Organic reactions

Question 1

Conditions to turn primary alcohol into an aldehyde

Answer 1

Distillation and use of oxidising agent like Acidified potassium dichromate (vii)

Question 2

How to turn primary alcohol into a carboxylic acid?

Answer 2

Heat under reflux and add oxidising agent of acidified potassium dichromate (vii)

Question 3

How to turn secondary alcohols into ketones?

Answer 3

Heat under reflux with oxidising agent like acidified potassium dichromate (vii)

Question 4

Colour change for reduction of dichromate (vii) ions?

Answer 4

orange to green

Question 5

Conditions of oxidising for tertiary alcohols?

Answer 5

They do not oxidise under normal conditions

Question 6

How to dehydrate alcohols to alkenes?

Answer 6

Heat under reflux and add concentrated phosphoric acid

Question 7

How to go from alcohols to haloalkanes?

Answer 7

Heat under reflux with concentrated sulphuric acid

Question 8

How to go from alkenes to alcohols?

Answer 8

Steam and phosphoric acid (electrophilic addition)

Question 9

How to go from an alkene to a haloalkane?

Answer 9

Room temp
Hydrogen halides in a gaseous state
(Electrophilic addition)

Question 10

How to go from alkene to an alkane?

Answer 10

Nickel catalyst
423 Kelvin
(Electrophilic addition)

Question 11

How to go from alkane to haloalkane?

Answer 11

UV Light
(Free radical substitution)

Question 12

Conditions of the nitration of Benzene?

Answer 12

Electrophilic substitution
Conc. HNO₃ and Conc. H₂SO₄ catalyst
50°C for mono nitration

Question 13

Conditions of halogenation of benzene?

Answer 13

Electrophilic substitution (Cl ⁺ or Br ⁺ )
Halogen (e.g.Cl₂) + Halogen Carrier catalyst (e.g. AlCl₃/FeCl₃)

Question 14

Benzene reacting with haloalkanes conditions

Answer 14

Electrophilic substitution ( CH₃⁺) = alkylation
Halogen carrier catalyst + reflux +anhydrous conditions
Friedel-Crafts reaction

Question 15

Benzene reacting with acyl chlorides conditions

Answer 15

Electrophilic substitution (CH₃C⁺O) = acylation
Halogen carrier catalyst + reflux + anhydrous conditions
Friedel-Crafts reactions

Question 16

Phenol reacting with Nitric acid conditions

Answer 16

Electrophilic substitution
dilute HNO₃, no catalyst (reacts much more readily than benzene)
forms 2 isomers: 2-nitrophenol and 4-nitrophenol

Question 17

Phenol reacting with bromine conditions

Answer 17

Electrophilic substitution
no catalyst + decolourises orange bromine
product = 2,4,6-tribromophenol =antiseptic

Question 18

Reactions of phenol and NaOH

Answer 18

Neutralisation reaction
Phenol = weak acid: not acidic enough to react with carbonates :(

Question 19

How to go from aldehydes to primary alcohols?

Answer 19

Nucleophilic addition (H⁻ Hydride ions)
Reducing agent = NaBH₄ (supplies hydride ions)
Add water)

Question 20

How to go from a ketone to a secondary alcohol?

Answer 20

Nucleophilic addition (H⁻ hydride ions)
Reducing agent = NaBH₄ (supplies hydride ions)
Then add water)

Question 21

Reactions of carbonyls and hydrogen cyanide (description, benefit)

Answer 21

Nucleophilic addition (:CN⁻⁻⁻)
HCN = weak acid, partially dissociates in water ⟶ CN⁻⁻⁻
CN⁻⁻⁻ attacks δ+ carbon on carbonyl group
Extends carbon chain
H⁺ (from H₂O or HCN) bonds to oxygen = hydroxyl group

Question 22

How to go from carboxylic acid to acyl chloride?

Answer 22

React with SOCl₂ = thionyl chloride
OH group replaced by Cl group

Question 23

How to go from acyl chloride to an ester?

Answer 23

React with an alcohol, faster and easier than by using a carboxylic acid and an alcohol

Question 24

How to go from a carboxylic acid to an ester?

