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A-level Chemistry y2 > 13: Organic Nitrogen compounds > Flashcards

13: Organic Nitrogen compounds Flashcards

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1
Q

What is a primary amine

A

Has just one carbon bonded to the amine nitrogen

So contains -NH₂ group

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2
Q

What is a secondary amine

A

Has 2 carbon chains bonded to the amine nitrogen

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3
Q

What is a tertiary amine

A

Has 3 carbon chains bonded to the amine nitrogen so has no H joined to the N atom

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4
Q

How to prepare an aliphatic (Non aromatic) primary amine

A

A haloalkane is heated under pressure with excess ammonia dissolved in ethanol

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5
Q

What feature of NH₃ allows it to act as a nucleophile

A

It has a lone pair on the N

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6
Q

Describe the mechanism of NH₃ reacting with a haloalkane to produce a primary amine

A

Delta positive on the C and delta negative on the halogen

Curley arrow from bond between C and halogen, to the halogen

Curley arrow from lone pair on NH₃ to the C that is bonded to the halogen

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7
Q

What is the initial product of haloalkane + excess ethanolic ammonia

A

The amine is initially produced as a salt

Addition of an alkali then produces the free amine

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8
Q

How to prepare secondary amines

A

Reaction of a haloalkane with excess ethanolic primary amine

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9
Q

How to prepare aromatic primary amines

A

Reduction of a nitroaromatic with tin and hydrochloric acid as the reducing agent

heated under reflux

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10
Q

What are the conditions for reduction of a nitroaromatic to produce an aromatic primary amine

A

Reducing agent is Tin and concentrated hydrochloric acid

Heat under reflux

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11
Q

Why is an aromatic amine initially a salt when produced by reduction of a nitroaromatic

A

Because of the acidic conditions

-NH₂ turns into -NH₃†

The free amine can be formed by addition of alkali

NH₃† + OH¯ → NH₂ + H₂O

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12
Q

What is a Nitrile group

A

C≡N

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13
Q

How to produce primary amines from a nitrile

A

Heat the nitrile with hydrogen in the presence of a nickel catalyst

This is a reduction reaction

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14
Q

What conditions are needed for reduction of a nitrile to produce a primary amine

A

Heat and a nickel catalyst

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15
Q

Why do amines have a considerably higher b.p. than similar sized alkanes

A

Amines can form hydrogen bonds, which require more energy to break

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16
Q

Are all amines soluble in water

A

Smaller amines are very soluble in water

Larger amines are less soluble in water

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17
Q

Why are larger amines like phenylamine less soluble in water than a smaller amine like methylamine

A

The larger the non-polar hydrocarbon part, the less soluble it is. As that section cannot form hydrogen bonds

18
Q

Are primary and secondary amines acidic or basic

A

They are weak bases

19
Q

Explain how amines are basic

A

It can use the lone pair of electrons on the nitrogen to accept a proton (ie to form a dative covalent bond to a hydrogen ion)

20
Q

What does the reaction of amine plus acid produce

A

Salt

eg. C₆H₅NH₂ → C₆H₅NH₃†Cl¯

21
Q

What is an amino acid

A

A compound that contains both an amine group and a carboxylic acid group

22
Q

What is an α-amino acid

A

Contain a primary amine group (-NH₂) and a carboxylic acid group (-COOH) attached to the same carbon atom

23
Q

what kind of isomerism do amino acids have and why

A

Optical isomerism

All common amino acids have a chiral centre (apart from aminoethanoic acid)

24
Q

Why can an amino acid react with both acids and bases

A

Because it contains an acidic group (-COOH) and a basic group (NH₂)

25
Q

What is the general structure of a primary amide

A

Carbon is bonded to R (an organic chain), NH₂ and double bonded to O

26
Q

How to prepare a primary amide

A

The condensation reaction of an acyl chloride with ammonia

27
Q

What does the reaction ethanoyl chloride + ammonia produce

A

ethanamide + ammonium chloride

28
Q

What is the general structure of a secondary amide

A

C is double bonded to oxygen and bonded to R₁ and NH

The NH is also bonded to R₂

R₁ and R₂ are just organic chains

29
Q

How to prepare secondary amides

A

Reaction of acyl chloride and primary amine

30
Q

How to prepare Nitriles using haloalkanes

A

Haloalkane will react with cyanide ions by nucleophilic substitution to produce a nitrile

Conditions: React with sodium cyanide (NaCN), dissolved in ethanol

31
Q

What are the conditions for substitution of haloalkanes by cyanide to produce a nitrile

A

React with sodium cyanide (NaCN), dissolved in ethanol

32
Q

Describe and name the mechanism of haloalkane reacting with cyanide ions to produce a nitrile

A

Nucleophilic substitution

Delta positive on the C that is bonded to the halogen and delta negative on the halogen

Curley arrow from bond between C and halogen, to the halogen

Curley arrow from the lone pair (on :C≡N¯) to the C that is bonded to the halogen

33
Q

What does the addition of HCN to an aldehyde or ketone produce

A

A hydroxynitrile

34
Q

What is a hydroxynitrile

A

Contains -OH and -C≡N

35
Q

What are the conditions for reaction between an aldehyde or ketone with HCN to produce a hydroxynitrile

A

React with sodium cyanide, acidified with sulfuric acid (this mixture generates HCN)

36
Q

Describe and name the mechanism of the reaction between an aldehyde or ketone with HCN to produce a hydroxynitrile

A

Nucleophilic addition

First step:

Delta positive on C that is bonded to the O and a delta negative on the O

Curley arrow from the double bond between C and O to the O

Curley arrow from CN¯ to the C that is bonded to the O

Second step:

Curley arrow from lone pair on :O¯ to a H†

37
Q

Why are reactions to put CN on a molecule important

A

Because they extend the carbon chain

38
Q

What is the product of a nitrile reacting with hydrogen in the presence of a nickel catalyst

A

Primary amine

39
Q

How are nitriles hydrolysed

A

By heating with aqueous acid

40
Q

What does the hydrolysis of a nitrile form

A

A carboxylic acid

A-level Chemistry y2 (20 decks)

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