Aromatics And Amines Flashcards
What is an aliphatic chemical
One that contains straight or branched chain organic substances
What is an aromatic / arene
One that contains benzene
What is molecular formula of benzene
C6H6
Describe the structure of benzene
Six carbon atoms in an hexagonal ring
Each carbon atom bonded to 2 carbons and one hydrogen atoms
Six p orbital electrons delocalised in a ring structure above and below the plane of carbon atoms
Why is benzene a planar molecule
All the c-c bongs are the same and have a length and bond every between a c-c single bond and a carbon carbon double bond
Why is benzene more stable than the theoretical structure by kekule
Enthaply of hydrogenation for benzene is 208 but for structure it’s 360 due to stability from delocalised electrons
Why does benzene undergo electophilic substitution instead of addition
It would break the delocalised system which would disrupt the stability of of benzene, substitution preserved the stability also benzene has high electron density so it can attract electrophiles
Why is benzene toxic
Why does methyl benzene react more readily
It is a carcinogen
The methyl side group releases electrons into the devalued system which makes it more attractive to electrophiles
What is the mechanism for the nitration of benzene called
Electrophilic substitution
What are the reagents for the nitration of benzene and conditions
Concentrated sulfuirc acid
Concentrated nitric acid
50 degrees Celsius
What is the electrophiles in the nitration of benzene
NO2 +
Why is nitration of benzenes and important reaction
Makes useful compounds like explosives and formation of amines which came be used in pharmaceuticals and dye
What is the equation for the formation of the electrophiles in the nitration of benzene
HN03 + H2SO4 ->. NO2+ HSO4- H2O
What is formed in the nitration of benzene
Nitrobenzene
What is formed in friedel crafts acylation
A phenyl ketone
What are the reagents and conditions for friedel crafts acylation
Acyl chloride in presence of anhydrous aluminium chloride catalyst
What is the mechanism for friedel crafts acylation and what is the condition
Electrophilic substitution
Heat under reflux at 50 degrees c
Why are friedel craft acylation reactions important
They introduce a reactive functional group onto benzene rings
How are aromatic amines made by reducing nitrobenzene
Heat under reflux with concentrated hydrochloric acid and tin to form a salt ( c6h5nh3+cl-)
The salt reacts with the alkali naoh to form aromatic amine
What type of reaction forms amines by nitrobenzene
Reduction
Why do primary aliphatic amines act as bronsted Lowry bases
The lone pair of electrons in the nitrogen is readily available for forming a dative covalent bond with a H+ so it accepts a proton
Why are primary aliphatic amines weak bases
Only a low concentration of hydroxide ions is produced
Why are primary aliphatic amines stronger bases then ammonia
The alkyl groups are electron releasing and push electrons towards the nitrogen atom so the lone pair of electrons on nitrogen are more readily available
Why are secondary amines stronger bases than primary amines
They have more alkyl groups substituted into the nitrogen atom in place of H so more electron density is pushed into the N atom so lone pair more readily available
