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A Chem Finale pt 1. > Unit 4.6 Amines > Flashcards

Unit 4.6 Amines Flashcards

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1
Q

Define aliphatic amines?

A

Straight chain

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2
Q

Define aromatic amines?

A

Ring structures

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3
Q

Define base?
(2/things)

A
  • Can accept a proton
  • /donate a pair of electrons
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4
Q

Define nucleophile?
(2-way)

A
  • Electron rich species
  • with a lone pair to donate
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5
Q

Define polar?

A

Dipoles with a separation of charge

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6
Q

Define dative bond?
(2-way)

A
  • Electron pair in a covalent bond
  • from only one atom
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7
Q

Define inductive effect?
(2-way)

A
  • Movement of e- density
  • along a σ-bond
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8
Q

Show me acetyl group?
(Whiteboard)

A

R-C(=O)-CH3

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9
Q

Show me acyl chloride [group]?

A

R-C(=O)-Cl

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10
Q

Show me ethanoyl chloride?

A

H3C-C(=O)Cl

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11
Q

Define ethanoylation?
(2-way)

A
  • Adding on (2 carbon) acyl group
  • into compound
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12
Q

Define in situ?
(aren’t ya glad?)

A

In the reaction mixture

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13
Q

Show me diazonium ion?
(Whiteboard…)

A

However, a description:
Benzene connected to +N≡N

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14
Q

Define chromophore?
(3-way)

A
  • An atom/group whose presence is responsible
  • for the colour of a compound
  • e.g. R-N=N-R
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15
Q

Describe amines?
(2 things)

A
  • Organic compounds
  • Containing nitrogen derived from ammonia (NH3)
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16
Q

How are amines generally classified?
(2 simple dimples)

A
  • Just like alcohols
  • Primary, secondary, tertiary
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17
Q

Show me the “formula” for primary amine?

A

R-NH2

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18
Q

Show me the “formula” for secondary amine?

A

R-(NH)-R1

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19
Q

Show me the “formula” for tertiary amine?

A

R-NR1R2

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20
Q

Explain how “simple primary amine”, methylamine, is a polar molecule?
H3CNH2
(1 thing + 2-way)

A
  • N atom more e- - neg than H atoms
  • ∴ atom pulls bonded electron pair
  • towards itself creating dipoles
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21
Q

How do amines act as weak bases?
(2-1-way)

A
  • Due to lone pair of electrons
  • , on nitrogen atom,
  • being able to accept a proton
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22
Q

Show how amines are able to accept a proton (weak base), using methylamine, through “eqn”
(Whiteboard)

A

Not rlly eqn, it’s got the features of a mechanism… not actually a mechanism

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23
Q

What determines the strength of the amines?
(1 imp, 2-way + 1)

A
  • Its ability to accept a proton
  • Depending on size of σ-charge
  • …. on amino nitrogen atom
  • AND availability of the nitrogen lone pair
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24
Q

We have methylamine and phenylamine…. compare.
Explain whether methylamine is the stronger base
CH3NH2
(2-way + 1 + 2-way)

A
  • Methyl group will donate e--density
  • … towards the N atom
  • Increases e--density on N
  • Makes it easier to donate the….
  • e--pair (acts as a base)
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25
Q

We have methylamine and phenylamine…. compare.
Explain whether phenylamine is the stronger base
C6H5NH2
(2-way + 1 + 2-way)

A
  • Lone pair of e- on N atom
  • … becomes delocalised into the ring
  • Lowers e--density on N atom
  • Makes it less likely to…
  • act as a base (donates e- pair)
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26
Q

Because amines are bases, what can they therefore react with?

A

Acid, to form salts

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27
Q

Write eqn showing methyl amine being neutralized by hydrochloric acid.
State the product name.

A

CH3NH2 + HCl -> CH3NH4Cl
Methylammonium chloride

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28
Q

Write eqn of reaction between ethylamine and nitric acid.
State the product name.

