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Organic Chemistry > 3.3.9 Carboxylic acids and derivatives (A2) > Flashcards

3.3.9 Carboxylic acids and derivatives (A2) Flashcards

1
Q

what is the functional group of carboxylic acids?

A

R-COOH

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2
Q

what is the pH of carboxylic acids?

A

weak acids - pH 3-6

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3
Q

what is the name of a carboxylic acid which includes a benzene ring?

A

benzanoic acid

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4
Q

can carboxylic acids form H bonds with water? what does this mean?

A

yes
carboxylic acids with up to and including 4 carbons are completely soluble in water

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5
Q

when can carboxylic acids form H bonds with eachother?

A

in the solid state

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6
Q

what do the H bonds account for in terms of properties?

A

much higher boiling point than their counterpart alkanes

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7
Q

what is mechanism is likely to happen in carboxylic acids? why?

A

nucleophilic addition
delta positive carbon is very susceptible to nucleophilic attack and addition reactions are likely to happen as there is an area of unsaturation

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8
Q

what happens to carboxylic acids in solution?

A

partially ionised
forms carboxylate ion and a proton (H+)

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9
Q

what is the chemical reactivity of carboxylic acids?

A

despite being weak acids, any carboxylic acid will still react with sodium hydrogencarbonate (NaHCO3)

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10
Q

what happens in the reaction between sodium hydrogen carbonate (NaHCO3) and a carboxylic acid?

A

releases carbon dioxide
we would see bubbling

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11
Q

what can we use to distinguish between carboxylic acids and alcohols?

A

sodium hydrogencarbonate
carboxylic acid bubbles
alcohol gives no reaction

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12
Q

what do we use the test with sodium hydrogencarbonate to do?

A

distinguish between carboxylic acids and alcohols
carboxylic acids bubble - release of CO2
and alcohols give no reaction

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13
Q

what are carboxylic acids in a reaction?

A

proton donors

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14
Q

what are the salts produced by the reactions of carboxylic acids called generally?

A

carboxylate salts

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15
Q

what would a reaction of a ethanoic acid produce as a salt?

A

ethanoate salts

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16
Q

what salt would be produced from a reaction involving methanoic acid?

A

methanoate salts

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17
Q

what does the reaction of ethanoic acid and sodium hydroxide produce?

A

sodium ethanoate and water

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18
Q

what does a reaction between propanoic acid and aqueous sodium carbonate produce?

A

sodium propanoate
water
carbon dioxide

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19
Q

do carboxylic acids ionise partially or completely in water?

A

partially ionise in solution

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20
Q

what is the charge on a carboxylate ion called?

A

delocalised electron charge

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21
Q

what is the functional group of an ester?

A

RC=OO-R’

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22
Q

what are esters used for?

A

cleaning products, perfumes, flavourings

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23
Q

how do we form an ester?

A

carboxylic acid + alcohol

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24
Q

what is the equation for forming an ester?

A

carboxylic acid + alcohol –> ester + water

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25
Q

how would we get a higher yield of ester from the carboxylic acid + alcohol reaction?

A

increase volume of carboxylic acid / alcohol
remove water is it is formed

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26
Q

how can we get the carboxylic acid and alcohol back from the ester?

A

hydrolysis

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27
Q

what does an addition elimination reaction of an ester form?

A

carboxylic acid
alcohol

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28
Q

what conditions does an addition elimination reaction involving an ester?

A

room temperature
acid catalyst

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29
Q

what do we obtain after addition elimination of esters? how do we obtain the desired product?

A

mixture of carboxylic acid, water, ester and alcohol
fractional distillation

30
Q

other than an acid catalyst for addition elimination, what else can be used to hydrolyse an ester?

A

bases

31
Q

when we use a base to hydrolyse an ester, what are the products?

A

alcohol and salt of the carboxylic acid (carboxylate salt)

32
Q

what happens when we use a base to hydrolyse an ester?

A

products are carboxylate salt and alcohol
because this is removing the carboxylic acid from the mixture, an equilibrium is NOT REACHED so reaction goes to EQUILIBRIUM

33
Q

what type of mechanism is the hydrolysis of esters?

A

addition elimination

34
Q

what is the use of esters as plasticisers?

A

added to plastics to make them more flexible

35
Q

why are esters used as plasticisers?

