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Chemistry Organic 2 > Chapter 26 (Compounds Containing the Carbonyl Group) > Flashcards

Chapter 26 (Compounds Containing the Carbonyl Group) Flashcards

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1
Q

What is a carbonyl group?

A

C=O bond within a molecule.

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2
Q

What is the general formula for an aldehyde?

A

R-CHO

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3
Q

What is the general formula for a carboxylic acid?

A

R-COOH

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4
Q

How is an aldehyde formed?

A

Reacting a primary alcohol in acidified potassium dichromate (VI) and distilling off the product.

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5
Q

What method oxidises aldehyde to carboxylic acids?

A

Reflux

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6
Q

What are the results for fehling’s solution?

A

Blue to Brick Red for an aldehyde

No change for ketone

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7
Q

What are the results for Tollen’s reagent?

A

Silver mirror for aldehyde

No change for ketone

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8
Q

What are the intermolecular forces in carbonyls?

A

Cannot form hydrogen bonds to themselves but are attracted to permanent dipole forces.

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9
Q

How does the size of a carbonyl molecule affect solubility?

A

Smaller carbonyls are soluble as they can form hydrogen bonds with water. Up to 4 carbons dissolve in water and more carbons greatly decrease solubility.

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10
Q

Compare C=C and C=O

A

C=O is stronger than C=C and does not undergo reactions as easily.

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11
Q

What is the oxidising agent that causes alcohol’s and aldehydes to oxidise?

A

Potassium Dichromate/K2Cr2O7

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12
Q

What is the reagent and condition for oxidising an aldehyde to a carboxylic acid?

A

Reagent: Potassium Dichromate/K2Cr2O7

Conditions: Heat under Reflux

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13
Q

What is the observation when Potassium Dichromate is reduced?

A

Orange Dichromate ion (Cr2O7^2-) reduced to green Cr^3+ ion.

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14
Q

What is the formula for Tollens’ Reagent?

A

[Ag(NH3)2]+

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15
Q

What is the general equation for oxidising an aldehyde to an carboxylic acid?

A

R-CHO + [O] > R-COOH + H2O

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16
Q

What is the ionic equation for ethanal and Tollens’ Reagent?

A

CH3CHO + 2Ag+ + H2O > CH3COOH + 2Ag + 2H+

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17
Q

What is the ionic equation for ethanal and Fehling’s Solution?

A

CH3CHO + 2Cu2 + + 2H2O > CH3COOH + Cu2O + 4H+

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18
Q

What is the reagent and conditions for reducing a carbonyl?

A

Reagent: NaBH4 in aqueous ethanol or LiAlH4

Condition: Room temperature and pressure

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19
Q

How is the carboxyl reducing agent represented?

A

[H]

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20
Q

What type of reaction do aldehydes and ketones undergo when reacted with cyanide anions and hydride ions?

A

Nucleophilic Addition

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21
Q

Why is KCN used instead of HCN?

A

HCN is too weak as it proves to few ions so it would be a slow reaction.

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22
Q

Why is a racemate produced when cyanide attacks a carbonyl group?

A

It has a trigonal planar shape so it is equally likely to be attacked to either side.

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23
Q

What are aldehyde reduced to?

A

Primary alcohols

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24
Q

What are ketones reduced to?

