Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > Carboxylic Acids and Derivatives > Flashcards

Carboxylic Acids and Derivatives Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

What are carboyxlic acids?

A

They contain the carboxyl group (-COOH)

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

What is the general formula for aliphatic carboxylic acids?

A

CnH2nO2

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

How to name carboxylic acids?

A

Replace ‘-e’ with ‘-oic acid’

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

How to name salts of carboxylic acids?

A

Replace ‘-oic acid’ with ‘-oate’

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

How does the boiling point of carboxylic acids change as the number of carbon atoms increases?

A

As the number of carbon atoms increases, the number of electrons in the molecule increases and more energy is required to overcome the stronger id-id between carboxylic acid molecules

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

What is glacial acid and why is it called that?

A

Anhydrous ethanoic acid as it freezes to an ‘ice-like’ solid at 17 degree celsius

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

How do carboxylic acids’ boiling point compared to alcohols of similar Mr and why?

A

Carboxylic acids have a higher boiling point compared to alcohols of similar Mr
- carboxylic acids have more extensive hydrogen bonds than alcohol as there are more sites for the formation of hydrogen bonds
- carboxylic acids form stronger hydrogen bonds than alcohol molecules as the O-H bond in -COOH is more polar due to the presence of electron-withdrawing carbonyl group

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

Are carboxylic acids soluble in water?

A

Lower carboxylic acid molecules are soluble in water because carboxylic acids can form hydrogen bonds with water molecules

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

What happens to the solubility of carboxylic acids as number of C increases?

A

As the length of non-polar hydrocarbon chain increases, solubility in water decreases while solubility in non-polar solvents increases

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

What happens when carboxylic acids in pure form and dissolved in non-polar solvents like benzene?

A

Carboxylic acids form dimers through the formation of hydrogen bonds between two acid molecules

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

What does the strength of acids depend on?

A

The stability of anion formed

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

What is the carboxylate anion stabilised by and what are the implications?

A

Carboxylate anion is stabilised by resonance, where the negative charge is delocalised over the -COO⁻, thus the two C-O bonds are equal in length

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

What affects the relative acidity of carboxylic acids?

A
  • Electron-donating groups intensify the negative charge on the -COO⁻ group, thereby destabilising the anion and reducing acid strength
  • Electron-withdrawing groups disperse the negative charge on the -COO⁻ group, thereby stabilising the anion and increasing acid strength
  • benzoic acids are stronger acids than aliphatic acids due to delocalisation of negative charge on the benzoate anion into the ring, making the benzoate anion more stable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why is the delocalisation of negative charge into the benzene ring possible?

A

It possible because the C atom of -COO⁻ group is sp² hybridised, similar to the sp² hybridised C atom in the benzene ring, allowing overlap of the unhybridised p orbitals

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

What is the strength of carboxylic acids in relation to other compounds?

A

Mineral acids > RCOOH > phenol > water > alcohol

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

What are the ways to prepare carboxylic acids?

A
  • oxidation of primary alcohols and aldehydes
  • oxidation of alkylbenzenes
  • oxidation of alkenes with structure RCH=CHR’
  • hydrolysis of nitriles
  • hydrolysis of acyl chlorides and esters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the reagents and conditions for the oxidation of primary alcohols and aldehydes to prepare carboxylic acids?

A

acidified KMnO4 or acidified K2Cr2O7, heat under reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the reagents and conditions for the oxidation of alkylbenzenes to prepare carboxylic acids?

A

acidified KMnO4, heat under reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the reagents and conditions for the oxidation of alkenes with the structure RCH=CHR’ to prepare carboxylic acids?

A

acidified KMnO4, heat under reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is vinegar produced?

A

Oxidation of ethanol by enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the equation for vinegar production?

A

CH3CH2OH + O2 -(enzymes)-> CH3COOH + H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the reagents and conditions for the hydrolysis of nitriles?

A
  • acid hydrolysis: dilute HCl (aq)/ dilute H2SO4, heat under reflux
  • alkaline hydrolysis: NaOH (aq), heat under reflux, followed by acidification with dilute HCl (aq)/ H2SO4 (aq)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the equation for acid hydrolysis of nitriles?

A

RCN + 2H₂O + H⁺ → RCOOH + NH₄⁺

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the equation for alkaline hydrolysis of nitriles?

