pmt amines Flashcards

1
Q

How do you name amines?

A

-amine or amino-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why are amines so reactive?

A

The lone pair of electrons on the Nitrogen - due to polar N-H bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What shape are amines around the N? Bond angle?

A

Trigonal pyramidal, 107o due to lone pair on N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What kind of intermolecular forces do they have? Why?

A

Hydrogen bonding due to polar N-H bond and lone pair of electrons on N atom.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Do amines have intermolecular forces which are stronger than or weaker than alcohols? Why?

A

Weaker, as N has a lower electronegativity than O → weaker hydrogen bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What state are amines at 298K?

A

Short chains are gases, longer chains are volatile liquids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do they smell of? Why?

A

Fishy smell - rotting fish/flesh releases di- and triamines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which primary amines are soluble in water/alcohols? Why?

A

Up to 4 carbon atoms, as they can hydrogen bond to water molecules. After this, non-polarity of hydrocarbon chain makes them insoluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What kind of solvents are most other amines soluble in?

A

Less or non-polar solvents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Solubility of phenylamine? Why?

A

Not very soluble, due to the non-polarity of the benzene ring - C6H5 cannot form hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can/when do amines act as bases?

A

When they bond with a H+ ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can/when do amines act as nucleophiles?

A

When they bond with an electron-deficient C atom (donate lone pair from N)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the product from the basic action of an amine with water?

A

RNH3+ - ammonium ion, which forms a salt with an anion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Is the product (ammonium ion) soluble in water? Why?

A

Yes, as it is ionic so is attracted to the polar bonds in H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How could you regenerate the soluble amine from the ammonium salt?

A

Add a strong base (NaOH) → removes H+ ions from ammonium ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In order to be the strongest base, what must a particular amine have (out of a set of amines)?

A

Greatest electron density around the N atom, making it a better electron pair donor (attracts protons more)

17
Q

What does positive/negative inductive effect mean?

A

Positive inductive effect = donate electrons, increase density around N
Negative means remove electrons, decrease density around N

18
Q

What effect do alkyl groups have (on electron density and base strength)?

A

Positive inductive effect - increase electron density around N → stronger base

19
Q

What effect do aryl groups have (on electron density and base strength)?

A

Negative inductive effect - decrease electron density around N → weaker base

20
Q

Why are 3o amines never good bases?

A

They are insoluble in water

21
Q

Place these in order of base strength (in general): NH3, 1o amine, 2o amine, phenylamine

A

2o amine > 1o amine > NH3 > phenylamine

22
Q

How can primary amines then form 2o, 3o amines and 4o ammonium ions?

A

Multiple substitutions; primary amine is a nucleophile that attacks the original haloalkane etc

23
Q

What are the problems with this method?

A

Not efficient as low yield of 1o amine due to multiple substitutions

24
Q

How would you maximise the yield of the primary amine?

A

Use excess ammonia

25
Q

What type of mechanism is the reaction of a haloalkane with a cyanide ion?

A

Nucleophilic substitution

26
Q

What conditions does this reaction require? What is the product formed?
of a haloalkane + CN

A

Ethanol as a solvent A nitrile is formed

27
Q

Why is using a nickel/hydrogen catalyst a purer method of synthesising amines?

A

Only the primary amine can be formed

28
Q

In which industries/products are amines used?

A

Dyes, nylon, drugs, synthesis of new molecules

29
Q

What are cationic surfactants (used in fabric/hair conditioners)?

A

Quaternary ammonium salts, with a cation that is charged at one end (N+) and non-polar at the other.

30
Q

How do cationic surfactants work in fabric/hair conditioner?

A

Negative charges on the surface of the fabric/hair are attracted to the cation, removing them from the surface; prevents build-up of static electricity and keeps hair flat and fabric smooth

31
Q

How do cationic surfactants sit when placed in water?

A

Charged end in the water, non-polar end sticking out of the water/at the surface