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Chemistry A-Level > 6.2 nitrogen compounds > Flashcards

6.2 nitrogen compounds Flashcards

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1
Q

name the shape, bonding and bond angles in an ammonia molecule

A

pyramidal
covalent and hydrogen bonding
107 degrees

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2
Q

what is an amine?

A

amines are compounds derived from ammonia

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3
Q

what is meant by primary, secondary and tertiary amines?

A

primary - 2 hydrogens, 1 organic group attached to N
secondary - 1 hydrogen, 2 organic groups attached to N
tertiary - 3 organic groups attached N

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4
Q

what suffix is used when naming amines?

A

amine

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5
Q

what word comes before the amine suffix when naming amines?

A

the longest group attached to the nitrogen

eg. if a propyl group is the longest group attached to the N, its called propylamine

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6
Q

how do you name the other groups attached to the nitrogen?

A

other groups are names in alphabetical order

eg. EthylMethypropylamine

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7
Q

what do you put at the start of the name of a secondary amine?

A

N - …

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8
Q

what do you put at the start of the name of a tertiary amine?

A

N,N - …

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9
Q

what is a base?

A

substance which accepts protons in aqueous solution

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10
Q

amine + acid = ?

A

alkyl ammonium salt

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11
Q

ethylamine + hydrochloric acid = ?

A

ethylammonium salt

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12
Q

butylamine + nitric acid = ?

A

butylammonium nitrate

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13
Q

amine + water = ?

A

ammonium salt - N forms dative covalent bond with H and forms an ammonium ion

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14
Q

PREPARING ALIPHATIC AMINES: name the 3 ingredients

A

haloalkane
excess ethanolic ammonia
ethanol

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15
Q

PREPARING ALIPHATIC AMINES: what’s the first step?

A
  • nucleophilic substitution between HALOALKANE and AMMONIA

- lone pair on ammonia accepts halogen

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16
Q

PREPARING ALIPHATIC AMINES: what are the conditions for the first step?

A
  • sealed container with ethanol so ammonia doesn’t escape because its very volatile
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17
Q

PREPARING ALIPHATIC AMINES: what’s the second step?

A
  • add excess ammonia to form amine and ammonium salt
  • excess ammonia shifts equilibrium to the right to ensure no more substitution into di/tri/tetra amines and for max yield
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18
Q

PREPARING ALIPHATIC AMINES: give the overall equation for the preparation of ethylamine using bromoethane

A

CH₃CH₂Br + 2NH₃ ⇋ CH₃CH₂NH₂ + NH₄⁺Br⁻

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19
Q

PREPARING AROMATIC AMINES: name the ingredients

A

nitroarene
tin
concentrated HCl
sodium hydroxide - NaOH

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20
Q

PREPARING AROMATIC AMINES: name 3 conditions for the preparation

A
  • reducing agent: mixture of tin and conc HCl –> [H]
  • 100 degrees
  • reflux
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21
Q

what is a nitroarene?

A

a benzene ring with a nitrate group attached (NO₂)

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22
Q

PREPARING AROMATIC AMINES: what happens during the reaction? how many hydrogens are needed?

A

the nitroarene is reduced
6 hydrogens are needed
- 2 replace the O₂ on the nitrate group
- four go to the water 2H₂O

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23
Q

PREPARING AROMATIC AMINES: what is the overall equation for the reaction?

A

nitrobenzene + 6[H] –> phenylamine + 2H₂O

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24
Q

PREPARING AROMATIC AMINES: what is added after 30 mins?

A

NaOH - added to neutralise excess acid

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25
Q

what two groups make up amino acids?

A

the amine group and the carboxyl group

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26
Q

what is an alpha amino acid?

A

simplest amino acid - one carbon in the centre with amine group and carboxyl group either side of it

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27
Q

which word can be used to describe the dual property of an amino acid?

A

AMPHOTERIC - acts as both a base and an acid

28
Q

which is the simplest form of amino acid?

A

glycine

29
Q

what is created when amino acid groups interact with each other? what interaction takes place?

A

a zwitterion is created when the H on the OH in the carboxyl group joins to the lone pair on the amine group

proton goes from carboxyl group to amine group

30
Q

what is a zwitterion?

A

amine group is +ve and carboxyl group is -ve

so no overall charge

31
Q

when do zwitterions form? what is this condition called?

A

at a certain pH depending on the R group

ISOELECTRIC POINT

32
Q

what happens when you lower the pH/more H+ ions to an amino acid at the isoelectric point?

A

becomes POSITIVE
carboxyl group neutralises bc it accepts H+ ions
amine group remains positive
equilibrium shifts to the left towards carboxyl group

33
Q

what happens when you increase pH/more OH- ions to an amino acid at the isoelectric point?

A

becomes NEGATIVE
amine group neutralises - donates H+ to OH- ions
carboxyl group remains negative
equilibrium shifts to the right towards the amine group

34
Q

describe what an alpha amino acid is

A

an amino acid where the -COOH and -NH2 groups are on the same carbon

35
Q

what is a condensation reaction involving amino acids?

A

when amino acids react to form peptides and peptide links

36
Q

how are polypeptides made between two amino acids?

A

water is released from the H of an NH₂ group and the OH from the COOH group form water.

water is released and the two amino acids bonds together

37
Q

which reaction takes place to break the peptide links between amino acids? what conditions are required?

A

HYDROLYSIS takes place.

peptides are hydrolysed in ALKALI or ACIDIC conditions (never only by water)

38
Q

what is an acyl group?

