December 30, 2024, 05:36:35 PM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: Axial chirality  (Read 3847 times)

0 Members and 1 Guest are viewing this topic.

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Axial chirality
« on: July 30, 2013, 10:43:08 AM »
As I couldn't find any good text about this topic, I have to ask a question:

Why are axial enantiomers represented as this:

but not as in the attached picture?
« Last Edit: July 30, 2013, 11:43:29 AM by Raderford »
Logged

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: Axial chirality
« Reply #1 on: July 30, 2013, 02:23:03 PM »
Because they are not planar. If they were planar, as you have drawn, they would not be chiral (mirror plane in the plane of the page). Your representations do not indicate which enantiomer you have.
Logged
My research: Google Scholar and Researchgate

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: Axial chirality
« Reply #2 on: July 31, 2013, 06:17:19 AM »
I think also that these conformations I drew would be very unstable, because of steric hindrances. Then that's why the true enantiomers can't interconvert easily. How do I know which one is Sa, and which one is Ra?
Logged

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: Axial chirality
« Reply #3 on: July 31, 2013, 08:06:03 AM »
R/S assignment example here.
Logged
My research: Google Scholar and Researchgate

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: Axial chirality
« Reply #4 on: July 31, 2013, 08:47:53 AM »
Ok, thanks.
Logged

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: Axial chirality
« Reply #5 on: July 31, 2013, 08:53:18 AM »
Why aren't allenes planar as alkenes?
Logged

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: Axial chirality
« Reply #6 on: July 31, 2013, 09:07:30 AM »
It's to do with the molecular obitals - you can easily google stuff like this yourself.

e.g. http://bouman.chem.georgetown.edu/S02/lect12/lect12.htm
Logged
My research: Google Scholar and Researchgate

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: Axial chirality
« Reply #7 on: July 31, 2013, 09:18:23 AM »
Sorry, I tried, but couldn't so easy. Thank you for the help, it is clear now.
Logged
Pages: [1]   Go Up
« previous next »
Sponsored Links