Organic Chemistry

Addition

Formation of 1, 2-dibromoethane from ethene and bromine

(i) Ethane

$\underset{\text{sodium propionate}}{\text{C}_2\text{H}_5\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \underset{\Delta}{\xrightarrow{\text{CaO}}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} + \text{Na}_2\text{CO}_3$

(ii) Methane

$\underset{\text{methyl iodide}}{\text{CH}_3\text{I}} + \underset{\text{nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{\text{methane}}{\text{CH}_4} +\text{HI}$

(iii) Ethene [ethylene]

$\underset{\text{ Bromo ethane [ethyl bromide]}}{\text{C}_2\text{H}_5\text{Br}} + \underset{\text{alcoholic}}{\text{KOH}} \xrightarrow{\text{boil}} \underset{\text{ethene [ethylene]}}{\text{H}_2\text{C}=\text{C}\text{H}_2} + \text{KBr} + \text{H}_2\text{O}$

(iv) Ethyne [Acetylene]

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(i) Calcium carbide and water: forms ethyne [acetylene]

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(ii) Ethene and water (steam): form Ethanol [ethyl alcohol]

$\underset{\text{Ethene}}{\text{C}_2\text{H}_4} + \underset{\text{water[steam]}}{\text{H}_2\text{O}} \xrightarrow[\text{acid}]{\text{H}^+} \underset{\text{ethanol}}{\text{C}_2\text{H}_5\text{OH}}$

(iii) Bromoethane and an aqueous solution of sodium hydroxide: form Ethanol [ethyl alcohol]

$\underset{\text{bromoethane}}{\text{C}_2\text{H}_5\text{Br}} + \underset{\text{aq. sodium hydroxide}}{\text{NaOH}} \longrightarrow \underset{\text{Ethanol [ethyl alcohol]}}{\text{C}_2\text{H}_5\text{OH}} + \text{NaBr}$

Structural formula of Ethane [saturated]:

Structural formula of Ethene [unsaturated]:

Ethane ⟶ Substitution reaction

The non-availability of electrons in the single covalent bond makes them less reactive and therefore undergo characteristic substitution reaction only.

Ethene ⟶ Addition reaction

The availability of electrons in the double or triple bond makes them more reactive and therefore undergo characteristic addition reactions only.

2C₂H₆ + 7O₂ [excess] ⟶ 4CO₂ + 6H₂O + Δ

Alcohol ⟶ Ethyl alcohol [C₂H₅OH]

Aldehyde ⟶ Acetaldehyde [CH₃CHO]

Acid ⟶ Acetic acid [CH₃COOH]

Anhydrous acetic acid on cooling below 16.5°C, crystallizes out in the pure form, forming a crystalline mass resembling ice [m.p. around 17 °C] . Hence, pure acetic acid is called glacial acetic acid.

Ester is formed by the reaction between acetic acid and an alcohol.

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

Addition reaction

Reaction of ethyne with chlorine:

Substitution reaction

They can undergo addition as well as substitution reactions.

Reason — The non availability of electrons in the single covalent bond makes them less reactive and therefore they undergo characteristic substitution reactions only.

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(i) C₅H₁₀ [Rest all are alkanes and this is an alkene]

(ii) Nitric acid [Rest all are organic acids and this is inorganic acid]

Bromine solution

Generally ionic compounds exist in solid state. Melting and boiling points of covalent compounds are generally low. The general formula for alkane is C_nH_2n+2. For alkynes the general formula is C_nH_2n-2

(i) methane from sodium acetate :

$\underset{\text{sodium acetate}}{\text{CH}_3\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \underset{\Delta}{\xrightarrow{\text{CaO}}} \underset{\text{methane}}{\text{CH}_4} + \text{Na}_2\text{CO}_3$

(ii) one mole of ethene with one mole of chlorine gas:

(iii) ethyne from 1, 2 – dibromoethane.

(i) By boiling ethyl chloride with aqueous NaOH.

$\underset{\text{ Chloroethane [ethyl chloride]}}{\text{C}_2\text{H}_5\text{-Cl}} + \text{NaOH [aq.]} \xrightarrow{\text{boil}} \underset{\text{ Ethanol [ethyl alcohol]}}{\text{C}_2\text{H}_5\text{OH}} + \text{NaCl}$

(ii) By boiling ethyl chloride with alcoholic KOH.

$\underset{\text{ Chloroethane [ethyl chloride]}}{\text{C}_2\text{H}_5\text{-Cl}} + \underset{\text{ alcoholic KOH}}{\text{KOH [aq.]}} \xrightarrow{\text{boil}} \underset{\text{ Ethene [ethylene]} }{\text{C}_2\text{H}_4} + \text{KCl} +\text{H}_2\text{O}$

(iii) Ethene is absorbed in conc. sulphuric acid at 80 °C under 30 atmos. to give ethyl hydrogen sulphate, which on hydrolysis with steam gives ethanol.

$\underset{\text{ Ethene} }{\text{C}_2\text{H}_4} + \underset{\text{conc.}}{\text{H}_2\text{SO}_4} \underset{30 \text{ atmos.}}{\xrightarrow{80 ^{\circ} \text{C}}} \underset{\text{ Ethyl hydrogen sulphate} }{\text{C}_2\text{H}_5\text{-HSO}_4}$

$\underset{\text{ Ethyl hydrogen sulphate }}{\text{C}_2\text{H}_5\text{-HSO}_4} + \underset{\text{steam}}{\text{H}_2\text{O}} \longrightarrow \underset{ \text{ Ethanol [ethyl alcohol]} }{\text{C}_2\text{H}_5\text{-OH}} + \text{H}_2\text{SO}_4$

(iv) By heating ethyl alcohol with concentrated H₂SO₄ at 170°C.

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

(1) Isomerism is the phenomenon due to which two or more compounds have the same molecular formula but differ in molecular arrangement or in structural formula.

Example : Isomers of pentane are (i) n pentane, (ii) isopentane and (iii) neo-pentane

IUPAC name of C₄H₁₀ is Butane.

(i) Ethyne

(ii) Methanol

(i) Structural formula of Ethanoic acid is shown below:

(ii) Structural formula of But-2-yne is shown below:

(i) Compound 'X' is Ethene (H₂C=CH₂). Its structural formula is shown below:

Ethene [CH₂=CH₂] has undergone addition reaction.

(ii) Brown colour of bromine is discharged.

(iii) Ethanol

$\underset{\text{Ethene}}{\text{C}_2\text{H}_4} + \underset{\text{ water} }{\text{H}_2\text{O}} \underset{\text{acid}}{\xrightarrow{\text{H}}^+} \underset{\text{ ethanol} }{\text{C}_2\text{H}_5\text{OH}}$

(iv) Ethanol can be converted into ethene, by dehydrating it with concentrated H₂SO₄ at 170°C.

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

Ethyne [Acetylene]

(i) Due to unique nature of carbon atoms, which includes tetravalency, catenation and leading to formation of isomers, millions of organic compounds are known. Hence, almost 90% of all known compounds are organic in nature.

(ii) When methane burns in an insufficient supply of air, carbon monoxide is produced which is extremely poisonous for human beings as it cuts off the oxygen supply and forms carboxy haemoglobin in the blood, leading to death.

(i) Carboxyl – COOH

CH₃-COOH

(ii) addition reaction

The availability of electrons in the double or triple bond makes them more reactive and therefore undergo characteristic addition reactions only.

(iii) Six
Below is the structural formula of Ethane:

(i) The catalyst used for conversion of ethene to ethane is commonly nickel.

