basic chemistry copyright © 2011 pearson education, inc. 1 chapter 17 organic chemistry 17.1...

Basic Chemistry Copyright © 2011 Pearson Education, Inc.1

Chapter 17 Organic Chemistry

17.1 Alkanes

Compounds in food contain many organic compounds.


IUPAC Names


Structural Formulas

Alkanes are written with structural formulas that are• expanded to show each bond• condensed to show each carbon atom and the

attached hydrogen atoms

Basic Chemistry Copyright © 2011 Pearson Education, Inc.

Drawing Structural Formulas

Carbon atoms in a chain• maintain their tetrahedral

shape• are connected in a zigzag

pattern• are drawn as two dimensional • can be written in many ways

4


Some Structural Formulas

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Rotation of the end CH3-groups provides different representations for butane.


Learning Check

Draw the condensed structural formula for heptane.


Solution

Heptane, an alkane, has seven carbon atoms in its carbon chain.

CH3─CH2─CH2─CH2─CH2─CH2─CH3


Learning Check

Name each of the following:

A. CH3─CH2─CH2─CH3

B. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3


Solution

A. CH3─CH2─CH2─CH3

four carbon atoms; butane

B. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3

eight carbon atoms; octane


Isomers of Butane

Isomers• have the same

molecular formula• have different atomic

arrangements• for butane are a

straight chain and a branched chain


Naming Alkanes with Substituents

In the IUPAC system,• a carbon branch is named as an alkyl

group• halogen atoms are named as halo


Naming Alkanes


Example of Naming an Alkane

Give the IUPAC name of CH3 CH3

CH3─CH─CH─CH2─CH2─CH3

STEP 1 Write the alkane name of the longest continuous chain of carbon atoms.

hexane STEP 2 Number the carbon atoms starting from the

end nearer a substituent. CH3 CH3


1 2 3 4 5 6


Example of Naming an Alkane (continued)

STEP 3 Give the location and name of each substituent as a prefix to the alkane name.

CH3 CH3 methyl groups on carbons 2 and 3


1 2 3 4 5 6

2,3-dimethylhexane


Learning Check

Give the IUPAC name of

Cl CH3

CH3─CH2─CH─CH─CH3


Solution


pentane

STEP 2 Number the carbon atoms starting from the end nearer a substituent.

Cl CH3


5 4 3 2 1


Solution (continued)

STEP 3 Give the location and name of each substituent as a prefix to the alkane name.

Cl CH3


5 4 3 2 1

3-chloro-2-methylpentane

chloro on carbon 3 methyl on carbon 2


Learning Check

Give the IUPAC name for the following:

Cl CH3

| |CH3─CH2─CH─CH2─C─CH2─CH3

|

Cl


Solution


heptane

STEP 2 Number the carbon atoms starting from the end nearer a substituent.

Cl CH3


1 2 3 4 5 | 6 7

Cl


Solution (continued)STEP 3 Give the location and name of each

substituent as a prefix to the alkane name.

Cl CH3


1 2 3 4 5 | 6 7

Cl

3,5-dichloro-5-methylheptane

chloro on carbon 3 methyl and chloro on carbon 5


Drawing Alkane Formulas

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Learning Check

Draw the condensed structural formula for

2-bromo-4-chlorobutane.


SolutionSTEP 1 Draw the main chain of carbon atoms. For

butane, there are four carbon atoms in the chain.

C─C─C─C

STEP 2 Number the chain and place the substituents on the carbons indicated by the numbers.

Br C─C─C─C─Cl

1 2 3 4


Solution (continued) Br

C ─ C ─ C ─ C ─ Cl

1 2 3 4

STEP 3 Add the correct number of hydrogen atoms to give four bonds to each C atom.

Br CH3─CH─CH2─CH2─Cl

Needs 3 H

Needs 1 H

Need 2 H each

basic chemistry copyright © 2011 pearson education, inc. 1 chapter 17 organic chemistry 17.1...

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