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A Chem Finale pt 1. > Unit 4.5 Carboxylic Acids > Flashcards

Unit 4.5 Carboxylic Acids Flashcards

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1
Q

Weird starting?

A

I suppose

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2
Q

What is the pH of ethanoic acid?

A

3 pH

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3
Q

What is the pH of phenol?

A

5 - 6 pH

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4
Q

What is the pH of water?

A

It should be 7 pH

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5
Q

What is the pH of ethanol?

A

7.3 pH

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6
Q

How is an ethanoate ion created?

A

Ethanoic acid + water

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7
Q

Equation formula of the creation of ethanoate ion

A

CH3COOH + H2O ⇌ CH3COO- + H+/H3O+

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8
Q

How do acids tend to dissociate
(2-way)

A
  • When in water
  • liberating a hydrogen ion
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9
Q

How do u determine the strength of an acid?
(1 additional thing)

A
  • How well they dissociate in H2O
  • The more H+(aq) ions dissociated = strong acid
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10
Q

Explain stabilisation of ethanoate ion?
(3-way)

A
  • More stable than phenoxide ion
  • as negative charge can be delocalised
  • over the 2 equivalent oxygen atoms
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11
Q

Equation of ethanoate ion stabilisation?
(might be asked to draw, so get whiteboard)

A

H3C(=O)O- <-> H3CO-(=O) -> H3CO–O (- in between o’s)

Highly refer to booklet

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12
Q

Explain stabilisation of phenoxide ion?
(2-way + 2-way)

A
  • Stabilised through resonance of the negative charge
  • through the ring system
  • Less stable than ethanoate
  • as the resonance structures aren’t equivalent
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13
Q

Explain stabilisation of ethanol?
(2-way + 2-way)

A
  • Very little tendency for ethanol,
  • to give away the proton
  • No resonance structures possible
  • to support the negative charge
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14
Q

Ethanoic acid rxn with sodium hydroxide?
(2 things)

A
  • Reacts
  • Acid neutralised to form a salt
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15
Q

Ethanoic acid rxn with metal carbonate?
(2 things)

A
  • Reacts
  • Formation of CO2 gas (effervescing)
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16
Q

Phenol rxn with sodium hydroxide?
(2 things)

A
  • Reacts
  • Acid neutralised to form a salt
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17
Q

Phenol rxn with metal carbonate?

A

No reaction.

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18
Q

Ethanol rxn with sodium hydroxide?

A

No reaction.

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19
Q

Ethanol rxn with metal carbonate?

A

No reaction.

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20
Q

What is the equation for the formation of a carboxylic acid from a primary alcohol?
([O]-> means oxidation)

A

H3CCH2OH [O]-> H3CCOH [O]-> H3CCOOH

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21
Q

What’s an oxidant that can oxidise primary alcohols to a carboxylic acid?

A

Acidified potassium dichromate

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22
Q

Chemical formula for acidified potassium dichromate?

A

H+/K2Cr2O7

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23
Q

What is the colour change observation of the formation of a carboxylic acid from a primary alcohol?

A

Orange to green

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24
Q

But what are primary alcohols usually form into after being oxidised?
(2 things)

A
  • Aldehydes
  • Carboxylic acids
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25
Q

And what do secondary alcohols form after being oxidised?

A

Ketones

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26
Q

What conditions needed for the oxidation of primary/secondary alcohols?

A

[Heat] under reflux

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27
Q

What about tertiary alcohols formation after being oxidised?
(4 !!! things)

A
  • Resistant to oxidation
  • Under severe conditions however
  • May yield carboxylic acids
  • Containing fewer carbon atoms than parent alcohol
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28
Q

How may the oxidation of the primary alcohol be sometimes considered a two-stage process?
(1 thing + 2-way + 1 thing)

A
  • To obtain the aldehyde…
  • Mild conditions must be used with the aldehyde
  • distilled of as it forms
  • Shall avoid carboxylic acid formation
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29
Q

Draw the eqn of the 2-stage process version of oxidation of a primary alcohol
(Prob refer to booklet, whiteboard)

A

H3CC(OH)H2 -> H3CH(=O) -> H3C(=O)OH

First -> = [O] & distillation
Second -> = [O]
A secret arrow from beginning to end = [O] & reflux

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30
Q

How are carboxylic acids reduced?

A

With the use of Lithium Aluminium Hydride
(LiAlH4)

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31
Q

What conditions are required to reduce carboxylic acids?

A

In ethoxyethane (diethylether) ^｡^

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32
Q

Write the eqn of the reduction of propanoic acid, state conditions required too
(Whiteboard)

A

CH3CH2COOH + 4[H] -> CH3CH2CH2OH

-> = (LiAlH4) in ethoxyethane

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33
Q

How would u form aromatic carboxylic acids?

