What are the seven isomers of C4H10O

Isomerism in alcohols

Different structures of the hydrocarbon residue

Isomerism is the occurrence of two or more chemical compounds with the same empirical formula and molecular mass, but which differ in the connection or the spatial arrangement of the atoms. The appropriate connections will beIsomers called and can be represented by different structural formulas.

As with hydrocarbons, alcohols have numerous isomers with increasing chain length. The following compounds are both pentanols, which differ due to the different branching of the hydrocarbon radical.


$ \ mathrm {H \ - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ {\ overset { \ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ OH \ qquad {\ color {Brown} { and}} \ qquad H \ - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; \; \; \; - \! \! \! {\ overset {{\ Large H} \ - \ {\ overset {\ huge H} {\ overset | {\ Large C}}} \ - \ {\ Large H}} {\ overset {|} {\ underset {\ Large H \ - \ {\ underset {\ huge H} {\ underset {|} C}} \ - \ H} {\ underset | C}}}} \; \! \! \! - \; \; \; \; {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ OH} $


However, the different structures of the two compounds shown are the reason that they differ in their properties. Therefore it has to be two different substances. The naming is as follows: First you determine the longest carbon chain with an OH group. First you look for the longest carbon chain that carries one. This gives the root name of the alcohol you are looking for. The position of the OH group or the side chains is indicated by numbering the C atoms. The two pentanols above are called pentanol-1 and 2,2-dimethylpropanol-1, respectively.



Different positions of the functional group (hydroxyl group)

In the case of positional isomers (also called local isomers or regioisomers), the same functional group (hydroxyl group) is in different positions. Depending on how many other carbon atoms are connected to the carbon atom to which the hydroxyl group is attached, one speaks of primary, secondary or tertiary alcohols. There are also quaternary carbon atoms, but no quaternary alcohols.



primary butanol (= butanol-1)

$ \ mathrm {H \ - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ {\ overset { \ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ OH} $

secondary butanol (= butanol-2)

$ \ mathrm {H \ - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ {\ overset { \ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large OH} {\ underset {|} {C}}}}} \; - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ H} $


tertiary butanol (= 2-methylpropanol-2)

$ \ mathrm {H \ - \ {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ {\ overset { \ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \; \; \; \; - \! \! \! {\ overset {{\ Large H} \ - \ {\ overset {\ huge H} {\ overset | {\ Large C}}} \ - \ {\ Large H}} {\ overset {|} {\ underset {\ Large OH} {\ underset | C}}}} \; \! \! \! - \; \; \; \; {\ overset {\ Large H} {\ overset {|} {\ underset {\ Large H} {\ underset {|} {C}}}}} \ - \ H} $


When oxidizing agents are brought together with the various alcohols, different properties can easily be demonstrated in experiments. Primary alcohols, such as ethanol and 1-propanol, are easily oxidized to aldehydes. If you oxidize secondary alcohols, you get ketones:



Tertiary alcohols cannot be oxidized without decomposition.