(ii) Acetaldehyde when oxidized with acidified potassium dichromate, forms acetic acid.

(iii) Ethanoic acid reacts with ethanol in presence of conc. H₂SO₄, so as to form a compound and water. The chemical reaction which takes place is called esterification

(i) Reaction between 1, 2 – dibromoethane and alcoholic potassium hydroxide:

(ii) Monochloro ethane is hydrolysed with aqueous KOH:

$\underset{\text{ Chloroethane [ethyl chloride]}}{\text{C}_2\text{H}_5\text{-Cl}} + \text{KOH [aq.]} \xrightarrow{\text{boil}} \underset{\text{ Ethanol [ethyl alcohol]} }{\text{C}_2\text{H}_5\text{-OH}} + \text{KCl}$

(iii) A mixture of sodalime and sodium acetate is heated:

$\underset{\text{sodium acetate}}{\text{CH}_3\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \underset{\Delta}{\xrightarrow{\text{CaO}}} \underset{\text{methane}}{\text{CH}_4} + \text{Na}_2\text{CO}_3$

(iv) Ethanol under high pressure and low temperature is treated with acidified potassium dichromate:

$\underset{ \text{ ethanol[ethyl alcohol]}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ethanal [acetaldehyde] }}{\text{CH}_3\text{CHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{ \text{ethanoic acid[acetic acid]} }{\text{CH}_3\text{COOH}}$

(v) Water is added to calcium carbide:

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(vi) Ethanol reacts with sodium at room temperature:

$\underset{\text{ ethanol} }{2\text{C}_2\text{H}_5\text{OH}} + 2\text{Na} \longrightarrow \underset{\text{ sodium ethoxide} }{2\text{C}_2\text{H}_5\text{ONa}} + \text{H}_2$

Reddish brown bromine dissolved in water turns colourless when ethyne is passed through it.

(i) Ethyne

(ii) Acetic acid

(iii) Ethene

(iv) Ethanol

(i) Anhydrous acetic acid on cooling below 16.5°C, crystallizes out in the pure form, forming a crystalline mass resembling ice [m.p. around 17°C] . Hence, pure acetic acid is called glacial acetic acid.

(ii) Reaction between ethyl alcohol and acetic acid:

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl acetate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

Ethyl alcohol is dehydrated by concentrated sulphuric acid at a temperature of about 170°C.

(i) Methanoic acid:

(ii) Ethanal:

(iii) Ethyne:

(iv) Acetone:

(v) 2-methyl propane:

Ethane gas

$\underset{\text{sodium propionate}}{\text{C}\text{H}_3\text{-C}\text{H}_2\text{.COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} + \text{Na}_2\text{CO}_3$

Subsitution reaction

When bromine is passed through solutions of each of the gases in an inert solvent [CCl₄] at room temperature, incase of ethene gas, brown colour of bromine is discharged whereas in case of ethane gas brown colour remains brown.

They can undergo both substitution as well as addition reactions.

Reason — The non availability of electrons in the single covalent bond makes them less reactive and therefore alkanes undergo characteristic substitution reactions only.

(i) Methane is produced

$\underset{\text{ methyl iodide}}{\text{CH}_3\text{I}} + \underset{ \text{ nascent hydrogen}}{2\text{[H]}} \underset{\text{alcohol}}{\xrightarrow{\text{Zn/Cu couple}}} \underset{ \text{ methane}}{\text{CH}_4} + \text{HI}$

(ii) Ethene is formed

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

(iii) Ethyne is formed

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(iv) ethyl alcohol is formed.

$\underset{\text{ Bromoethane [ethyl bromide]}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{ alcoholic KOH}}{\text{KOH [aq.]}} \xrightarrow{\text{boil}} \underset{ \text{ ethyl alcohol}} {\text{C}_2\text{H}_5\text{OH}} + \text{KBr}$

(i) Iso-butane is an isomer of n-butane. Its structure is shown below:

(ii) 2-propanol:

(iii) Diethyl ether:

(i) Methane is a saturated hydrocarbon whereas Ethene is an unsaturated hydrocarbon. In saturated hydrocarbons, all the four valencies of each carbon atom are satisfied by the hydrogen atoms, forming single covalent bond. Thus, due to non-availability of electrons methane is less reactive and hence does not undergo addition reactions.
On the other hand, ethene has two carbon atoms forming a double covalent bond as their valencies are not fully satisfied by hydrogen atoms. The availability of electrons in the double bond makes ethene more reactive and it undergoes addition reactions.

(ii) Ethyne is an unsaturated hydrocarbon having two carbon atoms forming a triple covalent bond as their valencies are not fully satisfied by hydrogen atoms whereas ethane is a saturated hydrocarbon containing only single bonds which are stronger and less reactive. The availability of electrons in the triple bond in case of ethyne makes it more reactive than ethane which does not have electrons available in the single covalent bond.

(iii) Hydrocarbons have high calorific value. They are easily combustible and the reaction is exothermic releasing heat energy. Hence, they are excellent fuels.

Ethyne

Ethanol reacts with sodium to give sodium ethoxide

$\underset{\text{ ethanol} }{2\text{C}_2\text{H}_5\text{OH}} + 2\text{Na} \longrightarrow \underset{\text{ sodium ethoxide} }{2\text{C}_2\text{H}_5\text{ONa}} + \text{H}_2$

Ketones

(i) Preparation of ethane from sodium propionate.

$\underset{\text{sodium propionate}}{\text{C}\text{H}_3\text{-C}\text{H}_2\text{.COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} + \text{Na}_2\text{CO}_3$

(ii) Preparation of ethanol from monochloroethane and aq. sodium hydroxide.

$\underset{\text{ monochloroethane}}{\text{C}_2\text{H}_5\text{-Cl}} + \underset{ \text{ aq. sodium hydroxide}}{\text{NaOH[aq]}} \xrightarrow{\text{boil}} \underset{ \text{ Ethanol [ethyl alcohol]} }{\text{C}_2\text{H}_5\text{-OH}} + \text{NaCl}\$

When ethene is passed through alkaline potassium permanganate solution (cold dil. KMnO₄), it decolourizes the purple coloured solutions whereas on passing Ethane, alkaline potassium permanganate solution remains purple.

(i) Vapours of ethyne mixed with hydrogen are passed over a catalyst eg., nickle [Pd. or Pt.] at high temperatures of around 300°C.

(ii) Ethylene dibromide is boiled with conc. alcoholic KOH soln. in a round bottom flask. Ethyne is collected by downward displacement of water.

(i) Structural formula of ethanol is shown below:

(ii) Structural formula of 1-propanal is shown below:

(iii) Structural formula of ethanoic acid is shown below:

(iv) Structural formula of 1, 2, dichloroethane is shown below:

(i) Ethyne

(ii) Ethane

They can undergo addition as well as substitution reactions

Reason — The availability of electrons in the double or triple bond makes them more reactive and therefore they undergo characteristic addition reactions only.

When the gaseous product from dehydration of ethanol is passed through bromine water, the brown colour of bromine water is discharged.

(i) Ethanoic acid to ethyl ethanoate. :

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(ii) Ethyne is formed

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(iii) Sodium ethanoate to methane

$\underset{\text{sodium acetate}}{\text{CH}_3\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{methane}}{\text{CH}_4} + \text{Na}_2\text{CO}_3$

(i) Dimethyl ether contains the functional group Alkoxy (ether). It is circled in its structural formula below:

(ii) Propanone contains the functional group Keto. It is circled in its structural formula below:

(i) Catalytic hydrogenation (addition)

(ii) Methane

(iii) Esterification

(iv) Catenation

(v) Dehydrohalogenation

Conversion of ethene to ethane is an example of hydrogenation.

