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Organic Chemistry

K Warne – Grade 10

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ORGANIC CHEMISTRY Organic chemistry is the study of carbon containing

compounds derived from living organisms.

Oil is formed over millions of years from the break down of dead creatures and plants.

80+ million compounds-

natural & synthetic.

Crude Oil (petroleum) is a mixture of many thousands of these different compounds and is the main source of many of these chemicals.

They are called hydrocarbons because they predominantly contain the elements hydrogen and carbon.

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Distillation of Crude Oil

Lower boiling point substances ............... and move up.

As the temp drops substances .............. and run off.

..................temp

................... temp

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Homologous seriesThis is a series of compounds which all contain the same functional group, and have similar chemical properties. 

ALKANES ALKENES ALKYNS

CH4

CH2 =CH

2CH ≡CH

CH3-CH

3 CH

2 =CH –CH3

CH3C≡CH

Each has a general formula:

ALKANES: CnH2n+2

The members of the series differ by the number of CH2 units.

CH3-CH3, CH3-CH2-CH3, CH3-CH2-CH2-CH3

Graduation in physical properties:  eg: boiling points.

CH4 (GAS), C8H18 (LIQUID), C30H62 (SOLID)CC C

H

H

HH

H

H H

H

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ALKANESSATURATED HYDROCARBONS – contain maximum amount of ……………………………. - only ……………………….. bonds (no ……………………….. bonds)

NAMING ALKANES

No of C atoms Prefix Formula Alkane

1 Meth CH4 Methane

2 Eth CH3CH3 Ethane

3 Prop CH3CH2CH3 Propane

4 But CH3CH2CH2CH3 Butane

5 Pent CH3CH2CH2CH2CH3 Pentane

6 Hex C6H14 Hexane

7 Hept C7H16 Heptane

8 Oct C8H18 octane

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Alkenes

Esters

Amines

(alcohol)~yl

(acid)~oate

Amino -

CH3CONH2

Acylchlorides

Amides

~oyl Chloride

~amide

Aldehydes

Carboxylic Acids

~al

~oic acid

CH3- IHaloalkanes

Ketones

Halo~

~one

CH2 = CH2

Alcohols

~ene

~olFunctional

groups

The functional groups are

………………. or

………………….. of atoms which determine the

……………………. of organic molecules. 

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STRUCTURES OF ALKANES

METHANE CH4

Bond Angle109.5o Shape Tetrahedral

Can be illustrated as:

H

H C H

H

Methane is a colourless and ouderless flammeable gas. Mr 12+4 = 16g.mol-1

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ISOMERSC4H10 - can have two different structuresStraight chain. CH3 CH2 CH2 CH3 BUTANE

Branched chain CH3 CH CH3

CH3

METHYL PROPANE

Compounds that have the same molecular formula but different structural formula are said to be ISOMERS of each other.

TASK: illustrate the structures of the three different isomers of C5H12.

Use models OR CHEMSKETCH to help you.

branch

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Names & StructuresExamples2- methylbutane

CH3

CH3 CH CH2 CH3

CH3

CH3 C CH3

CH3

2,2 – dimethyl propane

TASK: illustrate the structures of:

2-methylpentane.

2,3 – dimethylbutane.

2,2,3 -trimethylpentane

CH3CH(CH3)CH2CH2CH3

CH3CH(CH3)CH(CH3)CH3

CH3C(CH3)2CH(CH3)CH2CH3

The 2 can be left off as there are no other possibilities. 2 and 3-methylbutane are the same molecule!

1 2 3 4

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THE RULES FOR NAMING ORGANIC COMPOUNDS1. Choose the longest unbroken chain of Carbon atoms and

assign a name for the carbon chain using the prefixes; meth-1, eth-2 etc.

2. Identify any carbon chain branches (alkyl groups). These are assigned names using the same prefixes as above along with the suffix “-yl” – methyl, ethyl etc.

3. Identify the functional groups present in the molecule. Assign a prefix or suffix according to their homologous series. These will be written in front of the name of the carbon chain.

5. Number the Carbon atoms in the longest chain so that the branches/functional groups have the lowest number possible. Allocate a number for every group/branch no matter how many times it occurs. Where groups are on the same carbon write their names in alphabetical order.

6. Prefixes are used for groups that occur more than once.

Di – 2 Tri – 3 Tetra – 4 Penta – 5 etc.

7. Groups are written in alphabetical order.

8. The final name is written as one word with commas between numbers, hyphens separating numbers from words.

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Give the names of the following alkanes

3-methylpentane

2,4-dimethylpentane

2,2,4-trimethyl

hexane

(a)CH3 CH2 CH CH2 CH3

CH3

(b) CH3 CH CH2 CH CH3

CH3 CH3

(c) CH3 C(CH3)2 CH2 CH(CH3) CH2 CH3

(d) CH3CH2CH(CH3)C(CH3)3 2,2,3-trimethylpentane

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Examples of Alkenes

………………, C2H4

H H

C C

H H

OR …………………….

PROPENE CH2 CH CH3

TASK: Use ball & stick models or sketches to construct and name 3 different structures for C4H8 each one with one double bond.

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Alkynes

H-C≡C-H

H-C≡C-CH3

H-C≡C-CH2-CH3

CH3-C≡C-CH3

Ethyne

propyne

But–1-yne

But–2-yne

Very reactiveTriple bond unstable!Attracts electrophiles.

Alkynes are very unstable and reactive. Acetylene burns with very high temp?

C Cx

x xx

C C CH

H

H

H

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Hi -

This is a SAMPLE presentation only.

My FULL presentations, which contain loads more slides and other resources, are freely available on my resource sharing website:

www.sciencecafe.org.za

(paste into your browser if link above does not work)Have a look and enjoy!

Keith Warne