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CH26 Carbonyl group Flashcards

(78 cards)

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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
What intermolecular forces present
H bonds in solid state
26
What are esters
Formed from carboxylic acids and alcohols | RCOOR' (C=O and C-O-C)
27
Equation for reaction of ethanoic acid and propan-1-ol
CH3COOH + CH3CH2CH2OH --> CH3COOCH2CH2CH3 + H2O
28
Naming esters
Start with group that replaced hydrogen Then acid part Propyl (alcohol) Ethanoate (carboxylic acid)
29
Physical properties of esters
Volatile | Pleasant smells
30
Uses of esters
Flavourings Perfumes Solvents Plasticisers
31
Common natural esters
Fats and oils
32
Equation for equilibrium of ethanoic acid in solution
CH3COOH ⇌ CH3COO- + H+
33
What happens to negative charge on ethanoate ion in terms of electrons
Electrons delocalise so negative charge is shared across carboxylate group
34
How to distinguish carboxylic acids from other -OH compounds
Add NAHCO3 - acids with produce sodium salt, water and carbon dioxide
35
Equation for reaction of ethanoic acid and NaOH
CH3COOH + NaOH --> H2O + CH3COO-Na+
36
Equation for ethanoic acid and Na2CO3
2CH3COOH + Na2CO3 --> 2CH3COO-Na+ + H2O + CO2
37
What catalyst needed for formation of esters from alcohols and carboxylic acids
Concentrated strong acrid - H2SO4
38
What catalyst needed for hydrolysis of esters
Dilute strong acid - H2SO4
39
Alternate method of hydrolysis
Base hydrolysis
40
Advantages of base hydrolysis
Reaction goes to completion due to neutralisation by base - more product in mixture
41
Which alcohol forms esters that make up animal and vegetable oils
Glycerol
42
Difference between oil and fat
``` Oil = liquid at RT and not saturated Fats = solid at RT and saturated ```
43
Products of hydrolysing fats and oils
Propane-1,2,3-triol and sodium salts of acid that make up the ester
44
Uses of these products
Soaps and cleaning products
45
What does the long hydrocarbon chain of the carboxylate ion do
Mixes with grease
46
What does the COO- group do
Mixes with water
47
Common uses of glycerol
Stops creams drying out Solvent in medicines and food Plasticising materials
48
How to make biodiesel
NaOH catalyst - 60 degrees C | Lipids + 3CH3OH --> 3 methyl esters + glycerol
49
What does transesterification mean
Converting 1 type of ester to another
50
What kind of crops is biodiesel made from
Rapeseed or soybean oil
51
How is the reaction mixture of biodiesel purified and separated
Settling tank or centrifuge Remove remainder with water Add acid to neutralise excess alkali catalyst forming solid soap which can be removed
52
Problem with producing biodiesel
Crops for food used to make fuel
53
What are carboxylic acid derivatives
Molecules that contain the acyl group
54
2 acid derivatives and functional groups
Acyl chlorides - RCOCl | Acid anhydrides - RCOOCR
55
Which factors determine how readily the acylation of a nucleophile by an acid derivative occurs
Magnitude of delta + How easily the atom being substituted is lost How good the nucleophile is
56
What effect do the Cl and O atom in acyl chlorides / acid anhydrides have on the partial charge of carbonyl carbon
Increases partial + charge by attracting electrons - meaning they react more readily with nucleophiles
57
Are acyl chlorides or acid anhydrides more reactive
Acyl chlorides
58
Name of mechanism by which acylation occurs
Addition-elimination
59
If nucleophile is ammonia for acylation of acyl chloride or acid anhydride - what is product
Amide
60
Equation for reaction of ethanoyl chloride and ammonia
CH3COCl + 2NH3 --> CH3CONH2 + NH4Cl
61
If nucleophile is a primary amine, what are products of acylation
N-substituted amide
62
Equation for reaction of ethanoyl chloride and methylamine
CH3COCl + CH3NH2 --> CH3CONHCH3 + CH3NH3Cl
63
If nucleophile is an alcohol what is product of acylation
Ester
64
Equation for reaction of ethanoyl chloride and ethanol
CH3COCl + CH3CH2OH --> CH3COOCH2CH3 + HCl
65
If nucleophile is water, what are products of acylation
Carboxylic acid
66
What is name of acylation with water
Hydrolysis
67
Equation for reaction of ethanoyl chloride and water
CH3COCl + H2O --> CH3COOH + HCl
68
Commercially important acylation reaction
Manufacture of aspirin
69
Advantages of using ethanoic anhydride as acylating agent over ethanoyl chloride
Cheaper Less corrosive Safer - produces ethanoic acid instead of HCl
70
What would you observe in a melting point determination is sample not pure
Sample melts over a large range | Sample's melting point below accepted value due to impurities
71
Why might melting point appear different to true value
Temperature of material in machine different to temperature on thermometer - apparatus error
72
When removing flue gases - what are the issues
Disposal of large amounts of CaSO3 and CO2 produced
73
What conditions needed to form methyl esters from an acid anhydride or acyl chloride
React with methanol and heat gently under reflux
74
When purifying by recrystallisation, why is minimum volume of hot solvent used
So a saturated solution is created
75
Why is the solution filtered hot when purifying by recrystallisation
Remove insoluble impurities and ensure crystals do not form on filter paper
76
Why is solution cooled in ice bath
Higher yield
77
Why are crystals washed with cold water
Remove insoluble impurities
78
How to separate crystals from reaction mixture
Filter under reduced pressure using Buchner funnel

Chemistry (18 decks)

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