$\underset{\text{ Chloroethane [ethyl chloride]}}{\text{C}_2\text{H}_5\text{-Cl}} + \text{NaOH [aq.]} \xrightarrow{\text{boil}} \underset{\text{ Ethanol [ethyl alcohol]}}{\text{C}_2\text{H}_5\text{-OH}} + \text{NaCl}$

(i) Nickel or platinum or palladium.

(ii) Addition reaction

(a) Propene

(b) 2-butyne

(c) ethanal

(i) Carbon dioxide and water are produced:

$2\text{C}_2\text{H}_6 + 7\text{O}_2[\text{excess}] \longrightarrow 4\text{CO}_2 + 6\text{H}_2\text{O} + \Delta$

(ii) Calcium hydroxide and ethyne are produced

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(iii) Ethene and water are produced

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

(i) 2-methyl propane :

(ii) Ethanoic acid :

(iii) Butan – 2 – ol :

(i) Compound A is Ethene. Its structure is shown below:

(ii) Brown colour of bromine is discharged.

The compound formed when ethene reacts with hydrogen is C₂H₆

$\underset{\text{ ethene [ethylene]}}{\text{H}_2\text{C}=\text{C}\text{H}_2} + \text{H}_2 \xrightarrow[300^{\circ}\text{C}]{\text{Nickle}} \underset{\text{ethane}}{\text{C}_2\text{H}_6}$

Alkyne
Reason — As the general formula for alkyne is C_nH_2n-2. Hence, when C is 10 then H is 18.

Carboxylic acids

$\underset{\text{methyl iodide}}{\text{CH}_3\text{I}} + \underset{\text{nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{\text{methane}}{\text{CH}_4} +\text{HI}$

(i) Glacial acetic acid

(ii) Ethyne or acetylene

(iii) Isomerism

(iv) Ketone or Alkanone

(i) ethane from sodium propionate : ethane is formed

$\underset{\text{sodium propionate}}{\text{C}_2\text{H}_5\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \underset{\Delta}{\xrightarrow{\text{CaO}}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} + \text{Na}_2\text{CO}_3$

(ii) ethyl alcohol is formed.

$\underset{\text{ Bromoethane [ethyl bromide]}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{ alcoholic KOH}}{\text{KOH [aq.]}} \xrightarrow{\text{boil}} \underset{ \text{ ethyl alcohol}} {\text{C}_2\text{H}_5\text{OH}} + \text{KBr}$

On warming, the mixture gives fruity smell. Acetic acid on heating with an alcohol and a dehydrating agent [conc. H₂SO₄] forms an ester-ethyl acetate.

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(i) 2, 3 – dimethyl butane :

(ii) Diethyl ether :

(iii) Propanoic acid :

(i) C₂H₆

(ii) Methoxy methane

Catenation

(i) Methanal

(ii) 1-Propanol

(iii) 2-Butene

Write the structural formula of the two isomers of butane.

Structural formula of the two isomers of butane are given below:

1. Butane [n-butane]

2. 2-Methyl propane [iso-butane]

Hydrogen gas is produced during reaction of ethanol and sodium as shown below:

$\underset{\text{ ethanol} }{2\text{C}_2\text{H}_5\text{OH}} + 2\text{Na} \longrightarrow \underset{\text{ sodium ethoxide} }{2\text{C}_2\text{H}_5\text{ONa}} + \text{H}_2$

(a) Hydrocarbons with general formula C_nH_2n-2

1. IUPAC name of the homologous series — Alkynes
2. Characteristic bond type — Triple covalent bond
3. IUPAC name of the first member of the series — Ethyne

(b) Hydrocarbons with general formula C_nH_2n+2

1. IUPAC name of the homologous series — Alkanes
2. Characteristic bond type — Single covalent bond
3. IUPAC name of the first member of the series — Methane

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(i) Y is ethyl acetate and Z is conc. sulphuric acid

(ii) Structural formula of X (ethanoic acid) is shown below:

(iii) Esterification reaction

Methane

(i) Conversion of ethanol to ethene by the action of conc. sulphuric acid is an example of dehydration

(ii) Substitution reactions are characteristic reactions of alkanes

The balanced chemical equation for the reaction of chlorine gas with ethene is given below:

(i) The IUPAC names are:
     A: Propyne
     B: Ethanal

(ii) The special feature of the structure of ethyne is that the two carbon atoms are linked by triple covalent bond formed by sharing three pairs of electrons between the two carbon atoms. The availability of electrons on the triple bond makes ethyne more reactive and hence it undergoes characteristics addition reactions only.

(iii) Ethane [C₂H₆]

(iv) Structural formula of acetic acid is shown below:

Ethane [C₂H₆] : M.W. = 2[12] + 6[1] = 30

Methane [CH₄] : M.W. = 12 + 4[1] = 16

Ethene [C₂H₄] : M.W. = 2[12] + 4[1] = 28

Ethyne [C₂H₂] : M.W. = 2[12] + 2[1] = 26

Hence, increasing order of molecular weight :

Methane < Ethyne < Ethene < Ethane

(i) Ethene from bromoethane

$\underset{\text{ Bromoethane [ethyl bromide]}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{ alcoholic KOH}}{\text{KOH}} \xrightarrow{\text{boil}} \underset{ \text{ ethene [ethylene]} } {\text{H}_2\text{C}=\text{C}\text{H}_2} + \text{KBr} + \text{H}_2\text{O}$

(ii) Ethyne from calcium carbide

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{cold water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(iii)

$\underset{\text{ sodium acetate}}{\text{CH}_3\text{.COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \underset{\Delta}{\xrightarrow{\text{CaO}}} \underset{\text{methane}}{\text{C}\text{H}_4} + \text{Na}_2\text{CO}_3$

(i) Propanoic acid [C₃H₇CHO]

(ii) Ethene [C₂H₄]

(iii) Ethyl alcohol

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(iv) 1,1,2,2 tetrachloroethane

Glacial acetic acid

Ethane gas

$\underset{\text{ ethene [ethylene]}}{\text{H}_2\text{C}=\text{C}\text{H}_2} + \text{H}_2 \xrightarrow[300^{\circ}\text{C}]{\text{Nickle}} \underset{\text{ethane}}{\text{C}_2\text{H}_6}$

C₃H₄

Reason — C₃H₄ is an Alkyne as it follows the general formula C_nH_2n-2 and Alkynes contain a triple carbon-carbon covalent bond.

Effervesence of hydrogen gas is seen when a piece of sodium metal is put into ethanol at room temperature.

$\underset{\text{ ethanol} }{2\text{C}_2\text{H}_5\text{OH}} + 2\text{Na} \longrightarrow \underset{\text{ sodium ethoxide} }{2\text{C}_2\text{H}_5\text{ONa}} + \text{H}_2$

(i) Ethane from bromoethane using Zn/Cu couple in alcohol

$\underset{\text{bromoethane}}{\text{C}_2\text{H}_5\text{Br}} + \underset{\text{nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} +\text{HBr}$

(ii) Complete combustion of ethane

$2\text{C}_2\text{H}_6 + 7\text{O}_2 \longrightarrow 4\text{CO}_2 + 6\text{H}_2\text{O} + \Delta$

A: 2,2 dimethyl pentane

B: methanol

A: acetaldehyde — Ethanal

B: acetylene — Ethyne

Sodalime is preferred to sodium hydroxide in the laboratory preparation of methane since it is not deliquescent and does not attack glass.

