1
Q
What is the key difference between primary and secondary alcohols?
A
Primary alcohols have no more than one carbon atom directly bonded to the carbon of the C-OH group, while secondary alcohols have two carbon atoms bonded to that carbon.
2
Q
What functional group do all primary alcohols contain?
A
-CH,OH
3
Q
What functional group do all secondary alcohols contain?
A
-CH(OH)
4
Q
What is an example of a primary alcohol?
A
propan-1-ol
5
Q
What is an example of a secondary alcohol?
A
pentan-3-ol
6
Q
What are two common methods of forming primary and secondary alcohols?
A
- From halogenoalkanes by a substitution reaction
- By reducing aldehydes, ketones, or carboxylic acids
7
Q
True or False: All primary alcohols can be formed by reducing ketones.
A
False
8
Q
Fill in the blank: Secondary alcohols have _______ carbon atoms bonded to the carbon atom of the C-OH group.
A
two
9
Q
What is the process used to produce butan-1-ol from 1-bromobutane?
A
Refluxing halogenoalkane with an aqueous solution of an alkali
Typically sodium or potassium hydroxide is used in the reaction.
10
Q
What method is used to separate butan-1-ol from unreacted 1-bromobutane?
A
Fractional distillation
11
Q
Fill in the blank: The reaction of a halogenoalkane with an alkali produces an _______.
A
Alcohol
12
Q
True or False: Fractional distillation is effective because butan-1-ol and 1-bromobutane have the same boiling point.
A
False
13
Q
What ion acts as the nucleophile in the described reaction?
A
Hydroxide ion (OH)
14
Q
In nucleophilic substitution, which atom does the hydroxide ion attack?
A
The relatively positive carbon atom (8+) of the C-Br bond
15
Q
What is the general order of hydrolysis rate for haloalkanes?
A
C-I > C-Br > C-Cl
16
Q
What happens to the yield of alcohol if the concentration of alkali is too high?
A
The yield of alcohol is reduced
17
Q
What type of solution can also reduce the yield of alcohol?
A
Ethanolic solution of the alkali
18
Q
What can aldehydes and ketones be reduced to?
A
Primary and secondary alcohols respectively
19
Q
What reducing agent is often represented by [H] in equations?
A
Sodium tetrahydridoborate (III) or sodium borohydride, NaBH4
20
Q
Fill in the blank: Aldehyde + 2[H] → _______
A
Alcohol
21
Q
What is phenylmethanal commonly known as?
A
Benzaldehyde
22
Q
What is not powerful enough to reduce carboxylic acids?
A
Sodium tetrahydridoborate (III)
23
Q
What is the stronger reducing agent used for carboxylic acids?
A
Lithium tetrahydridoaluminate (III) or lithium aluminium hydride, LiAlH4
24
Q
Fill in the blank: Lithium aluminium hydride is dissolved in _______
A
Ethoxyethane
25
What is a safer reaction for reduction?
Reduction using sodium tetrahydridoborate(III)
## Footnote
It is considered safer compared to lithium tetrahydridoaluminate(III) due to disposal issues.
26
What is a disposal issue related to lithium tetrahydridoaluminate(III)?
Difficult to dispose of in an easy way
## Footnote
This makes it less desirable for certain reactions.
27
What is a characteristic of ethoxyethane?
Very flammable
## Footnote
Its flammability poses safety risks during reactions.
28
What is used to obtain a good yield of alcohol in the reduction process?
An excess of the reducing agent
## Footnote
This helps ensure that the reaction goes to completion.
29
How can the excess reducing agent be removed?
By adding a dilute acid
## Footnote
This step is necessary after the reduction process.
30
What technique is used to separate the organic product from the aqueous mixture?
Using a separating funnel or solvent extraction
## Footnote
The choice depends on the miscibility of the alcohol with water.
31
When is a separating funnel used?
When the alcohol produced is immiscible with water
## Footnote
This allows for easier separation of layers.
32
What is solvent extraction?
A technique involving adding an organic solvent like ethoxyethane
## Footnote
This is used to separate the organic product from the aqueous phase.
