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Chemistry > CH26 Carbonyl group > Flashcards

CH26 Carbonyl group Flashcards

1
Q

What is carbonyl group

A

C=O

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2
Q

Functional group and general formula for aldehyde

A

RCHO

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3
Q

Functional group for ketone

A

RCOR’

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4
Q

Naming aldehydes

A

-al suffix

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5
Q

Naming ketones

A

-one suffix

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6
Q

What intermolecular forces do they have - why

A

Permanent dipole-dipole due to polar C=O bond

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7
Q

How soluble in water

A

Very - form H bonds between water molecules and O of C=O

As chain length increases, solubility decreases

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8
Q

Which bond in carbonyl compounds is usually involved in reactions - why

A

C=O, due to polarity of the bond

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9
Q

Strongest bond in carbonyl compounds

A

C=O

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10
Q

Why is addition of HCN important for nucleophilic adddition

A

Increases length of C chain by 1 C atom

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11
Q

Will product of nucleophilic addition of HCN to carbonyl have optical isomers - why

A

Yes - carbonyl carbon is planar, so :CN- can attack from above or below forming 2 enantiomers

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12
Q

Name of product of nucleophilic addition of HCN to carbonyl

A

Hydroxynitriles

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13
Q

What is Fehling’s solution + colour

A

Copper complex ions

Blue

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14
Q

What happens when aldehyde is added to Fehling’s

A

Reduced to Cu+ ion

Colour change to brick red ppt

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15
Q

What happens when ketone is added to Fehling’s

A

No visible change

Stays blue

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16
Q

What is in Tollen’s reagent + colour

A

Silver complex ions

Colourless

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17
Q

What happens when aldehyde is added to Tollen’s

A

Ag+ reduced to Ag

Silver mirror forms

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18
Q

What happens when ketone added to Tollen’s

A

No visible change

Stays colourless

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19
Q

Another oxidising agent for alcohols and aldehydes

A

Acidified potassium dichromate (VI) - H2SO4 and K2Cr2O7

Colour change from orange to green

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20
Q

Reducing agent for aldehydes and ketones

A

NaBH4 - releases H- ion

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21
Q

Equation for reduction of pentan-2-one

A

CH3COCH2CH2CH3 + 2[H] –> CH3CH(OH)CH2CH2CH3

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22
Q

Functional group of carboxylic acid

A

-COOH (C=O and C-OH)

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23
Q

Naming carboxylic acids

A

-oic acid

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24
Q

Are they soluble in water - why

A

Yes - acid group forms H bonds with water molecules

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25
Q

What intermolecular forces present

A

H bonds in solid state

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26
Q

What are esters

A

Formed from carboxylic acids and alcohols

RCOOR’ (C=O and C-O-C)

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27
Q

Equation for reaction of ethanoic acid and propan-1-ol

A

CH3COOH + CH3CH2CH2OH –> CH3COOCH2CH2CH3 + H2O

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28
Q

Naming esters

A

Start with group that replaced hydrogen
Then acid part
Propyl (alcohol) Ethanoate (carboxylic acid)

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29
Q

Physical properties of esters

A

Volatile

Pleasant smells

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30
Q

Uses of esters

A

Flavourings
Perfumes
Solvents
Plasticisers

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31
Q

Common natural esters

A

Fats and oils

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32
Q

Equation for equilibrium of ethanoic acid in solution

A

CH3COOH ⇌ CH3COO- + H+

33
Q

What happens to negative charge on ethanoate ion in terms of electrons

A

Electrons delocalise so negative charge is shared across carboxylate group

34
Q

How to distinguish carboxylic acids from other -OH compounds

A

Add NAHCO3 - acids with produce sodium salt, water and carbon dioxide

35
Q

Equation for reaction of ethanoic acid and NaOH

A

CH3COOH + NaOH –> H2O + CH3COO-Na+

36
Q

Equation for ethanoic acid and Na2CO3

A

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

37
Q

What catalyst needed for formation of esters from alcohols and carboxylic acids

A

Concentrated strong acrid - H2SO4

38
Q

What catalyst needed for hydrolysis of esters

A

Dilute strong acid - H2SO4

39
Q

Alternate method of hydrolysis

A

Base hydrolysis

40
Q

Advantages of base hydrolysis

A

Reaction goes to completion due to neutralisation by base - more product in mixture

