Module 6: Carbonyl Compounds V2 Flashcards
1
Q
Draw a diagram to show how a π-bond is formed in a carbonyl compound (aldehyde/ketone)
A
2
Q
Describe the reactivity of a carbonyl compound (aldehyde/ketone)
A
Carbonyls contain a C=O bond and are either aldehydes or ketones. ✓
Sideways overlap of p-orbitals on C and O forms a π-bond above and below the plane of the C-O. ✓
Oxygen is more electronegative than carbon, there is a permanent dipole across the bond resulting in a polar bond. ✓
Nucleophiles such as OH-, H- and CN- are attracted to the Cδ+ atom in the C=O. ✓
3
Q
Draw the structure of the following:
1) 3,4-dimethylpentanal
2) Cyclopentanone
3) 2-chloro-3,4-dimethylpentanal
4) 2,3,4,5,6-pentamethyl heptanal
5) 2-bromo-6-chloro-5-ethyl-4-methylnonan-3-one
6) 4-penten-2-one
A
4
Q
A
5
Q
- Complete oxidation of butan-1-ol
- Complete oxidation of pentan-3-ol
- Partial oxidation of phenylmethanol
- Oxidation of hexanal
- Oxidation of benzldehyde
A
6
Q
Write equations showing the structure of the product made when the following molecule is added to an excess of acidified dichromate under distillation.
A
No reaction, as ketones cannot be oxidised further. ✓
7
Q
Write equations showing the structure of the product made when the following molecule is added to an excess of acidified dichromate under distillation.
A
8
Q
Write equations showing the structure of the product made when the following molecule is added to an excess of acidified dichromate under distillation.
A
9
Q
Write equations showing the structure of the product made when the following molecule is added to an excess of acidified dichromate under distillation.
A
10
Q
Write equations showing the structure of the product made when the following molecules are added to an excess of acidified dichromate under reflux.
A
11
Q
Give the reagents and conditions for the reduction of alehydes and ketones (to form primary and secondary alcohols respectively)
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12
Q
A
13
Q
A
14
Q
Write equations showing the reduction of the following with NaBH4:
A
15
Q
Write an equation showing the reduction of the following with NaBH4:
A
16
Q
A
17
Q
Using curly arrows, and partial charges, draw a mechanism for the reduction of benzaldehyde.
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18
Q
Using curly arrows, and partial charges, draw a mechanism for the reduction of cyclopentanone.
A
19
Q
Using curly arrows, and partial charges, draw a mechanism for the reduction of 2,3-dimethylbutanal.
A
20
Q
2-hydroxybutanenitrile can be prepared from propanal.
1) State the reagents required for this reaction
2) Write an equation for this reaction using
a) Skeletal formula
b) Molecular formula
3) Draw a mechanism for this reaction
A
21
Q
2-methylpropanal can react with NaCN and sulfuric acid to form a hydroxynitrile. Draw a mechanism for this reaction.
A
22
Q
2-methylpropanal can react with NaCN and sulfuric acid to form a hydroxynitrile. Name the mechanism of this reaction.
A
Nucleophilic addition. ✓
23
Q
A
C. ✓
24
Q
This question is about the synthesis of a polymer. The flowchart below shows the synthesis of polymer I starting from benzene.
a) Draw the structures of the missing compounds in the boxes and add the missing reagents on the dotted lines
b) Polymer I cannot be disposed of in landfill sites as it is not biodegradable. Suggest two ways of processing waste polymer I other than landfill and recycling.
A
a) in image
b) Use as an organic feedstock ✓
Combustion for energy production ✓
25
Describe a test to to identify a carbonyl compound
Add 2,4-dinitrophenylhydrazine (2,4-DNPH) ✓
Orange precipitate made ✓
26
Explain the main steps in identifying an aldehyde as being uniquely pentanal. Your answer must not include spectroscopy.
Add 2,4-DNPH and an orange precipitate is made ✓
Filter, recrystalise and dry the precipitate ✓
Take the melting point and match it to known values ✓
Each precipitate has its unique melting point ✓
27
Describe a test to test for the aldehyde ethanal.
