Effect of a long carbon chain on hydrogen bonding?

[kkentm]

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So does having a long carbon chain decrease hydrogen bonding like it decreases dipole-dipole interactions? I figure since hydrogen bonding is just a really strong dipole-dipole interaction, extending the length of the carbon chain should make the molecule less polar and thus have weaker hydrogen bonds. Is this correct?

 

[muhali3]

Afaik, it does. But mostly because of steric hindrance. I'm not sure it would have weaker hydrogen bonds, it would just be less capable of forming hydrogen bonds because the chain is in the way.

 

[Majik]

Afaik, it does. But mostly because of steric hindrance. I'm not sure it would have weaker hydrogen bonds, it would just be less capable of forming hydrogen bonds because the chain is in the way.

Yeah, although I partially agree with everything you said. The oxygen in -OH (for example) would be just as electronegative if the carbon cain was 3 carbons long as opposed to 200 carbon bonds. The actual chain length does not effect the strength of a hydrogen bond. The type of a hydrogen bond can vary in strength however (ie. the H of an F-H bond and the N of an N-H bond is the strongest possible Hydrogen Bond). However, like muhali mentioned, there's less of an opportunity to H-bond because there's less F,O, or N's floating nearby. I think of more interest though is the solubility of this type of solution. As the carbon chain increases, it becomes increasingly non-polar and less polar, therefore, larger chain hydrocarbons are soluble with other nonpolar molecules.

 

[kkentm]

yeah, i think i was confusing the concepts of solubility with intermolecular forces.