Esterification

The structures of isomers of pentane are shown below:

Pentane [n-pentane]

2-Methyl butane [iso-pentane]

2,2 Dimethyl Propane [neo-pentane]

Alkenes are a homologous series of unsaturated hydrocarbons characterized by the general formula C_nH_2n. Alkenes undergo addition reactions and also undergo hydrogentaion to form alkanes.

Organic Chemistry is the study of carbon compounds excluding oxides of carbon, metallic carbonates and related compounds like metal cyanides, metal carbides.

Natural sources of organic compounds are:

1. Plants
2. Animals
3. Coal
4. Petroleum
5. Fermentation
6. Wood

Importance of organic compounds — Organic compounds are extremely useful to us in our daily life. The soaps and shampoos we use while taking bath, the powders, perfumes, we apply on the body, the clothes we wear, food we eat i.e., carbohydrates, proteins, fats, vitamins, etc., fuels we use, natural gas, petroleum products, medicines, explosives, dyes, insecticides, are all organic compounds.
There is hardly any walk of life where we do not need organic compounds.

(a) Tetravalency of carbon atoms — Carbon has four valence electrons. It forms four covalent bonds by mutually sharing it's four electrons with other atoms. Carbon is hence tetravalent or exhibits tetravalency. [At. no. of C = 6; Elec. Config. = 2,4]

(b) Catenation — Carbon atoms possess a unique property to link together (self linking) to form very long chains. This property is known as catenation. Catenation is shown by other elements also but Carbon exhibits this property of the maximum extent. This is due to the greater strength of carbon-carbon bond and due to tetra-covalency of carbon.

1. Formation of single, double and triple covalent bonds — Carbon is tetravalent having a valency of four. In order to satisfy its valency, it forms single, double and triple covalent bonds by sharing one, two or three pairs of electrons respectively between two carbon atoms as well as with other atoms like oxygen, nitrogen and so on.

2. Formation of straight chain, branched chain and cyclic compounds — The combination of carbon atoms with each other gives rise to straight or branched or cyclic and closed chains.

Due to unique nature of carbon atoms, which includes tetravalency, catenation and leading to formation of isomers, millions of organic compounds are known or synthesized [almost 90% of all known compounds are organic in nature]. Hence, a separate branch of chemistry called Organic Chemistry is required for the study of carbon and its compounds.

Five differences between the characteristics of organic and inorganic compounds:

Classification of organic compounds:

A Homologous series is a group of organic compounds having a similar structure and similar chemical properties in which the successive compounds differ by a CH₂ group.

General Characteristics of members of homologous series are:

1. General Formula — All members of a homologous series share the same general formula. (Same elements and same functional group). For example, the general formula for alkane is C_nH_2n+2, alkene is C_nH_2n, alkyne is C_nH_2n-2.
2. Molecular Mass — Each member of the series differs from the preceding one by the addition of CH₂ group and by molecular mass of 14 a.m.u [CH₂ = 12 + 2 = 14].
3. Physical Properties — The physical properties of the members change gradually showing gradation in properties as the number of carbon atoms per molecule increases, i.e. as molecular mass increases.
   For example, melting point, boiling point and the density of the successive members of the homologous series increase with increase in molecular mass.
4. Chemical Properties — Members of a homologous series have similar chemical properties.
   For example, Methane reacts with chlorine to form methyl chloride:
   CH₄ + Cl₂ ⟶ CH₃Cl + HCl
   Similarly, ethane reacts to form ethyl chloride
   C₂H₆ + Cl₂ ⟶ C₂H₅Cl + HCl
5. Preparation — All the members of a homologous series can be prepared by using the same general method of preparation.

Condensed structural formula of ethene:

H₂C=CH₂

Branched structural formula of ethene:

All groups derived from parent alkane by loss of 'H' atom are called alkyl groups.

Alkyl group of Methane is Methyl (CH₃)
Alkyl group of Ethane is Ethyl (C₂H₅)

An atom, radical or bond which defines the structure of an organic compound and confers characteristic properties to it is known as a functional group.

Isomers & Isomerism — Organic compounds having the same molecular formula but differing in molecular arrangement or in structural formula are called Isomers and the phenomenon is called Isomerism.

Characteristics of Isomers:

1. Properties of Isomers — Isomers of the same homologous series have similar chemical properties but differ in physical properties.
2. Number of Isomers — Number of Isomers increases with increase in number of carbon atoms. [e.g., C₄H₁₀ has two isomers, C₅H₁₂ has three isomers]

Difference between Chain Isomerism and Position Isomerism:
Chain Isomerism occurs due to the difference in arrangemnet of Carbon atoms in the chain whereas Position Isomerism occurs due to the difference in position of functional group.

Isomers of Pentane exhibit chain isomerism:

n-pentane

iso-pentane

Isomers of Butyne exhibit position isomerism:

but-1-yne

but-2-yne

Nomenclature is the system of assignment of names to organic compounds.

Need for Nomenclature — Large number of organic compounds due to:

1. Varying molecular structures of organic compounds.
2. Isomerism in organic compounds

increases need for correct, methodical and systematic naming of each compound.

Basic rules of Nomenclature by the trivial system:

The basis of naming organic compounds by the trivial system is its :

1. Source
2. Properties
3. Latin or greek origin of compounds

For example,
Methane (CH₄) was named marsh gas since it was obtained from marshy places.
The name Acetic acid is derived from it's source 'vinegar' [Latin : acetum]

Longest Chain Rule — The longest continuous chain of 'C' atoms, known as parent chain is selected. The longest chain need not be straight.
For example,

(i) The longest chain is of 5 carbon atoms, so root word is 'pent'

(ii) Longest chain is of 7 carbon atoms, so the root word is 'hept'. The reamining carbon atom (unnumbered) is considered a branch.

Smallest number for functional groups rule — In case, any functional group is also present in the chain, then the carbon atom are numbered in such a way that the functional group gets the smallest possible number.
For example,

Hydrocarbons — Hydrocarbons are compounds that are made up only of carbon and hydrogen atoms.

Classification of Hydrocarbons — Hydrocarbons are sub-divided into two main groups, the aliphatic (open) and cyclic (closed) chain compounds. The open chain compounds or aliphatic hydrocarbons are further sub-divided into saturated hydrocarbons and unsaturated hydrocarbons. Example of saturated hydrocarbons is the homologous series of Alkanes. Examples of unsaturated hydrocarbons are the homologous series of Alkenes and Alkynes.

