Does more branching lead to lower boiling point in alkanes?


> 
> List the following alkanes in order of increasing boiling point. 
> 
> 
> A. $\ce{CH3(CH2)4CH3}$  
> 
>  B. $\ce{(CH3)2CHCH(CH3)2}$  
> 
>  C. $\ce{CH3CH2CH(CH3)CH2CH3}$ 
> 
> 
> Answer: $C<B<A$, low to high.
> 
> 
> 


Why is it that B has not a lower boiling point than C? Is it not more branched? I believe branching decreases surface area, leading to less intermolecular interactions, and to a higher boiling point.




B has more branching and this means that molecules of B pack less efficiently and so there are fewer Van der Waals forces between them and so B has the lowest boiling point. On the other hand A is a linear molecule and so packs efficiently, has stronger VdWs forces and so has the highest boiling point. As @DavePhD's data shows $\ce{B < C < A}$


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$A$ n-hexane, boiling point 69 degrees C. 


$B$ 2,3 dimethyl butane, boiling point 58 degrees C. 


$C$ 3-methyl pentane, boiling point 63 degrees C. 


$B<C<A$


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