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Are there any molecules that are chiral that are also gases at room temperature?

Failing that, what chiral molecules have a high vapor pressure? Propylene oxide has a boiling point of only 34 C, so that seems like a good one. Are there others?

EDIT: I appreciate all of the great suggestions! I should have mentioned before, but I am looking for something that can be purchased in both R and S enantiomers.

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  • $\begingroup$ Chances look slim. Bromochlorofluoromethane has a bp of 41.2 deg C according to Chemspider. Looking at the HCFC page of Wikipedia doesn't hit paydirt. $\endgroup$ – Epicentre Nov 6 '14 at 5:08
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The molecule has to be small. trans-1,2-difluorocyclopropane is certainly chiral, and its predicted boiling point is ~ 5 deg C. trans-1,1,2,3-tetrafluorocyclopropane is another likely candidate. This one will be easier to prepare (from perfluoropropylene oxide and trans-1,2-difluoroethylene).

Separation of enantiomers is the hard part.

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    $\begingroup$ Sorry, you lost me, what is "trans-1,1,2,3-tetrafluoroethylene" $\endgroup$ – ron Nov 6 '14 at 15:10
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    $\begingroup$ It's tetrafluorocyclopropane. Note to self: don't post without coffee. $\endgroup$ – Abel Friedman Nov 6 '14 at 18:17
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1-Chloro-1,2,2,2-tetrafluoroethane has bp -12 Celsium. For comparison, 1-chloro-1-fluoroethane has bp +16 Celsium. In most cases, replacing good share of hydrogen in an organic molecule with fluorine leads to significant decrease of bp. perfluoropropylene oxide has bp -27 Celsium, comparing to +34 of vanilla propylene oxide you noted.

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Considering molecules that have been prepared and resolved:

1,3-dimethylallene (2,3-pentadiene) boils a bit above room temperature at 48.5 C (see page 11 of this reference for the experimental preparation), but likely has a reasonable vapor pressure since it has a lower molecular weight than pentane. The advantage to this molecule is that it has already been (at least) partially resolved (see here and here) in a one-step hydroboration.

Another simple hydrocarbon to consider is trans-cyclooctene. It has a higher boiling point (143 C) but a significant vapor pressure, it flashes at 25 C. The molecule is chiral and has also been resolved.

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If you use deuterium and tritium, you can make stereocenters from methyl groups. For example, 1-deutero-1-tritioethane is be chiral.

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