Hydrocarbons

Question 1

Aromatic compounds

Answer 1

Benzene and its derivatives

Question 2

Alicyclic/carboeyclic compounds

Answer 2

compounds which consist only of carbon atoms

Question 3

Heterocyclic Compounds

Answer 3

Compounds in which ring atoms are of carbon and some other element

Question 4

Albanese are also referred as

Answer 4

Paraffins

Question 5

Newman’s projection

Answer 5

molecule is viewed at the C—C bond head on.
They can be eclipsed or staggered

Question 6

Relative Stability of Conformations

Answer 6

In staggered form of ethane there are maximum repulsive forces, minimum energy and maximum stability of molecule
In the eclipsed form the electron clouds of the carbon hydrogen bonds come closer to each other resulting in increase in electron cloud repulsions, molecule have to possess more energy and thus has lower stability

Question 7

Torsional/dihedral angle

Answer 7

angle of rotation about C—C bond

Question 8

alkenes is made up of

Answer 8

one σ and one π-bond.

Question 9

Alkenes are ____ reactive than Alkanes

Answer 9

More; due to availability of n e’

Question 10

Rules for IUPAC:

Answer 10

name of the parent alkene with position number of double bond is written first and then names of substituents prefixed to it.

Question 11

Structural Isomerism:

Answer 11

Ethene and propene have no structural isomers, but there are three structures of butenes.

Question 12

Geometrical Isomerism:

Answer 12

a carbon-carbon double bond is made up of one σ bond and one π-bond. The π-bond presents free rotation about the double bond.
Presentation of rotation about the carbon-carbon double bond gives rise to the phenomenon

Question 13

Alkyne 1st member

Answer 13

Acetylene

Question 14

Preparation of alkanes:

Answer 14

Hydrogenation: addition of hydrogen takes place in the presence of finely divided nickel catalyst
2. Decarboxylation: sodium salt of carboxylic acid is heated strongly with soda lime
Wurtz reaction: 2 molecules of alkyl hallide when treated with sodium metal & dry ether
Reduction of alkyd hallide with zinc & acid or zinc & NaOH
Reduction of alcohols, aldehides, ketone & fatty acids with hot hydroiodide acid & red phosphorous at 150°C in sealed tube
Kolbe’s electrolysis: aqueous sol. of Na & K salts of fatty acids are electrolised

Question 15

Free radical mechanism steps:

Answer 15

Initiation
Propagation
Termination

Question 16

Action of steam on hydrocarbons form:

Answer 16

Water gas, syngas

Question 17

Pyrolysis/cracking:

Answer 17

Decomposition of higher alkanes into lower alkanes, ene, yne.. by applying heat

Question 18

Preparation of alkenes:

Answer 18

1. From alkynea, hydrogenation: Lindlar’s catalyst + Alkynes give alkenes
2. Alkyl hallide: dehydrogenation
3. Vicinal dihallide: dehalogenation
4. Acidic dehydration

Question 19

Chemical properties of alkanes:

Answer 19

Addition of dihydrogen alkenes give alkanes
Addition of dihalogen
Addition of sulphuric acid: forms alkyl hydrogen sulphate
Addition of water
Oxidation with Bayer’s reagent: vicinal dialcohol
Addition of ozone(ozonolysis)

Question 20

Preparation of alkynes:

Answer 20

Action of water in calcium carbide
From vicinal dihallide

Question 21

Chemical properties of alkynes

Answer 21

Acidic character
Addition reaction(addition of h, br, hbr)

Question 22

Preparation of benzene:

Answer 22

1. Cyclic polymerization of ethyne
2. Decarboxylation
3. Reduction

Question 23

Chemical properties of benzene

Answer 23

Nitration
Sulphonation
Chlorination
Hydrogenation

Question 24

Electrophilic substitution of benzene:

Answer 24

Formation of electrophile by chlorination
Forms carbonation
Removal of H+ in the presence of anion
Friedel Kraft’s alkynation
Friedel kraft’s acylation
Nitration
Sulphonation