33
What is produced by reacting primary or secondary alcohols with hydrogen halides?
Halogenalkanes
## Footnote
These reactions are generally slow and reversible, often giving poor yields.
34
What catalyst is used in the chlorination of alcohols?
Anhydrous zinc chloride
## Footnote
Hydrogen chloride gas is passed into the alcohol in the presence of this catalyst.
35
What alternative reagents can be used in chlorination reactions?
* Phosphorus(V) chloride
* Sulfur(VI) oxide dichloride (SOCl)
## Footnote
SOCl is often preferred because its co-products are gaseous, making separation easier.
36
What is one method for iodination of alcohols?
Reflux the alcohol with an excess of hydriodic acid
## Footnote
This method involves the reaction CH₃CH₂CH(OH) + HI → CH₃CH₂CH₃ + H₂O.
37
What is the product formed when an alcohol reacts with ethanoyl chloride?
An ester is formed
## Footnote
During the reaction, misty fumes of hydrogen chloride are seen.
38
Why does the reaction of alcohol with ethanoyl chloride yield a better ester than using a carboxylic acid?
The reaction is not reversible
## Footnote
This irreversibility improves the yield of the ester.
39
What is a disadvantage of using ethanoyl chloride in the production of esters?
It is not a cost-efficient process in industry
## Footnote
The cost of acid chlorides makes this method less economical.
40
What are the reactants in the iodination reaction of alcohols?
Alcohol and hydriodic acid
## Footnote
The example given is CH₃CH₂CH(OH) reacting with HI.
41
What do primary and secondary alcohols react with to produce esters?
Carboxylic acids
## Footnote
This reaction forms esters and water.
42
What is the general reaction formula for the reaction between alcohol and carboxylic acid?
alcohol + carboxylic acid → ester + H2O
## Footnote
This equation represents the formation of esters.
43
What is added to the mixture of alcohol and carboxylic acid to increase the equilibrium yield of the ester?
Concentrated sulfuric(VI) acid
## Footnote
This catalyst helps drive the reaction towards ester formation.
44
What is the purpose of heating the mixture under reflux?
To promote the reaction and reach equilibrium
## Footnote
This technique allows the reaction to proceed without loss of volatile components.
45
What does the distillate generally consist of after distillation of the products?
Ester, water, unreacted alcohol, and carboxylic acid
## Footnote
The distillate may form two layers if the ester is immiscible with water.
46
How is the ester extracted from the distillate?
Using a separating funnel
## Footnote
This technique separates the two immiscible layers.
47
What solution is the ester shaken with to remove any remaining carboxylic acid?
Sodium hydrogencarbonate solution
## Footnote
This step neutralizes the carboxylic acid.
48
What substance is used to dry the ester?
Anhydrous calcium chloride
## Footnote
It reacts with any remaining alcohol and water.
49
What can be done to obtain a pure product of the ester?
Redistill the ester
## Footnote
This process further purifies the ester by separating it from impurities.
50
What is a water bath used for?
A water bath is used for heating substances in a controlled manner.
51
What acid is commonly used in ester formation?
Ethanoic acid.
52
What is the role of H2SO4 in the esterification process?
H2SO4 acts as a catalyst in the esterification process.
53
What is one important use of esters outside of cosmetics?
Esters are used as solvents, for example, in nail varnish.
54
What are phenols?
Aromatic compounds where -OH groups are bonded directly to a benzene ring
55
What is the structure of phenol?
C6H5OH
## Footnote
Phenol consists of a benzene ring (C6H5) with a hydroxyl group (-OH) attached.
56
What is PCMX?
4-chloro-3,5-dimethylphenol, the active ingredient in Detto|T™
57
How does the reactivity of phenols compare to alcohols?
Phenols have different reactivity due to overlap of oxygen's lone pair with the delocalised π system
58
What effect does extended delocalisation in phenols have on the ring structure?
Creates higher electron density, making it more susceptible to attack by electrophiles
59
Is phenol a stronger or weaker acid than ethanol?
Stronger acid
60
How does phenol's acidity compare to ethanoic acid?