Add Tollens’ reagent ✓
Silver mirror precipitate made indicating aldehyde present ✓
28
Explain why propanone and propan-1-ol will not react with tollens’ reagent
29
A student adds Tollens' reagent to a testube containing butanal. Explain what is observed. Include equations in your answer
30
The carbonyl compounds, F and G, shown below, contribute to the flavour of coffee.
Describe suitable chemical tests, with observations, that would confirm the presence of the functional groups in F and G.
F has an aldehyde functional group…
Add Tollens’ reagent, silver mirror precipitate formed ✓
G has a C=C functional group…
Add Br2, bromine water decolourised ✓
F has a no C=C functional group…
Add Br2, bromine water stays orange ✓
G has an ketone functional group…
Add Tollens’ reagent, no silver mirror precipitate formed ✓
G has an ketone functional group…
Add 2,4-DNPH reagent, orange precipitate ✓
31
32
A student plans to carry out some chemical tests on both cinnamaldehyde and methylcinnamaldehyde.
Suggest a suitable chemical test to confirm that both compounds contain an unsaturated carbon chain. Your answer should include the reagent and observations.
Add Br2(aq) ✓
Bromine water decolourised ✓
33
State which of the following will react with tollens' reagent:
a) ethanal.
b) benzaldehyde.
c) benzoic acid.
d) Cyclobutanone.
a) ethanal. ✓
b) benzaldehyde. ✓
34
State which of the following will react with 2,4-DNPH:
a) ethanal.
b) benzaldehyde.
c) benzoic acid.
d) Cyclobutanone.
a) ethanal. ✓
b) benzaldehyde. ✓
d) Cyclobutanone. ✓
35
Benzaldehyde reacts with tollens reagent. Write an equation for this reaction and state the type of reaction taking place.
Oxidation. ✓
36
The following reacts with tollens reagent. Write an equation for this reaction.
37
Explain why both butanone and butanol will not react with Tollen’s reagent.
38
You are provided with three test-tubes containing three colourless liquids. The liquids are an aldehyde, a ketone and an alcohol. Explain how you would identify each functional group using common laboratory chemicals. State any observations made and write equations for any reduction reactions taking place.
To each liquid, add 2,4-dinitrophenylhydrazine and an orange precipitate is made for the aldehyde and ketone but not for an alcohol. ✓
Filter, recrystalise and dry the precipitate ✓
OR add Na metal, alcohols fizzes but aldehydes and ketones do not.
Then add add Tollens’ reagent. ✓
Silver mirror precipitate made showing presence of aldehyde. ✓
Tollens is too weak an oxidising agent and cannot oxidise alcohols or ketones ✓
39
Add 2,4-dinitrophenylhydrazine and an orange precipitate is made ✓
Filter, recrystalise and dry the precipitate ✓
Take the melting point and match it to known values ✓
Each precipitate has its unique melting point ✓
40
Complete the following synthesis map by filling in the correct intermediates, products and reagents/ conditions.
41
i) What would you observe during reaction 1?
ii) In reaction 1, compound E was heated under reflux with excess K2Cr2O7/ H2SO4.
Suggest why these conditions were used, rather than the reaction mixture being distrilled during the process.
iii) Name the type of reaction taking place in reaction 2.
i) Colour change orange to green. ✓
ii) To ensure carboxylic acid is formed. ✓
Distillation only makes the aldehyde. ✓
iii) Reduction. ✓
42
4.56 of compound E was converted into compound G using the method shown in the flowchart.
3.15g of compound G was formed.
Calculate the percentage yield of compound G.
Give your answer to three significant figures.
Mr of compound E is 160.
43
Compound G is heated for several hours under reflux, in the presence of a concentrated sulfuric acid catalyst. An ester and a small inorganic molecules are formed.
Complete the equation below to show the two products formed by this reaction.
44
Alkylithium compounds, RLi, can be used to increase the number of carbon atoms in an organic compound. Different alkyl groups, R, add carbon chains with different chain lengths.
Rli provides a source of R- ions, which act as a nucleophile.
