Topic 6 - Organic Chemistry 1 (P2)

Question 1

Write the reaction for the complete combustion of pentane, stating any necessary conditions.

Answer 1

• C5H12 + 8O2 > 5CO2 + 6H2O
• You need an excess of oxygen for complete combustion

Question 2

Write the equation for the free radical substitution of methane reacting with chlorine, stating any necessary conditions.

Answer 2

• UV Light condition
• CH4 + Cl2 > CH3Cl + HCl

Question 3

Write the equation for the ________ substitution of Halogenoalkanes (OH-), stating any necessary conditions.

Answer 3

• Nucleophilic Substitution
• C2H5Br > C2H5OH
• Heat under reflux, aqueous water present

Question 4

How to determine the rate of reaction of halogenoalkanes:

Answer 4

• Strength of Carbon-X bond (C-F bond strongest, slowest rate).

Question 5

How to determine the rate of hydrolysis of halogenoalkanes (with conditions):

Answer 5

• Use aqueous silver nitrate (AgNO3) and time how long it takes to form the following precipitates:
• • Cl = white
• • Br = cream
• • I = yellow
• Carry out the reaction in aqueous conditions, or an elimination reaction can occur.

Question 6

Write the reaction for the nucleophilic substitution of C2H5Br (CN-), state conditions.

Answer 6

• C2H5Br with NaCN/KCN > C2H5CN + NaBr/KBr
• Heat under reflux in ethanolic conditions so an alcohol doesn’t form.

Question 7

Write the reaction for the nucleophilic substitution of bromoethane (NH3), state any conditions.

Answer 7

• C2H5Br + NH3 > C2H5NH2 + HBr
• Heat under reflux in a sealed container (to stop ammonia escaping), ethanolic conditions (no water present).

Question 8

Write the reaction(s) of 2-bromopropane and Potassium Hydroxide, state any conditions.

Answer 8

H H H If CH3CH2OH
H-C-C-C-H + OH- > H H H
H Br H. C=C-C-H (PROPENE)
H H

H H H If H2O
H-C-C-C-H + OH- > H H H
H Br H. H-C-C-C-H (PROPAN-2-OL)
H OH H

Question 9

Hydration of alkenes

Answer 9

Steam with conc H3PO4 catalyst at 300°C

Question 10

Hydrogenation of alkenes

Answer 10

H2 with Ni catalyst

Question 11

Electrophilic addition of an alkene to form a mono-substituted bromoalkane

Answer 11

HBr

Question 12

Electrophilic addition of an alkene to form a di-substituted bromoalkane

Answer 12

Br2

Question 13

Free radical substitution of alkanes

Answer 13

Cl2(g) and UV light

Question 14

Nucleophilic substitution of haloalkane to form alcohol

Answer 14

OH-(aq) heat under reflux

Question 15

Nucleophilic substitution of haloalkane to form amine

Answer 15

Excess ethanolic NH3, heated in a sealed tube

Question 16

Nucleophilic substitution of haloalkane to form nitrile

Answer 16

KCN in ethanol, heat under reflux

Question 17

Partial oxidation of primary alcohol

Answer 17

K2Cr2O7 / H+, heat and distil

Question 18

Full oxidation of primary alcohol

Answer 18

K2Cr2O7 / H+, heat under reflux

Question 19

Oxidation of tertiary alcohols

Answer 19

No reaction

Question 20

Dehydration of alcohols

Answer 20

Al2O3 at 300°C or conc H2SO4 cat at 170°C or heated with conc H3PO4 cat

Question 21

Substitution of the OH group in alcohols for chlorine

Answer 21

PCl3, PCl5 or SOCl2

Question 22

Substitution of the OH group in alcohols for bromine

Answer 22

Warm conc H2SO4 and NaBr or red phosphorus and Br2

Question 23

Substitution of the OH group in alcohols for iodine

Answer 23

Warm conc H3PO4 and NaI or red phosphorus and I2

Question 24

Reagent that will react with both alcohols and carboxylic acids to produce sodium alkoxides and carboxylates

Answer 24

Na

Question 25

Iodoform reaction

Answer 25

I2(aq) / OH-

Question 26

Esterification of alcohols

Answer 26

Carboxylic acid and conc H2SO4 catalyst

Question 27

Oxidative cleavage of alkenes

Answer 27

Hot, acidified, conc KMnO4

Question 28

Oxidative addition of alkenes

Answer 28

Cold, acidified, dilute KMnO4

Question 29

Reagent that will reduce carbonyls and carboxylic acids

Answer 29

LiAlH4 in dry ether

Question 30

Reagent that will only reduce carbonyls and not carboxylic acids

Answer 30

NaBH4 in alkaline aqueous methanol

Question 31

H2(g) with Ni or Pt catalyst

Answer 31

Catalytic hydrogenation of carbonyls

Question 32

Nucleophilic addition of carbonyls to form cyanohydrins

Answer 32

HCN with NaCN catalyst

Question 33

Condensation of carbonyls

Answer 33

2,4-DNPH

Question 34

Elimination of haloalkanes

Answer 34

Ethanolic OH- heat under reflux

Question 35

Reagent that will react with only carboxylic acids to produce sodium carboxylates

Answer 35

NaOH or NaHCO3 or Na2CO3

Question 36

Hydrolysis of nitriles to form carboxylic acids

Answer 36

H2SO4 (aq) and heat under reflux

Question 37

Hydrolysis of nitriles to form sodium carboxylates

Answer 37

NaOH (aq) and heat under reflux

Question 38

Heat under reflux with H2SO4(aq)

Answer 38

Hydrolysis of esters to produce carboxylic acids

Question 39

Heat under reflux with NaOH(aq)

Answer 39

Hydrolysis of esters to produce sodium carboxylates

Question 40

Fehling's reagent (alkaline solution of Cu2+)

Answer 40

Oxidation of aldehydes to form carboxylate ion, which gives a characteristic brick red ppt

Question 41

Tollens' reagent (alkaline solution of Ag+)

Answer 41

Oxidation of aldehydes to form carboxylate ion, which gives a characteristic silver mirror