26 - Compounds containing the carbonyl group Flashcards
What are secondary alcohols oxidised to?
Ketones
Give an example of a reducing agent.
Lithium Alumimium (III) Hydride/LiAlH4
How are primary alcohols oxidised to carboxylic acids?
Reactant, method
Acidified potassium dichromate
Heat under reflux
How is a hydroxynitrile formed?
Mechanism, reactant, condition
Nucleophilic addition
:CN-
dilute acid
What type of mechanism is the reduction of an aldehyde to a primary alcohol?
Nucleophilic addition
Describe a positive Fehling’s test for an aldehyde.
Blue solution forms a brick red precipitate.
Describe and explain the solubility of carboxylic acids in water.
Acids with fewer than about five carbons dissolve in water (H bonds); those with a higher molecular weight are insoluble owing to the larger hydrocarbon portion, which is hydrophobic.
How is an ester named?
Alkyl group followed by carboxylic acid salt
Give 4 uses of esters.
Solvents, plasticisers, perfumes, food flavourings.
What conditions are esters hydrolysed under?
Acidic or alkaline
Define biodiesel.
Biodiesel is a mixture of methyl esters of long-chain carboxylic acids.
How is biodiesel produced?
Biodiesel is produced by reacting vegetable oils with methanol in the presence of a catalyst.
What are vegetable oils and animal fats esters of?
Propane-1,2,3-triol. aka glycerol
What are sodium salts used as?
Soaps
What is an acyl group?
R(C=O)Z
What is an acyl chloride?
R(C=O)Cl
What is an acid anhydride?
R(C=O)O(C=O)R’ looks kind of like a di ketone joined by an O
Are acyl chlorides or acid anhdyrides more reactive?
Acyl chlorides
What can acid anhydrides and acyl chlorides react with in order of reactivity?
- Primary amines
- Ammonia
- Alcohol
- Water
Why is ethanoic anyhydride used over ethanoyl chloride in the production of aspirin?
- Cheaper
- Less corrosive
- Safer (produces ethanoic acid not hydrogen chloride)
- Reacts less readily with water
Why is KCN hazardous?
Toxic
Describe how a crystalline solid is separated and purified.
Filter
Dissolve in minimum volume
Of hot solvent
Cool
Filter using Buchner funnel
Wash with cold solvent and dry
Why is KCN used rather than HCN?
HCN is a weak reducing agent.
Why does an aldehyde undergo nucleophilic addition but an alkene does not? (3)
Nucleophile attracted to C partial positive
Electron rich C=C
Repels nucleophile