A

RCN + H₂O + OH⁻ → RCOO⁻ + NH₃
(Upon addition of dilute HCl, RCOO⁻ becomes RCOOH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Do carboxylic acids behave like carbonyl compounds or alcohols?

A

Carboxylic acids behave like neither because the close proximity of C=O and O-H groups in -COOH functional group causes them to modify each other’s properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Is carboxyl carbon more or less susceptible to nucleophilic attack and why?

A

It is less susceptible to attack by nucleophiles than the carbonyl carbon in aldehydes and ketones because a lone pair in the p orbital of the O atom of the -OH group will be delocalised into the pi bond of the -C=O group, causing a drift of electron density from O atom of the -OH group towards the electron deficient carbon, thus reducing the positive charge on the carboxyl carbon via the resonance effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the reactions of carboxylic acids?

A
  • Acid property
    • reaction with reactive metals
    • reaction with bases
    • reaction with carbonates or
      hydrogencarbonates
  • Condensation to form esters
  • Nucleophilic substitution to form acyl chlorides
  • Reduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the type of reaction of carboxylic acids with reactive metals?

A

Acid-metal reaction or redox

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the equation of carboxylic acids and reactive metal?

A

RCOOH + Na → RCOONa + 1/2H₂

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the equation for the reaction of carboxylic acids with bases?

A

RCOOH + NaOH → RCOO⁻Na⁺ + H₂O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What medium must reaction of bases be carried out and why?

A

Aqueous medium because carboxylic acids exhibit their acidic property, undergo dissociation to give H⁺ in aqueous medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the type of reaction of carboxylic acids with carbonates or hydrogencarbonates?

A

Acid-carbonate reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the equation of carboxylic acids with carbonates?

A

2RCOOH + Na₂CO₃ → 2RCOO⁻Na⁺ + CO₂ + H₂O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the equation of carboxylic acids with hydrogencarbonates?

A

RCOOH + NaHCO₃ → COO⁻Na⁺ + CO₂ + H₂O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How to distinguish carboxylic acids from phenols and alcohols?

A

Add carbonates or hydrogencarbonates
- carboxylic acids: CO₂ evolved will form white ppt. with limewater
- phenols and alcohols: do not react with carbonates or hydrogencarbonates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What happens when you add mineral acids to salt of carboxylic acids?

A

RCOO⁻Na⁺ + H⁺ → RCOOH + Na⁺
Mineral acids are stronger than carboxylic acids, thus it will convert the salt back to original acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What bonds does the acid property of RCOOH cleave?

A

O-H bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What bonds does condensation to form esters and nucleophilic substitution to form acyl chlorides?

A

Cleavage of C-O bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are the reagents and conditions for carboxylic acids to undergo condensation to form esters?

A

alcohol (R’OH), a few drops of conc. H2SO4, heat under reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the type of reaction that carboxylic acids undergo to form esters?

A

Condensation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the equation of carboxylic acids undergoing condensation to form esters?

A

RCOOH + R’-OH ⇌ RCOOR’ + H₂O

41
Q

What does H2SO4 act as in the condensation of carboxylic acids to form esters?

A

The reaction of carboxylic acids to form esters is slow and reversible
- conc. H2SO4 act as catalyst
- conc. H2SO4 act as dehydrating agent to remove water formed and favour forward reaction

42
Q

Do carboxylic acids react with phenols to form esters and why?

A
  • Carboxylic acids do not react with phenols to form esters as phenol is a weaker nucleophile than alcohols
  • to form phenyl esters, phenol must be first converted to phenoxide and reacted with acyl chlorides
43
Q

What is the mechanism for carboxylic acids undergoing condensation reaction to form esters?

A

addition-elimination reaction

44
Q

Apart from forming esters, what other condensation reactions can carboxylic acids undergo?

A

Condensation reaction between two carboxylic acids to form an acid anhydride

45
Q

What is the reagents and conditions for the reaction of carboxylic acids to form acyl chlorides?

A
  • PCl₅, room temperature
  • PCl₃, room temperature
  • SOCl₂, room temperature
46
Q

What is the type of reaction of carboxylic acids reacting to form acyl chlorides

A

nucleophilic substitution

47
Q

What is the equation of carboxylic acids and PCl₅?