	Alkanes	Alkenes	Alkynes
General formula	CnH2n+2	CnH2n	CnH2n-2
Characteristic bond	Contains a single C – C covalent bond	Contains a double C = C covalent bond	Contains a triple C≡C covalent bond
IUPAC Name of first 3 members	Methane, Ethane, Propane	Ethene, Propene, 1-Butene	Ethyne, Propyne, 1-Butyne
Common Name of first 3 members	Methane, Ethane, Propane	Ethylene, Propylene, 1-Butylene	Acetylene, Methyl acetylene, Ethyl acetylene
Condensed Structural Formula
Branched Structural Formula
Availability of electrons	Not available	Available	Available
Reactivity	Less reactive	More reactive	Most reactive
Characteristic Reaction	Substitution reaction	Addition reaction	Addition reaction

The structural formulae are shown below:

Alkane

(a) Methane

(b) Ethane

(c) Propane

(d) Butane - Chain isomers

(i) 1-butane (n-butane)

(ii) 2-methyl propane [iso-butane]

(e) Pentane - Chain isomers

(i) 1-pentane [n-pentane]

(ii) 2-methyl butane [iso-pentane]

(iii) 2-2-dimethylpropane [neo-pentane]

Alkene

(b) Ethene

(c) Propene

(d) Butene - Position isomers

(i) 1-butene

(ii) 2-butene

(d) Butene - Chain isomers

(i) 2-methyl prop-1-ene

(e) Pentene - Position isomers

(i) 1-pentene

(ii) 2-pentene

(e) Pentene - Chain isomers

(i) 2-methyl but-1-ene

(ii) 3-methyl but-1-ene

Alkyne

(b) Ethyne

(c) Propyne

(d) Butyne - Position isomers

(i) 1-butyne

ii) 2-butyne

(e) Pentyne — Position isomers

(i) 1-pentyne

(ii) 2-pentyne

(e) Pentyne — Chain isomer

(i) 3-methyl but-1-yne

Alcohol

(a) Methanol [methyl alcohol]

(b) Ethanol [ethyl alcohol]

(c) Propanol — Position isomers

(i) 1-propanol [n-propylalcohol]

(ii) 2-propanol [iso-propylalcohol]

(d) Butanol — Position isomers

(i) 1-butanol

(ii) 2-butanol

(d) Butanol — Chain isomers

(i) 2-methyl propan-1-ol

(ii) 2-methyl propan-2-ol

(e) Pentanol — Position isomers

(i) 1-pentanol

(ii) 2-pentanol

(iii) 3-pentanol

Aldehydes

(a) Methanal [formaldehyde]

(b) Ethanal [acetaldehyde]

(c) Propanal [propionaldehyde]

(d) Butanal [butraldehyde]

Carboxylic acids

(a) Methanoic acid [formic acid]

(b) Ethanoic acid [acetic acid]

(c) Propanoic acid [propionic acid]

(d) Butanoic acid [butyric acid] - Chain isomer

(i) 2-methyl propanoic acid [iso-butyriac acid]

Ketones

(a) Propanone [acetone]

(b) 2-Butanone [ethyl methyl ketone]

(c) 3-Pentanone [diethyl ketone]

Alkyl Halides

(a) Monochloro methane [methyl chloride]

(b) Bromoethane [ethyl bromide]

(c) Iodomethane [methyl iodide]

Ether

(a) Methoxy methane [dimethyl ether]

(b) Methoxy ethane [ethyl methyl ether]

(c) Ethoxy ethane [diethyl ether]

Ester

(a) Methyl methanoate [methyl formate]

(b) Methyl ethanoate [methyl acetate]

(c) Ethyl ethanoate [ethyl acetate]

(i) 3-Methyl butanol

(ii) 2, 2-dimethyl propanol

(iii) 3-Bromo 2-methyl butanoic acid

(iv) 3-Methyl butanal

(v) 3-Methyl butan 2-one

(a) Methane [CH₄] by decarboxylation :

$\underset{\text{ sodium acetate}}{\text{CH}_3\text{.COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{methane}}{\text{C}\text{H}_4} + \text{Na}_2\text{CO}_3$

(b) Methane [CH₄] from alkyl halide :

$\underset{\text{ methyl iodide}}{\text{CH}_3\text{I}} + \underset{ \text{ nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{ \text{ methane}}{\text{CH}_4} + \text{HI}$

(c) Ethane [C₂H₆] by decarboxylation :

$\underset{\text{sodium propionate}}{\text{C}_2\text{H}_5\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} + \text{Na}_2\text{CO}_3$

(d) Ethane [C₂H₆] from alkylhalide :

$\underset{\text{ethylbromide}}{\text{C}_2\text{H}_5\text{Br}} + \underset{\text{nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} +\text{HBr}$

(e) Ethene [C₂H₄] by dehydration :

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

(f) Ethene [C₂H₄] by dehydrohalogenation :

$\underset{\text{ Bromoethane}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{alcoholic}}{\text{KOH}} \xrightarrow{\text{boil}} \underset{ \text{ ethene} } {\text{C}_2\text{H}_4} + \text{KBr} + \text{H}_2\text{O}$

(g) Ethyne [C₂H₂] from Calcium Carbide :

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2$

(h) Ethyne [C₂H₂] from 1,2, dibromoethane [ethylene dibromide] by -dehydrohalogenation :

(i) Ethanol [C₂H₅OH] by hydrolysis of alkylhalide:

$\underset{\text{ Bromo Ethane}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{aqueous}}{\text{KOH}} \xrightarrow{\text{boil}} \underset{ \text{ ethanol}} {\text{C}_2\text{H}_5\text{OH}} + \text{KBr}$

(j) Ethanol [C₂H₅OH] by hydration of ethene:

$\underset{\text{Ethene}}{\text{C}_2\text{H}_4} + \underset{\text{[conc.]}}{\text{H}_2\text{SO}_4} \xrightarrow[30 \text{ atmos.}]{80^{\circ} \text{C}} \underset{\text{Ethyl hydrogen sulphate}}{\text{C}_2\text{H}_5\text{-HSO}_4}$

$\underset{\text{Ethyl hydrogen sulphate}}{\text{C}_2\text{H}_5\text{-HSO}_4} + \underset{\text{[steam]}}{\text{H}_2\text{O}} \longrightarrow \underset{\text{ ethanol} }{\text{C}_2\text{H}_5\text{OH}} + \text{H}_2\text{SO}_4$

$\bigg[\underset{\text{Ethene}}{\text{C}_2\text{H}_4} + \underset{\text{ steam} }{\text{H}_2\text{O}} \xrightarrow[\text{acid}]{\text{H}^\text{+}} \underset{\text{ ethanol} }{\text{C}_2\text{H}_5\text{OH}}\bigg]$

(k) Ethanoic acid [CH₃COOH] by oxidation of alcohol :

$\underset{\text{ Ethanol}}{\text{C}_2\text{H}_5\text{OH}} +[\text{O}]\xrightarrow[\text{acidified}]{\text{K}_2\text{Cr}_2\text{O}_7} \underset{\text{[Acetaldehyde]} }{\text{CH}_3\text{CHO}} + \text{H}_2\text{O}$

$\underset{\text{[Acetaldehyde]} }{\text{CH}_3\text{CHO}} +[\text{O}]\xrightarrow[\text{acidified}]{\text{K}_2\text{Cr}_2\text{O}_7} \underset{\text{[Acetic acid]} }{\text{CH}_3\text{COOH}}$

(a) Conversion of Methane to Carbon tetrachloride by substitution [diffused sunlight]:

$\underset{\text{ methane} }{\text{CH}_4} + 4\text{Cl}_2 \xrightarrow[\Delta]{\text{diffused sunlight}} \underset{\text{Carbon tetrachloride}}{\text{CCl}_4} + 4\text{HCl}$

(b) Conversion of Methane to Carbon dioxide by complete oxidation:

$\underset{\text{ methane} }{\text{CH}_4} + 2\text{O}_2\text{[excess]} \longrightarrow \text{CO}_2 + 2\text{H}_2\text{O} + \Delta$

(c)(i) Conversion of Methane to Methanol to Methanal to Methanoic acid by catalytic oxidation using catalyst copper [Cu]:

$$\begin{aligned}\underset{\text{ methane}}{2\text{CH}_4} + \text{O}_2 \xrightarrow[200 \text{^{\circ} C}]{\text{Cu tube}} \underset{\text{methanol}}{2\text{CH}_3\text{OH}} \\[1em] \underset{\text{methanol}}{2\text{CH}_3\text{OH}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{\text{methanal} }{\text{2HCHO}} + 2\text{H}_2\text{O} \\[1em] \underset{\text{methanal} }{\text{2HCHO}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{\text{methanoic acid} }{\text{2H-COOH}}\end{aligned}$$