The diagram below shows an incomplete mechanism for the reaction of Rli with benzaldehyde, followed by reaction with aqueous acid.
a) Complete, using curly arrows and relevant dipoles, the mechanism for stage. Give the structure of the intermediate and the organic product.
b) A chemist needs to prepare the organic compound X from benzaldehyde.
Draw the structure of the alkylithium compound needed for this synthesis.
45
Describe a simple chemical test to show that cyclohexanone is not an aldehyde.
Add Tollen’s reagent. ✓
No silver mirror precipitate formed. ✓
46
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48
49
Explain why ethanoic acid is a liquid at room temperature, but ethane is a gas
Ethanoic acid has hydrogen bonding between molecules ✓
Ethane has induced dipole-dipole interactions between molecules ✓
Hydrogen bonding is stronger and requires more energy to overcome ✓
50
Explain why pentanoic acid has a higher boiling point compared to ethanoic acid
Pentanoic acid has more carbon atoms and a longer carbon chain ✓
More points of surface contact between molecules ✓
Pentanoic acid has stronger induced dipole-dipole interactions between molecules ✓
Which requires more energy to overcome ✓
51
Explain why the 3-methylbutanoic acid has a lower boiling point compared to pentanoic acid
3-methylbutanoic acid is more branched than pentanoic acid ✓
3-methyl butanoic acid has less points of surface contact between molecules ✓
3-methylbutanoic acid has weaker induced dipole-dipole interactions between molecules ✓
Which requires less energy to overcome ✓
52
State and explain the difference in solubility of butanoic acid and butanedioic acid
butanedioic acid is more soluble in water ✓
And has more OH groups ✓
butanedioic acid forms more hydrogen bonds with water ✓
53
State and explain why butanoic acid is less soluble than ethanoic acid
The greater the carbon chain length, the less soluble the carboxylic acid is in water ✓
There are stronger induced dipole-dipole interactions in longer carbon chains ✓
Which break up hydrogen bonds between molecules ✓
54
Ethanoic acid reacts with Mg.
a) Write an equation for this reaction and draw the structure of the salt made.
b) State what is observed.
c) Using oxidation states, prove that this is a redox reaction.
d) Using the number of electrons transferred, show that this is a redox reaction.
e) Write half equations to show the redox processes taking place.
55
56
57
State and explain the bond angle and shape around the C atom in methanoic acid
58
State and explain the bond angle and shape around the O (in OH) atom in methanoic acid
59
Using a labelled diagram, explain why methanoic acid has a higher boiling point compared to methane.
60
D. ✓
61
62
Using a labelled diagram, explain why methanoic acid is soluble in water.
63
A student adds a piece of sodium carbonate to a test-tube containing phenol. State and explain the observation made.
No visible change. ✓
Phenol is too weak an acid to react with metal carbonates. ✓
64
A student adds a piece of sodium metal to a test-tube containing ethanol. State the observation made.
Fizzing. ✓
65
Write balanced equations for the following reactions.
1. Propanoic acid with potassium oxide
2. Butanoic acid with magnesium hydroxide
3. Methanoic acid with potassium carbonate
4. Ethanoic acid with sodium hydrogen carbonate
66
Write an equation for the reaction of the following with
a) Potassium metal
b) Potassium hydroxide
c) Potassium carbonate.
67
Give two uses of Esters.
Food flavourings. ✓
Perfumes. ✓
68
69
Give the equation for the reaction between propanoic acid and butan-1-ol.
Name the ester formed.
70
An alcohol reacts with a carboxylic acid to form an ester.
a) State the reagents and conditions required.
b) State the type of reaction taking place.
c) State two alternative methods of making an ester which produces a higher yield.
a) under reflux ✓ in the presence of concentrated sulfuric acid catalyst. ✓
b) Condensation reaction. ✓
c) Reacting an alcohol with
Acid anhydrides ✓
Acyl chlorides. ✓
71
What is meant by a "condensation reaction"
reaction where water is removed. ✓
72
Using skeletal formula, write equations for the formation of:
1) methyl propanoate
2) ethyl butanoate
3) ethyl methanoate
73
Using skeletal formula, write equations for the formation of:
1) phenyl methanoate
2) 2-methylpropyl hexanoate
74
Using skeletal formula, write equations for the formation of phenyl benzoate.