A

Secondary alcohols

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25
What type of reaction is between a nickel catalyst and a carbonyl group?
Catalytic hydrogenation
26
What are the reagents and conditions when a carbonyl undergoes catalytic hydrogenation?
Reagents: Hydrogen and nickel catalyst Conditions: High Pressure
27
What is the general equation for oxidising an alcohol to an acid?
R-OH + 2[O] > R-COOH + 2H2O
28
How are carboxylic acids tested for?
Sodium carbonate which forms CO2 if acid is present which will be shown be effervescent
29
How are esters produced?
Reacting an alcohol with a carboxylic acid using an acid catalyst.
30
What are plasticisers used for?
Added to polymers to increase their flexibility.
31
What reaction produces esters?
Esterification which is a condensation reaction.
32
What reaction form triglycerides?
Esterification
33
How are soaps formed?
Hydrolysing fats/oils by boiling with sodium hydroxide.
34
What is the name of the reaction which forms soaps?
Saponification
35
What is used in an esterification reaction?
Acid catalyst and three moles of water per ester linkage.
36
What are fats?
Naturally occurring tri-esters formed between glycerol (propane-1,2,3-triol) and long chain fatty acids.
37
Why are soaps anionic detergents?
The carboxyl group is hydrophilic (attracted to water) and the non-polar hydrocarbon chain is hydrophobic (attracted to oils)
38
What is biodiesel and how is it made?
Mixture of methyl esters of fatty acids and is prepared from vegetable oils and methanol using a sodium hydroxide catalyst (NaOH).
39
What is the process of preparing biodiesel called?
Transesterification
40
How does the strength of carboxylic acids change as chain gets longer?
Weaker as electron density is pushed on to the COO- ion making it more negative and less stable so.
41
How do you make carboxylic acids stronger?
Add a chlorine atom which are electronegative and withdraw electron density for COO- ion making it less negative and more stable so stronger.
42
Why can methanoic acid be oxidised and what does it form?
It's structure has an aldehyde group as there is an O-H and a H (and =O) Forms carbonic acid (H2CO3) which decomposes to give CO2.
43
What are the conditions and reagent for an esterification reaction?
Reagent: Acid catalyst (H2SO4) Condition: Heat under reflux
44
Why do esters not form hydrogen bonds?
Although they are highly polar, there is no hydrogen bonded to an electronegative atom
45
How are esters hydrolysed?
Either heating with an acid or with NaOH
46
Why is the reaction between an ester and NaOH not reversible?
A carboxylic acid salt is produced (e.g. sodium propanoate) which is an anion of the carboxylic acid. The anion is resistant to attack by weak nucleophiles so is not reversible.
47
What is the reagent and conditions for reacting an acid with an ester?
Reagent: Dilute Acid (e.g. HCl) Condition: Heat under reflux
48
What is the reagent and conditions for reacting sodium hydroxide with an ester?
Reagent: Dilute NaOH Conditions: Heat under reflux
49
What are the properties of glycerol?
Forms hydrogen bonding very easily and is readily soluble in water.
50
Why can and can't biodiesel be referred to as carbon-neutral?
Can: The CO2 given off when the biodiesel is burnt was extracted from the air by photosynthesis when the plant grew. Can't: Energy is needed to irrigate plants, extract oil, heat reaction with methanol mixture which if the energy for these processes comes from fossil fuel then not carbon-neutral.
51
What is produced when an acyl chloride reacts with water and what are the reagent and condition?
Carboxylic acid (+HCl) Reagent: Water Condition: Room temperature
52
What is produced when an acid anhydride reacts with water and what are the reagent and condition?
2 x Carboxylic acid Reagent: Water Condition: Room temperature
53
What is the general formula for an acyl group?
R-CO-
54
What is the name of the reaction where an acyl group is inserted and what type of reaction?
Acylation Reaction Nucleophilic Addition Elimination Reaction
55
What is produced when an acyl chloride reacts with alcohol and what are the reagent and condition?
Ester (+HCl) Reagent: Alcohol Condition: Room temperature
56
What is produced when an acyl anhydride reacts with alcohol and what are the reagent and condition?
Ester + Carboxylic Acid Reagent: Alcohol Condition: Room Temperature
57
What is produced when an acyl anhydride reacts with ammonia and what are the reagent and condition?
Primary Amide Reagent: Ammonia Condition: Room temperature
58
What is produced when al chloride reacts with ammonia and what are the reagent and condition?
Primary Amide Reagent: Ammonia Condition: Room temperature
59
What is produced when an acyl chloride reacts with a primary amine and what are the reagent and condition?
Secondary Amide Reagent: Primary Amide Condition: Room temperature
60
What is produced when an acyl anhydride reacts with a primary amine and what are the reagent and condition?
Secondary Amide Reagent: Primary Amide Condition: Room temperature
61
What are the steps in producing aspirin?
1) Dissolve the impure compound in a minimum volume of hot solvent. 2) Hot filter solution through filter paper quickly. 3) Cool the filtered solution by inserting beaker in ice. 4) Suction filtrate with Buchner flask to separate out crystals. 5) Wash the crystals with distilled water. 6) Dry the crystals between absorbent paper
62
Why is the impure compound dissolved in a hot solvent when making aspirin?
Solvent will dissolve both compound and impurities when hot but compound will not dissolve well when cold.
63
Why is the minimum volume of a solvent used when making aspirin?
The minimum volume is used to obtain a saturated solution and to enable crystallisation when cooling.
64
Why is the solution filtered quickly when producing aspirin?
Removes any insoluble impurities and prevents crystals reforming during filtration.
65
Why is the solution cooled in ice beaker after filtering when producing aspirin?
Crystals will reform but soluble impurities will remain in solution because they are present in small quantities. Ice will increase yield of crystals.
66
How and why is suction filtration with a Buchner flask used to separate crystals when producing aspirin?
Water pump connected to Buchner flask reduces pressure and speeds up filtration.
67
Why are the crystals washed with distilled water when producing aspirin?
To remove soluble impurities.
68
Why is there a loss of yield when producing aspirin?
* Crystals lost when filtering or washing * Some products stay in solution after recrystallisation * Other side reactions occur
69
What are the pros and cons of using acyl chlorides vs acyl anhydrides?
Acyl chloride have faster reactions but produce corrosive HCl gas Acyl anhydrides have slower reactions/are less reactive (easier to control) but are cheaper and side products less toxic
70
What are the three steps in an addition-elimination reaction?
1) Addition of a nucleophile to the acyl compound 2) Elimination of the electronegative leaving group 3) Deprotonation (removal of H+)
71
Why are two moles of ammonia/amine nucleophiles used in an acylation reaction?
One acts as a nucleophile and the other reacts with the acid produced in the reaction.
72
What is added when reacting water or an alcohol to an acyl and why?
A base to neutralise the acid by product (HCl)
73
What is produced when acyl chloride reacts with water?
Carboxylic acid and HCl
74
What is produced when acyl chloride reacts with an alcohol?
Ester and HCl
75
What is produced when an acyl chloride reacts with an amine?
Amide and NH4Cl
76
What is formed when an acyl chloride reacts with an ammonia?
N-substituted amide and NH3RCl
77
What is produced when an acid anhydride reacts with water?
2 Carboxylic acids
78
What is produced when an acid anhydride reacts with an an alcohol?
Ester and carboxylic acid
79
What is produced when an acid anhydride reacts with an amine?
Amide and NH4RCOO
80
What is produced when an acid anhydride reacts with an ammonia?
N-substituted amide and NH3RRCOO
81
What type of reaction includes an acyl group?
Nucleophilic addition-elimination
82
What causes a polymer to be biodegradable?
can be hydrolysed OR can be reacted with/attacked by acid/base/nucleophiles/H O/OH–

Chemistry Organic 2 (9 decks)

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