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WJEC Chemistry > Alcohols > Flashcards

Alcohols Flashcards

1
Q

Define Hydrolysis

A

Decomposition of a compound by reaction with water.

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2
Q

Define Alkaline Hydrolysis

A

Hydrolysis: splitting compound with elements of water, Alkaline: relating to an alkali/alkali metal/base (pH>7) Alkali metals are the first column Li, Na, K, etc

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3
Q

Define Reagent

A

Substance used in a chemical reaction to detect, measure, examine or produce other substances

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4
Q

What is formed from the alkaline hydrolysis of a halogenalkane?

A

An Alcohol (OH replaces the Halogen via Nucleophilic Substitution)

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5
Q

What is formed from adding NaOH(aq) and heat to a Halogenalkane?

A

An Alcohol (OH replaces the Halogen via Nucleophilic Substitution)

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6
Q

What is formed from Nucleophilic Substitution of a Halogenalkane?

A

An Alcohol (OH replaces the Halogen via Nucleophilic Substitution)

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7
Q

An alcohol is formed using NaOH(aq) and heat from what?

A

A Halogenalkane (OH replaces the Halogen via Nucleophilic Substitution)

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8
Q

An Alcohol is formed using Nucleophilic Substitution from what?

A

A Halogenalkane (OH replaces the Halogen via Nucleophilic Substitution)

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9
Q

What mechanism occurs in the alkaline hydrolysis of Halogenalkane?

A

Nucleophilic Substitution to form an Alcohol

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10
Q

What mechanism occurs when NaOH(aq) and heat are added to a Haolgenalkane?

A

Nucleophilic Substitution occurs to form an Alcohol

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11
Q

Write a balanced equation and name all reagents and conditions to form an Alcohol from a Halogenalkane

A

CH3CH2Br + OH- ->
CH3CH2OH + Br-
Reagent: NaOH(aq)
Condition: Heat

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12
Q

Define Reduction

A

A half reaction in which a chemical species decreases it’s oxidation number (usually by electron gain)

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13
Q

Define Reducing Agent

A

A Reducing Agent donates electrons and is itself oxidised

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14
Q

What are the reagents and conditions for the formation of alcohols from carbonyls?

A

Just a Reducing Agent: NaBH4

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15
Q

NaBH4 is used to form a Secondary Alcohol from what?

A

A Ketone is reduced by NaBH4 to form a Secondary Alcohol

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16
Q

NaBH4 is used to form a Primary Alcohol from what?

A

An Aldehyde is reduced by NaBH4 to form a Primary Alcohol

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17
Q

A Carbonyl is treated with NaBH4 to form what?

A

Either a Primary or a Secondary Alcohol depending on whether the Carbonyl is an Aldehyde or Ketone respectively.

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18
Q

A Secondary Alcohol will be formed from the reduction of what?

A

Only a Ketone forms a Secondary Alcohol by reduction (Haloalkanes can form them by Hydrolyis) Both Aldehydes and Carboxylic Acids reduce to form a Primary Alcohol

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19
Q

NaBH4 is used to form a Primary Alcohol from what?

A

An Aldehyde is reduced by NaBH4

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20
Q

What are the reagents and conditions to form an Alcohol from a Carboxylic Acid?

A

LiAlH4 in Dry Ether acts as a Reducing Agent on the Carboxylic acid forming a Primary Alcohol
(NaBH4 does not work, as an even stronger reducing agent is needed)

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21
Q

LiAlH4 with a Carboxylic acid forms what?

A

A Primary Alcohol is the result of reduction by the LiAlH4 of the Acid

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22
Q

An Alcohol is formed with LiAlH4 from what?

A

A Carboxylic Acid is reduced by LiAlH4 to form a Primary Alcohol

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23
Q

How many ways are the to form an Alcohol?

A 
Five Ways:
Alkaline Hydrolysis of a Haloalkane
Reduction of an Aldehyde
(But not a Ketone)
Reduction of a Carboxylic Acid
Electrophilic addition from an alkene
Diazotisation of an amine
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24
Q

How can a Primary Alcohol be formed?

A 
Five Ways:
Alkaline Hydrolysis of a Haloalkane
Reduction of a Carbonyl
Reduction of a Carboxylic Acid
Electrophilic addition from an alkene
Diazotisation of an amine
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25
Q

How can a Secondary Alcohol be formed?

A

Two Ways:
Alkaline Hydrolysis of a Haloalkane
Reduction of a Ketone
(But not an Aldehyde)

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26
Q

How can a Tertiary Alcohol be formed?

