More Or Less Polar

[Luann]

"Other differences between saturated and polyunsaturated fats are in their effects on surfaces (as surfactant), charges (dielectric effects), acidity, and their solubility in water relative to their solubility in oil. The polyunsaturated fatty acids are many times more water soluble than saturated fatty acids of the same length."

Come again? A C-C bond in a hydrocarbon is not polar, but a C-H sure is. Making the saturated fat more alike to water, which is polar.

 

[PeatThemAll]

The C=C double bonds in PUFAs create a curve in the carbon chain. This changes the properties of the chain at many levels (how it stacks with similar one, attraction/repulsion to solvents, etc.)

 

[Luann]

Right but it doesn't make the Carbon and H atoms less likely to pull their own ways, at least more than a C bonded to a C would.

 

[PeatThemAll]

True, at the chain level perspective. But those empty orbitals on the C=C also have a way of interacting/influencing their surroundings, compared to saturated C-C only. C-C has no electronegativity difference, C-H has a small one, but that C=C electronic cloud is a class above.

 

[Luann]

thanks @PeatThemAll, your response makes sense up to the last part: C=C is a class above; a class above what? Thx

 

[PeatThemAll]

In terms of reactivity, the orbitals/electron clouds of the C=C open it to a bunch of reactions that saturated ones won't be subject to (with regards to electronegativity/electron displacement / and temporary polarity deltas (+/-) ). Simply see them as more fragile, more easily "bothered" by their environment.

 

[Luann]

Thanks, so is that increased reactivity a feature of all double or pi bonds made with a carbon, or just C on C? 'Ppreciate you.