A

Oxidation of an aromatic ring next to the alkyl group

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34
Q

What’s the oxidising agent used for the formation of aromatic carboxylic acids?
and then what?

A
  • Alkaline potassium permanganate
  • Acidifcation (HCl aq)
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35
Q

How is formation of aromatic carboxylic acids allowed?
(2-way + 2-way)

A
  • Alkyl group influenced by
  • neighboring aromatic ring
  • Somewhat like special reactivity of
  • alpha C-H bonds
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36
Q

Draw the eqn of oxidation of 4-bromomethylbenzene indicating conditions required ig?
(Whiteboard)

A

“4-bromomethylbenzene” -> [the aromatic carboxylic acid]

-> = 1, KMnO4/OH-
2, (H2O) HCl (aq)

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37
Q

Define decarboxylation?

A

Getting rid of a carboxylic acid

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38
Q

How do u perform decarboxylation?
(True 4-way)

A
  • If carboxylic acid/its sodium salt
  • strongly heated with sodalime
  • carbon atom removed
  • producing an alkane & a carbonate
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39
Q

Eqn of a typical decarboxylation of a carboxylic acid
(Whiteboard)

A

CH3CH2COOH + 2NaOH -> CH3CH3 + Na2CO3 (-H2O)

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40
Q

What are the usual decarboxylating reagents?
(2)

A
  • NaOH
  • or (preferably) sodalime
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41
Q

Why is decarboxylation often carried out using the sodium salt of the acid…. RATHER than than acid?

A

Generally more effective

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42
Q

Eqn of the sodium salt version
(Decarboxylation)
(Whiteboard)

A

CH3CH2COONa + NaOH -> CH3CH3 + Na2CO3

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43
Q

What is decarboxylation an example of?

A
  • Descending homologous series
  • in which means the length of
  • carbon chain decreases
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44
Q

What’s next?

A
  • Formation of nitriles
  • Hydrolysis of Nitriles and Amides
  • Reduction of nitriles
    (Apparently some of these have 4.4 stuff too…. just great right ¬.¬)

The issue is that it’s not rlly the best clarification. Or maybe because i’m too comfortable at my environment. Or maybe the timing was definitely impeccable

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45
Q

Typical general formula of esters?

A

RCOOR1

And well, It’s like the carbon within connected to both =O and -O
It should be easy to understand…. assuming ik how to draw it D:

46
Q

How do u prepare esters from a carboxylic acid?
(3 things)

A
  • Heat w/
  • Carboxylic acid + alcohol
  • In presence of an acid catalyst
47
Q

Eqn of the preparation of esters thru ethanol + methanoic acid
(whiteboard)

A

C2H5OH + CH3COOH -> CH3COOC2H5 + H2O

-> = H+ & 60°C

48
Q

What’s the function of the acid catalyst for the preparation of esters from the conversion of carboxylic acids?
(1 thing + 2-way)

A
  • Protonate the carboxylic acid
  • To allow resulting positive species
  • to undergo nucleophilic attack by the alcohol
49
Q

The end process for the preparation of esters from the conversion of carboxylic acids?
(3-way)

A
  • Elimination of a proton
  • and a molecule of water
  • results formation of the ester
50
Q

What’s a convenient route for the creation of esters from the conversion of carboxylic acids?
(3 points)

A
  • Use dry (gaseous) hydrogen chloride as catalyst
  • Results better yields (no alkene side chain formed)
  • The Fischer-Speier method
51
Q

How would u form internal esters?
(1 thing + 2-way)

A
  • Only in some hydroxyacids
  • Their ring structure of such an ester…
  • broken on hydrolysis
52
Q

How would u perform ester hydrolysis?
(4-way)

A
  • Heat w/
  • dilute mineral acids
  • (hydrochloric/sulfuric acid)
  • = hydrolysed
53
Q

What are the 2 hydrolysis’ that can be performed on the ester?

A
  • Acid hydrolysis
  • Alkaline hydrolysis
54
Q

Show the eqn of acid hydrolysis on the ester
(Whiteboard)

A

RCOOR1 + H+/H2O -> RCOOH + R1OH

55
Q

Show the eqn of alkaline hydrolysis on the ester
(Whiteboard)

A

RCOOR1 + NaOH -> RCOONa + R1OH

56
Q

How would u gain the sodium salt from alkaline hydrolysis on the ester?

A

Add a dilute acid
(HCl)

57
Q

How would u form acid chlorides from the conversion of carboxylic acids?