A

Alkaline Hydrolysis of a Haloalkane is the only way

The Carbon attached to the Halogen has to have 3 R groups for this to occur

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27
Q

Draw Alkaline Hydrolysis of a Halogen Alkane

A 
Br= any halogen
R= carbon chain/H group

C-Br have (d+) and (-) respectively,
C has 3 other R groups,
HO- curvy-> C opposite to Br(d-),
from C-Br bond curvy-> Br(d-),
-------Across the Arrow-------
Intermediate both dotted bond,
All in straight brackets (-) sign
-------Across the Arrow-------
Br- formed separately
OH bonded opposite Br original
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28
Q

Draw formation of Alcohol from Haloalkane

A 
Br= any halogen
R= carbon chain/H group

C-Br have (d+) and (-) respectively,
C has 3 other R groups,
HO- curvy-> C opposite to Br(d-),
from C-Br bond curvy-> Br(d-),
-------Across the Arrow-------
Intermediate both dotted bond,
All in straight brackets (-) sign
-------Across the Arrow-------
Br- formed separately
OH bonded opposite Br original
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29
Q

Draw Haloalkane reacting woth NaOH(aq) in heat

A 
Br= any halogen
R= carbon chain/H group

C-Br have (d+) and (-) respectively,
C has 3 other R groups,
HO- curvy-> C opposite to Br(d-),
from C-Br bond curvy-> Br(d-),
-------Across the Arrow-------
Intermediate both dotted bond,
All in straight brackets (-) sign
-------Across the Arrow-------
Br- formed separately
OH bonded opposite Br original
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30
Q

Draw formation of Alcohol using Nucleophilic Substitution Mechanism

A 
Br= any halogen
R= carbon chain/H group

C-Br have (d+) and (-) respectively,
C has 3 other R groups,
HO- curvy-> C opposite to Br(d-),
from C-Br bond curvy-> Br(d-),
-------Across the Arrow-------
Intermediate both dotted bond,
All in straight brackets (-) sign
-------Across the Arrow-------
Br- formed separately
OH bonded opposite Br original
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31
Q

NaOH(aq) and heat are use to form an alcohol, draw this.

A 
Br= any halogen
R= carbon chain/H group

C-Br have (d+) and (-) respectively,
C has 3 other R groups,
HO- curvy-> C opposite to Br(d-),
from C-Br bond curvy-> Br(d-),
-------Across the Arrow-------
Intermediate both dotted bond,
All in straight brackets (-) sign
-------Across the Arrow-------
Br- formed separately
OH bonded opposite Br original
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32
Q

What is the product of an Alcohol reacting with a Carboxylic Acid?

A

An Ester and Water

33
Q

An Ester is formed from a Carboxylic Acid and what?

34
Q

An Ester is formed from an Alcohol and what?

A

Either a Carboxylic Acid

or an Acyl Chloride

35
Q

What reagents and conditions are used for an Alcohol reacting with a Carboxylic Acid?

A

Reagent=Catalyst=Conc H2SO4

Conditions=Heat

36
Q

What reagents and conditions are used when an Ester is formed from a Carboxylic Acid?

A

Reagent=Catalyst=Conc H2SO4

Conditions=Heat

37
Q

What reagents and conditions are used when an Ester is formed from an Alcohol

A

If reacted with a Carboxylic Acid:
Reagent=Catalyst=Conc H2SO4
Conditions=Heat

If reacted with an Acyl Chloride:
The Ethanoyl Chloride should be Anydrous and a fume cupboard should be used

38
Q

In Esterification using a Carboxylic Acid and an Alcohol why is Conc H2SO4 used?

A

Any strong H+ will act as a catalyst here but they use Conc H2SO4 because it can also act as a Hydrating agent, removing H2O from the equilibrium which will shift the equilibrium to the right and increase the yield of Ester

39
Q

H2SO4 acts as what in the Esterification of a Carboxylic Acid and Alcohol?

A

A Catalyst and a Hydrating Agent

40
Q

Define Hydrating Agent

A

A Species that causes Hydration; the incorporation of molecular water into a complex molecule with elements of another species

41
Q

Define Catalyst

A

A substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.

42
Q

Give an equation for an Ester being formed from an Alcohol

A

With a Carboxylic Acid:
RCOOH+R1-OH -> RCOOR1+H2O

With an Acyl Chloride
CH3COCl+ROH -> CH3COOR+HCl

43
Q

Give an equation for an Ester being formed from a Carboxylic Acid

A

RCOOH+R1-OH -> RCOOR1+H2O

With Conc H2SO4 and heat

44
Q

What is the product of an Alcohol and an Acyl Chloride?

A

An Ester and HCl

45
Q

An Ester is formed from Ethanoyl Chloride and what?

A

An Alcohol

46
Q

What Reagents and Conditions are used for an Alcohol reacting with Ethanoyl Chloride?

A

Anhydrous conditions are needed for the Ethanoyl Chloride, as it is Hydrolysed in the presence of H2O forming HCl gas (corrosive)

47
Q

What type of reaction occurs when an alcohol and Ethanoyl Chloride react?

A

Esterification (sometimes called Ethanoylation)

48
Q

Give an Equation for an Ester being formed from an Acyl Chloride

A

CH3COCl+ROH -> CH3COOR+HCl

49
Q

Give an equation for an alcohol reacting with an Acyl Chloride

A

CH3COCl+ROH -> CH3COOR+HCl

50
Q

Dehydration of an Alcohol results in what?

