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4541 CHEMISTRY Chapter 11
B : NON-HYDROCARBON
11.8 ALCOHOL
1. Alcohols are organic compounds that contain carbon, hydrogen and oxygen atoms.
2. The general formula for alcohol is :
CnH2n + 1OH where n = 1, 2, 3, ……, ∞
3. Each member of alcohol series contains hydroxyl as the functional group ( -OH ) which is
covalently bonded to the carbon atom.
4. Naming alcohol using IUPAC nomenclature :
S1 : Determine the number of carbon atoms in the longest carbon chain which
contains the hydroxyl group ( –OH ) ⇒obtain the name of alkane with the same
number of carbon atom as alcohol.
S2 : Replace the ending “e” from the name of alkane with “ol ”
Example :
Methane ⇒Methanol
Ethane ⇒Ethanol
Propane ⇒Propanol
Butane ⇒Butanol
Penthane ⇒Pentanol
S3 : Number the carbon atom in the longest carbon chain which is joined to the
hydroxyl group -OH with the smallest number ⇒ the number is placed in front of the “ ol ” to indicate which carbon atom the hydroxyl group is attached to.
Example :
Butan-2-ol
⇒the “ -OH ” is attached at the second carbon atom from the end.
The structural formula :
H H H H H H H H
H C C C C OH or H C C C C H
H H H H H H OH H
Chapter 11 Carbon Compounds26
4 carbon atoms -OH
-OH at the 2nd C
Butan-1-ol
C4H
9OH
Butan-2-ol
C4H
9OH
Isomer
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4541 CHEMISTRY Chapter 11
S4 : For alcohols with branches, write the names of all the branches as prefix.
H H H CH3 H
H C C C C C H
H OH H H H
5. Isomerism in alcohol :
Isomers are molecules that have same molecular formula but different structural
formula.
Activity 13 :-
Complete the following table :
Name of
alcohol
Molecular
Formula
Condensed
structural formula
Structural Formula &
IUPAC name
Number of
isomers
Methanol CH3OH 0
Ethanol C2H5OH CH3CH2OH 0
Propanol C3H7OHPropan-1-ol
2
Propan-2-ol
Chapter 11 Carbon Compounds27
Name : 4-methylpentan-2-ol
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4541 CHEMISTRY Chapter 11
Butanol 4
Methanol and ethanol do not have isomers because each molecule only has one structural formula.
Isomerism in alcohol begins with propanol .
6. Preparation of Ethanol
Chapter 11 Carbon Compounds28
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4541 CHEMISTRY Chapter 11
Two methods of preparation of Ethanol
(i) Preparation of ethanol, C2H5OH in the laboratory ( Fermentation of glucose)
Fermentation is a process in which microorganism such as yeast act on
carbohydrates (sugar or starch) to produce ethanol and cabon dioxide.
Yeast is added to glucose solution ( or fruit juices such as grape/pineapple juice)
and left in a warm place for a three days in the absence of oxygen.
Yeast contains enzyme ( zymase) which break down the sugar/starch into glucose
(hydrolisis process) and then to ethanol and cabon dioxide.
Fermentation equation :
C6H12O6 → 2C2H5OH + 2CO2
Glucose Ethanol
The ethanol is purified by fractional distillation. (78 0C)
(ii) Industrial production of ethanol, C2H5OH ( Hydration of ethene)
• Alkene is reacted with steam (H2O) at temperature; 300 oC and pressure; 60 atm
in presence of phosphoric acid (H3PO4) as a catalyst.
• Chemical equation of the reaction :
C2H4 + H2O → C2 H5OHEthene steam ethanol
7. Physical properties of alcohol
1 Alcohols with one to eleven carbon atoms exist as liquids.
2 Methanol, ethanol and propanol are miscible in all proportions with water.
The solubility of alcohol in water decreases with increasing of their molecular
size // number of carbon atom.
3 Physical properties of ethanol, C2H5OH :
• colourless liquid
• mixes with water in all proportions
• less dense than water
• boiling point is 78 oC at 1 atm.
Chapter 11 Carbon Compounds29
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4541 CHEMISTRY Chapter 11
8. Chemical properties of ethanol, C2H5OH
(a) Combustion of ethanol
(i) Ethanol burns in air to produce water and carbon dioxide. Ethanol burns
readily with a blue flame and without producing soot.
