Halogenoalkane + Alcahol

Question 1

What reagents + conditions are needed for alcohols in elimination reactions + what catalyst is required

Answer 1

Produce Alkene + water (H2O)
phosphoric acid + heat

Question 2

How do 1+ 2 alcahols react to form chloroalkanes + what reactants are needed

Answer 2

Alcahol + PCl5 = Chloroalkane + HCl + POCl3
- produces steamy white fumes of HCl
= done in fume cupboard
Nucleophilic sub

Question 3

How do 3 alcahols react to form chloroalkanes + what reactants are needed

Answer 3

Conc HCl + shake
- Nucleophilic sub

Question 4

How does the reactivity change between 1,2 + 3 Halogenoalkanes

Answer 4

Primary < secondary < tertiary
Tertiary is most reactive = alkyl groups disperse positive charge making it more stable = lower activation energy needed to react/ lose the halogen group

Question 5

How does reactivity change of Halogenoalkanes down group 7

Answer 5

Down group 7 = atoms get larger + bond length increases = C-X bond not as strong= less energy needed to break + more reactive

Question 6

How can we measure the reactivity of halogenoalkanes

Answer 6

Hydrolysis of halogenoalkanes with silver Nitrate
- ethanol used as solvent for insoluble HA

HA substitutes halogen for -OH in water
Halide ions released react with silver ions = precipitate
The faster the precipitate forms the higher the reactivity

Question 7

What conditions are needed to form an amine from a Halogenoalkane

Answer 7

Warm excess ethanolic ammonia or NH3 gas

C2H5Cl + NH3 = C2H5NH2 + NH4+

NH3 also acts as base and accepts the eliminated H+ ion

Nucleophilic substitution
Amines have a fishy smell

Question 8

What conditions are needed to form a Nitrile from a Halogenoalkane

Answer 8

Potassium cyanide - KCN
Under reflux

Increases the carbon chain length

Question 9

How do alcohols form bromoalkanes

Answer 9

Alcahol + HBr
H2SO4 - 50% sulphuric acid catalyst + NaBr = used to make HBr in situ

Question 10

How do alcohols form iodoalkanes

Answer 10

Alcahol + PI3
PI3 made from red phosphorous + Iodine
2P + 3I2 = 2PI3

Question 11

What colour are the different sliver halide produced from hydrolysis of Halogenoalkanes with silver nitrate

Answer 11

AgCl = white
AgBr = cream
AgI = yellow

Question 12

What are the conditions of oxidation of alcahols to carboxylic acids

Answer 12

Potassium dichromate
Heat Under reflux
Sulphuric acid

Question 13

What are the conditions for oxidising an alcohol to a ketone

Answer 13

Potassium dichromate
Sulphuric acid
Heated under Reflux or Distillation (but reflux is faster)

Question 14

Conditions for elimination reaction of halogenoalkanes

Answer 14

Potassium hydroxide - KOH
Ethanolic conditions
Heated under reflux

Forms alkene

Question 15

Conditions for substitution reaction of Halogenoalkanes to alcahols

Answer 15

Potassium hydroxide- KOH
Aqueous conditions
Heat under reflux

Question 16

What is heating under reflux used for

Answer 16

Used to heat reaction mixture for a long time without losing any liquid
1- liquid boils + vapours rise
2- vapours are cooled and condense
3- condensate returns to flask

Question 17

What conditions are needed to form a diol from a Alkene

Answer 17

Potassium manganate - KMnO4
= oxidising agent
Acidified by H2SO4

Colour change of purple to colourless
- When manganate ions are reduced they turn colourless