A

CH3CH2NH2 + HNO3 -> CH3CH2NH3NO3
Ethylammonium nitrate

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29
Q

Write eqn of reaction between methylamine and sulfuric acid.
State the product name.

A

2 CH3NH2 + H2SO4 -> (CH3NH3)2SO4
Methylammonium sulfate

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30
Q

Define “monoprotic” acid
(2 + e.g.)

A
  • Acid that can only donate
  • one proton per molecule
  • e.g. HCl
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31
Q

Define “diprotic” acid
(2 still + e.g.)

A
  • Acid that can only donate
  • two protons per molecule
  • e.g. H2SO4
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32
Q

What are the 2 ways to prepare primary aliphatic amines?

A
  • From halogenoalkanes
  • From nitriles (4.5)
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33
Q

Equation of preparing “primary aliphatic amines” from halogenoalkanes
(Whiteboard)

A

CH3CH2Cl + NH3 -> CH3CH2NH2 + HCl

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34
Q

Word equation of preparing “primary aliphatic amines” from halogenoalkanes.
Stating conditions + reagents?
(Whiteboard…?)

A

Chloroethane + Ammonia dissolved in Etoh -> Ethylamine + Hydrochloric acid

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35
Q

Why must solvent be ethanol?
(Preparing “primary aliphatic amines” from halogenoalkanes)
(2-way + 1-way)

A
  • In water, N lone pair can…
  • accept a proton to form ammonium hydroxide
  • L.P. not available to act as a base
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36
Q

Why is preparing primary aliphatic amines from halogenoalkanes a nucleophilic substitution reaction?
(2-way + 2-way + 2-way)

A
  • Electron rich N atom (lone pair) attacks….
  • the e- deficient C atom
  • C = e- - deficient due to Cl atom…
  • being more e- - negative
  • AND Cl draws bonded e- pair closer…
  • to itself creating a dipole (Cσ+ - Clσ-)
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37
Q

What would happen if u had excess of NH3?
(Preparing “primary aliphatic amines” from halogenoalkanes)
(5-way + 1….)

A
  • Leads to formation of:
  • NH4Cl
  • Secondary amines
  • Tertiary amines
  • Quaternary amines
  • Ethyl further substituted
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38
Q

Equation of preparing primary aliphatic amines from nitriles?
(whiteboard)

A

H3C-C≡N + 4[H] -> H3CCH2NH2

Of course, in displayed form

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39
Q

How is preparing primary aliphatic amines from nitriles possible??

A

Nitriles are reduced to form amines (4.5 booklet…)

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40
Q

Reducing agent of nitriles?

A

LiAlH4
(Lithium aluminium hydride)

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41
Q

What’s an alternate reducing agent for nitriles?
(3-way)

A
  • Hydrogen &…
  • Metal catalyst such as…
  • Platinum/palladium/nickel
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42
Q

What conditions needed for the alternate reducing agent for nitriles?
(2 things)

A
  • Depends on choice of catalyst
  • Higher temp & pressure favoured
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43
Q

Write balanced symbol eqn of formation of propylamine
State conditions and reagents
(Reducing nitriles… alternate)
(Displayed formula pls)

A

H3CCH2C≡N + 2H2 -> H3CCH2CH2NH2

-> = Pt catalyst, (heat)

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44
Q

How is aromatic amines prepared from nitrobenzene?
(4.2 booklet ¬.¬)

A

From the formation of nitrobenzene from benzene

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45
Q

Show me the 3 step equation of the formation of nitrobenzene from benzene
(Aromatic amines from nitrobenzene)
(Whiteboard… well, alternatively)

A

H2SO4 + HNO3 -> H2NO3+ + HSO4-

H2NO3+ -> H2O + NO2+

HSO4- + H2O -> H3O+ + HSO4-

Alternately… :
Step 1 - Forming the electrophile
Step 2 - Electrophilic attack
Step 3 - Regeneration of the catalyst

46
Q

Show me the overall equation of the formation of nitrobenzene from benzene
And state which is the generation of the electrophile.
(Whiteboard)

A

H2SO4 + HNO3 -> HSO4- + NO2+ + H2

NO2+ = generation of the electrophile

47
Q

What is the mechanism name of the formation of nitrobenzene from benzene?