C2H5OH + 3O2 → 2CO2 + 3H2O
(ii) Combustion of ethanol releases large amount of heat (ethanol is suitable for use as a fuel )
Activity 13 :-
☺ Balance the following equations :
2C3H7OH + 9O2 → 6CO2 + 8H2O
C4H9OH + O2 → CO2 + H2O
C5H11OH + O2 → CO2 + H2O
C6H13OH + 9O2 → 6CO2 + 7H2O
(b) Oxidation of ethanol
(i) Ethanol is oxidised by an oxidising agent such as acidified potassium
manganate(VII), KMnO4 or acidified potassium dichromate(VI),
K 2Cr2O7 solution.
(ii) Both these oxidising agents are represented as 2[O] in the chemical
equation.
(iii) One oxygen atom joins the ethanol molecule to form C = O and the other
oxygen atom is joined to the two hydrogen atoms that are removed from the
ethanol to form H2O.
(iv) Oxidation of alcohol is the process where an alcohol molecule loses two Hatoms and receives one O atom.
Example :
C2H5OH + 2[O] → CH3COOH + H2O
Ethanol Ethanoic acid water
Chapter 11 Carbon Compounds30
From oxidising agent
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4541 CHEMISTRY Chapter 11
or
H H H
H C C H + 2[O] → H C C + H2O
H OH H
Activity 14 :-
☺Complete the following equations :
C3H7OH + 2[O] → C2H5 COOH + H2O
or
CH3CH2 CH2OH + 2[O] → ……………………… + H2O
Propanol propanoic acid
or
H H H
H C C C H + 2[O] → + H2O
H H OH
……………………..
(v) Alcohol undergoes oxidation reaction to produce carboxylic acid.
CnH2n+1 + 2[O] → Cn’H2n’+1COOH + H2O
This reaction is used to prepare carboxylic acid.
(c) Dehydration of ethanol
(i) Dehydration of an alcohol involves the removal of water molecule from each
of alcohol molecule.
(ii) Water molecule from the alcohol molecule is removed by a dehydrating
agents such as porcelain chips / aluminium oxide ( alumina ) / concentrated
sulphuric acid / concentrated phosphoric acid .
Chapter 11 Carbon Compounds31
O
OH
n’ = n - 1
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4541 CHEMISTRY Chapter 11
(iii) There are two ways to carry out the dehydration of ethanol in the laboratory :
1 Hot vapour of ethanol is passed over a heated catalyst such as porcelain
chips /aluminium oxide.
1 Ethanol is heated under reflux with excess of concentrated sulphuric acid
/ concentrated phosphoric acid.
☺Draw a labeled diagram to show the set-up of apparatus to carry out the
dehydration of ethanol.
(iv) Dehydration of ethanol produces ethene and water.
Equation for the reaction :
H H H H
porcelain
H C C H H C C H + H2O
∆H OH
or
C2H5OH → C2H4 + H2OEthanol Ethene
Chapter 11 Carbon Compounds32
∆
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4541 CHEMISTRY Chapter 11
(d) Production of cosmetics main component in
production of cosmetics, creams, lotions, soaps and others.
10. Alcohol Misuse and Abuse
Activity 16 :-
Complete the following chart :
Chapter 11 Carbon Compounds34
STARCH
GLUCOSE
……………. ETHENE PETROLEUM
Combustion
in excess
oxygen
Oxidation
by an oxidising
agent
Dehydration
by a dehydrating
agent
…………………. and
………………….
Fermentation
Hydration
…………………. and
………………….
…………………. and
………………….
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4541 CHEMISTRY Chapter 11
2.9 CARBOXYLIC ACID [ ORGANIC ACID ]
1. An acid that comes from anorganic source, either from plants or animals such as ethanoic acid in vinegar, citric acid
in lemon and methanoic acid from ants.
2. Consists of elements : carbon, C
; hydrogen, H ; and oxygen, O.
3. The difference compared to
alcohol is that carboxylic acids have two oxygen atoms whereas alcohols have only one
oxygen atom.
4. Functional group is the carboxyl
group :
5. The general formula of the
carboxylic acid is :
CnH2n+1COOH n = 0,1, 2, 3........
