Organic Chem: Reactions

Question 1

Alkane: Combustion

Answer 1

1.1) Combustion (Oxidation):
- Exothermic in nature, occurs in excess O2.
Gen: Alkane + Oxygen —> CO2 + H20

CH4 + 2(O2) —> CO2 + 2(H2O)

Question 2

Alkene: Hydrogenation

Answer 2

1.1) Hydrogenation (Addition Reaction)
Gen: Alkene + H2 —> Alkane
- Dissolved in organic solvent with Ni, Pt or Pd catalyst
in H2 atmosphere

Question 3

Markovnikov’s Rule

Answer 3

The halide will attach to the carbon that has the most attached carbons (e.g. the 2nd carbon in propene will receive the halide during hydrohalogenation). The hydrogen will go to the other carbon.

Question 4

Zaitsev’s Rule of Elimination

Answer 4

The highest bond number gets preference when the products are created.

Question 5

Alkane: Halogenation

Answer 5

1.2) Halogenation (Substitution Reaction)
Gen: Alkane + Halogen —> Haloalkane + Hydrogen halide

CH4 + Cl2 —> CH3Cl + HCl

• (Needs energy (Δ) + hf in reaction)

Question 6

Alkane: Elimination

Answer 6

1. 3) Cracking (Elimination Reaction)
   - Used to break large alkanes down into smaller products
   - Thermal: High temp + pressure, no catalyst
   - Catalytic: Low temp + pressure, catalyst

Gen: Large alkane —> smaller alkene + 2nd product

C2H6 —> C2H4 + H2

• Catalyst can be Pt.
• (One product is given, you must draw the other)

Question 7

Alkene: Halogenation

Answer 7

1.2) Halogenation (Addition Reaction)
Gen: Alkene + Halogen —> Haloalkane

Ethene + Chlorine gas —> 1,2-dichloroethane

Question 8

Alkene: Hydrohalogenation

Answer 8

1.3) Hydrohalogenation (Addition Reaction)
- No water present
- MKV rule applies
Gen: Alkene + Hydrogen Halide —> Haloalkane

Ethene + Hydrogen chloride —> 1-chloroethane

Question 9

Alkene: Hydration

Answer 9

1.4) Hydration (Addition Reaction)
- Steam and suitable catalyst e.g. H3PO4
- MKV rule applies
Gen: Alkene + Water —> Alcohol

Propene + water —> propan-2-ol

Question 10

Alkyne: Combustion

Answer 10

1.1) Combustion/Oxidation (Oxidation Reaction)
Gen: Alkyne + O2 —> H2O + CO2 + Energy

Ethyne + Oxygen Gas —> Carbon Dioxide + Water

Question 11

Alkyne: Hydrogenation

Answer 11

1.2) Hydrogenation (Addition Reaction)

Gen: Alkyne + H2 —> Alkene (Lindlar, half reaction)

Ethyne + H2 —> Ethene

               OR

Gen: Alkyne + H2 —> Alkane (Pt, Pd or Ni, full reaction)

Ethyne + 2(H2) —> Ethane

Question 12

Alkyne: Halogenation

Answer 12

1.3) Halogenation (Addition Reaction)

Gen: Alkyne + Halogen —> Haloalkene —> Haloalkane

Ethyne + Chlorine —> 1,2-dichloroethene

1,2-dichloroethene + Bromine —> 1,2-dibromo-1,2-dichloroethane

Question 13

Alkyne: Hydrohalogenation

Answer 13

1. 4) Hydrohalogenation (Addition Reaction)
   - MKV rule applies

Gen: Alkyne + Hydrogen halide —> Haloalkene —> Haloalkane

But-1-yne + Hydrogen bromide —> 2-bromobut-1-ene

2-bromobut-1-ene + Hydrogen bromide —> 2,2-dibromobutane

Question 14

Haloalkane: Diluted Strong Base

Answer 14

1. 1) Diluted Strong Base (Substitution Reaction)
   - Heat reflux in dilute alkali solution

Gen: Haloalkane + Base —> Alcohol + Metal halide

1-bromoethane + sodium hydroxide —> ethan-1-ol + sodium bromide

• first mixed in alcohol then mixed in diluted base

Question 15

Haloalkane: Hydrolysis

Answer 15

1. 2) Hydrolysis (Substitution Reaction)
   - Must first be mixed in alcohol

Gen: Haloalkane + Water —> Alcohol + Hydrogen halide

1-bromoethane + Water —> ethan-1-ol + hydrogen bromide

Question 16

Haloalkane: Ammonia Reaction

Answer 16

1.3) Reaction with Ammonia (Substitution Reaction)

Gen: Haloalkane + Ammonia —> Amine + Hydrogen halide

1-chloromethane + ammonia —> methylamine + hydrogen chloride

Question 17

Haloalkane: Regular Strong Base

Answer 17

1.4.) Regular Strong Base (Substitution Reaction)

Gen: Haloalkane + Strong base —> Alkene + Water + Metal Halide

2-bromobutane + sodium hydroxide —> but-2-ene (main) + but-1-ene (by product) + sodium bromide + water

Question 18

Alcohol: Oxidation

Answer 18

1. 1) Primary (Oxidation Reaction)
   - Acidified potassium dichromate/permanganate) (H+, K2Cr2O7)

Gen: Alcohol —> Aldehyde —> Carboxylic Acid

Propan-1-ol —> propanal —> propanoic acid

1. 2) Secondary
   - Same conditions as Primary

Gen: Alcohol —> Ketone

Propan-1-ol —> Propanone

Question 19

Alcohol: Substitution (Dehydrolysis)

Answer 19

2) Substitution Reaction

Gen: Alcohol + Anhydrous hydrogen halide —> haloalkane + water

propan-1-ol + hydrogen bromide —> 1-bromopropane + water

Question 20

Alcohol: Dehydration

Answer 20

3) Dehydration (Elimination)
- H2SO4 + heat catalyst
- Zaitsev’s Rule

Gen: Alcohol —> Alkene + Water

butan-1-ol —> but-2-ene (main) + but-1-ene (by product) + Water

Question 21

Carboxylic Acid: Esterification

Answer 21

1) Esterification (Addition)
- Reaction with alcohol, H2SO4 + heat catalyst needed

Gen: Alcohol + Carboxylic Acid —> Ester + Water

methanol + propanoic acid —> methyl propanoate + water