75
4-hydroxybutanoic acid can react with itself in a condensation reaction. Write an equation to form one of the products.
76
Give the equation for the formation of ethanoic anhydride from its consistuent acids.
77
Give the equation for the formation of methanoicpropanoic anhydride from its consistuent acids.
78
Give the equation for the reaction of ethanoic anhydride reacting with propan-1-ol. Name the products.
79
The following acid anhydride reacts with ethanol to form a mixture of products. Give the struture of all four products, including a balanced equation on how each pair is made.
80
Write an equation for the acid hydrolysis of propyl ethanoate, using skeletal formula only.
81
Write an equation for the base hydrolysis of propyl ethanoate, using skeletal formula only.
82
Write fully balanced equations for the hydrolysis of propyl benzoate using:
a) Acid hydrolysis
b) Base hydrolysis
83
Write a fully balanced equation for the base hydrolysis of the following
84
Define what is meant by a "hydrolysis reaction"
The reaction with water to break down a compound. ✓
85
Write an equation for the conversion of the butanoic acid to an acyl chloride and name the acyl chloride that is made
86
Write an equation for the conversion of the following carboxylic acid to an acyl chloride
87
Write an equation, using skeletal formula, for the reaction between butanoyl chloride and water. Include the name of the organic product in your answer.
State the type of reaction taking place.
Condensation reaction. ✓
88
Write an equation, using skeletal formula, for the reaction between butanoyl chloride and ethanol. Include the name of the organic product in your answer.
State the type of reaction taking place.
Condensation reaction. ✓
89
Write an equation, using skeletal formula, for the reaction between butanoyl chloride and excess ammonia to make a primary amide. Include the name of the organic product in your answer.
State the type of reaction taking place.
90
Write an equation, using skeletal formula, for the reaction between butanoyl chloride and excess ethyl amine to make a secondary amide. Include the name of the organic product in your answer.
91
When synthesizing primary amides from acyl chlorides, explain why excess ammonia is used.
A second equivalent of ammonia is used to neutralise the HCl. ✓
otherwise the HCl would protonate the amide. ✓
92
When synthesizing secondary amides from acyl chlorides, explain why excess amine is used.
A second equivalent of amine is used to neutralise the HCl. ✓
otherwise the HCl would protonate the amide. ✓
93
Complete the following synthesis map for acyl chlorides
94
This question is about aromatic carboxylic acids and their derivatives. The flowchart below shows some reactions of compound H. In the boxes, draw the organic products of these reactions.
95
96
Complete the following synthesis map, including reagents and conditions to synthesize the target molecule.
| Propan-2-ol only, or drawn structure NOT propan-1-ol
97
Complete the following synthesis map, including reagents and conditions to synthesize the target molecule.
98
Complete the following synthesis map, including reagents and conditions to synthesize the target molecule.
99
Complete the following synthesis map, including reagents and conditions to synthesize the target molecule.
100
B 2-Methylpentan-1-ol. ✓
C 3-Methylpentan-2-ol. ✓
## Footnote
A is a tertiary alcohol. Can't be oxisided in the first place to form a carbonyl compound.
101
Draw the structure of the carbonyl compound used to synthesize the following hydroxynitriles.
102
Plan a two-step synthesis to form product B from starting material A including reagents and conditions for each step.
103
Qualitative tests are carried out on an aliphatic compound which contains 3 carbon atoms.
The results are shown below.
Deduce the structure of the compound.
104
Qualitative tests are carried out on an aromatic compound which contains 8 carbon atoms.
The results are shown below.
Deduce 3 plausible structures of the compound.
105
Oud (agarwood) contains a variety of chemical compounds, including esters, which contribute to its complex scent profile. Some of the esters found in oud and agarwood oil include the compounds below.
Give the balanced equations for the formation of the following esters from their initial carboxylic acid.
106
Give the equation for the reaction between propanoic acid and butan-1-ol.
Name the ester formed.
107
Glycolic acid, shown below, can react to form all possible organic products.
Draw both products formed from this reaction.
108
The reaction between A and B forms a mixture of four compounds.
Draw the structure of each of them.
109
Complete the following synthesis map