Answer 24

Add alcohol
Heat with acid catalysts (H₂SO₄)
Reversible reaction: separate product as it forms using fractional distillation
N.B Oxygen in ester bonds comes from alcohol

Question 25

How to go from an ester back to a carboxylic acid?

Answer 25

Add water Acid hydrolysis Reflux ester with hot quests acid e.g. HCl, H₂SO₄ (dilute)

Question 26

How to get an alcohol and a salt from an ester?

Answer 26

react with an alkali Base hydrolysis reflux ester with a hot aqueous alkali e.g. NaOH (dilute)

Question 27

How to get phenylamine from nitrobenzene?

Answer 27

Heating under reflux with tin catalysts + conc. HCl if 2 substitutions: 12[H] and 4H₂O !! Must add NaOH (phenyl amine +HCl ⟶ salt :( ) Reduction

Question 28

Amino Acid + Acid ⟶

Answer 28

Amino Acid + Acid ⟶ Salt If pH is lower than isoelectric point, amino acid behaves as a base: amino group reacts NH₂ ⟶ NH₃⁺ = cation

Question 29

Amino Acid + Base ⟶

Answer 29

Amino Acid + Base ⟶ Salt + Water If pH is higher than isoelectric point, amino acid behaves as an acid: COOH group reacts COOH ⟶ COO⁻⁻⁻ = anion

Question 30

Amino acid + Alcohol ⟶

Answer 30

Amino acid + Alcohol ⟶ Ester + water Strong acid catalyst (H₂SO₄)

Question 31

Amino Acid + Amino Acid ⟶

Answer 31

Amino Acid + Amino Acid ⟶ Amide (dipeptide) Condensation reaction: elimination of H₂O Forms a dipeptide = secondary amide

Question 32

Dicarboxylic acid + Diamine ⟶

Answer 32

Dicarboxylic acid + Diamine ⟶ Polyamide + water Condensation polymer (loses H₂O)

Question 33

Dicarboxylic acid + Diol ⟶

Answer 33

Dicarboxylic acid + Diol ⟶ Polyester + water Condensation polymer (loses H₂O)

Question 34

H⁺ Polyamide + 2H₂O ⟶

Answer 34

H⁺ Polyamide + 2H₂O ⟶ Dicarboxylix acid + diamine Polyamide hydrolyses more easily with an acid than a base = acid hydrolysis

Question 35

Polyester + 2NaOH ⟶

Answer 35

Polyester + 2NaOH ⟶ Dicarboxylix acid salt + Diol Polyesters hydrolysis more easily with a base than an acid = base hydrolysis

Question 36

Haloalkane + CN⁻⁻⁻ ⟶

Answer 36

Haloalkane + CN⁻⁻⁻ ⟶ Nitrile + X⁻⁻⁻ Nucleophilic substitution Reflux haloalkane with potassium cyanide in ETHANOL SOLVENT

Question 37

Nitrile + 4[H] ⟶

Answer 37

Nitrile + 4[H] ⟶ Primary amine Reduction (method 1) Use Lithium Aluminium Hydride: LiAlH₄, which is a strong reducing agent, and dilute acid

Question 38

Nitrile + 2H₂ (g) ⟶

Answer 38

Nitrile + 2H₂ (g) ⟶ Primary amine Reduction (method 2 - used in industry) Hydrogen gas, metal catalyst (e.g. Platinum or Nickel) High temp + pressure N.B Nitriles can also be reduced with sodium metal and ethanol !!

Question 39

Nitrile + 2H₂O + HCl ⟶

Answer 39

Nitrile + 2H₂O + HCl ⟶ Carboxylic acid + NH₄Cl Acid hydrolysis reflux nitrile in dilute HCl (with heat)

Question 40

Haber Process

Answer 40

N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g) Forward reaction = exothermic High pressure favours forward reaction BUT low temp decreases yield so compromise @ 450°C High pressure = dangerous & expensive compromise of 200 atm. Finely divided porous iron catalyst

Question 41

Acyl chloride + alcohol =

Answer 41

ester + HCl

Question 42

Acyl chloride + Phenol

Answer 42

ester +HCl

Question 43

Acyl chloride + Water

Answer 43

Carboxylic acid + HCl

Question 44

Acyl chloride + Ammonia/amines

Answer 44

Amide + NH4Cl (ammonia chloride)