.g. H2SO4)

SUBSTITUTION
Alcohol + Sodium halide → Haloalkane
conc. H2SO4 catalyst

OXIDATION
Primary alcohol + [O] → Aldehyde (distillation) OR Carboxylic acid (heating under reflux)
Secondary alcohol + [O] → Ketone (reflux)
[O] = K2Cr2O7/H2SO4 oxidising agent

ESTERIFICATION
Alcohol + Carboxylic acid → Ester + Water
H2SO4 catalyst

Question 5

What are the reactions of aldehydes?

Answer 5

OXIDATION
Aldehyde + [O] → Carboxylic acid
Heating under reflux
[O] = K2Cr2O7/H2SO4 oxidising agent

REDUCTION (Nucleophilic addition)
Aldehyde + [H] → Primary Alcohol
[H] = NaBH4

PREPARATION OF HYDROXYNITRILES (Nucleophilic addition)
Aldehyde + NaCN → Hydroxynitrile (H+ provided by H2O)
OR
Aldehyde + HCl → Hydroxynitrile (H+ provided by HCl)

Question 6

What are the reactions of ketones?

Answer 6

REDUCTION (Nucleophilic addition)
Ketone + [H] → Secondary Alcohol
[H] = NaBH4

PREPARATION OF HYDROXYNITRILES (Nucleophilic addition)
Ketone + NaCN → Hydroxynitrile (H+ provided by H2O)
OR
Ketone + HCl → Hydroxynitrile (H+ provided by HCl)

Question 7

What are the reactions of carboxylic acids?

Answer 7

NEUTRALISATION
Same as other weak acids.

ESTERIFICATION
Alcohol + Carboxylic acid → Ester + Water
H2SO4 catalyst

PREPARATION OF ACYL CHLORIDES
Carboxylic acid + SOCl2 → Acyl chloride + SO2 (g) + HCl (g)

Question 8

What are the reactions of esters?

Answer 8

ACID HYDROLYSIS
Ester + Water → Carboxylic acid + Alcohol
H+ catalyst

ALKALINE HYDROLYSIS
Ester + OH- (from an Alkali (aq) (e.g. NaOH)) → Carboxylate ion (RCOO- or RCOONa (if NaOH is used)) + Alcohol

Question 9

What are the reactions of acyl chlorides and acid anhydrides?

Answer 9

Acyl chloride + Alcohol → Aliphatic Ester + HCl

Acyl chloride + Phenol → Aromatic ester + HCl

Acyl chloride + Water → Carboxylic acid + HCl

Acyl chloride + Ammonia → Primary amide + NH4Cl

Acyl chloride + Amine → Secondary amide + CH3NH3Cl

Acid anhydrides react in a similar way to acyl chloride with the parent carboxylic acid as the second product instead of HCl.

Question 10

What are the reactions of nitriles?

Answer 10

REDUCTION
Nitrile + H2 → Amine
Nickel catalyst

HYDROLYSIS
Nitrile + Water + HCl → Carboxylic acid + NH4Cl

Question 11

What are the reactions of benzene?

Answer 11

NITRATION (Electrophilic substitution)
Benzene + HNO3 → Nitrobenzene + Water
H2SO4 catalyst, 50°C

HALOGENATION (Electrophilic substitution)
Benzene + Halogen → Halobenzene + H+
Halogen carrier (catalyst) (e.g. FeBr3 or FeCl3)

ACYLATION
Benzene + Acyl chloride → Aromatic ketone + HCl
Halogen carrier, AlCl3

ALKYLATION
Benzene + Haloalkane → Halobenzene + HCl
Halogen carrier, AlCl3

Question 12

What are the reactions of phenol?

Answer 12

NEUTRALISATION
Phenol + NaOH → Salt (e.g. C6H5ONa) + Water

BROMINATION
Phenol + Bromine (aq) → 2,4,6-tribromophenol + HBr
Room temperature and no catalyst needed as phenol is more reactive than bromine.

NITRATION
Phenol + HNO3 → Nitrophenol + H2O