A
  • Reaction between carboxylic acid
  • and phosphorus pentachloride (PCl5)
  • Yields acid/acyl chlorides
58
Q

Eqn of formation of acid chlorides from the conversion of carboxylic acids?
(Whiteboard)

A

CH3COOH + PCl5 -> CH3COCl + POCl3 + HCl

CH3COCl = ethanoyl chloride
POCl3 = phosphoryl chloride

59
Q

Alternate reagents for the formation of acid chlorides from the conversion of carboxylic acids?
(Only 2)

A
  • Phosphorus trichloride
  • Sulphur dichloride oxide (thionyl chloride)
60
Q

Eqn of formation of acid chlorides with phosphorus trichloride?
(Conversions of carboxylic acids)
(Whiteboard)

A

3 CH3COOH + PCl3 -> 3 CH3COCl + H3PO3

61
Q

Eqn of formation of acid chlorides with sulphur dichloride oxide (thionyl chloride)?
(Conversions of carboxylic acids)
(Whiteboard)

A

CH3COOH + SOCl2 -> CH3COCl + SO2 + HCl

62
Q

What does it mean if acid chlorides are reactive and acylating agents?
(2-way)

A
  • Reagents which can introduce…
  • the RCO- group into a molecule
63
Q

Which is more reactive?
CH3COCl (Ethanoyl chloride)
or
C6H5COCl (Benzoyl chloride OR benzenecarbonyl chloride)

A

….. It’s ethanoyl chloride.
The CH3COCl

64
Q

How would u gain the carboxylic acid back from an ethanoyl chloride?
(2 things)

A
  • Acid chloride hydrolysis
  • Ethanoyl chloride readily hydrolysed by water
65
Q

Eqn of the hydrolysis of ethanoyl chloride?
(Whiteboard)

A

CH3COCl + H2O -> CH3COOH + HCl

66
Q

What happens when u open a bottle of ethanoyl chloride?
(3-way)

A
  • Misty fumes of hydrogen chloride seen
  • as compounds reacts with….
  • atmospheric water vapour
67
Q

Rate of hydrolysis between acid chloride and ester?

A

Acid chloride > Ester

68
Q

What is an amide?

A

a -C(=O)NH2 group

69
Q

How would u form amides from carboyxlic acids?

A
  • Dehydration of the ammonium salt of the acid
  • Excess of the acid is refluxed
  • … w/ ammonium carbonate for several hrs
70
Q

Eqn of the formation of amides
(Conversion of carboxylic acids)
(Whiteboard)

A

2 CH3COOH + (NH4)2CO3 ⇌ 2 CH3COO- NH4+ + CO2 + H2O

71
Q

Displayed formula of CH3COO- NH4+

A

Refer to booklet man

72
Q

What does the excess acid prevent?
Show eqn.
(Form amides from carboxylic acids)

A
  • Dissociation of the ammonium salt
    RCOONH4 ⇌ RCOOH + NH3
73
Q

Show the eqn of the ammonium salt dehydrating from heat

A

RCOONH4 -> RCONH2 + H2O

74
Q

How would u make nitriles from amides?

A

Dehydrating the amide (loss of water)

75
Q

How do u dehydrate the amide?

A
  • Heating solid mixture of amide
  • w/ phosphorus(V) oxide (P4O10)
76
Q

“In-depth detail” of making nitrile from amide?

A
  • Water removed from amide group
  • Leaves a nitrile group, -CN
  • Liquid nitrile collected by simple distillation
77
Q

Show eqn of gaining ethanenitrile by dehydrating ethanamide
State reagent used
(Whiteboard)

A

CH3CONH2 + P4O10 -> CH3CN + H2O

REAGENT = Phosphorus(V) oxide aka P4O10

78
Q

What group is nitrile?

A

-C≡N group

79
Q

How do u introduce a cyanide ion into a halogenoalkane?

A

Thru nucleophilic substitution

80
Q

How do u introduce a cyanide ion into a carbonyl compound?

A

Thru nucleophilic addition

81
Q

What do both nucleophilic addition/substitution provide a means of?
(Nitriles from halogenoalkanes)
(2-way)

A
  • Increasing the length
  • of a carbon chain in an organic molecule
82
Q

What condition is required to introduce a cyanide ion into a halogenoalkane?

A

Refluxed w/ ethanolic potassium cyanide

83
Q

Eqn for halogenoalkane refluxed with ethanolic potassium cyanide
State what type of mechanism it is.
(Whiteboard)

A

RCH2I + KCN -> RCH2CN + KI

Nucleophilic substitution

84
Q

Draw the mechanism for halogenoalkane refluxed with ethanolic potassium cyanide
(It’s kinda similar…)
(Whiteboard)

A

The honors are yours

85
Q

If u add HCN to ethanal/propanone, what’s that mechanism called?

A

Nucleophilic addition

86
Q

What is the rate and how do u increase it?… for the addition of HCN to ethanal/propanone?