A

An Alkene and H2O

51
Q

Alcohol reacts with Conc H2SO4 to form what?

A

An Alkene and H20

52
Q

What type of reaction occurs when Conc H2SO4 is added to an Alcohol?

A

A Dehydration reaction

If a Carboxylic Acid is also present, Esterification can occur

53
Q

A Non-Primary Alcohol can form up to 3 different products, why is this?

A

When Dehydration of an Alcohol occurs, the OH group is removed along with a H from the Carbon attached to the Carbon that is attached to the OH
Draw and check with Butan-2-ol

54
Q

3 possible products can be formed from adding Conc H2SO4 to what?

A

A Secondary or Tertiary Alcohol

55
Q

Show Ethan-1-ol being dehydrated by Conc H2SO4

A

CH3CH2OH -> CH2=CH2+H2O

56
Q

Show Butan-2-ol being dehydrated by Conc H2SO4

A

CH3CH2CH(OH)CH3 -> CH3CH2CH=CH2

Or
CH3CH2CH(OH)CH3 ->
CH3CH=CHCH3 E and Z

57
Q

Define Distillation

A

The process of purifying a liquid by boiling it and then condensing it’s vapours

58
Q

Define Oxidation

A

Oxidation is the gain of oxygen or the loss of Hydrogen
Or
Oxidation is the loss of electrons

59
Q

Define Oxidising Agent

A

An Oxidising Agent is a species that causes oxidation in another and is itself reduced

60
Q

What results from the Oxidation of an Alcohol?

A

If the Alcohol is Primary an Aldehyde or Carboxylic Acid is formed, but if it is Secondary a Ketone is formed. (An Aldehyde will be formed only if the Alcohol is heated gently and distilled off before it oxidises further to a Carboxylic Acid)

61
Q

What are the reagents and conditions needed to oxidise an Alcohol?

A

Acidified Dichromate VI (Cr2O7/H+)
For Aldehyde: warm gently and distill off before further oxidised
For Carboxylic Acid: Heat Under Reflux from Alcohol or just heat further from Aldehyde
For Ketone: Heat Under Reflux

62
Q

What are the reagents and conditions needed to form an Aldehyde?

A

A Primary Alcohol Needs to be Warmed Gently with Acidified Dichromate VI and the aldehyde needs to be distilled off before it oxidises further to a Carboxylic Acid

63
Q

What is the observation noted when an alcohol is oxidised to a Carbonyl or Carboxylic Acid?

A

Solution goes from Orange to Green as the Cr ion is reduced from +6 oxidation state to +2

64
Q

What reagents and conditions are needed to form a Carboxylic Acid from an Aldehyde?

A

Acidified Dichromate VI and Heat

65
Q

When forming an Aldehyde from a Primary Alcohol how is the Aldehyde removed and why?

A

It is removed via distillation as it’s boiling point is lower due to only having Van Der Waals forces which are weaker than the extra Hydrogen bonding the Carboxylic Acid and Alcohol both have more of due to their OH group

66
Q

Why can a ketone not be oxidised further from an alcohol?

A

In order to form a carboxylic acid from a secondary alcohol C-C bond would need to be broken, but they are too strong

67
Q

A Ketone is formed by Oxidising what?

A

A Secondary Alcohol by Heating under reflux with Acidified Dichromate VI

68
Q

An Aldehyde is formed by oxidising what?

A

A Primary alcohol with Acidified Dichromate VI and warming gently

69
Q

A Carboxylic Acid is formed by Oxidising what?

A

An Alcohol by Heating Under Reflux or an Aldehyde by Heating further.
Both with Acidified Dichromate VI

70
Q

How are alcohols formed from an alkene?

A 
Electrophilic Addition
60atm
H2O
H3PO4
330°C
71
Q

How can an amine be converted to an alcohol?

A

Diazotisation
KNO2/HCl (HNO2)
Warm

Produces N2 gas

72
Q

When an amine is converted to an alcohol what is the bi product?

73
Q

What are the conditions to convert an alcohol to an alkene?

A

Either
1) excess H2SO4 conc & 170°C
Or
2) pass alcohol vapour over Al2O3 at 360°C

74
Q

What are two large scale uses for alcohols?

A

As a solvent

As a fuel

75
Q

Why are alcohols good fuels?

A

Clean flame
Complete oxidation
Lots of energy evolved

76
Q

Where is ethanol widely used as a fuel?

A

In S America from fermentation of sugar wastes

77
Q

How are halo alkenes formed from alcohols?

A

Nucleophilic substitution

Using either PCl5 or HBr (KBr H2SO4(l) )

78
Q

What are the conditions used to convert an alcohol to a chloralkane?

A

PCl5
Room temp
Anhydrous

79
Q

What are the conditions needed to convert an alcohol to a bromo alkane?

A

KBr(s) H2SO4(l) (HBr)

Warm

WJEC Chemistry (7 decks)

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