AS Mechanisms

Question 1

Halogenoalkane + hydroxide ions (aq)
RX + OH^-

Answer 1

Mechanism: Nucleophilic substitution
Product: alcohol and halide

Question 2

Halogenoalkane + cyanide ions
RX + CN^-

Answer 2

Reactant: KCN or HCN (ethanolic)
Chain lengthens by 1 C
Mechanism: Nucleophilic Substitution
Product: nitrile and halogen ion (halide)

Question 3

Halogenoalkane + ammonia
RX + NH3

Answer 3

Mechanism: Nucleophilic Substitution
Products: amine and ammonium ion (NH4X)
Conditions: sealed copper tube, excess ammonia
Reactant: warm conc. ethanolic ammonia
Ammonia acts as a Nucleophile and then a base

Question 4

Halogenoalkane + hydroxide ions (ethanolic)
RX + OH^-

Answer 4

Product: alkene + halide (e.g potassium bromide ) + water
Reactant: NaOH or KOH
Mechanism: Elimination
Conditions: ethanolic
Hydroxide ion acts as a base as it accepts a proton

Question 5

Alkenes + bromine (halogen)
R1=R2 + X2

Answer 5

Product: dibromoalkane
Reactant: Br2
Mechanism: Electrophilic Addition
Conditions:

Question 6

Alkenes + sulfuric acid
R1=R2 + H2SO4

Answer 6

Product: alkylhydrogensulfate
Reactant: conc. H2SO4
Mechanism: Electrophilic Addition
Conditions: conc. sulfuric acid

Question 7

Name of the intermediate

Answer 7

Carbocation

Question 8

Preference of intermediates

Answer 8

Tertiary>secondary>primary
More stability is created by a tertiary carbocation having more electron donating alkyl groups than a primary carbocation

Question 9

Alkenes + hydrogen bromide
R1=R2 + HX

Answer 9

Product: bromoalkane (Halogenoalkane)
Reactant: HX
Mechanism: Electrophilic Addition
Conditions:

Question 10

Free radical sub of ozone

Answer 10

(UV light) Cl2 —> 2Cl’

Question 11

Alkanes + bromine

Answer 11

Mechanism: Free radical substitution
Conditions: UV light

Question 12

Free radical step 1

Answer 12

Initiation
Zero radicals —> 2 radicals

Question 13

Free radical step 2

Answer 13

Propagation
One radical —> one radical
Reaction 1: react with new radical formed from initiation
Reaction 2: Reaction 1 product with original reactant

Question 14

Alcohols + sulfuric acid or phosphoric acid
R-OH + H2SO4 or H3PO4

Answer 14

Product: Alkenes
Reactant:
Mechanism: Acid catalysed elimination
Conditions:
Catalyst: H2SO2 or H3PO4

Question 15

Alkene + water
R1=R2 + H20

Answer 15

Product: Alcohol
Reactant: H20
Mechanism: ——- acid catalysed addition, hydration
Conditions:
Catalyst: H3PO4

Question 16

Halogenoalkane —> alcohol

Answer 16

Reactant: aqueous hydroxide ions
Mechanism: Nucleophilic substitution
Conditions: Heat under reflux

Question 17

Halogenoalkane —> nitrile

Answer 17

Chain length +1
Reactant: cyanide ion (alcoholic)
Mechanism: Nucleophilic substitution
Conditions: heat under reflux

Question 18

Halogenoalkane —> amine

Answer 18

Reactant: Ammonia (alcoholic)
Mechanism: Nucleophilic substitution
Conditions: heat under pressure (sealed copper tube)

Question 19

Halogenoalkane —> alkene

Answer 19

Reactant: ethanolic hydroxide ions
Mechanism: elimination
Conditions: heat under reflux

Question 20

Alkene —> dihaloalkane

Answer 20

Reactant: X2
Mechanism: Electrophilic addition
Condition: room temp

Question 21

Alkene —> Haloalkane

Answer 21

Reactant: HX
Mechanism: Electrophilic Addition
Conditions: room temp

Question 22

Alkene —> alkylhydrogensulfate

Answer 22

Reactant: conc. sulfuric acid
Mechanism: Electrophilic Addition
Catalyst: conc. sulfuric acid
Conditions: conc. sulfuric acid

Question 23

Alcohols —> Alkenes

Answer 23

Reactants:
Catalysts: conc. H2SO4 or H3PO4
Mechanism: elimination
Conditions:

Question 24

Alkenes —> alcohols

Answer 24

Reactants: H2O + H3PO4
Catalysts: H3PO4
Mechanism: Hydration or acid catalysed Electrophilic addition
Conditions: 70 atm 300 degrees catalyst

Question 25

Alkene —> Halogenoalkane

Answer 25

Reactant: X2 Mechanism: Free Radical Substitution Conditions: UV light

Question 26

Alkene —> polymer / poly(alkene)

Answer 26

Reactant: Ziegler-Natta Mechanism: Addition Polymerisation Catalyst: Ziegler-Natta catalyst Conditions: High pressure

Question 27

Primary alcohol —> aldehyde

Answer 27

Reactant: conc sulfuric acid and potassium dichromate Mechanism: Partial Oxidation Conditions: heat and distill Catalyst: conc H2SO4 + K2CR2O7

Question 28

Secondary alcohol —> ketone

Answer 28

Reactant: conc sulfuric acid and potassium dichromate Mechanism: Oxidation Conditions: heat under reflux Catalyst: conc H2SO4 + K2CR2O7

Question 29

Aldehyde —> carboxylic acid

Answer 29

Reactant: conc sulfuric acid and potassium dichromate Mechanism: Oxidation Conditions: heat under reflux + excess oxidising agent Catalyst: conc H2SO4 + K2CR2O7

Question 30

alkylhydrogensulfate --> alcohol

Answer 30

Product: alcohol + sulfuric acid reformed Reactant: water Mechanism: Hydrolysis (nucleophilic substitution) Conditions: warm/heat

Question 31

Heterolytic fission example

Answer 31

In Nucleophilic substitution the covalent bond between the carbon atom and the halogen atom breaks. This is heterolytic fission as both electrons move onto the halogen