Chapter 28: Further Synthetic Routes

Question 1

What products can benzene react to form?

Answer 1

• Nitrobenzene
• Halobenzene
• Alkylbenzene
• Phenylketone

Question 2

Benzene to nitrobenzene. Reactants, conditions and mechanism if applicable.

Answer 2

• Reactants: concentrated nitric acid and benzene
• Conditions: concentrated sulfuric acid catalyst
• Mechanism: electrophilic substitution
• HNO3 (conc) + H2SO4 (conc) -> NO2+ + HSO4- + H2O
• C6H6 + NO2+ -> C6H5NO2 + H+
• H+ + HSO4- -> H2SO4

Question 3

Benzene to bromobenzene. Reactants, conditions and mechanism if applicable.

Answer 3

• Reactants: bromine and benzene
• Conditions: halogen carrier catalyst
• Mechanism: electrophilic substitution
• Br2 + FeBr3 -> FeBr4- + Br+
• C6H6 + Br+ -> C6H5Br + H+
• H+ + FeBr4- -> FeBr3 + HBr

Question 4

Benzene to alkylbenzene. Reactants, conditions and mechanism if applicable.

Answer 4

• Reactants: haloalkane and benzene
• Conditions: halogen carrier catalyst
• Mechanism: electrophilic substitution
• Benzene + haloalkane -> alkyl benzene + hydrogen halide

Question 5

Benzene to phenylketone. Reactants, conditions and mechanism if applicable.

Answer 5

• Reactants: acyl chloride and benzene
• Conditions: iron (III) chloride/ aluminium chloride
• Mechanism: electrophilic substitution
• Benzene + acyl chloride -> phenylketone + hydrogen chloride

Question 6

What can phenol react to form?

Answer 6

• 2,4,6-tribromophenol
• Nitrophenol
• Metal phenoxide
• Ester

Question 7

Phenol to 2,4,6-tribromophenol. Reactants, conditions and mechanism if applicable. Give 2 extra details.

Answer 7

• Reactants: phenol and bromine water
• Conditions: room temperature, no catalyst
• Mechanism: electrophilic substitution
• C6H5OH + 3Br2 -> 2,4,6-tribromophenol + 3HBr
• Bromine water is decolourised
• A white precipitate (2,4,6-tribromophenol) is formed

Question 8

Phenol to nitrophenol. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 8

• Reactants: phenol and dilute nitric acid
• Conditions: room temperature, no catalyst
• Mechanism: electrophilic substitution
• Phenol + dilute nitric acid -> 2-nitrophenol/ 4-nitrophenol + water
• A mixture of 2-nitrophenol and 4-nitrophenol is formed

Question 9

Phenol to sodium phenoxide. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 9

• Reactants: phenol and sodium hydroxide
• Conditions: room temperature, no catalyst
• Products: sodium phenoxide and water
• Neutralisation

Question 10

Phenol to ester. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 10

• Reactants: phenol and acid anhydride/ acyl chloride
• Conditions: room temperature, no catalyst
• Products: ester and carboxylic acid/ hydrogen chloride
• Carboxylic acids are not reactive enough to esterify phenol

Question 11

What can aldehydes react to form?

Answer 11

• Carboxylic acids
• Primary alcohols
• Hydroxynitriles

Question 12

Aldehyde to carboxylic acid. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 12

• Reactants: aldehyde and [O]
• Conditions: heat under reflux, K2Cr2O7/ H2SO4
• Water is not formed as it was already formed in the step going from an alcohol to an aldehyde

Question 13

Aldehyde to primary alcohol. Reactants, conditions and mechanism if applicable.

Answer 13

• Reactants: aldehyde and 2[H]
• Conditions: NaBH4/ H2O
• Mechanism: nucleophilic addition

Question 14

Aldehyde to hydroxynitrile. Reactants, conditions and mechanism if applicable.

Answer 14

• Reactants: aldehyde and HCN
• Conditions: NaCN/ H2SO4
• Mechanism: nucleophilic addition

Question 15

What can ketones react to form?

Answer 15

• Secondary alcohols
• Hydroxynitriles

Question 16

Ketone to secondary alcohol. Reactants, conditions and mechanism if applicable.

Answer 16

• Reactants: ketone and 2[H]
• Conditions: NaBH4/ H2O
• Mechanism: nucleophilic addition

Question 17

Ketone to hydroxynitrile. Reactants, conditions and mechanism if applicable.

Answer 17

• Reactants: ketone and HCN
• Conditions: NaCN/ H2SO4
• Mechanism: nucleophilic addition

Question 18

What can carboxylic acids react to form?

Answer 18

• Esters
• Acyl chlorides

Question 19

Carboxylic acid to ester. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 19

• Reactants: carboxylic acid and alcohol
• Conditions: H2SO4, heat
• Products: ester and water
• This reaction is esterification

Question 20

Carboxylic acid to acyl chloride. Reactants, conditions and mechanism if applicable.