41
Q

Which alcohol forms esters that make up animal and vegetable oils

A

Glycerol

42
Q

Difference between oil and fat

A 
Oil = liquid at RT and not saturated
Fats = solid at RT and saturated
43
Q

Products of hydrolysing fats and oils

A

Propane-1,2,3-triol and sodium salts of acid that make up the ester

44
Q

Uses of these products

A

Soaps and cleaning products

45
Q

What does the long hydrocarbon chain of the carboxylate ion do

A

Mixes with grease

46
Q

What does the COO- group do

A

Mixes with water

47
Q

Common uses of glycerol

A

Stops creams drying out
Solvent in medicines and food
Plasticising materials

48
Q

How to make biodiesel

A

NaOH catalyst - 60 degrees C

Lipids + 3CH3OH –> 3 methyl esters + glycerol

49
Q

What does transesterification mean

A

Converting 1 type of ester to another

50
Q

What kind of crops is biodiesel made from

A

Rapeseed or soybean oil

51
Q

How is the reaction mixture of biodiesel purified and separated

A

Settling tank or centrifuge
Remove remainder with water
Add acid to neutralise excess alkali catalyst forming solid soap which can be removed

52
Q

Problem with producing biodiesel

A

Crops for food used to make fuel

53
Q

What are carboxylic acid derivatives

A

Molecules that contain the acyl group

54
Q

2 acid derivatives and functional groups

A

Acyl chlorides - RCOCl

Acid anhydrides - RCOOCR

55
Q

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

A

Magnitude of delta +
How easily the atom being substituted is lost
How good the nucleophile is

56
Q

What effect do the Cl and O atom in acyl chlorides / acid anhydrides have on the partial charge of carbonyl carbon

A

Increases partial + charge by attracting electrons - meaning they react more readily with nucleophiles

57
Q

Are acyl chlorides or acid anhydrides more reactive

A

Acyl chlorides

58
Q

Name of mechanism by which acylation occurs

A

Addition-elimination

59
Q

If nucleophile is ammonia for acylation of acyl chloride or acid anhydride - what is product

A

Amide

60
Q

Equation for reaction of ethanoyl chloride and ammonia

A

CH3COCl + 2NH3 –> CH3CONH2 + NH4Cl

61
Q

If nucleophile is a primary amine, what are products of acylation

A

N-substituted amide

62
Q

Equation for reaction of ethanoyl chloride and methylamine

A

CH3COCl + CH3NH2 –> CH3CONHCH3 + CH3NH3Cl

63
Q

If nucleophile is an alcohol what is product of acylation

A

Ester

64
Q

Equation for reaction of ethanoyl chloride and ethanol

A

CH3COCl + CH3CH2OH –> CH3COOCH2CH3 + HCl

65
Q

If nucleophile is water, what are products of acylation

A

Carboxylic acid

66
Q

What is name of acylation with water

A

Hydrolysis

67
Q

Equation for reaction of ethanoyl chloride and water

A

CH3COCl + H2O –> CH3COOH + HCl

68
Q

Commercially important acylation reaction

A

Manufacture of aspirin

69
Q

Advantages of using ethanoic anhydride as acylating agent over ethanoyl chloride

A

Cheaper
Less corrosive
Safer - produces ethanoic acid instead of HCl

70
Q

What would you observe in a melting point determination is sample not pure

A

Sample melts over a large range

Sample’s melting point below accepted value due to impurities

71
Q

Why might melting point appear different to true value

A

Temperature of material in machine different to temperature on thermometer - apparatus error

72
Q

When removing flue gases - what are the issues

A

Disposal of large amounts of CaSO3 and CO2 produced

73
Q

What conditions needed to form methyl esters from an acid anhydride or acyl chloride

A

React with methanol and heat gently under reflux

74
Q

When purifying by recrystallisation, why is minimum volume of hot solvent used

A

So a saturated solution is created

75
Q

Why is the solution filtered hot when purifying by recrystallisation

A

Remove insoluble impurities and ensure crystals do not form on filter paper

76
Q

Why is solution cooled in ice bath

A

Higher yield

77
Q

Why are crystals washed with cold water

A

Remove insoluble impurities

78
Q

How to separate crystals from reaction mixture

A

Filter under reduced pressure using Buchner funnel

Chemistry (18 decks)

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