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Why is clyclohexane a better solvent than cyclohexene? watch

    • Thread Starter

    Please help

    Maybe because cyclohexane, due to it's structure, breaks up faster and easier creating radicals or ions that breaks up the molecule being dissolved better than cyclohexene making it a better solvent.

    I mean, while polar molecules are what makes a good solvent (in most cases) making cyclohexene better due to induced dipoles, cyclohexane has a structure which makes electrons closer together, increasing repulsion.

    keyword though - "maybe..."

    Well we know for a fact that cyclohexane is a fully saturated cyclic alkane whereas cyclohexene is an unsaturated cyclic alkene. What are the physical properties of the two, and why might this make cyclohexane a better solvent than cyclohexene?

    I think the main points for A level:
    - Cyclohexane is comparatively unreactive due to itsstability.This is because the entire cyclic ring structure is connected by sigma C-C and C-H bonds. This combined with the fact C and H atoms have similar electronegativities gives an unreactive stable hydrophobic structure. There are no distinct polar regions with which to readily undergo a mechanistic reaction. This makes Cyclohexane a viable candidate as a solvent if we can dissolve other chemicals without getting side reactions.

    - Cylohexene is a lot more reactive and is therefore comparatively unstable. The Pi-sigma C=C double bond in the structure has a larger electron density. This makes the structure inherently susceptible to nucleophilic attack where a polar X-H or induced polarity in a Br-Br type reactant initiates a nucleophilic addition reaction. This makes Cyclohexene a bad candidate as a solvent if it easily participates in side reactions we don't want.

    (There might be an example of where cyclohexane is used e.g. some kind of spectra technique I can't recall off the top of my head where having a neutral unreactive solvent that gives a unique peak is useful. Although I might be confusing that with tetramethylSilane Si(CH3)4).

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