Amines

Question 1

Draw the structures for a primary secondary and tertiary amine and a quarter any ammonium ion.

Answer 1

Question 2

What is the prefix and suffix for an amine

Answer 2

-Amine
or
amino-

Question 3

Why are amines so reactive

Answer 3

Lone pair of electrons on the nitrogen means that it is readily available to react with other molecules

Question 4

What shape are Amines (include bond angles)

Answer 4

Trigonal Pyramid
107 Due to lone pair on N

Question 5

What kind of intermolecular forces to amines experience?

Answer 5

Hydrogen Bonding due to a very large electronegative difference between N-H & a lone pair causing a permanent dipole so strong it can form attraction between multiple molecules surrounding the mole

&vdw

Question 6

Do amines have a higher or lower melting point then alcohols?

Answer 6

Lower
Nitrogen has a lower electronegativity then oxygen so the electronegative difference is lower so weaker hydrogen bonding occurs between molecules

Question 7

At 298K what state are amines in

Answer 7

Short chains are gasses

Longer chains are volatile liquids

Question 8

What sent do amines have?

Answer 8

Fishy smell - rotting fish

Question 9

Up to what carbon chain are amines are soluble in a polar solvent and why?

Answer 9

Up to 4 carbons
The polar bonds of N-H make the molecule polar enough to be soluble in polar solvents
After 4 the non-polarity of the hydrocarbon chain make the molecule not polar enough to disolve

Question 10

What kind of solvents are amines soluble in?

Answer 10

Non-Polar solvents (large chain length) & polar solvents (small chain length)

Question 11

What is the solubility of Phenylamine

Answer 11

Not very soluble
due to the Non-polarity of the benzene ring not being able to form hydrogen bonds

Question 12

When can amines act as bases

Answer 12

When they form a ammonium ion (bonded with a H+)

Question 13

When do amines act as nucleophiles?

Answer 13

Standard molecule
When there’s an electron-deficient carbon that the amine can donate its electron pair two in close proximity

Question 14

Draw the mechanism for the basic action of an amine with water
What is the product

Answer 14

RNH3+ or NH4+ ammonium ion which can form a salt with an anion

Question 15

Is an ammonium salt soluble in water?

Answer 15

Yes, it’s ionic and can attract to the polar bonds within water molecules

Question 16

How do you form an amine from a soluble ammonium salt

Answer 16

add a strong base (NaOH)
Removes the H+ ions from the ammonium ion

Question 17

For an amine to be a strong base they have to have _________________________

Answer 17

the greatest electron density around the nitrogen atom
Positive inductive effect causes the electron pair to react with other molecules more readily

Question 18

What is the positive inductive effect?

Answer 18

Positive inductive effect —> pushes electrons towards the nitrogen , to increase electron density of the nitrogen so the lone pair reacts more readily with electrophiles

Question 19

What effect to alkyl groups have on the electron density of an amine and its base strength?

Answer 19

Increases the positive inductive effect which increases the electron density around the nitrogen atom
This intern makes the amine a stronger base due to the lone pair being donated more readily

Question 20

What effect to aryl groups (derived from an aromatic ring) have on electron density and bace strength of an amine?

Answer 20

negative inductive effect
-decreases electron density around the Nitrogen
Making it a weaker base as it cannot donate electrons as readily

Question 21

Why are tertiary amines actually not powerful bases?

Answer 21

They are insoluble in water due to there not being any N-H bonds in the molecule so hydrogen bond cannot form

Question 22

Place the following molecules in order of bace strength

NH3, Primary Amine , Secondary Amine , Tertiary amine and phenylamine

Answer 22

Strongest

Secondary
tertiary
primary
ammonia
aromatic amines

Weakest

Question 23

Answer 23

Question 24

How can primary amines then form Secondary Tertiary amines and Quaternary Ammonium ions?

Answer 24

In excess ammonia
Multiple nucleophilic substitutions starting with a haloalkane
Primary amine acts a nucleophile on the haloalkane
Bonds with the now alkane chain and a hydrogen leaves the molecule by joining an ammonia to form an ammonium ion
this forms a secondary amine
This process repeats but with the secondary amine as the nucleophile and tertiary ion until a quaternary i ammonium. ion is formed

Question 25

Why is the addition of of ammonia to a haloalkane a problem forming primary amines

Answer 25

Low yield of primary amines due to it bonding with other haloalkanes

Question 26

how do you form a nitrile from a halo alkane?

Answer 26

Nucleophilic substation of a cyanide ion
Ethanolic and aqueous conditions

Question 27

How do you form an amine from a nitrile

Answer 27

Nucleophilic addition (reduction)
H2 and Nickel catalyst
or
LiAlH4 reducing agent

Question 28

Why is synthesis from nitriles a better method for producing amines then synthesis straight from a haloalkane?

Answer 28

Form directly haloalkanes: Low yield of primary amines due to primary amines reacting further to produce secondary tertiary and quaternary ammonium slats

From nitrates only the primary amine can form so yield is massively higher

Question 29

What conditions are need for nitrobenzene from benzene

Answer 29

Concentration H2SO4 and HNO3 to form the NO2+ ion for electrophilic attack

Question 30

How do you form an ammonium salt from nitrobenzene

What conditions are needed?

Answer 30

Reduction using Tin/HCL —-> forms an ammonium salt
Room temperatures
add NaOH to the intermediate salt to release the phenylsmime

Under Reflux

Question 31

What is the Equation for the reaction of nitrobenzene —> Phenylamine
What the conditions?
Explain the reaction

Answer 31

Nitrobenzene is refluxed with tin catalyst and Hcl
A salt is formed
add NaOH to the salt to release the phenylamine

Question 32

What mechanism is used for forming amides from acyl chlorides and amines

Answer 32

Nucleophilic Addition elimination

Question 33

Draw the mechanism for the reaction of etanoyl chloride with ethanamide

Answer 33

Question 34

Which industries/ products are amines used?

Answer 34

Dyes, Nylon, Drugs, Synthesis of new molecules

Question 35

What are cationic surfactants

Answer 35

Quaternary ammonium slats with a cation that is charged at one end, and non-polar at the other end

Question 36

How to cationic surfactants work in conditioners

Answer 36

Negative charges on the surface of the hair or fabric are attracted to the cation
This removes the negative charge from the surface and prevents static electricity build up to keep there fabric flat and smooth

Question 37

How do cationic surfactants sit when placed in water

Answer 37

Charged end in the water and the non polar end repelled (out of the water)

Question 38

Why is KCN used rather HCN in the production of a hydroxy nitrile

Answer 38

1) HCN is a gas which is hard to store
2) Reacts to produce dangerous byproducts

Question 39

The strength of an amines basic action depends on what?

Answer 39

The availability of the lone pair being donated on the nitrogen atom

Question 40

1,6 Diaminohexane is made from 1,6dibromohexane

Name the Reagents, conditions, and Give an equation for the reaction.

Answer 40

Excess Ammonia

Ethanoic, Heat within Sealed Container

Question 41

Name the reducing against used to reduce nitriles into amines.

Answer 41

H2 with Nickel Catalyst