chemistry m5 organic chemistry

Objectives Homologous Series

Naming Compounds Alkanes Reactions of

Alkanes Alkenes Reactions of AlkenesIntroduction

ORGANIC CHEMISTRYx

ORGANIC CHEMISTRYThe study of compounds containing carbon

except carbonates, the allotropes and oxides of carbon.

ENTER




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OBJECTIVES

After you have completed the viewing of this tutorial, you will be able to: • Recall that carbon forms branched and unbranched chains and

ring compounds • Illustrate that carbon atoms can form single bonds, double bonds

and triple bonds• List the general characteristics of a homologous series• Write general and molecular formulae for members of a given

homologous series• Write formulae to represent simple organic compounds• Describe the reactions of alkanes and alkenes• Write equations for the reactions of alkanes and alkenes.




ORGANIC CHEMISTRYx

INTRODUCTION: Carbon is Unique!

1. It has 4 electrons in its outer shell 2. It can bond to 4 other atoms.3. It can form single, double and triple bonds.

C-CSINGLE BOND

C=CDOUBLE BOND

C CTRIPLE BOND




ORGANIC CHEMISTRYx

CARBON IS UNIQUE!

It can form long chains with other carbon atoms:

C CC C

Straight Branched

Ring

C C

CC

C

C

C CC

C




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Bonding in Organic Compounds

• Covalent bonds are usually formed in organic compounds.

• Show the bonding present in methane, CH4.

FEEDBACK




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FEEDBACK

C H

H

H

HX

X

X X




ORGANIC CHEMISTRYx

CHARACTERISTICS OF HOMOLOGOUS SERIES

Organic compounds are grouped into families called homologous series.• Members can be represented by the same general

molecular formula.• Members display similar chemical properties.• There is a gradual change in physical properties as

the carbon chain increases.• The relative molecular mass increases by 14 as the

carbon chain increases by one.




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HOMOLOGOUS SERIES

HOMOLOGOUS SERIES GENERAL MOLECULAR FORMULA

Alkanes CnH2n+2

Alkenes CnH2n

Alcohols CnH2n+1OH

Carboxylic Acids (Alkanoic Acids) CnH2n+1COOH




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NAMING ORGANIC COMPOUNDS

1. Find and name the longest continuous carbon chain.2. Identify and name any group(s) attached to this chain.3. Number the chain consecutively, starting at the end nearer

to a substituent group.4. Indicate the position of each substituent group by an

appropriate number. 5. If there are more than one substituent then list them in

alphabetical order. Note. Use the prefixes di, tri, tetra etc., to designate several groups of the same kind. These prefixes are not considered when putting substituents in alphabetical order.




ORGANIC CHEMISTRYx

Name the compound.

C

H

C C C C

H H

H

H

H

H H H H H

C

H

HH

CHECK

• Find and name the longest continuous carbon chain.

• Identify and name any group(s) attached to this chain.

• Number the chain consecutively, starting at the end nearer to a substituent group.

• Indicate the position of each substituent group by an appropriate number.

• If there are more than one substituent then list them in alphabetical order. Use the prefixes di, tri, tetra etc., to designate several groups of the same kind. (These prefixes are not considered when putting substituents in alphabetical order.)

X




ORGANIC CHEMISTRYx

Name the compound.

C

H

C C C C

H H

H

H

H

H H H H H

C

H

HH






X

Name of compound: 2-methyl pentane




ORGANIC CHEMISTRYx

Name the compound.

C C C C C

C






X

C C

C

H H H

H

H

H

H H H

H

H

H

HH

HHH

H

H

H

CHECK




ORGANIC CHEMISTRYx

Name the compound.

C C C C C

C






X

CHECK

C C

C

H H H

H

H

H

H H H

H

H

H

HH

HHH

H

H

H

Name of compound: 2, 4-dimethyl heptane




ORGANIC CHEMISTRYx

ALKANES: Saturated hydrocarbons

General Molecular Formula for Alkanes: CnH2n+2

Molecular Formula

Name Relative Molecular Formula

State at room temperature

CH4 Methane 16 gasC2H6 Ethane 30 gasC3H8 Propane 44 gasC4H10 Butane 58 gasC5H12 Pentane 72 liquidC6H14 Hexane 86 liquidC7H16 Heptane 100 liquidC8H18 Octane 114 liquidC9H20 Nonane 128 liquidC10H22 Decane 142 liquid




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ALKANES

Draw the structural formula of butane.

FEEDBACK




ORGANIC CHEMISTRYx

You should realize there are two ways of drawing the structural formula of butane:

ALKANES

H

C

H

C

H

H H

H

C

H H

CH H H C

H

C

H

H H

C

H

H

C HH

H

Continue




ORGANIC CHEMISTRYx

Both structures have four carbon atoms and ten hydrogen atoms, i.e. they have the same molecular formula but different structural formula. They are called ISOMERS.

ALKANES - Isomers

H

C

H

C

H

H H

H

C

H H

CH H H C

H

C

H

H H

C

H

H

C HH

H

Continue

C CC C C CC

C




ORGANIC CHEMISTRYx

ISOMERS are compounds with the same molecular formula but different structural formula. Name the compounds below.

ALKANES - Isomers

H

C

H

C

H

H H

H

C

H H

CH H H C

H

C

H

H H

C

H

H

C HH

H

CHECK




ORGANIC CHEMISTRYx

ISOMERS are compounds with the same molecular formula but different structural formula. Name the compounds below.

