6- Aromatic Compounds and Amines Flashcards
Describe the structure of benzene
Planar cyclic structure- each carbon forms a single covalent bond to two other carbons, and one to an attached hydrogen. The remaining electron sticks out above and below the planar ring, making a ring of delocalised electrons. All bond lengths are the same
When is the prefix “Phenyl” used?
If the benzene ring is attached to an amine, alcohol, ketone or alkene group
How do you number the benzene ring?
From the functional group, clockwise
What is an electrophile?
An electron pair acceptor
What reaction does the benzene ring undergo?
Electrophilic substitution
Write the overall reaction for the nitration of benzene
HNO3 + Benzene (+H2SO4) = C6H5NO2 + H2O
Write the equation for the formation of the nitronium ion
HNO3 + H2SO4 = HSO4- + NO2+ + H2O
What species undergoes electrophilic substitution to make nitrobenzene?
NO2+
Why doesn’t a benzene ring undergo electrophilic addition?
It would destroy the delocalised ring of electrons
What are the uses of nitration reactions?
To make amines, dyes, explosives and pharmaceuticals
What are halogen carriers?
A substance that is used to make an electrophile stronger
What are the conditions for Friedal-Crafts acylation?
AlCl3, reflux in a non-aqueous solvent
What is the full equation for Friedal-crafts acylation?
Acyl group + benzene = Phenylketone + HCl
What halogen carrier is used in Friedal-Crafts acylation?
AlCl3
Write the reaction for making the carbocation used in Friedal-Crafts acylation
RCOCL + AlCl3 = RCO+ + AlCl4-
Describe a cationic surfactant
Compounds that are partially soluble and partially insoluble in water. This means they will help grease and water mix together. Cationic surfactants are made from quaternary salts with one long hydrocarbon chain. The head will dissolve in water, and the tail will dissolve in grease
Why can amines act as bases?
They can accept protons
What does the strength of the ammonium base depend on?
How available the nitrogen’s lone pair of electrons is. They will be more available if the electron density is higher. The more available, the stronger the base
What is the functional group for an amide?
-CONH2
Why do amides behave differently to amines?
The carbonyl group pulls electrons away from the NH2 group
How do you name an amide?
Suffix is always amide and prefix is from the acyl group
How do you get N-substituted amides?
When one of the hydrogens on the nitrogen of an amide has been replaced by an alkyl group
How do you name an N-substituted amide?
N-(alkyl group attached) prefix (acyl group) suffix (amide)
How can amines be made from halogenoalkanes?
Reflux, with ethanolic ammonia
How is an amine formed from a nitrile?
Reduction of the nitrile, LiAlH4 in dry ether followed by a dilute acid, high temperature and a high pressure
Write the equation for the reduction of a nitrile to make an amine
RCN + 4[H] + (LiAlH4 + dilute acid) = RCNH2
Why isn’t the reduction of a nitrile using LiAlH4 used in industry?
LiAlH4 is too expensive
How are amines made from nitriles in industry?
Catalytic hydrogenation
Write the equation for the catalytic hydrogenation of a nitrile to an amine
RCN + 2H2 (+ Ni + high temperature and high pressure = RCNH2
What conditions are needed for the industrial production of amine from nitriles?
Nickle catalyst and a high temperature and a high pressure
What is the name of the mechanism that is used to form N-substituted amides from an acyl chloride and a primary amide?
Nucleophilic addition- elimination
What is a nucleophile?
A lone pair donor
What are the conditions to make an N-substituted amide from an acyl chloride?
an amine, 25 degrees c
How are aromatic amines made?
The reduction of a nitro compound such as nitrobenzene
1) nitrobenzene + tin + conc.HCl heated under reflux
2) Salt product from 1 add an alkali such as NaOH