A

RCOOH + PCl₅ → RCOCl + POCl₃ + HCl

48
Q

What is the equation of carboxylic acids and PCl₃?

A

3RCOOH + PCl₃ → 3RCOCl + H₃PO₃

49
Q

What is the equation of carboxylic acids and SOCl₂?

A

RCOOH + SOCl₂ → RCOCl + SO₂ + HCl

50
Q

What are the reagents and conditions for the reduction of carboxylic acids?

A

LiAlH₄ in dry ether

51
Q

What is the equation for the reduction of carboxylic acids?

A

RCOOH + 4[H] → RCH₂OH + H₂O

52
Q

Can carboxylic acids be reduced by other reducing agents?

A

No because carboxylic acids are more difficult to reduce than aldehydes and ketones and cannot be reduced by milder reducing agents like H2,Ni, heat or NaBH4

53
Q

What reactions can methanoic acid and ethanoic acid undergo?

A

Oxidation by acidified KMnO4

54
Q

What is the equation for methanoic acid undergoing oxidation?

A

HCOOH + [O] → CO₂ + H₂O

55
Q

What is the equation for ethanoic acid undergoing oxidation?

A

(COOH)₂ + [O] → 2CO₂ + H₂O

56
Q

What reactions do HCOOH undergo and why?

A
  • Oxidation by Fehling’s reagent and Tollens’ reagent (false positive)
  • HCOOH has an aldehyde group (-CHO) and is easily oxidised
57
Q

What do HCOOH not form?

A

It does not form RCOCl because it is high unstable and decomposes to give CO and HCl

58
Q

How are carboxylic acid derivatives formed?

A

Carboxylic acid derivatives are formed when the -OH portion of the carboxyl group is replaced by another substituent. They all contain the RCO- group (acyl group)

59
Q

What are some classes of carboxylic acid derivatives?

A
  • acyl chloride (RCOCl)
  • primary amide (RCONH₂)
  • ester (RCOOR’)
  • acid anhydride R(CO)O(CO)R’
60
Q

How to name acyl chlorides?

A

Change ‘oic acid’ to ‘oyl chloride’

61
Q

How to name ester?

A

Alkyl group attached to oxygen (alcohol portion) + change ‘oic acid’ to ‘oate’ (carboxylic acid portion)

62
Q

How to name amide?

A

Change ‘oic acid’ to ‘amide’

63
Q

How to name acid anhydride?

A

Names of acid + ‘anhydride’

64
Q

How do the boiling points of acyl chlorides and esters compared to carboxylic acids and alcohols of similar Mr?

A

Boiling points of acyl chlorides and esters are lower than carboxylic acids and alcohols because lesser energy is required to overcome the weaker pd-pd between acyl chlorides or ester molecules compared to stronger hydrogen bonds between carboxylic acids or alcohols molecules

65
Q

How do the boiling point of amides compared to carboxylic acids derivatives of comparable Mr?

A

-NH2 group allows hydrogen bonds to be formed between amide molecules, thus amides have higher boiling point

66
Q

What does the solubility of acid derivatives in water depend on?

A

Size of non-polar hydrocarbon group: the larger the size of hydrocarbon group, the less soluble the acid derivatives

67
Q

Are acyl chlorides soluble in water?

A

Soluble, they dissolve in water to form carboxylic acids and HCl (aq)

68
Q

What is the equation of acyl chlorides in water?

A

RCOCl + 2H₂O → RCOOH + HCl

69
Q

Are esters soluble in water?

A

slightly soluble (up to 3-5 C)

70
Q

Are amides soluble in water?

A

Fairly soluble due to hydrogen bonds between molecules of amides and water molecules

71
Q

What type of reaction does acyl chlorides undergo?

A
  • Hydrolysis (or nucleophilic substitution)
  • Condensation to form esters
  • Condensation to form amides
72
Q

What are the reagents and conditions for the hydrolysis of acyl chlorides?

A

Water, room temperature

73
Q

What is the equation for the hydrolysis of acyl chlorides?

A

RCOCl + H₂O → RCOOH + HCl

74
Q

What is the distinguishing test for acyl chlorides?