(c)(ii) Conversion of Methane to Methanol to Methanal to Methanoic acid by controlled slow oxidation using acidified K₂Cr₂O₇:

$\underset{\text{ Methane} }{\text{CH}_4} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ methanol}}{\text{CH}_3\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text { methanal}}{\text{HCHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{methanoic acid} }{\text{HCOOH}}$

(d) Conversion of Methane to Methanal by catalytic oxidation using catalyst MoO:

$\underset{\text{ methane}}{\text{CH}_4} + \text{O}_2 \xrightarrow[350 - 500 \text{^{\circ} C}]{\text{MoO}} \underset{\text{methanal} }{\text{HCHO}} + \text{H}_2\text{O}$

(e) Conversion of Methane to Ethyne by Pyrolysis [dehydrogenation]:

$\underset{\text{ methane}}{2\text{CH}_4} \xrightarrow{1500 ^{\circ} \text{C}} \underset{\text{ethyne} }{\text{C}_2\text{H}_2} + 3\text{H}_2$

(a) Conversion of Ethane to Hexachloro ethane by substitution [diffused sunlight]:

$\underset{\text{ ethane} }{\text{C}_2\text{H}_6} + \text{Cl}_2 \underset{\Delta}{\xrightarrow{\text{diffused sunlight}}} \underset{\text{monochloroethane}}{\text{C}_2\text{H}_5\text{Cl}}+ \text{HCl}$

$\underset{\text{monochloroethane} }{\text{C}_2\text{H}_5\text{Cl}} + \underset{\text{[excess]}}{\text{Cl}_2} \longrightarrow \underset{\text{dichloroethane}}{\text{C}_2\text{H}_4\text{Cl}_2}+ \text{HCl}$

$\underset{\text{dichloroethane}}{\text{C}_2\text{H}_4\text{Cl}_2} + \text{Cl}_2 \longrightarrow \underset{\text{trichloroethane}}{\text{C}_2\text{H}_3\text{Cl}_3}+ \text{HCl}$

$\underset{\text{trichloroethane}}{\text{C}_2\text{H}_3\text{Cl}_3} + \text{Cl}_2 \longrightarrow \underset{\text{tetrachloroethane}}{\text{C}_2\text{H}_2\text{Cl}_4}+ \text{HCl}$

$\underset{\text{tetrachloroethane}}{\text{C}_2\text{H}_2\text{Cl}_4} + \text{Cl}_2 \longrightarrow \underset{\text{pentachloroethane}}{\text{C}_2\text{H}\text{Cl}_5}+ \text{HCl}$

$\underset{\text{pentachloroethane}}{\text{C}_2\text{H}\text{Cl}_5} + \text{Cl}_2 \longrightarrow \underset{\text{hexachloroethane}}{\text{C}_2\text{Cl}_6}+ \text{HCl}$

(b) Conversion of Ethane to Carbon dioxide by complete oxidation:

$\underset{\text{ ethane}}{2\text{C}_2\text{H}_6} + 7\text{O}_2\text{[excess]} \longrightarrow \text{4CO}_2 + 6\text{H}_2\text{O} + \Delta$

(c)(i) Conversion of Ethane to Ethanol to Ethanal to Ethanoic acid by catalytic oxidation using catalyst copper [Cu]:

$$\begin{aligned}\underset{\text{ ethane}}{2\text{C}_2\text{H}_6} + \text{O}_2 \xrightarrow[200 \text{^{\circ} C}]{\text{Cu tube}} \underset{\text{ethanol}}{2\text{C}_2\text{H}_5\text{OH}} \\[1em] \underset{\text{ethanol}}{2\text{C}_2\text{H}_5\text{OH}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{\text{ethanal}}{2\text{CH}_3\text{CHO}} + 2\text{H}_2\text{O} \\[1em] \underset{\text{ethanal}}{2\text{CH}_3\text{CHO}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{ \text{ethanoic acid} }{2\text{CH}_3\text{COOH}}\end{aligned}$$

(c)(ii) Conversion of Ethane to Ethanol to Ethanal to Ethanoic acid by controlled slow oxidation using acidified K₂Cr₂O₇:

$\underset{\text{ Ethane} }{\text{C}_2\text{H}_6} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{ \text{ethanol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ethanal}}{\text{CH}_3\text{CHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ethanoic acid}}{\text{CH}_3\text{COOH}}$

(d) Conversion of Ethane to Ethanal by catalytic oxidation using catalyst MoO:

$\underset{\text{ ethane}}{\text{C}_2\text{H}_6} + \text{O}_2 \xrightarrow[350 - 500 \text{^{\circ} C}]{\text{MoO}} \underset{\text{ethanal} }{\text{CH}_3\text{CHO}} + \text{H}_2\text{O}$

(e) Conversion of Ethane to Ethene by Pyrolysis [dehydrogenation]:

$\underset{\text{ ethane}}{\text{C}_2\text{H}_6} \xrightarrow[\text{catalyst [Al}_2\text{O}_3\text{]}]{500 ^{\circ} \text{C}} \underset{\text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2$

(a) Conversion of Ethene to Ethane by Catalytic hydrogenation (H₂):

$\underset{\text{ ethene}}{\text{C}_2\text{H}_4} + \text{H}_2 \xrightarrow[300^{\circ}\text{C}]{\text{Nickle}} \underset{\text{ethane}}{\text{C}_2\text{H}_6}$

(b) Conversion of Ethene to 1,2 dichloroethane by Halogenation (Cl₂):

(c) Conversion of Ethene to 1,2 dibromoethane by Halogenation (Br₂):

(d) Conversion of Ethene to 1,2 diiodoethane by Halogenation (I₂):

$\underset{\text{ ethene}}{\text{C}_2\text{H}_4} + \text{I}_2 \xrightarrow[\text{[inert solvent]}]{\text{CCl}_4} \underset{\text{1,2, di iodoethane}}{\text{C}_2\text{H}_4\text{I}_2}$

(e)(i) Conversion of Ethene to Bromoethane by Halogen acids (HBr):

$\underset{\text{ ethene}}{\text{C}_2\text{H}_4} + \text{HBr} \longrightarrow \underset{\text{Bromoethane}}{\text{CH}_3\text{CH}_2\text{Br}}$

(e)(ii) Conversion of Ethene to Chloroethane by Halogen acids (HCl):

$\underset{\text{ethene}}{\text{C}_2\text{H}_4} + \text{HCl} \longrightarrow \underset{\text{Chloroethane}}{\text{CH}_3\text{CH}_2\text{Cl}}$

(f) Conversion of Ethene to Polyethylene by Polymerization:

Ethene polymerises to produce polythene

$\underset{\text{ethene}}{\text{n H}_2\text{C = C}\text{H}_2} \xrightarrow[\text{high pressure catalyst}]{\text{high temperature}} \underset{\text{(Polythene)}}{\Big[\text{H}_2\text{C—C}\text{H}_2\Big]_\text{n}}$

(a) Conversion of Ethyne to Ethane [2 steps] by Catalytic hydrogenation (H₂):

(b) Conversion of Ethyne to 1,1,2,2 tetrachloroethane [2 steps] by Halogenation (Cl₂):

