How do you compare which is more stable without using the heat of hydrogenation or combustion or any other numeric factual value: $\ce{(CH3)2-C=CH2}$ or $\ce{CH3-CH=CH-CH3}$ (cis)?

  • $\begingroup$ Wouldn't we expect the most substituted alkene to be most (thermodynamically) stable? $\endgroup$ – electronpusher May 23 '19 at 16:25
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    $\begingroup$ @electronpusher both the compounds have two methyl groups each. $\endgroup$ – Tapi May 23 '19 at 16:26
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    $\begingroup$ @Karl I was taught "fill in the correct term for two substituents at the same carbon">trans>cis $\endgroup$ – Groverkss May 23 '19 at 17:59
  • $\begingroup$ Numbers are better than intuition. Both alkenes have the same molecular formula. Heats of Formation (kcal/mol) are helpful: isobutylene (-4.3), (Z)-2-butene (-1.7). $\endgroup$ – user55119 May 23 '19 at 19:18
  • $\begingroup$ @Groverkss You're right chemgapedia.de/vsengine/vlu/vsc/de/ch/12/oc/vlu_organik/alkene/… $\endgroup$ – Karl May 23 '19 at 20:12

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