3.3.14 Organic Synthesis

Question 1

Alkane → Halogenalkane

State the reaction and the conditions

Answer 1

• Free-radical substitution
• X₂, UV light

Question 2

Halogenalkane → Secondary/tertiary amines, their salts and quaternary ammonium salts

State the reaction and the conditions

Answer 2

• Nucleophilic substitution
• Ammonia, heat
• (not primary halogenalkanes)

Question 3

Halogenalkane → Primary Amine

State the reaction and the conditions

Answer 3

• Nucleophilic substitution
• Excess ammonia, heat
• (primary halogenalkanes only)

Question 4

Halogenalkane → Nitrile

State the reaction and the conditions

Answer 4

• Nucleophilic substitution
• KCN_(aq), ethanol, reflux

Question 5

Halogenalkane → Alcohol

State the reaction and the conditions

Answer 5

• Nucleophilic substitution
• Warm, NaOH_(aq), reflux

Question 6

Halogenalkane → Alkene

State the reaction and the conditions

Answer 6

• Elimination
• KOH, ethanol, reflux

Question 7

Nitrile → Primary Amine

State the reaction and the conditions

Answer 7

• Reduction
• LiAlH₄, dry ether, dilute H₂SO₄
• OR hydrogen gas, platinum/nickel catalyst, high temperature and pressure

Question 8

Alkene → Halogenalkane

State the reaction and the conditions

Answer 8

• Electrophilic Addition
• HX, 20°C

Question 9

Alkene → Dibromoalkane

State the reaction and the conditions

Answer 9

• Electrophilic addition
• Br₂, 20°C
• (test for unsaturation)

Question 10

Alkene → Alcohol

State the reaction and the conditions

Answer 10

• Hydrolysis
  
  • H₃PO₄ catalyst, steam, 300°C, 60 atm
• Electrophilic addition
  
  • H₂O, H₂SO₄ catalyst

Question 11

Alcohol → Alkene

State the reaction and the conditions

Answer 11

• Elimination
• conc H₂SO₄, reflux

Question 12

Alcohol → Carboxylic Acid

State the reaction and the conditions

Answer 12

• Oxidation
• K₂Cr₂O₇, H₂SO₄, relfux
• (primary alcohols only)

Question 13

Alcohol → Aldehyde/ketone

State the reaction and the conditions

Answer 13

• Oxidation
• K₂Cr₂O₇, H₂SO₄, heat in distillation apparatus

Question 14

Aldehyde/ketone → Alcohol

State the reaction and the conditions

Answer 14

• Reduction/nucleophilic addition
• NaBH₄ in water with methanol

Question 15

Aldehyde/ketone → Hydroxynitrile

State the reaction and the conditions

Answer 15

• Nucleophilic addition
• KCN_(aq), H₂SO₄, 20°C

Question 16

Carboxylic Acid → Ester

State the reaction and the conditions

Answer 16

• Esterification
• alcohol, conc. H₂SO₄ catalyst, heat

Question 17

Ester → Carboxylic Acid

State the reaction and the conditions

Answer 17

• Hydrolysis
• dilute H₂SO₄ catalyst, H₂O, reflux
• OR dilute NaOH(aq), reflux

Question 18

Acyl Chloride / Acid Anhydride → Carboxylic Acid

State the reaction and the conditions

Answer 18

• Nucleophilic Addition-Elimination
• H₂O, 20°C

Question 19

Acyl Chloride / Acid Anhydride → Ester

State the reaction and the conditions

Answer 19

• Nucleophilic Addition-Elimination
• Alcohol, 20°C

Question 20

Acyl Chloride / Acid Anhydride → Primary Amine

State the reaction and the conditions

Answer 20

• Nucleophilic Addition-Elimination
• NH₃, 20°C

Question 21

Acyl Chloride / Acid Anhydride → N-Substituted Amide

State the reaction and the conditions

Answer 21

• Nucleophilic Addition-Elimination
• Amine, 20°C

Question 22

State the reaction and conditions

Answer 22

Question 23

State the reaction and conditions

Answer 23

Question 24

State the reaction and conditions

Answer 24

Question 25

State the conditions

Answer 25

Question 26

State how chemists design synthesis routes to be safe

Answer 26

Chemists try designing routes that use non-hazardous starting materials to limit the potential for accidents and environmental damage

Question 27

State how chemists design synthesis routes to be less wasteful

Answer 27

* Use processes with high atom economies and high percentages yields * Waste can be reduced by designing synthesis routes that have as few steps as possible

Question 28

Why are processes with high atom economies and high percentages yields preferred?

Answer 28

∵ they convert more of starting material into useful products

Question 29

Give an example of how you can reduce both hazards associated with process and amount of waste created by a synthesis route

Answer 29

Avoiding solvents

Question 30

Explain how avoiding solvents reduces hazards

Answer 30

Solvents are often flammable and toxic so pose safety risks

Question 31

Explain how avoiding solvents reduces waste

Answer 31

If solvent has to be disposed after reaction is complete = lots of waste