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CHEMISTRY2 > ORGANIC CHEMISTRY - carboxylic acids and derivatives > Flashcards

ORGANIC CHEMISTRY - carboxylic acids and derivatives Flashcards

1
Q

what is a carboxylic acid? functional group?

A
  • COOH ( C=O , C-OH)
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2
Q

how do you name carboxylic acids?

A

-oic acid

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3
Q

are carboxylic acids soluble in water? why? what influences their solubility?

A
  • yes
  • acid group can form hydrogen bonds with water molecule
  • hydrocarbon chain length influences their solubility
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4
Q

what are the intermolecular forces in carboxylic acids?

A

hydrogen bonds
vdw

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5
Q

what are esters? functional group, general formula?

A
  • formed from carboxylic acids + alcohols
    RCOOR
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6
Q

how do you name esters?

A

alcohol (yl) carboxylic acid (oate)

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7
Q

what characteristic physical properties do esters have?

A

volatile, pleasant, fruity smells

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8
Q

what are some uses of esters?

A

perfumes
flavourings
plasticisers

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9
Q

what are some common natural esters?

A

fats and oils

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10
Q

write the equation for the equilibrium formed by an ethanoic acid in a solution?

A

CH3COOH ( aq) ⇌ CH3COO- (aq) + H+(aq)

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11
Q

what happens to the negative charge on the ethanoate ion in terms of electrons?

A

electrons delocalise so the negative charge is shared across the whole of the carboxylate group

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12
Q

how can you distinguish carboxylic acids from other -OH containing compounds?

A

add NaHCO3
sodium salt, water and co2 produced

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13
Q

write an equation of the reaction of ethanoic acid and NaOH?

A

CH3COOH + NaOH —> H2O + CH3COO-Na+

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14
Q

write an equation for the reaction of ethanoic acid with Na2CO3?

A

2CH3COOH + Na2CO3 —> H2O + CO2 + 2CH3COO-Na+

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15
Q

what catalyst is needed for the formation of esters from alcohols and carboxylic acids?

A

concentrated H2SO4

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16
Q

what catalyst is needed for the hydrolysis of esters?

A

dilute strong acid H2SO4

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17
Q

what is an alternative method for hydrolysis?

A

base hydrolysis

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18
Q

what are the + of base hydrolysis?

A

reaction goes to completion due to neutralisation by base

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19
Q

what alcohol makes up esters founds in animals and vegetable oils?

A

propane- 1,2,3 triol

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20
Q

what is the difference between oil and fat?

A

oil - (l) at room temp unsaturated
fats - (s) saturated

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21
Q

products of hydrolysing fats and oils?

A

prpoane-1,2,3-triol
sodium salts of the acids that make up the acid

22
Q

uses of products from fat + oil hydrolysis?

A

soaps and cleaning products

23
Q

what does the long hydrocarbon chain of the carboxylate ion do?

A

mix with grease

24
Q

what does the COO- group do?

A

mix with water

25
Q

how does the carboxylate ion with a long hydrocarbon chain make a good cleaning agent?

A

means that grease can be removed with water

26
Q

systematic name of glycerol?

A

propane-1,2,3-triol

27
Q

common uses of glycerol?

A
  • prevents creams from drying out
  • solvent in medicine
28
Q

how do you make biodiesel?

A

NaOH catalyst
60 degrees
lipid + 3CH3OH —> 3methyl ester + glycerol

29
Q

what are the problems with producing biodiesel?

A

crops used to make food are being used to make fuel

30
Q

what are carboxylic acid derivatives?

A

molecules that have the acyl group as part of their structure, formed from carboxylic acids

31
Q

draw the mechanism for the acylation of a nucleophile by an acid derivative

A

drawing on pmt

32
Q

which factors determine how readily the acylation of a nucleophile by an acid derivative occurs?

A
  • magnitude of the delta + charge on the carbonyl group which depends on the electronegativity of the group being substituted
  • how readily the nucleophile will electrons
  • how easily the group being substituted is lost
33
Q

What effect does the chlorine and oxygen atoms in the acyl chloride have on the partial charge on the carbonyl carbon?

A

Increases the partial positive charge by attracting electrons = they react more readily with nucleophiles

34
Q

are acyl chlorides or acid anhydrides more reactive?

A

acyl chlorides

35
Q

what is the name of the mechanism by which acyl chlorides and acid anhydrides acylate nucleophiles?

A

nucleophilic addition - elimination

36
Q

if the nucleophile is ammonia for the acylating of acyl chlorides or acid anhydrides, what are the products of the reaction?

A

an amide

37
Q

if the nucleophile is a primary amine, what are the products of the acylation of acyl chlorides and acid anhydrides?

A

N-substituted amide

38
Q

if the nucleophile is an alcohol ,what are the products of the acylation of acyl chlorides and acid anhydrides?

A

an ester

39
Q

if the nucleophile is water, what are the products of the acylation of acyl chlorides and acid anhydrides?

A

carboxylic acid ( hydrolyses the ester linkage)

40
Q

write an equation for the reaction of ethanoyl chloride and water?

A

CH3COCl +H2O —> CH3COOH + HCl

41
Q

what is a commercially important acylation reaction?

A

the manufacture of aspirin

42
Q

what are the + of using ethanoic anhydride as an acylating agent over ethanoyl chloride.

A

cheaper
less corrosive
does not react readily with water
safer as ethanoic acid is produced than HCl which is corrosive.

43
Q

what would you observe for the melting point of an impure sample?

A

sample melts over a large range
sample mp below accepted value due to impurities disrupting structures

44
Q

why is mp diff to true value?

A

apparatus error

45
Q

when removing flue gases, what are the issues?

A

disposal of large amounts of CaSO3 and CO3 is produced

46
Q

when purifying by recrystallisation, why is the minimum volume of hot solvent used?

A

so a saturated solution is created, so many crystals will be formed as soon as possible

47
Q

why is the solution filtered hot when purifying by recrystallisation?

A

to remove insoluble impurities and to ensure that crystals do not form in filter paper

48
Q

why is the solution cooled by an ice bath when purifying by recrystallisation?

A

to ensure that as many crystals as possible fall out of the solution - higher yield

49
Q

why are crystals washed with cold water when purifying by recrystallisation?

A

to remove soluble impurities

50
Q

how will you remove crystals from the reaction mixture when purifying by recrystallisation?

A

filter under reduced pressure using a Buchner funnel

51
Q

why might percentage yield be below 100%?

A

product lost by filteration, drying and weighing
product is left dissolved in the solution - some does not crystallise
sample is still wet

CHEMISTRY2 (7 decks)

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