Structural isomers: same molecular formula different structures (or structural formulae)Functional group isomers: Compounds with the same molecular formula but with atoms arranged to give different functional groups Chain isomers: Compounds with the same molecular formula but different structures of the carbon skeleton Isomers Structural isomerism can arise from •Chain isomerism •Position isomerism •Functional group isomerism C C C H H H H H C C H H H H H H H H C C C H H H H H H C C H H H H H H C C C H H H H H C H H C H H H H pentane 2,2-dimethylpropane 2-methylbutane position isomers: Compounds with the same molecular formula but different structures due to different positions of the same functional group on the same carbon skeleton C C H H Br H C H H H H C C H H H Br C H H H H 1-bromopropane 2-bromopropane C O C H H H H H H C O H H H C H H H ethanol: an alcohol Methoxymethane: an ether C C C C C C H H H H H H H H H H H H Cyclohexane- cyclo alkane CH3CH2CH2CH2CH=CH2 hexene- alkene Note: alkene and cyclo alkanes have the same general formula. Hexene and cyclohexane have the same molecular formula but have a different functional group
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3.3.1.3 Isomerism
Structural isomerism
Students should be able to:
• define the term structural isomer
• draw the structures of chain, position and functional group isomers
3.1 Introduction Organic Page 7
Oxford Textbook Pages : 186
CGP Revision Guide Pages : 131