(c) Conversion of Ethyne to 1,1,2,2 tetrabromoethane [2 steps] by Halogenation (Br₂):

(d) Conversion of Ethyne to 1,2 diiodoethene by Halogenation (I₂):

$\underset{\text{ ethyne}}{\text{HC ≡ CH}} + \text{I}_2 \xrightarrow{\text{alcohol}} \underset{\text{1,2 di iodoethene}}{\text{H — } \overset{\underset{\normalsize{|}}{\normalsize{I}}}{\text{C}} = \overset{\underset{\normalsize{|}}{\normalsize{I}}}{\text{C}} \text{ — H}}$

(e)(i) Conversion of Ethyne to 1,1 dibromo ethane by Halogen acids (HBr):

(e)(ii) Conversion of Ethyne to 1,1 dichloro ethane by Halogen acids (HCl):

(f)(i) Conversion of Ethyne to Copper Acetylide by Ammoniacal Cuprous Chloride:

$\underset{\text{ ethyne}}{\text{HC ≡ CH}} + 2\text{CuCl} + 2\text{NH}_4\text{OH} \longrightarrow \underset{\text{Copper Acetylide}}{\text{Cu-C ≡ C-Cu}} + 2\text{NH}_4\text{Cl} + 2\text{H}_2\text{O}$

(f)(ii) Conversion of Ethyne to Silver Acetylide by Ammoniacal Silver Nitrate:

$\underset{\text{ ethyne}}{\text{HC ≡ CH}} + 2\text{AgNO}_3 + 2\text{NH}_4\text{OH} \longrightarrow \underset{\text{Silver Acetylide}}{\text{Ag-C ≡ C-Ag}} + 2\text{NH}_4\text{NO}_3 + 2\text{H}_2\text{O}$

(a) Conversion of Ethanol to Carbon dioxide by burning:

$\underset{ \text{ ethanol}}{\text{C}_2\text{H}_5\text{OH}} + 3\text{O}_2 \longrightarrow 2\text{CO}_2 + 3\text{H}_2\text{O}$

(b) Conversion of Ethanol to Ethanal to Ethanoic acid by oxidation using acidified K₂Cr₂O₇:

$\underset{ \text{ethanol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[\underset{\text{[acidified]}}{\text{K}_2\text{Cr}_2\text{O}_7}]{\text{[O]}} \underset{\text{ethanal}}{\text{CH}_3\text{CHO}} \xrightarrow[\underset{\text{[acidified]}}{\text{K}_2\text{Cr}_2\text{O}_7}]{\text{[O]}} \underset{ \text{ethanoic acid} }{\text{CH}_3\text{COOH}}$

(c) Conversion of Ethanol to Sodium ethoxide using sodium:

$\underset{\text{ethanol} }{2\text{C}_2\text{H}_5\text{OH}} + 2\text{Na} \longrightarrow \underset{\text{sodium ethoxide} }{2\text{C}_2\text{H}_5\text{ONa}} + \text{H}_2$

(d) Conversion of Ethanol to Ethyl ethanoate using ethanoic acid and conc. H₂SO₄:

$\underset{\text{ethanol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{ethanoic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(e) Conversion of Ethanol to Ethene using conc. H₂SO₄ at 170°C:

$\underset{\text{ethanol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\underset{\text{[excess]}}{\text{Conc. H}_2\text{SO}_4}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

(a) Conversion of Ethanoic acid [acetic acid] to Sodium acetate using alkali - NaOH:

$\underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} + \text{NaOH} \longrightarrow \underset{\text{Sodium Acetate}}{\text{CH}_3\text{COONa}} + \text{H}_2\text{O}$

(b) Conversion of Ethanoic acid [acetic acid] to Calcium acetate using alkali - Ca(OH)₂:

$2\underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} + 2\text{Ca(OH)}_2 \longrightarrow \underset{\text{Calcium Acetate}}{\text{(CH}_3\text{COO)}_2\text{Ca}} + 2\text{H}_2\text{O}$

(c) Conversion of Ethanoic acid [acetic acid] to Ammonium acetate using alkali - NH₄OH:

$\underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} + \text{NH}_4\text{OH}\longrightarrow \underset{ \text{Ammonium acetate}}{\text{CH}_3\text{COONH}_4} + \text{H}_2\text{O}\$

(d) Conversion of Ethanoic acid [acetic acid] to Ethyl ethanoate [ethyl acetate] using ethanol and conc. H₂SO₄:

$\underset{\text{Ethanol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{Ethyl Ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(i) In alkanes, all the four valencies of each carbon atom are satisfied by the hydrogen atoms, forming single covalent bond. The non-availability of electrons in the single covalent bond makes them less reactive and therefore they undergo substitution reaction only. Hence, they are called saturated hydrocarbon.

(ii) Alkenes are known as olefins [Oleum = oil; ficare = to make] because they form oily products on treatment with halogens (like chlorine or bromine).

(iii) Alkenes are unsaturated hydrocarbons having carbon atoms forming a double covalent bond as their valencies are not fully satisfied by hydrogen atoms whereas alkanes are saturated hydrocarbons as all the four valencies of its carbon atoms are satisfied by the hydrogen atoms. The availability of electrons in the double bond in case of alkenes makes them more reactive than alkanes which has do not have electrons available in the single covalent bond.

(iv) Ethanoic acid (CH₃ – COOH) contains only one – COOH group (carboxylic acid group) that is why it is called a monocarboxylic acid. As ethanoic acid does not contain a benzene ring, so it is an aliphatic monocarboxylic acid.

(i) Ethyl alcohol containing pyridine or copper sulphate is termed denaturated alcohol. It is used for industrial applications only and hence made undrinkable.

(ii) Anhydrous acetic acid on cooling below 16.5°C, crystallizes out in the pure form, forming a crystalline mass resembling ice [m.p. around 17°C] . Hence, pure acetic acid is called glacial acetic acid.

(iii) Esterification is the chemical process of heating carboxylic acids with alcohol in the presence of an acid catalyst to produce esters.

Chemical tests to distinguish between Ethane, Ethene and Ethyne:

Add Sodium Carbonate (Na₂CO₃) / Sodium Hydrogen Carbonate (NaHCO₃) solution to Ethanol and ethanoic acid. With Ethanol it will produce brisk effervescence of carbon dioxide (CO₂) gas whereas no effervescence is seen with Ethanol.

The chemical equation for reaction between Sodium Carbonate (Na₂CO₃) / Sodium Hydrogen Carbonate (NaHCO₃) and Ethanoic Acid is given below:

2CH₃COOH + Na₂CO₃ ⟶ 2CH₃COONa + H₂O + CO₂↑

CH₃COOH + NaHCO₃ ⟶ CH₃COONa + H₂O + CO₂↑

(i) Uses of Methane:

1. Methane is used as a domestic fuel.
2. Methane is used in the preparation of useful compounds like ethyne (acetylene), methanal (formal-dehyde), methanol, chloro-methane and tetrachloro-methane (carbon tetrachloride).
3. Methane is a source of carbon monoxide and hydrogen.

(ii) Uses of Ethane:

1. Ethane is used as a gaseous and automobile fuel.
2. Ethane is used in the preparation of ethene, ethanol, ethanal (acetaldehyde) and ethanoic acid (acetic acid).
3. It forms ethyl chloride which is used to make tetraethyllead. 1, 1, 1-trichloroethane is one solvent that is used a lot in dry cleaning.