A

ester (small molecule) can get in between the long chain molecules of plastic and allow them to slide over each other

36
Q

what is the reaction for making fats and oils a reaction between? what does it form?

A

glycerol (alcohol) + fatty acids (carboxylic acids)
forming triglyceride (triester of glycerol)

37
Q

what can we add to triglyceride (ester) to form glycerol (alcohol) and fatty acids (carboxylic acid)?

A

3 water molecules

38
Q

what happens in the hydrolysis of fats?

A

boil fats / oils with sodium hydroxide
glycerol and 3 sodium carboxylate salts produced

39
Q

what is produced from the hydrolysis of fats?

A

glycerol (alcohol) and sodium carboxylate salts

40
Q

how is sodium carboxylate salt used?

A

soap

41
Q

how many molecules of NaOH are added to a triglyceride to hydrolyse it?

A

3

42
Q

how do the carboxylate ions arrange themselves around an oil droplet in water? why? what is this used for?

A

arrange themselves with hydrophilic head in the surrounding water and hydrophobic tail in the oil. this leads to separation of the oil and water, used for soaps

43
Q

what is used to produce biodiesel from triglyceride (triester)?

A

methanol

44
Q

what are the mixture of fatty esters produced by the combination of triglyceride and methanol used for?

A

biodiesel

45
Q

what is produced by the reaction between triglyceride and methanol?

A

mixture of fatty esters (biodiesel)
glycerol

46
Q

what is the formula of an acyl group?

A

RC=O

47
Q

what is acylation?

A

addition of an acyl group to a nucleophile

48
Q

what is the ending when naming acyl chlorides?

A

(ethan)oyl chloride

49
Q

what is Z called in RC(O)Z?

A

Z= leaving group

50
Q

what are some examples of leaving groups?

A

Cl, OR’, OCOR’

51
Q

what does the speed of acylation reaction depend on?

A

depends how delta + the central carbon is
depends how stable the Z (leaving group) is
depends how strong the nucleophile is

52
Q

what is the relationship between the rate of the acylation reaction and the charge of the central carbon?

A

the more delta + the central carbon is, the quicker the reaction

53
Q

what is the relationship between the rate of the acylation reaction and the stability of the leaving group?

A

the more stable the Z (leaving group), the quicker the reaction

54
Q

what is the relationship between the rate of the acylation reaction and the strength of the nucleophile?

A

the easier the lone pair is donated, the quicker the reaction.

55
Q

what have the fastest acylation reactions?

A

acyl chlorides

56
Q

why do acyl chlorides have the fastest acylation reactions?

A

carbon is delta positive
leaving group is stable
nucleophile is strong (lone pair donated easily)

57
Q

what makes a better nucleophile?

A

how easily the e- pair is donated
(how basic the nucleophile is)

58
Q

what are the drawbacks to using ethanoic (acid) anhydrides?

A

lower atom economy
slower reaction

59
Q

what is the reason we don’t use acyl chlorides over acid anhydrides?

A

toxic by-product of HCl gas

60
Q

what type of molecules are formed when we react a primary amine with an acyl chloride?

A

amide
TOXIC HCl (hydrogen chloride) gas

61
Q

what type of molecules are formed when we react ammonia with an acyl chloride?

A

amide
toxic HCl gas

62
Q

what type of molecules are formed when we react an alcohol with an acyl chloride?

A

ester
toxic HCl gas

63
Q

what type of molecules are formed when we react an acyl chloride with water?

A

carboxylic acid
toxic HCl gas

64
Q

what type of molecules are formed when we react a primary amine with an acid anhydride?

A

amide
carboxylic acid

65
Q

what type of molecules are formed when we react ammonia with an acid anhydride?

A

amide
acid anhydride

66
Q

what type of molecules are formed when we react an alcohol with an acid anhydride?

A

ester
carboxylic acid

67
Q

what type of molecules are formed when we react water with an acid anhydride?

A

carboxylic acid
carboxylic acid

68
Q

what are the positives with reacting acyl chlorides?

A

reaction is extremely quick
high atom economy

69
Q

what are the positives with reacting acid anhydrides?

A

by-product is NON TOXIC

70
Q

what is the negative when using acyl chlorides in reaction?

A

TOXIC BY-PRODUCT of hydrogen chloride gas

71
Q

what are the negatives of using acid anhydrides in reaction?

A

reaction is slower
atom economy is lower

Organic Chemistry (16 decks)

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