A

Wheland intermediate

48
Q

Show the mechanism of the formation of nitrobenzene from benzene AKA wheland intermediate
(Whiteboard)

A

Alllllll on you

49
Q

What happens to the H+ afterwards
… and a jig
(Wheland intermediate)

A

HSO4- + H+ -> H2SO4

Not shown in the mechanism

50
Q

THEREFORE, write the overall eqn of the nitration of benzene (incl. the conditions)

A

“Benzene” + HNO3 -> “Nitrobenzene” + H2O

-> = H2SO4, < 50°C (below…)

51
Q

Why must rxn be done above 50°C?
(Nitration of benzene)
(2-way)

A
  • If done above 50°C
  • … multiple substitutions are likely to occur
52
Q

AFTER GAINING nitrobenzene, how to actually form an aromatic amine?

A

Must be reduced….

53
Q

Conditions and reagents of the reduction of nitrobenzene?

A

Conditions - reflux
Reagents - Tin, conc HCl

54
Q

Equation of the reduction of nitrobenzene?
(Whiteboard)

A

“Nitrobenzene” -> “Phenylamine” + 2 H2O

-> = A, Sn/HCl conc △, B, NaOH

55
Q

Hear me out, I can do this tmrw since i don’t rlly do anything on a maths day….

A

Yes yes yes

56
Q

What’s the “most commonly asked” acyl chloride in the exam?
(… what.)

A

Ethanoyl chloride

57
Q

Draw ethanoyl chloride and indicate the dipoles present and ig a jig
(Whiteboard)

A

H3CC(=O)Cl

On the edge:
σ+ = C
σ- = O

Shows how this reacts with a primary amine

58
Q

Show the mechanism of ammonia reacting with ethanoyl chloride
(ethanoyl chloride reacting with ethylamine)
(whiteboard)

A

The stage is yours

59
Q

After ammonia (ethylamine) reacts with ethanoyl chloride, a salt may also be formed. How?
(2-way)

A
  • Due to the formation of HCl
  • and the basic properties of ethylamine
60
Q

Write an eqn showing how a salt is formed
(After ethylamine reacts with ethanoyl chloride)

A

HCl + CH3CH2NH2 -> CH3CH2NH3Cl

61
Q

Write overall eqn of ethylamine reacting with ethanoyl chloride

A

2 CH3CH2NH2 + CH3COCl -> CH3CONHCH2CH3 + CH3CH2NH3Cl

62
Q

Word eqn of the overall eqn of ethylamine reacting with ethanoyl chloride

A

Ethylamine + Ethanoyl chloride -> N-ethylethanamide + Ethylammonium chloride

63
Q

The construction of the name “N-ethylethanamide” from CH3CONHCH2CH3

A

CH3CONH = N-ethyl
NHCH2CH3 = ethanamide

Together = N-ethylethanamide

64
Q

Ethylamine reacting with ethanoyl chloride…
State observation, conditions & reagents
(1 thing + 3-way)

A
  • Ethylamine used as conc. solution in water
  • Violent reaction…
  • producing white solid mixture of…
  • N-ethylethanamide and ethylammonium chloride
65
Q

What’s the reaction used to distinguish between 1°, 2° and 3° amines?

A

Reaction of amines with cold nitric(III) acid

66
Q

What does 1° amine produce?
(react w/ cold nitric(III) acid)
(2 things)

A
  • Produces nitrogen gas
  • Clear solution
67
Q

What does 2° amine produce?
(react w/ cold nitric(III) acid)
(2 things)

A
  • Produces insoluble oil
  • Known to be carcinogenic
68
Q

What does 3° produce?
(react w/ cold nitric(III) acid)

A

Produces clear solution of the ammonium salt

69
Q

Which is the correct formula for nitric (III) acid?
HNO3 or HNO2?
(Answer + 2-way reason)