A

R-C=O
|
NR₂

39
Q

what is a primary, secondary and tertiary amide?

A

primary - one carbon attached to the N
secondary - two carbons attached to the N
tertiary - three carbons attached to the N

40
Q

how do you name amides?

A

suffix - amide
root - longest carbon chain
other groups are added as a prefix

41
Q

what is optical isomerism?

A

when two molecules identically arranged in space are non-superimposable images of each other
the can’t be rotated to overlap onto each other

42
Q

what is a chiral molecule?

A

molecules with no plane of symmetry

43
Q

what is a chiral carbon?

A

a carbon atom with for distinct atoms or groups attached

44
Q

chiral molecules exist in different forms called ______.

what are these forms?

A

enantiomers - different enantiomers rotate plane polarised light in opposite directions

45
Q

what’s a racemate? what effect does it have on polarised light?

A

a 50:50 mixture of each enantiomer
a racemic mixture has no effect on polarised light because each enantiomer rotates oppositely and so cancel each other out.

46
Q

what is involved in addition polymerisation?

A

a single monomer that forms a repeat chain

47
Q

which two ways can polyester be formed by condensation polymerisation?

A
  • two monomers: diol (two OH groups) and a dicarboxylic acid (two carboxyl groups)
  • single monomer with both -OH and -COOH groups on it to self polymerise
48
Q

how is a polyester formed from condensation polymerisation?

A

a H from the diol and a OH from the dicarboxylic acid are removed to form water and an ester linkage is formed.
for every 2 monomers, 2 ester linkages are formed.

49
Q

which two ways can polyamides be formed by condensation polymerisation?

A
  • two monomers: diamine (two amine groups) and a dicarboxylic acid
  • a single monger with both an amine and carboxylic acid group on it (eg. alpha amino acid)
50
Q

how is a polyamide formed from condensation polymerisation?

A

H from amine group and OH from carboxylic acid group are removed to form water and an amide link is formed
for every 2 monomers, 2 amide linkages are formed

51
Q

give the structural formula for an ester linkage

A

O-C=O

52
Q

give the structural formula for an amide linkage

A

O=C-NH

53
Q

what is hydrolysis in terms of polymers?

A

breaking down polymers into its monomers

54
Q

how is the slow hydrolysis process of polymers sped up?

A

by using acidic or alkali conditions

55
Q

BASE hydrolysis of polyESTERS: what base is used? what products are obtained?

A

base used: NaOH/H₂O
carboxylate salt and diol formed
carboxyl groups deprotenate and Na+ is added to form salt ( COO⁻⁻Na⁺ )

56
Q

ACID hydrolysis of polyESTERS: what acid is used? what products are obtained?

A

acid used: H⁺/H₂O

diol and dicarboxylic are formed (original monomers)

57
Q

where is the ester linkage broken during hydrolysis?

A

between the C-O bond

O=C-/-O

58
Q

BASE hydrolysis of polyAMIDE: what base is used? what products are obtained?

A

base used: NaOH/H₂O
carboxylate salt and diamine formed
carboxyl groups deprotenate with Na+ (COO⁻⁻Na⁺)

59
Q

ACID hydrolysis of polyAMIDE: what acid is used? what products are obtained?

A 
acid used: H⁺/H₂O
diamie protenates (NH₃⁺) and dicarboxylic acid remains as original monomer
60
Q

what chemical can be used for the synthesis of C-C bonds? what is the functional group?

A

cyanide :C⁻≡N: (negative charge on C)

functional group CN⁻

61
Q

name two reactions/mechanisms in which can cyanide be used to synthesise C-C bonds. how does cyanide act in each reaction?

A

nucleophilic substitution with haloalkane
nucleophilic addition with carbonyl
cyanide acts as a NUCLEOPHILE

62
Q

nucleophilic substitution using cyanide:
describe the mechanism
what are the condition?

A

mechanism:

  • curly arrow from lone pair on C to the δ+ carbon in the carbon-halogen bond.
  • curly arrow from carbon-halogen bond to δ- halogen
  • carbon chain is lengthened by one with a nitrile group on the end + a halogen ion.
    condition: ETHANOL and REFLUX
63
Q

nucleophilic addition using cyanide:
describe the mechanism
what is the product formed?

A
  • curly arrow from lone pair on C to the δ+ carbon in the C=O bond.
  • INTERMEDIATE: curly arrow going from lone pair on :O⁻ in the C-O bond to the δ+ H in the H₂O
  • curly arrow from H-O bond in water to δ- O.
  • hydroxynitrile formed + :C≡N:
64
Q

which two ways can a nitrile group be removed to be more useful?

A
  • reduced to form amines

- hydrolysed to form carboxylic acids

65
Q

industrial method of reducing the nitrile group:

  • give the reducing agent
  • give the conditions and catalyst
  • give the general equation
A

reducing agent: hydrogen reducing agent

condition: high temp and high pressure
catalyst: nickel catalyst

RCN + 2H₂ –> RCH₂NH₂

66
Q

what type of hydrolysis is used to remove the nitrile group?

A

acid hydrolysis

67
Q

hydrolysis of nitrile:

  • give the conditions
  • give the two equations using ethanitrile
A

conditions: reflux with HCl

CH₃CN + 2H₂O + HCl –> CH₃COOH + NH₄Cl
CH₃CN –H⁺–> CH₃COOH

Chemistry A-Level (13 decks)

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