Alcohols
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Describe the properties of the OH group in alcohols
O = high electron density due to it’s high electronegativity and it’s lone pair of electrons O = It’s a Lewis base Low electron density on H -> group is weakly acidic Poor leaving group (but easily protonated to generate an excellent leaving group)
What is an alcohol called when the OH group is removed? 2
An alkoxide anion RO- alkoxides
Describe the properties of an alkoxide anion.
An important base
Describe the acidity of an alcohol 2
Weaker acids than water Only have one ‘acidic’ proton per molecule
What are the two ways alcohols can be prepared
Using an alkene Using an alkyl halide
How can an alcohol be made from an alkene? 3
Addition reaction of an alkene (Hydration) (in the presence of an acid - catalyst) Water molecule is added to the double bond (H to one C and OH to another C) Alcohol is formed
How can an alcohol be made from an alkyl halide? 5
Elimination reaction - Loss of leaving group Alkyl halide loses it’s halo group e.g. F Water molecule attaches to alkane H2O bonded to alkane then loses a hydrogen (deprotonation) to form a OH group Alcohol is formed
Explain how alcohols can act as both an acid and a base
When an alcohol reacts with very strong bases or very strong acidic solutions, it can act as an acid (giving out its H +) or a base (releasing its −OH −) Reacts with strong base - alcohol gives out its H+ Reacts with strong acid - alcohol gives out it’s OH-
What can primary alcohols be oxidised into?
Aldehydes which can be further oxidised into carboxylic acid
What can secondary alcohols be oxidised into?
Ketones - no further oxidation
What can tertiary alcohols be oxidised into?
Can’t be oxidised
Give the reaction mechanism for the oxidation of ethanol to ethanal (primary alcohol)
Ethanol + O –>distillation –> ethanal + H2O Alcohol + O = aldehyde + water
Give the reaction mechanism for the oxidation of ethanol to ethanoic acid
Ethanol + 2O –> reflux–> ethanoic acid + water Alcohol + 2O = carboxylic acid + water