A
  • HNO2
  • Due to the oxidation numbers…
  • Most specifically, the nitrogen ofc
70
Q

What’s the jig with nitric(III) acid (AKA nitrous acid O_o)?
(a thing + 2-way)

A
  • It’s unstable
  • Therefore in a reaction…
  • prepared in situ
71
Q

Explain what it means for nitric(III) acid “prepared in situ”
(1 + (1) things)

A
  • Formed within the reaction
  • (It’s never isolated)
72
Q

Give an eqn of nitric(III) acid “prepared in situ”
(Whiteboard)

A

HCl+ NaNO2 -> HNO2 + NaCl

73
Q

Name and… (name) of NaNO2?

A

Sodium Nitrite
(Sodium nitrate(III) )

74
Q

After nitric (III) acid produced, why is it ‘almost’ impossible for a balanced symbol equation?
(Reaction of aliphatic primary amines with cold nitric(III) acid)
(2-way)

A
  • Variety of reactions can take place…
  • leading to a complex mixture of products
75
Q

Otherwise, a “simple” balanced symbol equation of the reaction of aliphatic primary amines with cold nitric(III) acid
And ig an observation

A

CH3CH2CH2NH2 + HNO2 -> CH3CH2CH2OH + N2 + H2O

Effervescing (N2)

76
Q

Describe the nitrogen gas in the reaction
(Reaction of aliphatic primary amines with cold nitric(III) acid)
(3-way)

A
  • Burst of colourless,
  • odourless
  • nitrogen gas
77
Q

How can the nitrogen gas be used to quantify the reaction?
(Intro + 3-way)

A
  • Knowing vol. of nitrogen gas….
  • Allows determining of the…
  • amount of amine present in solution
  • as gas produced in mole ratio in the eqn
78
Q

Why does a variety of products occur?
(Reaction of aliphatic primary amines with cold nitric(III) acid)
(1 thing + () + 2 things)

A
  • Diazonium ion formed in eqn
  • (N N or N2+
  • Extremely unstable
  • Falls apart to form nitrogen gas & a carbocation
79
Q

What products could be formed?
(Reaction of aliphatic primary amines with cold nitric(III) acid)
(Just know 3 ig)

A
  • Propan-1-ol
  • Propan-2-ol
  • 2° amine
  • Propene
  • Actually, there’s much more
80
Q

Why must u not need to form eqns of this?
(Reaction of aliphatic primary amines with cold nitric(III) acid)

A

Cuz, you’ll only need to state observations

81
Q

N° of steps for the formation of azo dyes?
(3-way technically)
(Aromatic amines with cold nitric (III) acid)

A

…. just 2
- Step 1 = Aromatic amine react w/ cold nitric (III) acid
- Step 2 = Formation of an azo dye is coupling

82
Q

Explain step 1 of the formation of azo dyes
(Aromatic amines with cold nitric (III) acid)
(3-way + 2 things)

A
  • Nitric(III) acid again produced in situ
  • … from sodium nitrite (NaNO2
  • … & excess hcl
  • Product again is diazonium ion
  • But more stable
83
Q

How is the diazonium ion more stable?
(Aromatic amines with cold nitric (III) acid)
(2-way)

A
  • The π-ring system helps stabilise
  • the +Ve nitrogen (-+N≡N)
84
Q

How to further improve stability of the reaction?
(Aromatic amines with cold nitric (III) acid)
(1 thing + 2-way)

A
  • Carried out below 10°C
  • If temp rises above 10°C….
  • diazonium ion will break down
85
Q

Explain step 2 of the formation of azo dyes
(Aromatic amines with cold nitric (III) acid)
(2 things + 2-way)

A
  • Formation of an azo dye is coupling
  • 2 step mechanisms
  • Product absorbs “wavelengths” of light
  • due to conjugate π system
86
Q

What does the azo group generally do in step 2?
(Aromatic amines with cold nitric (III) acid)
(2 things)

