c11_b_nonhydrocarbon(s) carbon compound

8/8/2019 C11_B_NonHydrocarbon(S) Carbon Compound

http://slidepdf.com/reader/full/c11bnonhydrocarbons-carbon-compound 1/21

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




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


Name : 4-methylpentan-2-ol




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





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.





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


From oxidising agent




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 .


O

OH

n’ = n - 1




(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


∆




(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 :


STARCH

GLUCOSE

……………. ETHENE PETROLEUM

Combustion

in excess

oxygen

Oxidation

by an oxidising

agent

Dehydration

by a dehydrating

agent

…………………. and

………………….

Fermentation

Hydration

…………………. and

………………….

…………………. and

………………….




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


C

O

OH

C

O

OH

H




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


C

O

OH




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





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





(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





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 → +

| | | | | | | |





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.





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.

…………………………………………………………………………………………


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




(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 .





(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.

…………………………………………………………………………………..


DIAGRAM 2




(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

c11_b_nonhydrocarbon(s) carbon compound

Documents