ochem question from destroyer

[skim1988]

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which isomer would give the lowest heat of combustion?

I know that the most stable isomer would give the lowest heat of combustion but why is it that the most stable isomer is the most branched? doesnt branching increase steric hindrance therefore decrease stability?

 

[UBCStudent128]

I don't actually own a DAT Destroyer so I don't know which question you're specifying but generally more branched is more stable. Thiis assuming everything else stays the same.

If you remember Zaitsev / Hoffman, alkenes with more subsituted are more stable via hyperconjugation.


The sterically hindered part, I think you're confusing with SN2 reactions.
In SN2 reactions more sterically hindered electrophiles slow down the reaction tremendously since it is very hard for the incoming nucleophile to have the exact geometry.

Or mabye you're confused with cyclohexanes where sterically hindered subsituents decrease the stability of the ring when placed in axial position relative to the equatorial position.

 

[LaughingGas]

Which question is it?

 

[skim1988]

its #22
thanks for the explanation!