Aromatic Compounds and Amines

Question 1

Draw the structure of benzene:

Answer 1

See Google.

Question 2

What is the length of the carbon carbon bonds in the benzene ring?

Answer 2

140 pm

Question 3

Describe the delocalised ring of electrons in benzene:

Answer 3

Each carbon atom forms single covalent bond to the club and on each side of it and to one hydrogen. The final unpaired electron on each carbon atom is located in the p-orbital that sticks out above and below the plane of the ring. The p-orbitals on each carbon atom combined to form a ring of delocalised electrons.

Question 4

Why do you Arenes (such as benzene) undergo electrophilic substitution reactions?

Answer 4

The benzene ring is a region of high electron density, so it attracts a lot of files. As the benzene ring’s so stable, it doesn’t under go electrophilic addition reactions, which would destroy the ring of delocalised electrons. Instead, it undergoes electrophilic substitution reactions were one of the hydrogen atoms (or another functional group on the ring) is substituted for the electrophile.

Question 5

Friedel-crafts acylation reactions produce?

Answer 5

Phenylketones

Question 6

In Friedel-Crafts acylation what halogen carrier is used?

Answer 6

AlCl3

Question 7

In Friedel-Crafts Acylation what are the conditions?

Answer 7

The reactants need to be heated under reflux in a non-aqueous (like dry ether).

Question 8

Nitration is used in the manufacture of:

Answer 8

Explosives and dyes.

Question 9

What are the chemicals used in nitration?

Answer 9

Benzene, concentrated nitric and sulfuric acid.

Question 10

Describe the process of nitration:

Answer 10

When you warm benzene with concentrated nitric and sulfuric acid, you will get nitrobenzene. Sulfuric acid acts as a catalyst - it helps to make the nitronium ion, which is the electrophile.

If you only want one NO2 group added, you need to keep the temperature below 55° C above the temperature you get lots of substitution.

Question 11

What are amines organic derivatives of?

Answer 11

Ammonia.

Question 12

Explain how quaternary ammonium salts are used as cationic surfactants:

Answer 12

The new positively charged, they will hang around with any negative ions that are near. The complexus formed are called quaternary ammonium salts.

Quaternary ammonium salts with at least one long hydrocarbon chain are used as cationic surfactants. The hydrocarbon tail will bind to nonpolar substances such as grease, whilst the cationic head will dissolve in water, so they are useful in things like fabric cleaners and hair products.

Question 13

Why is the lone pair of electrons in amines useful?

Answer 13

Amines act as weak bases because they except protons. There is a lone pair of electrons on the nitrogen atom that can from a dative covalent bond with an H+ ion.

The strength of the base depends on how available the nitrogen’s lone pair of electrons is. The more available the lone pair is, the more likely the amine is to accept a proton, the stronger a base it will be. A lone pair of electrons will be more available if it’s electron density is higher.

Question 14

Describe how an aliphatic amine is made from a halogenoalkane?

Answer 14

1) ammonia + halogenoalkane
Ammonia the carbon in the halogenoalkane.

2) —> alkylammonium salt
The halogen is released.

3) alkylammonium salt primary amine + ammonium salt
A second ammonia molecule donate it lone pair of electrons to a hydration, which breaks off from the alkylammonium salt.

Question 15

How are aromatic amines made?

Answer 15

Aromatic amines are made by reducing a nitro compound.

Question 16

How is the aromatic amine produced by reducing a Nitro compound?
Use nitrobenzene as your example.

Answer 16

1) Heat a mixture of a nitro compound, tin and concentrated hydrochloric acid under reflux - this makes of salt. For example, if you use nitrobenzene, the salt formed is C6H5NH3+Cl-
2) Turn the salt into aromatic amine, you need to add an alkali, such as sodium hydroxide solution.
3) Aromatic amines are useful compounds in organic synthesis - they’re used as the starting molecules for lots of dyes and pharmaceuticals.

Question 17

Amides are what type of acids derivatives?

Answer 17

Amides are carboxylic acid derivatives. They contain the functional group -CONH2

The carbonyl group pulls electrons away from the NH2 group, so amides behave differently to amines.