Module 1 - Rings, Acids, Amines Flashcards
Describe the structure of benzene according to delocalised model
P orbitals overlap above and below the plane creating pi bonds.
All bonds are the same length
Explain how information on the bond lengths in benzene provides support for the delocalised model
X-Ray’s show that all the bonds are the same length (discrediting Kekules structure)
What are aromatic compounds
Compounds that contain a benzene ring
Explains why alkenes will react via addition reactions at room temp but benzene won’t
In alkenes Carbon double bond is a localised high area of high electron density.
Delocalised electrons makes benzene very stable and unwilling to undergo addition reactions which would destroy stability
Explain why electrophiles are attracted to aromatic compounds
Aromatic compounds contain a benzene ring, which is a region of high electron density.
Electrophiles are electron deficient so are attracted to these regions
Give two examples of halogen carriers
AlCl3
Fe
Explain why halogen carriers are needed for benzene to react with bromine
Bromine not strong enough to react with the benzene ring on its own
What gas is evolved when phenol reacts with sodium metal
Hydrogen gas
Explain why phenol will react with bromine water but benzene won’t
Benzene the p orbital electrons are delocalised. This makes benzene very stable so it is unwilling to undergo addition reactions with halogens.
In phenols one lone pair of electrons in oxygen increases electron density of the ring.
This higher electron density means that phenol can polarise bromine and cause a reaction
Give two uses of phenols
Antiseptics/production of polymers/manufacture of resins
What is the difference between an aldehyde and a ketone
Aldehyde have carbonyl group at the end of the carbon chain, ketones have is in the middle
Describe the colour change that would be seen if ethanol was oxidised to ethanal using acidified potassium dichromate
Orange to green
Name a reducing agent which could be used to reduce an aldehyde to a primary alcohol
NaBH4
Name the reaction mechanism that takes place when ketones are reduced to alcohols
Nucleophilic addition
What does Brady’s reagent test for
Carbonyl groups
Describe how you could use Brady’s reagent and melting point data to determine the identity of an unknown compound
carbonyl compounds produces a crystalline compound with different melting points.
Purify crystals
Find their me,ting points and compare it against known melting points
What is tollens’ reagent
A solution of silver nitrate dissolved in aqueous ammonia
Describe what you would observe if a carboxylic acid reacted with magnesium metal
A gas
What two products are produced when an ester is broken down by acid hydrolysis
Carboxylic acid and alcohol
What two products are produced when an ester is broken down by base hydrolysis
Carboxylate ion and alcohol
Give two common uses of esters
Perfumes/flavouring food/adding scents to products
What is n unsaturated fatty acid
Carboxylic acid with a long hydrocarbon chain that contains one or more carbon-carbon double bonds
What two reactants do you need to produce a triester
Glycerol and fatty acids
What is cholesterol
Soft waxy material found in cell membranes and transported in your blood steam
