BY :Shubham

Hydrocarbons

BY :Shubham

Group Members

• Shubham Vashishth• Kulpreet Singh• Aman Shrestha• Prateek Diwakar• Ritvik Gupta• Rishabh Jain

BY :Shubham

Introduction

Hydrocarbons are organic compounds that contain only carbon and hydrogen. They are extremely important to our society because so many products are derived from them: fuels, fabrics, plastics, antifreezes, anaesthetics, insecticides, to name a few. The major source of aliphatic hydrocarbons is petroleum, an extremely complex mixture of compounds. Each of us, on the average, uses several tons of petroleum each year (directly or indirectly), mostly for fuel. Aromatic hydrocarbons are mainly obtained from coal, although small amounts are also obtained from petroleum.Eg.C4h10

BY :Shubham

Hydrocarbons may be saturated or unsaturated. A saturated hydrocarbon is one that is maxed out in terms of the number of hydrogen that can be present given the number of carbons in the compound; it is impossible to add more hydrogen atoms to the compound so it is saturated with hydrogen. Acyclic alkanes are saturated; there is no way additional hydrogen can be added while keeping the same number of carbons and maintaining normal bonding between the atoms.Alkenes, alkynes, aromatic compounds, and cyclic alkanes are unsaturated because hydrogen can be added to them, in theory and usually in practice, making them into acyclic alkanes.

Types of hydrocarbons

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Saturated HydrocarbonThe hydrocarbon that contain only carbon-carbon single bond is

called Saturated Hydrocarbon. These include open chain hydrocarbon as well as closed chain hydrocarbons. These compounds are called saturated because they have maximum number of bonded hydrogen

If different carbon atoms are joined together to form an open chain of carbon atoms with single bonds, they are called Alkanes.

For example: 2-Methylpropane (Isobutane)

If carbon atoms form a closed chain or ring, they are called Cycloalkanes.

For example: Cyclopentane

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Unsaturated HydrocarbonThe hydrocarbons which contain carbon-carbon multiple bond

(Double bonds or triple bond) are called unsturated hydrocarbon.

Depending upon multiple bond they are further classified as alkenes and alkynes.

o Alkenes : These are hydrocarbon which contain at least one carbon-carbon bond. For example: Ethene

o Alkynes: These are hydrocarbons which contain at least one carbon-carbon triple bond. For example: Ethyle

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Alkyl Groups

The removal of one hydrogen from a molecule of alkane gives the corresponding alkyl group. For example, if one hydrogen is removed from methane(CH4), we get an alkyl group called methyl ( -CH3). Thus alkyl groups are univalent groups with general formula CnH2n+1 .

Eg.

Structural IsomerismAlkenes show following types of structural isomerisms:i)Chain IsomerismThe isomers differ with respect to the chain of carbon

atoms. as in alkanes, ethene (C2H4) and propene(C3H6) can have only one structure but alkenes higher than propene have different structures.

For eg: 4 3 2 1 But-1-ene CH3−CH2−CH=CH2

ii)Position IsomerismThe isomers differ in the position of the double bonds.

For eg: CH2−CH=CH2−CH3 (But-1-ene) CH3−CH=CH−CH3 (But-2-ene)BY :Shubham

BY :Shubham

Aromatic hydrocarbonThe hydrocarbons which contain at least one special

type of hexagonal ring of carbon atoms with three double bond in the alternate positions are called aromatic hydrocarbon. The ring is called aromatic ring.

For example: i) Toluene ii) o-Xylene

The aromatic compounds may also contain more than one benzene rings. For example: i) Naphthalene ii) Anthracene

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Cycloalkanes Or Cyclic alkanesThese contain a closed chain or ring in

their molecules. They have the general formula CnH2n.

For example: i) Cyclopropane- or

ii)Cyclobutane- or

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Functional groups

Carbon forms bonds not only with hydrogen but also with other elements as well such as oxygen, sulphur and halogens. In a hydrocarbon chain, one or more hydrogen can be replaced by these elements in such a way that the tetravalency remains satisfied. Thus, an atom or a group of atoms which largely determines the chemical properties of an organic compound is called a functional group

These heteroatoms are also present in some groups and these groups confer characteristic properties of the compound regardless of the carbon chain.

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Some common functional groups

•Halo-groups: This group includes chlorine, bromine, fluorine and iodine.

•Alcohol: The hydroxyl group attached to a carbon chain forms alcohol.

General formula: CnH2n+1OH Suffix used: ol

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• Aldehyde: Carbon compounds containing -CHO groups.General formula: RCHOSuffix used: al•Ketone: Carbon compounds containing –CO-

groups.General formula: RCORSuffix used: one

•Carboxylic Acid: Carbon compounds containing -COOH groups.

General formula: RCOOHSuffix used: oic acid

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Homologous SeriesHomologous series is a family of

structurally similar compounds containing the same functional group in which two successive members differ by –CH2

All members of a homologous series are called homologues.

The most important homologous series are as follows:

Alkanes, alkenes, alkynes, alcohols, aldehydes, ketones, carboxylic acid, etc.

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Characteristics of Homologous series

• All the members of a homologous series can be represented by same general formula. For example, the general formula for Alkanes is C nH2n+2 where n is the number of carbon atoms. Similarly, aldehydes have the general formula CnH2n+1CHO or R–CHO.

• Each successive members differ in formula by a common difference of –CH 2. • The molecular mass of two successive members of homologous series differ

by 14u.• All the members of a particular homologous series show almost same

chemical properties because of the presence of the same functional group.• There is a gradual change(gradation) in the physical properties such as

density, melting point, boiling point, solubility, etc. ,with increase in molecular mass.

• All members of a homologous series can be prepared by the same general method of preparation.

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Nomenclature Of Alkanes

Nomenclature implies assigning proper name to the basis of certain standard rules so that the study of these compounds may become standard. The rules for naming them are as follows:

i) Longest Chain Rule

First of all, select the longest continues chain of carbon atoms in a molecule. 1 2 3 4 5 6 7 8 9For eg. CH3– CH– CH2– CH2– CH2–CH– CH2– CH2–CH3

CH3 CH2−CH3

In the example ,the longest chain has nine carbons and it is considered as parent root chain and carbon atoms which are not included in parent chain are called substituents.

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ii) Lowest set of locants

When two or more substituents are present, then end of the parent chain which gives the lowest set of the locants is preferred for numbering. This rule is called lowest set of locants.

This means that when two or more different sets of locants are possible, that set of locants which when compared term with other sets, each in order of increasing magnitude, has the lowest term at the first point of difference.

iii) Presence of more than one same substituent. If the same substituent or side chain occurs more than once,

the prefix di(for 2), tri(for 3), tetra(for 4), penta(for 5),hexa(for 6)…etc., are attached to the names of the substituents. The positions of the substituents are indicated separately and the numerals representing their positions are separated by commas.

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iv)Naming different substituents

If two or more different substituents or side chains are present in the molecule, they are named in the alphabetical order along with their appropriate positions. Prefix are ignored while comparing the substituents.

For eg: 1 2 3 4 5 CH3–CH–CH2–CH–CH3

CH3 CH3

2,4-Dimethylpentane

For eg: CH3CH3

5 4 3 2 1 CH3−CH3−C−CH3−CH3

CH3CH3

3 -Ethyl-2,3-dimethylpentane

BY :Shubham

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