6. For straight chain carboxylic
acid molecules, the name ends with ‘oic’ and acid.
Activity 17 :-
Complete the following table :
Number of
carbon atoms
Molecular Formula
CnH2n+1COOHn Structural Formula Name
1HCOOH 0
methanoic acid
Chapter 11 Carbon Compounds35
C
O
OH
C
O
OH
H
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4541 CHEMISTRY Chapter 11
2CH3COOH 1
ethanoic acid
3 2
4
5
6
.
7. For branched chain carboxylic
acid molecules :
• the name and position of the branched group is written as prefix
• the smallest number is given to the carbon atom that is joined to the functional
carboxyl group.
Example :
H H H O| | | //
H – C – C – C – C
| | | \
H H CH3 OH
2-methylbutanoic acid
Chapter 11 Carbon Compounds36
C
O
OH
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4541 CHEMISTRY Chapter 11
8. Preparation of ethanoic acid :
Laboratory preparation through oxidation of ethanol by acidified KMnO4 /
K 2Cr 2O7 solution
H H H O| | | //
H - C - C - OH + 2[O] → H - C - C + H2O
| | | \
H H H OH
ethanol ethanoic acid
Activity 18 :-
Draw the set-up of apparatus for the preparation of ethanoic acid by reflux method.
(preparation of ethanoic acid in laboratory)
Industrial preparation using petroleum and natural gas.
9. Chemical properties of
carboxylic acid
(i) Reacts as an acid with base, metal carbonates and metals that are more
electropositive than hydrogen.
(a) Carboxylic acid + electropositive metal → carboxylate salt + hydrogen gas
(b) Carboxylic acid + base → carboxylate salt + water
(c) Carboxylic acid + metal carbonate → carboxylate salt + water + carbon dioxide
Chapter 11 Carbon Compounds37
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4541 CHEMISTRY Chapter 11
Activity 19 :-
Complete the following equations :
(a) HCOOH + Mg → +
………….. acid magnesium ……………… + ........................
(b) C2H5COOH + KOH → + H2O
………………. ………………….. ……………… + water
(c) CH3COOH + Na2CO3 → CH3COONa + H2O + CO2
…………. acid sodium carbonate Sodium ethanoate + water + carbon dioxide
(d) C2H3COOH + K 2CO3 → + + CO2
(e) C2H5COOH + NaOH → +
(f) C5H11COOH + K →
(ii) React with alcohol to produce ester and water .
Carboxylic acid reacts with alcohol to produce ester and water with the presence
of concentrated sulphuric acid as a catalyst (Esterification reaction).
Carboxylic acid + Alcohol → Ester + Water
CnH2n+1COOH Cn’H2n’+1OH CnH2n+1COOCn’H2n’+1 H2O
(a) C2H5COOH + C2H5OH → C2H3COOC2H5 + H2O
propanoic acid ethanol ethyl propanoate
Chapter 11 Carbon Compounds38
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4541 CHEMISTRY Chapter 11
(b) C3H7COOH + C3H7OH → C2H3COOC2H5 + H2O
butanoic acid propanol propyl butanoate
(c) HCOOH + C2H5OH → C2H3COOC2H5 + H2O
methanoic acid ethanol ethyl methanoate
(d) ethanoic acid + ethanol → Ethyl ethanoat + water
H O H H
| // | |
H - C - C + HO - C - C - H →
| \ | |
H OH H H
ethanoic acid ethanol
(d) butanoic acid + pentanol → ………………………… + water
10. Uses of Carboxylic Acid
Chapter 11 Carbon Compounds39
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4541 CHEMISTRY Chapter 11
CH3COOH + C3H7OH → CH3 COOC3H7 + H2O
ethanoic acid propanol prophyl ethanoate
4. Naming of esters :
Name for esters are :
first : read from the alcohol component
followed by : the carboxylic acid component.