ALKANES - Isomers

H

C

H

C

H

H H

H

C

H H

CH H H C

H

C

H

H H

C

H

H

C HH

H

butane methylpropane or 2-methylpropane




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REACTIONS OF ALKANES

Combustion Halogenation

Cracking

Click on a reaction name to proceed.




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Reactions of Alkanes: COMBUSTION

When an alkane burns in excess air, carbon dioxide and water are produced.

ALKANE EXCESS OXYGEN CARBON DIOXIDE WATER+ +

Examples:CH4(g) + 2O2 (g) CO2 (g) + 2H2O (g)

2 C2H6 (g) + 7O2 (g) 4 CO2(g) + 6H2O(g)

Combustion Halogenation Cracking




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Write balanced equations for the combustion of butane and pentane in excess air.

FEEDBACK





ORGANIC CHEMISTRYx


Balanced equations for the combustion of butane and pentane in excess air:

2 C4H10(g) + 13O2 (g) 8CO2 (g) + 10H2O (g)

C5H12(g) + 8O2 (g) 5CO2(g) + 6H2O(g)

Butane

Pentane


What substances do you think can be produced if an alkane is burnt in a limited supply of air? Check your answers. Ask your teacher.




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Reactions of Alkanes: HALOGENATION

LIGHT has to be present for Halogenation to take place. The reaction takes place in a series of steps:

SHOW ME

Try and name the products.

CH4 (g) + Cl2 (g) CH3Cl (g) + HCl (g)

CH3Cl (g) + Cl2 (g) CH2Cl2 (g) + HCl (g)

CH2Cl2 (g) + Cl2 (g) CHCl3 (g) + HCl (g)

CHCl3 (g) + Cl2 (g) CCl4 (g) + HCl (g)





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Reactions of Alkanes: CRACKING

Cracking is the process by which long hydrocarbon chains are broken into smaller, more useful hydrocarbons.e.g. C12H26 (l) C7H16 (l) + C5H10 (l)

Note that the number of carbon atoms in the products adds up to the number of carbon atoms in the reactant. The same is true for the hydrogen atoms. Complete the equation of the reaction and name the products. C18H38 C10H22 + ________

FEEDBACK





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FEEDBACK

C18H38 C10H22 + C8H16

decane octene





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ALKENES: Unsaturated Compounds

• Characterized by the presence of a C-C double bond (C=C)• General Molecular Formula: CnH2n

Molecular Formula Name Relative Molecular Formula State at room temperature

C2H4 Ethene 28 gasC3H6 Propene 42 gasC4H8 Butene 56 gasC5H10 Pentene 70 liquidC6H12 Hexene 84 liquidC7H14 Heptene 98 liquidC8H16 Octene 112 liquidC9H18 Nonene 126 liquidC10H20 Decene 140 liquid




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ALKENES: Isomers

Note there are three isomers of butene:




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REACTIONS OF ALKENES

Alkenes undergo ADDITION reactions.

Combustion (Burning)

Halogenation(Reaction with a halogen)

Hydrogenation (Reaction with Hydrogen)

Hydration(Reaction with water)

Click on a reaction name to proceed.




ORGANIC CHEMISTRYx

REACTIONS OF ALKENES: Combustion

Just as with alkanes, when alkenes burn in excess air, carbon dioxide and water are produced.

ALKENE + EXCESS OXYGEN CARBON DIOXIDE + WATER

e.g. C2H4 (g) + 3O2 (g) 2CO2 (g) + 2H2O (g)

2C3H6 (g) + 9O2 (g) 6CO2 (g) + 6H2O (g)

Write balanced equations for the combustion of butene and pentene in excess air.








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REACTIONS OF ALKENES: Hydrogenation

Alkenes react with hydrogen in the presence of a nickel catalyst at 150 oC to produce the corresponding alkane.

ethene ethane C2H4 (g) + H2 (g) C2H6 (g)

H

C

H

C

H

H H

H

C

H H

C HHNi

150 oC HH+

Ni150 oC








ORGANIC CHEMISTRYx

REACTIONS OF ALKENES: Hydration

Alkenes react with water in the presence of phosphoric acid at 300 oC to produce the corresponding alcohol.

ethene water ethanol C2H4 + H2O C2H5OH

OH

C

H

C

H

H H

H

C

H H

COH HH H

H3PO4

300 oC

+

H3PO4

300 oC Combustion

(Burning)Halogenation

(Reaction with a halogen)Hydrogenation

(Reaction with Hydrogen)Hydration

(Reaction with water)




ORGANIC CHEMISTRYx

REACTIONS OF ALKENES: Halogenation

Alkenes react readily with halogens, even in the dark.

ethene Bromine 1,2-dibromoethane(red-brown) (colourless)

C2H4 (g) + Br2 (aq) C2H4 Br2 (l) This reaction is used to distinguish between saturated and unsaturated compounds.

Br

C

H

C

H

H H

Br

C

H H

C HBr H+ Br








ORGANIC CHEMISTRYx

Assignment

Click on the link below and test yourself on alkanes and alkenes.

http://www.gcsescience.com/q/qhyalk.html

http://www.gcsescience.com/q/qhyalk.html

chemistry m5 organic chemistry

Education

cc single bond c

c double bond c c triple

simple organic compounds

given homologous series

ring compounds

alkenes cnh2n alcohols

study of compounds

carbon atoms