Alcohols and Phenol Flashcards
Formation of 1° and 2° alcohols from halogenoalkanes
Mechanism, Reagents and Conditions
*Nucleophilic Substitution
> Reflux
> AQUEOUS sodium (or potassium) hydroxide
> Halogenoalkane
Formation of 1° and 2° alcohols by reduction of an aldehyde or ketone
(Reagents and Conditions)
> Sodium tetrahydridoborate (III) [NaBH4] dissolved in water
OR
Lithium tetrahydridoaluminate (III) [LiAlH4] dissolved in ethoxyethane
Formation of an alkene from halogenoalkanes
Type of reaction, Reagents and Conditions
*Elimination reaction
> Alcoholic sodium hydroxide
Production of an ester from an alcohol and an acyl chloride
Co-product, reagents and conditions
+ HCl gas
> Carried out in a fume cupboard
Production of an ester from an alcohol and a carboxylic acid
Reagents and Conditions
> Conc. sulphuric acid catalyst
Reflux
Neutralisation using sodium hydrogencarbonate
Dehydration of alcohols
Product, reagents and conditions
= Alkene
> Warm and pass alcohol vapour over aluminium oxide or pieces of broken pot
OR
> Warm the alcohol with an excess of concentrated sulphuric or phosphoric acid
The oxidation of 1° and 2° alcohols
Product, reagents and conditions
1° = Aldehyde (heat and distill off) or Carboxylic acid (reflux) 2° = Ketone, cannot be further oxidised > Acidified potassium dichromate (VI) K2Cr2O7/H+ Colour change is orange to green, for aldehyde, acid or ketone > Acidified potassium manganate (VII) KMnO4/H+ Colour change is purple to colourless
Test for Phenol
Reagents and conditions, and +ve result
> Iron (III) Chloride
+ve A purple solution is seen
Explain the acidity of phenol
Phenols are acidic in aqueous solution because the presence of the benzene ring tends to weaken the O-H bond causing phenol to lose a proton.
The phenoxide ion is more stable than expected because the negative charge tends to spread around the ring.
Why is phenol more susceptible to electrophilic substitution?
The presence of the OH group bonded directly to the ring increase its electron density, as a result phenol is much more reactive than benzene.
Phenol + Aqueous bromine water
Product and observation
= 2,4,6-tribromophenol
~ Decolourisation of bromine water
~ White precipitate
Describe the acidity of aliphatic alcohols
Aliphatic alcohols are not very acidic.
The alcoxide ion is not stabilised by delocalisation; the alkyl groups are electron donating increasing the negative charge on the oxygen.
Reaction of phenol with an acyl chloride
Product, mechanism, reagents and conditions
= Phenyl ester + HCl
* Electrophilic substitution
> Aqueous alkaline solution to neutralise HCl
Reaction of an alcohol with HCl
Product, reagents and conditions
= Chloroalkane + Water
> Shake at room temperature
Reaction of an alcohol with HBr
Product, reagents and conditions
= Bromoalkane + Water
> Conc. sulphuric acid
> Distill by warming
> Potassium/Sodium Bromide