Considerably weaker acid
61
What does the position of equilibrium indicate about phenol ionization?
Lies to the left
62
What gives added stability to the phenoxide anion?
Delocalisation of the negative charge
## Footnote
Delocalisation refers to the spreading out of the negative charge over a larger area, which stabilizes the anion.
63
Why is phenol not very soluble in water?
The -OH group is a small part of a largely hydrophobic molecule
## Footnote
Hydrophobic molecules do not interact favorably with water, leading to low solubility.
64
What is formed when phenol reacts with sodium hydroxide?
Sodium phenoxide and water
## Footnote
The reaction shows phenol acting as an acid by losing a proton.
65
What affects the acidity of phenol?
The presence of substituents on the benzene ring
## Footnote
Different substituents can either withdraw or donate electron density, influencing acidity.
66
Can phenol react with sodium carbonate or sodium hydrogencarbonate to produce carbon dioxide?
No
## Footnote
Phenol is a weak acid and does not have sufficient acidity to react with these carbonates.
67
What is a simple test to distinguish between ethanoic acid and phenol?
Add sodium carbonate solution
## Footnote
Ethanoic acid will produce bubbles of carbon dioxide, while phenol will not.
68
Fill in the blank: The reaction of phenol with sodium hydroxide produces _______.
Sodium phenoxide
## Footnote
This reaction demonstrates the acidic nature of phenol.
69
What group activates the benzene ring in phenol?
-OH group
## Footnote
The hydroxyl group increases the electron density in the benzene ring, making it more reactive towards electrophiles.
70
Which positions on the benzene ring are activated to a greater extent by the -OH group?
2-, 4-, and 6-positions
## Footnote
These positions are more likely to undergo substitution reactions due to the activation by the hydroxyl group.
71
What products are formed when phenol is treated with dilute nitric acid?
2-nitrophenol and 4-nitrophenol
## Footnote
The reaction leads to the substitution of hydrogen atoms at the activated positions.
72
What is the result of phenol reacting with bromine?
2,4,6-tribromophenol
## Footnote
The reaction with bromine water leads to the formation of a white precipitate of the tribrominated compound.
73
What happens to bromine molecules when they react with phenol?
They polarize, forming Bro+- Br°
## Footnote
The increased electron density in the phenol ring causes the polarization of bromine molecules.
74
What type of reaction occurs between phenol and bromine?
Electrophilic substitution
## Footnote
The -OH group makes the phenol ring susceptible to electrophilic attack.
75
What color is aqueous bromine?
Orange
76
What happens to the orange color of bromine when it reacts with phenol?
The orange color disappears - bromine is decolourised
77
What type of reaction occurs when bromine reacts with phenol?
Electrophilic substitution
78
What are the products of the reaction of bromine with phenol?
A colourless solution and a white precipitate
79
What role do alcohols and phenols play in chemical reactions?
They react as nucleophiles using their oxygen lone pairs.
80
Why is phenol less reactive as a nucleophile compared to alcohols?
Due to the delocalisation of an electron pair from the oxygen atom in a phenol.
81
What base can be added to speed up the reaction of phenol with ethanoyl chloride?
Pyridine
82
What is often used in preference to ethanoyl chloride due to its cost?
Ethanoic anhydride
83
Fill in the blank: Alcohols and phenols can react as nucleophiles by the use of their oxygen _______.
lone pairs
84
What is the general outcome of the reaction between phenol and ethanoyl chloride?
Formation of an ester
85
What happens when phenol is reacted with a less reactive acyl chloride like benzoyl chloride?
Aqueous conditions can be used as the acyl chloride is only slowly hydrolysed by water.
86
What is added to phenol in the reaction with benzoyl chloride?
Aqueous sodium hydroxide.
87
What color is produced when phenol reacts with iron(III) chloride?
Purple.
88
What functional group must be present for a compound to produce a color with iron(III) chloride?
-OH group bonded directly to a benzene ring.
89
What colors can the complex formed with iron(III) chloride be?
Purple, blue, or green.
90
What is the purpose of testing phenols with aqueous iron(III) chloride?
To differentiate between an aliphatic alcohol and a phenol.