Answer 20

• Reactants: carboxylic acid and SOCl2 (thionyl chloride)
• Products: acyl chloride, sulfur dioxide and hydrogen chloride
• Conditions: room temperature, no catalyst

Question 21

What can esters react to form?

Answer 21

• Carboxylic acid
• Carboxylate ion/ carboxylate salt

Question 22

Ester to carboxylic acid. Reactants, conditions and mechanism if applicable. Give 2 extra details.

Answer 22

• Reactants: ester and water
• Conditions: heat under reflux, aqueous H2SO4
• Products: carboxylic acid and alcohol
• This reaction is known as hydrolysis
• It is reversible (esterification)

Question 23

Ester to carboxylate ion/ carboxylate salt. Reactants, conditions and mechanism if applicable. Give 2 extra details.

Answer 23

• Reactants: ester and hydroxide ion/ NaOH
• Conditions: heat under reflux (aqueous NaOH if making the carboxylate ion)
• Products: carboxylate ion/ sodium carboxylate and alcohol
• This reaction is known as hydrolysis
• It is irreversible

Question 24

What can acyl chlorides react to form? Which mechanism do acyl chlorides undergo?

Answer 24

• Esters
• Carboxylic acids
• Primary amides
• Secondary amides
• Nucleophilic addition-elimination

Question 25

Acyl chlorides to ester. Reactants and conditions.

Answer 25

- Reactants: acyl chloride and alcohol - Conditions: room temperature, no catalyst - Products: ester and hydrogen chloride

Question 26

Acyl chloride to carboxylic acid. Reactants and conditions.

Answer 26

- Reactants: acyl chloride and water - Conditions: room temperature, no catalyst - Products: carboxylic acid and hydrogen chloride

Question 27

Acyl chloride to primary amide. Reactants and conditions.

Answer 27

- Reactants: acyl chloride and excess ammonia - Conditions: room temperature, no catalyst - Products: primary amide and ammonium chloride

Question 28

Acyl chlorides to secondary amide. Reactants and conditions.

Answer 28

- Reactants: acyl chloride and primary amine - Conditions: room temperature, no catalyst - Products: secondary amide and alkyl ammonium chloride

Question 29

What can acid anhydrides react to form?

Answer 29

- Esters - Carboxylic acids - Primary amides - Secondary amides

Question 30

Acid anhydride to ester. Reactants, conditions and mechanism if applicable.

Answer 30

- Reactants: acid anhydride and alcohol - Conditions: room temperature, no catalyst - Products: ester and carboxylic acid

Question 31

What can haloalkanes react to form?

Answer 31

- (Alcohols) - Amines - Nitriles

Question 32

What can primary amines react to form?

Answer 32

- Secondary and tertiary amines - Alkylammonium salts

Question 33

Haloalkane to primary amine. Reactants, conditions and mechanism if applicable.

Answer 33

- Reactants: haloalkane and excess ethanolic ammonia - Conditions: NaOH - Products: primary amine, NaX and H2O - First step: nucleophilic substitution

Question 34

Haloalkane to secondary amine. Reactants, conditions and mechanism if applicable.

Answer 34

- Reactants: haloalkane and primary amine - Conditions: NaOH - Products: secondary amine, NaX and H2O - First step: nucleophilic substitution

Question 35

Haloalkane to tertiary amine. Reactants, conditions and mechanism if applicable.

Answer 35

- Reactants: haloalkane and secondary amine - Conditions: NaOH - Products: tertiary amine, NaX and H2O - First step: nucleophilic substitution

Question 36

Haloalkane to nitrile. Reactants, conditions and mechanism if applicable.

Answer 36

- Reactants: haloalkane and NaCN/ KCN - Conditions: ethanol - Products: nitrile and NaX/ KX - Mechanism: nucleophilic substitution

Question 37

Amine to alkylammonium salt. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 37

- Reactants: amine and acid - Conditions: room temperature, no catalyst - Product: alkylammonium salt - Neutralisation

Question 38

What can nitrobenzene react to form?

Answer 38

- Phenylamine

Question 39

Nitrobenzene to phenylamine. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 39

- Reactants: nitrobenzene + 6[H] - Conditions: Sn and concentrated HCl - Product: phenylamine + 2H2O - Reduction

Question 40

What can amino acids react to form?

Answer 40

- Esters

Question 41

Amino acid to ester. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 41

- Reactants: amino acid and alcohol - Conditions: heat, aqueous H2SO4 - Products: ester and water - Ester contains NH3+ due to acidic conditions

Question 42

What can nitriles react to form?

Answer 42

- Amines - Carboxylic acids

Question 43

Nitrile to amine. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 43

- Reactants: nitrile and hydrogen - Conditions: Ni catalyst - Products: amine - Reduction

Question 44

Nitrile to carboxylic acid. Reactants, conditions and mechanism if applicable. Give 1 extra detail.

Answer 44

- Reactants: nitrile, water and hydrochloric acid - Conditions: heat and dilute HCl - Products: carboxylic acid and ammonium chloride - Acid hydrolysis