What type of structural isomerism exists between iso butyl alcohol and tertiary butyl alcohol?

I think that there exists only positional isomerism between them but the source from where I am studying says that they are both positional and chain isomers.

  • $\begingroup$ Positional isomers differ by change in locant of substituted carbon. Structural isomers differ in structure of chain. $\endgroup$ May 7, 2017 at 12:03

1 Answer 1


I think the best way to describe this isomerism is constitutional isomerism because it takes into consideration of both position of functional group and structure at the same time.

Constitutional isomers may have different carbon skeletons (as in isobutane and butane), different locations of a functional group along the chain (as in isobutyl alcohol and tertbutyl alcohol), or different functional groups (as in ethanol and dimethyl ether)

Positional isomers have the same carbon skeleton and same functional groups but differ in location of such functional groups (carbon skeleton remains unchanged). On the other hand, structural isomers the atoms are in completely different order , they arise because of the possibility of branching

I think the reason why these isomers are considered both structural and positional is that they both have the longest chain of max 3 carbons (hence same carbon skeleton), at the same time different location of -OH group (a different chain - structural)

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Hope this helps


Organic chemistry Mc Murry

Chemguide: Structural isomerism


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