6.1 - Isomerism and Carbonyl Compounds Flashcards
What is optical isomerism?
A type of stereoisomerism where the molecule has a chiral carbon atom. This allows the molecule to be arranged differently in space and therefore causes two enantiomers to be produced.
How does an optical isomer change light?
Optical isomers rotate plane polarised light.
One enantiomer rotates light in a clockwise direction, the other in an anti-clockwise direction.
What is a racemic mixture?
A mixture that contains equal quantities of each enantiomer.
How does a racemic mixture affect light?
Racemic mixtures are optically inactive and therefore do not affect light passing through.
How does an aldehyde differ from a ketone?
An aldehyde has a carbonyl (C=O) group on the end of its carbon chain whereas a ketone has a carbonyl group in the middle of its carbon chain.
How does Tollens’ reagent distinguish between an aldehyde and a ketone?
Aldehyde - a silver mirror forms.
Ketone - No visible change.
How does Fehling’s solution distinguish between an aldehyde and a ketone?
Aldehyde - Turns brick-red from blue.
Ketone - No visible change.
What is an aldehyde reduced to?
A primary alcohol.
What is a ketone reduced to?
A secondary alcohol.
What chemical can be used to reduce an aldehyde or a ketone?
Sodium tetrahydridoborate(III) - NaBH4.
What is a hydroxynitrile?
A molecule that contains a hydroxyl group (OH) and a nitrile group (CN).
How are hydroxynitriles produced?
Reacting an aldehyde or ketone with acidified potassium cyanide.
Why can hydroxynitriles produce racemic mixtures.
Double bonds are planar and so nucleophiles can attack from either side of the double bond.
How is an ester produced?
Heating a carboxylic acid with an alcohol in the presence of a strong acid catalyst.
How is an ester named?
Name the alcohol side first (the single bond O) and then name the carboxylic acid side (double bond 0).
What are the two types of hydrolysis for an ester?
Acid hydrolysis and base hydrolysis.
What is produced during the acid hydrolysis of an ester?
A carboxylic acid and an alcohol. It is a reversible reaction.
What is produced during the base hydrolysis of an ester?
A carboxylate ion and an alcohol. It is not a reversible reaction.
How is a fat or oil made?
An esterification reaction between glycerol and fatty acids.
What is the IUPAC name of glycerol?
Propane-1,2,3-triol.
What are the two types of fats?
Saturated and unsaturated fats.
Why do saturated fats have a higher boiling point than unsaturated fats?
Saturated fats can be packed closer together which increases the van der Waals forces between them.
How can a fat/oil be hydrolysed?
Heat with sodium hydroxide.
What does the hydrolysis of a fat produce?
Glycerol and a sodium salt.
What is an acyl chloride?
A molecule with a COCl functional group.
What is the general formula for an acyl chloride?
CnH2n-2OCl.
How is an acyl chloride named?
Similar to a carboxylic acid but they end in -oyl chloride.
What does an acyl chloride make when reacted with cold water?
A carboxylic acid and HCl.
What is made when an acyl chloride is reacted with an alcohol?
An ester and HCl.
What is made when an acyl chloride is reacted with ammonia?
An amide and HCl.
What is made when an acyl chloride is reacted with a primary amine?
An N-substituted amide and HCl.
What is an acid anhydride?
When two identical carboxylic acid molecules are joined together.
How is an acid anhydride made?
Two identical carboxylic acids react to produce an acid anhydride and water.
How is an acid anhydride named?
Take the name of the carboxylic acid used to produce the acid anhydride and take away the acid and add -anhydride.
What is produced when an acid anhydride reacts with water?
Two carboxylic acids.
What is produced when an acid anhydride reacts with an alcohol?
An ester and a carboxylic acid.
What is produced when an acid anhydride reacts with ammonia?
An amide and a carboxylic acid.
What is produced when an acid anhydride reacts with an amine?
An N-substituted amide and a carboxylic acid.
How is aspirin produced?
By reacting salicylic acid with ethanoic anhydride or ethanoyl chloride.
Why is ethanoic anhydride often used over ethanoyl chloride?
It is cheaper.
It is much safer as it doesn’t produce HCl fumes.