A
  • Attach in 4 position
  • If not available, 2 position
87
Q

What observation is there for phenol of step 2?
(Aromatic amines with cold nitric (III) acid)

A

Yellow orange

88
Q

What observations is there for phenyl amine of step 2?
(Aromatic amines with cold nitric (III) acid)

A

Aniline yellow

89
Q

Show the mechanism of “step 1” during the second step
(Aromatic amines with cold nitric (III) acid)
(Whiteboard)

A

Ok no biggie actually

90
Q

Show the mechanism of “step 2” with phenol
(Aromatic amines with cold nitric (III) acid)
(Whiteboard)

A

The little steps

91
Q

Show the mechanism of “step 2” with phenyl amine
(Aromatic amines with cold nitric (III) acid)
(Whiteboard)

A

The planner

92
Q

What to be aware of for the coupling of azo dyes?
(3 points)

A

In general:
- Look at the N’s
- The sharing of N≡N to N=N
- The difference between O and ≡ in benzene

93
Q

But either way, what are azo dyes?

A

Just used as dyes

94
Q

What do azo dyes account for?
Why?
(2 things + a way)

A
  • Approx. 60-70% of all dyes
  • used in food and textile manufacture
  • Due to their bright colour
95
Q

What do azo dyes contain?

A

… azo compounds

96
Q

What do azo compounds have?
(a thing + 2-way)

A
  • Functional group R-N=N-R’
  • In which R and R’ either
  • aromatic or alkyl
97
Q

Which group is called the “azo group”?

A

The N=N group

98
Q

How to tell if the derivative is more stable?
(Azo dyes)

A

Contains two aromatic (R) groups

99
Q

What gives azo compounds their distinctive colour?

A

The N=N group

100
Q

But, what is usually responsible for the colour of an azo compound?

A

The electron system within the group/compound

101
Q

If the electron system is responsible for the colour of an azo compound, what would they be called?

A

Chromophore

102
Q

Define chromophore generally?
(Total apologies bro….)
(3-way)

A
  • A group that absorbs radiation
  • in the visible part (and UV)
  • of the Em spectrum
103
Q

Explain the electron system in azo compounds and how it leads to the variety of different coloured azo dyes

(How many parts are there to this?)

A

5 damn steps:
1) 5 stuff
2) 5 stuff
3) true 5-way
4) true 3-way
5) LIKEWISE

104
Q

Explain the electron system in azo compounds and how it leads to the variety of different coloured azo dyes pt. 1
(3-way & 2-way)

A
  • Colour arises from overlap of pi orbitals
  • in the -N=N bond and
  • the pi electrons in the two benzene rings.
  • Creates an extended pi electron system (conjugated system)
  • … Which absorbs Em radiation
105
Q

Explain the electron system in azo compounds and how it leads to the variety of different coloured azo dyes pt. 2
(3-way + 2-way)

A
  • Chromophore is a region of a molecule
  • , where energy between two molecular orbitals…
  • falls within range of visible spectrum
  • ∴, light that lits chromophore…
  • can be absorbed by exciting an electron
106
Q

Explain the electron system in azo compounds and how it leads to the variety of different coloured azo dyes pt. 3
(5-way…. yikers)

A
  • In conjugated chromophores, the e-
  • … jumps between energy levels that are
  • extended pi orbitales created by
  • alternating single and double bonds
  • in the aromatic systems
107
Q

Explain the electron system in azo compounds and how it leads to the variety of different coloured azo dyes pt. 4
(3-way)

A
  • The chromophore structure will determine the
  • wavelength of light absorbed
  • and the reflected colour is seen
108
Q

Explain the electron system in azo compounds and how it leads to the variety of different coloured azo dyes pt. 5
(3-way)

A
  • The more unsaturated bonds (double)
  • the larger the wavelength
  • e.g. red absorbed so blue reflected
109
Q

That was hefty

A

Bruh

110
Q

Ofc, once you’ve finally finished this, u’d actually have…. at least below 3 days to learn all this

A

GAH!?!?

A Chem Finale pt 1. (9 decks)

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