A
  • Slow
  • Increases by addition of alkali/cyanide ions
87
Q

How does adding alkali for the addition of HCN to ethanal/propanone greatly increase rate?
(2-way)

A
  • Neutralises some of the HCN molecules
  • giving higher conc. of cyanide ions
88
Q

Equation of addition of HCN to ethanal/propanone?
(Whiteboard)

A

H3C-C(=O)-H + HCN/KCN -> H3C-CH(OH)-CN

89
Q

Mechanism of addition of HCN to ethanal/propanone?
(Do ethanal insteada propanone)
(Whiteboard)

A

Refer to the booklet

90
Q

What can only rotate plane polarised light?
(3 things, or whatever comes to ur mind)

A
  • Enantiomers
  • Racemic mixture
  • Chiral centre
91
Q

What are 2 other hydrolysis’ other than normal hydrolysis?

A
  • Acid hydrolysis
  • Alkali/Base hydrolysis
92
Q

What happens if u do alkali/base hydrolysis towards ethanenitrile?
(2-way)

A
  • Gain solution containing ethanoate ions
  • and ammonia
93
Q

Equation of alkali/base hydrolysis towards ethanenitrile?

A

H3C-C≡N -> H3C-C(=O)O-Na + NH3

-> = NaOH(aq)

94
Q

What’s the 2nd step to gaining the carboxylic acid after step 1 of alkali/base hydrolysis towards ethanenitrile?
(4 things)

A
  • Liberate the “weak acid”
  • Supply enough hydrogen ions from a strong acid
  • (Hydrochloric acid)
  • Enough to the mixture = acidic
95
Q

What’s the difference with alkali/base hydrolysis?
(2 things)

A
  • It is a two-step reaction
  • Produces a salt first
96
Q

What happens if u do acid hydrolysis towards ethanenitrile?
(2 things)

A
  • You gain an ethanoic acid
  • almost similar to normal hydrolysis
97
Q

Even if u do acid hydrolysis, how would u gain just the carboxylic/ethanoic acid?

A

Distill off the mixture

98
Q

How is acid hydrolysis performed towards ethanenitrile?
(2-way)

A
  • Nitrile heated under reflux
  • with dilute acid (e.g. dilute hydrochloric acid)
99
Q

Equation of acid hydrolysis towards ethanenitrile?
(Whiteboard)

A

H3C-C≡N -> H3C-C(=O)OH + +NH4

-> = (H+/H2O) or (HCl(aq))

100
Q

What other group can also be converted into their corresponding carboxylic acid likewise?

A

Amides
(NH2)

101
Q

How is acid hydrolysis performed + results towards ethanamide?
(2 things + 2-way)

A
  • Heat with dilute acid (e.g. HCl)
  • Ethanoic acid formed tog. with ammonium ions
  • If use HCl, final solution =
  • ammonium chloride & ethanoic acid
102
Q

Eqn of acid hydrolysis towards ethanamide?
(Whiteboard)

A

CH3CONH2 -> CH3COOH + NH4</sup>+</sup>Cl

-> Above = HCl(aq)
-> Below = △, (+ H2O + HCl)

103
Q

Draw the displayed formula of the eqn of acid hydrolysis towards ethanamide
(Whiteboard)

A

U got it

104
Q

How about alkaline/base hydrolysis towards amide?
(4 thingies)

A
  • Amide heating with NaOH
  • Ammonia gas given off
  • Left with solution of sodium ethanoate
  • Exactly like with nitriles w/ 2 steps to gain carboxylic acid
105
Q

Eqn of alkaline/base hydrolysis towards amide
(Whiteboard)

A

CH3CONH2 + NaOH -> CH3COO -Na + NH3 -> CH3COOH

2nd -> = HCl(aq)

106
Q

Rando as hell but, list 2 things lithium aluminium hydride (LiAlH4) can convert?

A
  1. Carboxylic acid -> 1° alcohol
  2. Nitrile -> amine
107
Q

Difference between amine + amide?

A

Amine = NH2
Amide = C(=O)NH

108
Q

Thus, what’s the reagent used to reduce nitriles to primary amines (CH3-NH2)?

A
  • Lithium aluminium hydride
  • Lithium tertahydridoaluminate(III)
  • LiAlH4
109
Q

Show simple equation formula for the reduction of nitriles?
(Whiteboard ig)

A

CH3CH2CN -> CH3CH2CH2NH2

aka

Propanenitrile -> Primary amine (propylamine)

110
Q

Show the eqn of the reduction of butanenitrile using lithium aluminium hydride
(Whiteboard)

A

CH3CH2CH2CN + 4 [H] -> CH3CH2CH2CH2NH2

But.. why it no say LiAlH4?

111
Q

Sorry but, refer to booklet at the back for reducing agents strength…. otherwise…. which ones generally stronger?

A

Sorry sorry, ease of reduction
But ofc, it’s the LiAlH4

112
Q

U finished it…..? Test is monday, and look at ur situation rn ,’:)

A

Yeahhh i don’t rlly want to plan my demise at least….

A Chem Finale pt 1. (9 decks)

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