13: Organic Nitrogen compounds Flashcards
What is a primary amine
Has just one carbon bonded to the amine nitrogen
So contains -NH₂ group
What is a secondary amine
Has 2 carbon chains bonded to the amine nitrogen
What is a tertiary amine
Has 3 carbon chains bonded to the amine nitrogen so has no H joined to the N atom
How to prepare an aliphatic (Non aromatic) primary amine
A haloalkane is heated under pressure with excess ammonia dissolved in ethanol
What feature of NH₃ allows it to act as a nucleophile
It has a lone pair on the N
Describe the mechanism of NH₃ reacting with a haloalkane to produce a primary amine
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
What is the initial product of haloalkane + excess ethanolic ammonia
The amine is initially produced as a salt
Addition of an alkali then produces the free amine
How to prepare secondary amines
Reaction of a haloalkane with excess ethanolic primary amine
How to prepare aromatic primary amines
Reduction of a nitroaromatic with tin and hydrochloric acid as the reducing agent
heated under reflux
What are the conditions for reduction of a nitroaromatic to produce an aromatic primary amine
Reducing agent is Tin and concentrated hydrochloric acid
Heat under reflux
Why is an aromatic amine initially a salt when produced by reduction of a nitroaromatic
Because of the acidic conditions
-NH₂ turns into -NH₃†
The free amine can be formed by addition of alkali
NH₃† + OH¯ → NH₂ + H₂O
What is a Nitrile group
C≡N
How to produce primary amines from a nitrile
Heat the nitrile with hydrogen in the presence of a nickel catalyst
This is a reduction reaction
What conditions are needed for reduction of a nitrile to produce a primary amine
Heat and a nickel catalyst
Why do amines have a considerably higher b.p. than similar sized alkanes
Amines can form hydrogen bonds, which require more energy to break
Are all amines soluble in water
Smaller amines are very soluble in water
Larger amines are less soluble in water
Why are larger amines like phenylamine less soluble in water than a smaller amine like methylamine
The larger the non-polar hydrocarbon part, the less soluble it is. As that section cannot form hydrogen bonds
Are primary and secondary amines acidic or basic
They are weak bases
Explain how amines are basic
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)
What does the reaction of amine plus acid produce
Salt
eg. C₆H₅NH₂ → C₆H₅NH₃†Cl¯
What is an amino acid
A compound that contains both an amine group and a carboxylic acid group
What is an α-amino acid
Contain a primary amine group (-NH₂) and a carboxylic acid group (-COOH) attached to the same carbon atom
what kind of isomerism do amino acids have and why
Optical isomerism
All common amino acids have a chiral centre (apart from aminoethanoic acid)
Why can an amino acid react with both acids and bases
Because it contains an acidic group (-COOH) and a basic group (NH₂)
What is the general structure of a primary amide
Carbon is bonded to R (an organic chain), NH₂ and double bonded to O
How to prepare a primary amide
The condensation reaction of an acyl chloride with ammonia
What does the reaction ethanoyl chloride + ammonia produce
ethanamide + ammonium chloride
What is the general structure of a secondary amide
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
How to prepare secondary amides
Reaction of acyl chloride and primary amine
How to prepare Nitriles using haloalkanes
Haloalkane will react with cyanide ions by nucleophilic substitution to produce a nitrile
Conditions: React with sodium cyanide (NaCN), dissolved in ethanol
What are the conditions for substitution of haloalkanes by cyanide to produce a nitrile
React with sodium cyanide (NaCN), dissolved in ethanol
Describe and name the mechanism of haloalkane reacting with cyanide ions to produce a nitrile
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
What does the addition of HCN to an aldehyde or ketone produce
A hydroxynitrile
What is a hydroxynitrile
Contains -OH and -C≡N
What are the conditions for reaction between an aldehyde or ketone with HCN to produce a hydroxynitrile
React with sodium cyanide, acidified with sulfuric acid (this mixture generates HCN)
Describe and name the mechanism of the reaction between an aldehyde or ketone with HCN to produce a hydroxynitrile
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†
Why are reactions to put CN on a molecule important
Because they extend the carbon chain
What is the product of a nitrile reacting with hydrogen in the presence of a nickel catalyst
Primary amine
How are nitriles hydrolysed
By heating with aqueous acid
What does the hydrolysis of a nitrile form
A carboxylic acid
