# Why do alkyl substituents stabilize alkenes?

My textbook states that because $$sp^2-sp^3$$ bonds are stronger than $$sp^3-sp^3$$ bonds, alkenes are more stable than alkanes. The rule given is that bonds with more $$s$$ character are stronger.

However, it then states that an alkene with more alkyl substituents at the C=C double bond is stronger than an alkene with just hydrogens attached around the double bonded carbons. Carbon $$sp^2-1s$$ Hydrogen bond is stronger than Carbon $$sp^2-sp^3$$ Carbon bond. So how can my textbook use bond strength to explain why the alkyl substituted alkene is more stable than the non-substituted alkene?

• If your understand hyperconjugation in MO theory, you may want to see this: chemistry.stackexchange.com/q/20362/44877 – Tan Yong Boon Sep 26 '19 at 4:51
• @TanYongBoon thank you. yes this is perfect response! was confused how hyperconjugation applied to case of alkenes vs carbocations – ebehr Sep 26 '19 at 5:02
• @TanYongBoon Btw, your profile is very impressive for a HSer. do you have plans of US college and PhD in chemistry in future? – ebehr Sep 26 '19 at 5:05
• Welcome to chemistry.SE!. Since you are new here, I advise you to go through the policies of our community. I don't want to sound mean but comment section is not for friendly chatting. I suppose, you have already found what you are looking for. If you have any further doubts, feel free to comment or edit the question. Thank you. – Nilay Ghosh Sep 26 '19 at 5:53
• @NilayGhosh Does stackexchange have a chat function? – ebehr Sep 26 '19 at 7:42