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Why is clyclohexane a better solvent than cyclohexene? watch
- Thread Starter
- 05-03-2016 00:05
- 05-03-2016 00:12
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..."
- 05-03-2016 16:24
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).