Example:
CH3COOH + C3H7OH → CH3 COOC3H7 + H2O
ethanoic acid propanol prophyl ethanoate
or
H O H H H H O H H H|| ||
H C C O-H H-O C C C H → H C C O C C C H + H-O-H
H H H H H H H H
ethanoic acid propanol propyl ethanoate
Activity 20 :-
Complete the following equations :
(i) H 2SO4
HCOOH + C2H5OH → + H2O
methanoic acid ethanol Ethyl methanoate water
(ii) H 2SO4
C3H7OH + C4H9COOH → C4H9COOC3H7 + H2O
Propanol pentanoic acid water
(iii) H 2SO4
C3H7COOH + C2H5OH → + H2O
Butanoic acid ethanol …………………………. water
(iv)
H H H O H H H H H
| | | || | | | | |
H – C – C - C - C - OH + HO - C - C - C - C - C - H → +
| | | | | | | |
Chapter 11 Carbon Compounds41
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4541 CHEMISTRY Chapter 11
H H H H H H H H
Butanoic acid pentanol
(v)
H H O H H H H| | || | | | |
H – C – C - C - OH + HO - C - C - C - C - H → +
| | | | | | |
H H H H H H H
Propanoic acid butanol …………………........... water
5. Physical properties of esters :
• Ester is a neutral compound with a sweet smell / fruity smell.
• Esters have low density ; less dense than water.
• Simple esters are colourless liquid at room temperature.
• Simple esters are very volatile.
• Insoluble in water.
6. Uses of esters :
Most simple esters are found naturally in fruits and flowers. The fragrance of flowers and
fruits is due to the presence of esters.
Example:
Ester Name Naturel source
CH3COOC5H11 Pentyl ethanoate Pineapple
C2H5COOCH3 Methyl propanoate Apple
C3H7COOC5H11 Pentyl butanoate Banana
Used in the preparation of cosmetics and perfumes.
As artificial flavour in processed of food and drinks
Used in the production of polyester ( synthetic fibers for making textiles)
Natural fats are esters which react with alkalis to produce soap.
Chapter 11 Carbon Compounds42
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4541 CHEMISTRY Chapter 11
Activity 21 :-
1 Compound J is prepared by the fermentation of glucose. Diagram 1 shows a few reactions
that involve compound J with the molecular formula C2H6O.
(a) Name the compound J.
…………………………………………………………………………………………
(b) Write the equation for the complete combustion of compound J in air.
…………………………………………………………………………………………
Chapter 11 Carbon Compounds43
Fermentation
Combustion
Heated Al
2O
3
RefluxCompound J and K
with concentrated H2SO
4
Glucose
Compound J
C2H
6O
Gas N
Gas M
Compound K
C2H
4O
2
Compound L
DIAGRAM 1
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4541 CHEMISTRY Chapter 11
(c) Gas M is produced when vapour of compound J is heated strongly and continuously
with aluminium oxide.
(i) Draw the set-up of the apparatus to carried out this reaction.
(ii) Name the type of reaction occur.
…………………………………………………………………………………..
(iii) Write the molecular formula and name the gas M.
…………………………………………………………………………………..
(iii) If gas M is passed through bromine water, predict your observation.
…………………………………………………………………………………..
(d) Compound K is produced when compound J is reacted with oxidising agent.
(i) Name an oxidising agent that can be use in this reaction.
…………………………………………………………………………………..
(ii) Write the chemical equation for the reaction.
…………………………………………………………………………………..
(iii) Draw the structural formula and name the compound K .
Chapter 11 Carbon Compounds44
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4541 CHEMISTRY Chapter 11
(iii) Compound K can react with calcium carbonate. Write the chemical equation
of this reaction..
…………………………………………………………………………………..
(e) A mixture of compound J and compound K with concentrated sulphuric acid is
heated under reflux to form compound L.Diagram 2 shows the wrong set-up of apparatus for heating under reflux.
(i) State two mistakes shown in the set-up in Diagram 2.
…………………………………………………………………………………..
…………………………………………………………………………………..
(ii) Name the type of reaction occur.
…………………………………………………………………………………..
Chapter 11 Carbon Compounds45
DIAGRAM 2
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4541 CHEMISTRY Chapter 11
(iii) Draw the structural formula of compound L.
(iv) Name the compound L in (d) (iii).
…………………………………………………………………………………..
(v) State two uses of compound L in our daily lives.
…………………………………………………………………………………..
…………………………………………………………………………………..
2 Describe how the following conversions can be carried out.
[Include the reagents used, suitable conditions and the chemical equations involved]
(a)
(b)
(c)
(d)
Glucose etene
Propan-1-ol propane
Butan-1-ol butyl propanoate
Ethanol sodium ethanoate
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