A
  • Add water: reaction is vigorous and resultant acidic solution turns moist blue litmus paper red
  • Then add AgNO3: white ppt. of AgCl formed
75
Q

How does benzoyl chloride’s reactivity compare with alkyl acyl chloride?

A

Benzoyl chloride is much less reactive than alkyl acyl chloride (reacts slowly with water) because declocalisation of electron density between p orbital of Cl atom and the pi bond of the C=O group and the pi electron cloud of benzene ring reduces partial charge on the carbonyl carbon

76
Q

What is the relative ease of hydrolysis of acyl chloride (RCOCl), alkyl chloride (RCl) and aryl chlorides (Ar-Cl)?

A

acyl chlorides (RCOCl) > alkyl chlorides (RCl) > aryl chlorides (Ar-Cl)
- Carbonyl carbon atom in -COCl is highly electron negative as it is bonded to 2 electronegative atoms O and Cl and hence is easily attacked by nucleophiles
- Carbon atom of C-Cl bond is less electron deficient than that in RCOCl
- aryl chlorides have stronger C-Cl bond due to delocalisation of lone pair of electrons on Cl atom into the benzene ring, resulting in partial double bond character

77
Q

What are the reagents and conditions of the hydrolysis of alkyl chlorides?

A

NaOH (aq), heat

78
Q

What are the reagents and conditions of the hydrolysis of aryl chlorides?

A

No reaction

79
Q

What type of reaction is the formation of esters from acyl chlorides?

A

Condensation

80
Q

What are the reagents and conditions for the formation of ester from acyl chlorides?

A
  • alcohol, room temperature
  • phenol, NaOH, room temperature
81
Q

Why is NaOH(aq) needed to react with acyl chlorides to form esters?

A

Phenol is a weak nucleophile and must be first converted to phenoxide ion, which is a stronger nucleophile

82
Q

What type of reaction is the formation of amides from acyl chlorides?

A

Condensation

83
Q

What is the equation to form primary amide from acyl chlorides?

A

RCOCl + NH3 → RCONH2 + HCl

84
Q

What is the equation to form secondary amides form acyl chlorides?

A

RCOCl + R’NH2 → RCONHR’ + HCl

85
Q

What is the equation to form tertiary amides from acyl chlorides?

A

RCOCl + R’NHR’’ → RCONR’R’’ + HCl

86
Q

What reactions do esters undergo?

A
  • Acid hydrolysis
  • Alkaline hydrolysis
87
Q

What happens when you hydrolyse esters?

A

Esters form back their corresponding carboxylic acids and alcohols

88
Q

Why can’t you just hydrolyse esters with water?

A

Hydrolysis of esters by heating with water occurs very slowly, this hydrolysis can be catalysed by heating with acid or induced by heating with alkali

89
Q

What are the reagents and conditions for acid hydrolysis?

A

dilute HCl (aq)/ H2SO4 (aq), heat under reflux

90
Q

What is the equation for acid hydrolysis of esters?

A

RCOOR’ + H2O ⇌ RCOOH + R’OH

91
Q

What are the reagents and conditions for alkaline hydrolysis of esters?

A

NaOH (aq), heat under reflux

92
Q

What is the other name for alkaline hydrolysis?

A

Saponification because traditionally soap is made by alkaline hydrolysis of fats and oils

93
Q

How does alkali induce hydrolysis of esters?

A

Alkalis induce hydrolysis by providing a stronger nucleophile, OH⁻

94
Q

What is the difference between acidic hydrolysis of esters and alkaline hydrolysis of esters apart from the medium?

A

alkaline hydrolysis reaction is irreversible while acidic hydrolysis of ester is reversible

95
Q

Why is alkaline hydrolysis of esters reaction irreversible?

A

Under alkaline conditions, carboxylate salt is obtained and the resonance stabilised carboxylate anion shows little tendency to react with an alcohol

96
Q

What are the uses of esters?

A
  • perfume and flavouring material
  • solvents for paints and vanishes
  • analgesic (painkiller)
97
Q

What are the uses of amides?

A
  • analgesic (painkiller)
  • caffeine
98
Q

What are the uses of ester?

A
  • aspirin
  • anaesthetic
99
Q

What is the type of reaction of carboxylic acids with bases?

A

Acid-base reaction

Chemistry (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions