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chemistry module 2 > Amines > Flashcards

Amines Flashcards

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1
Q

What is a primary, secondary and tertiary amine? Draw them

A

Primary 1° - one carbon directly bonded to the nitrogen atom

Secondary 2° - two carbons directly bonded to the nitrogen atom

Tertiary 3° - three carbons directly bonded to the nitrogen atom

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2
Q

Why are amines soluble in water?

A

The polar N-H, the N is slightly

-ve and the H is slightly +ve. They form H-bonds with the water molecules, therefore are soluble

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3
Q

Reduction of nitriles

-C (triple bond)N what can reduce nitriles to primary (1°) amines. Give the conditions

A

Tetrahydridoaluminate (lll)
Lithal
LiAlH4

Conditions- refluxes in dry ether

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4
Q

Show a reduction of ethanenitrile stating an appropriate reducing agent

A

1st page of amines notes.

CH3C(triple bond)N + 4[H] —> CH3CH2NH2

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5
Q

Reaction of halogenoalkanes and ammonia.

Describe the conditions and reagents and give an example e.g. bromoethane and ammonia

A

Mixed in ethanolic solution, heated in a sealed tube in the absence of air. Opened in sodium hydroxide solution which converts alkylammonium ion to the amine

CH3CH2Br + NH3 —> CH3CH2NH2 + HBr

1st page of amines notes

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6
Q

Preparation of phenylamine from nitrobenzene.

What are the reducing agents?
Write the eqn for the reaction between nitrobenzene and the reducing agent.
What are the conditions?
Write the eqn where sodium hydroxide liberated the phenylamine

A

Reducing agent - Tin and concentrated HCl

C6H5NO2 +6[H] —> C6H5NH2 + 2H20

Reflux nitrobenzene with tin and concentrated HCl with the addition of sodium hydroxide solution to liberate the amine.

C6H5NH3+Cl- + NaOH —> C6H5NH2 + NaCl + H20

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7
Q

Why can amines act as bases?

Give an example of methylamine and hydrochloric acid

A

They can accept a proton (H+) from an acid therefore acting as a base. The N has a line pair of electrons that forms a coordinate bond with the H+ ion.

CH3NH2 + HCl —>CH3NH3+Cl-

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8
Q

Are amines alkaline or acidic in solution?? Why?

A

Alkaline due to their reaction with water,

CH3NH2 + H2O —> CH3NH3 + OH-

The OH- is the alkaline bit

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9
Q

What does basic strength depend on?

A

Your ability to accept a H+ ion

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10
Q

What does a benzene ring do to the LP on the N atom

A

It delocalises the Lone Pair on the N atom into the delocalised system which stabilises it

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11
Q

What does an alkyl group do to the lone pair on the Nitrogen atom

A

It pushed the electrons towards the N atom which destabilises the lone pair

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12
Q

Put ammonia, 3° amine, phenylamine, 2° amine and 1° amine in order of decreasing basic strength

A 
Tertiary amine 
Secondary amine 
Primary amine 
Ammonia 
Phenylamine
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13
Q

Reactions of amines with ethanoyl chloride

e.g. ethylamine and ethanoyl chloride

A

CH3CH2NH2 + CH3COCl —> CH3CONHCH2CH3 + HCl

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14
Q

Reaction with nitrous acid

What is the formula or nitrous acid?
How is nitrous acid prepared?

A

HNO2

Prepared in situ from sodium nitrite and hydrochloric acid

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15
Q

Reactions with nitrous acid

What are the conditions for phenylamine to react with nitrous acid and what is formed ?

A

Below 5°C and forms the benzene diazonium ion C6H5N2+

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16
Q

Reactions of the benzene diazonium ion.

Above 5°C what does it form when warmed?

Give the reaction of benzene diazonium chloride.

What’s is observed?

A

Reacts with H20 to form phenol

C6H5N2Cl + H2O —> C6H5OH + N2 + HCl

Colourless gas N2

17
Q

Give the formula of an Azo group

A

—N (double bond) N—

18
Q

Give the coupling reactions of the benzene diazonium ion with both phenol and phenylamine.

State the colour of both the precipitates.

Give the name of both products

A

Look on last page of amines notes

19
Q

Why are dyes coloured?

What happens when there’s a bigger Pi delocalised system

A

Dyes are coloured because they have an extended Pi delocalised system that brings the electronic energy levels closer together and so light is absorbed in the visible region of the spectrum.

The larger the Pi delocalised system the more light that will be absorbed

20
Q

Aliphatic amines with nitrous acid

What happens to the diazonium ion and give a reaction e.g. ethyl amine

What is it mixed with?

A

It is not stable at any temperature and breaks down to form the alcohol

CH3CH2NH2 + HNO2 —> CH3CH2OH + N2 + H2O

Mixed with sodium nitrite and hydrochloric acid

21
Q

What are the conditions for benzene diazonium chloride to react with phenol?

A

Warmed

chemistry module 2 (13 decks)

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