(iii) Uses of Ethene:

1. Production of oxy-ethylene torch — For welding purposes and cutting metals.
2. Ripening of green fruits — Artificial ripening and preservation of fruits.
3. Catalytic hydrogenation — Used in hardening of oils.
4. Manufacture of —
   1. Synthetic chemicals — Ethylene glycol [anti-freeze], di-ethyl ether [solvent], ethylene oxide [fumigant], mustard gas [chemical warfare],
   2. Polymers — Polyetheylene, polyvinyl chloride [P.V.C.]- used in packaging, insulators, containers, rain coats etc.

(iv) Uses of Ethyne:

1. Production of oxy-acetylene torch — for welding and cutting metals [flame temp. 3500°C] .
2. Ripening of green fruits — Artificial ripening and preservation of fruits.
3. Manufacture of organic compounds — Acetic acid, Acetaldehyde, Acetylene dichloride, Ethyl alcohol, Oxalic acid.
4. Manufacture of synthetic products — Polymers, synthetic rubbers and fibres.

(v) Uses of Ethanol:

1. It is a good solvent for gums and resins.
2. It is used in thermometers and as a preservative for biological specimens due to its low freezing point.
3. It is used in the manufacture of chemicals such as chloroform, iodoform, ether, acetic acid and synthetic products like dyes, esters (perfumes), antiseptics, preservatives.
4. Ethyl alcohol is used in alcoholic drinks like whisky, wine and beer.
5. As a fuel in powdered form and as an antifreeze for automobile radiators.

(vi) Uses of Ethanoic acid:

1. In manufacture of important organic compounds — Vinyl acetate [used in resins], acetic anhydride [used in aspirin], cellulose acetate [used in synthetic fibres], various dyes, perfumes and medicines.
2. In the food industry — Vinegar for preserving and flavouring food.
3. As a solvent — It dissolves phosphorous, sulphur, iodine, resins, cellulose, etc.
4. As a laboratory reagent — It is used for preparing acetone, esters, etc.
5. As a coagulant — For coagulating rubber from latex.

Pent-1-ene

But-2-yne

3-methyl pentane

2-methyl-prop-1-ene

Pentan-3-ol

1, 1, 2, 2 tetrabromoethane

2-methyl butan-2-ol

2, 2 dimethylpropan-1-ol

2, 2 dimethyl propane

2-bromo-4-chloro pentane

1. 36
2. neo-pentane
3. bromoethane
4. propyne
5. carboxyl

1. $\text{1,2 dibromoethane} \xrightarrow{\text{A}} \text{Acetylene}$

$\text{Acetylene} \xrightarrow{\text{B}} \text{Silver acetylide}$

$\underset{\text{ ethyne}}{\text{HC ≡ CH}} + 2\text{AgNO}_3 + 2\text{NH}_4\text{OH} \longrightarrow \underset{\text{Silver Acetylide}}{\text{Ag-C ≡ C-Ag}} + 2\text{NH}_4\text{NO}_3 + 2\text{H}_2\text{O}$

2. $\text{Ethanol} \xrightarrow{\text{C}} \text{Ethene}$

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

$\text{Ethyl iodide} \xrightarrow{\text{D}} \text{Ethene}$

$\underset{\text{ ethyl iodide}}{\text{C}_2\text{H}_5\text{I}} + \underset{ \text{ alcoholic}}{\text{KOH}} {\xrightarrow{\text{boil}}} \underset{ \text{ ethene}}{\text{C}_2\text{H}_4} + \text{KI} +\text{H}_2\text{O}$

3. $\text{Bromoethane} \xrightarrow{\text{E}} \text{Ethane}$

$\underset{\text{bromoethane}}{\text{C}_2\text{H}_5\text{Br}} + \underset{\text{nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} +\text{HBr}$

$\text{Ethane} \xleftarrow{\text{F}} \text{Sodium propanoate}$

$\underset{\text{sodium propanoate}}{\text{C}_2\text{H}_5\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[300^{\circ}\text{C}]{\text{CaO}} \underset{\text{ethane}}{\text{C}_2\text{H}_6 \uparrow} + \text{Na}_2\text{CO}_3$

4. $\text{Sodium ethanoate} \xrightarrow{\text{G}} \text{Marsh gas}$

$\underset{\text{ sodium acetate}}{\text{CH}_3\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[300^{\circ}\text{C}]{\text{CaO}} \underset{\text{methane}}{\text{C}\text{H}_4 \uparrow} + \text{Na}_2\text{CO}_3$

Methane to Methanol to Methanal to Methanoic acid

$\underset{\text{ Methane} }{\text{CH}_4} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{methanol}}{\text{CH}_3\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text {methanal}}{\text{HCHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{methanoic acid}}{\text{HCOOH}}$

5. $\text{Sodium acetate + H}_2 \xleftarrow{\text{H}} \text{Acetic acid}$

$2\underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} + 2\text{Na} \longrightarrow \underset{\text{sodium acetate}}{2\text{CH}_3\text{COONa}} + \text{H}_2$

$\text{Acetic acid}\xrightarrow{\text{H}_1} \text{Ethyl ethanoate}$

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

1. The organic compound which forms carbon tetrachloride on reaction with chlorine. — B : Trichloromethane
2. The reagent which can distinguish between ethene and ethyne. — A : Ammoniacal CuCl₂
3. The substance which reacts with bromoethane to give ethanol. — E : Aqueous KOH
4. The substance which gives bromoethane on reaction with hydrogen bromide. — F : Ethene
5. The substance which reacts with acetic acid to give CH₃COOC₂H₅ — H : Ethanol

1. An alkyne to an alkene:

$\underset{\text{ ethyne [acetylene]}}{\text{H}_2\text{C}_2} + \text{H}_2 \xrightarrow[300^{\circ}\text{C}]{\text{Nickle}} \underset{\text{ethene}}{\text{C}_2\text{H}_4}$

2. An alkene to an alkane:

$\underset{\text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2 \xrightarrow[300^{\circ}\text{C}]{\text{Nickle}} \underset{\text{ethane}}{\text{C}_2\text{H}_6}$

3. An alkane to an alcohol:

$\underset{\text{ ethane}}{2\text{C}_2\text{H}_6} + \text{O}_2 \xrightarrow[200 \text{^{\circ} C}]{\text{Cu tube}} \underset{\text{ethanol}}{2\text{C}_2\text{H}_5\text{OH}}$

4. An alcohol to an alkene:

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170^{\circ}\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

5. A carboxylic acid to an ammonium salt :

$\underset{\text{ acetic acid}}{\text{CH}_3\text{COOH}} + \text{NH}_4\text{OH}\longrightarrow \underset{ \text{Ammonium acetate}}{\text{CH}_3\text{COONH}_4} + \text{H}_2\text{O}\$

Reversible reaction may be prevented by using conc. H₂SO₄ when the reaction is about to complete by removing H₂O.

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

As isomers have same general molecular formula and functional group (if any) and only differ in structural formula, hence, they show same chemical properties and differ in physical properties.

IUPAC is a systematic way of nomenclature of organic compounds that takes into account only one molecular structure of the compound. Hence, it assigns only one name to the compound.

In saturated hydrocarbons, all the four valencies of each carbon are satisfied by the hydrogen atoms, forming single covalent bond. The non-availability of electrons in the single covalent bond makes them less reactive and therefore undergo characteristic substitution reaction only. Addition reactions are not possible in case of saturated organic compounds.

Acetic acid (CH₃ – COOH) contains only one – COOH group (carboxylic acid group) that is why it is called a monocarboxylic acid. As acetic acid does not contain a benzene ring, so it is an aliphatic monocarboxylic acid.