March 29, 2024, 02:09:38 AM
Forum Rules: Read This Before Posting


Topic: Which of the following compounds won't rotate plane polarised light  (Read 3069 times)

0 Members and 1 Guest are viewing this topic.

Offline owlpower

  • Regular Member
  • ***
  • Posts: 43
  • Mole Snacks: +0/-1
Question : https://imgur.com/a/nGCsjOl

How do I tell which one won't rotate plane polarised light? I know that chiral molecules will rotate plane polarised light. They are all stereo isomers of each other, and I determined 1 to be RR, 2 to be SS, 3 to be RS and 4 to be SR. I also know meso compounds are chiral but do not exhibit optical activity...

Offline sjb

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 3652
  • Mole Snacks: +222/-42
  • Gender: Male
Re: Which of the following compounds won't rotate plane polarised light
« Reply #1 on: September 15, 2018, 03:58:50 AM »
I'd look again at your assignments. Why are 2 and 4 apparently different, for instance?

Offline owlpower

  • Regular Member
  • ***
  • Posts: 43
  • Mole Snacks: +0/-1
Re: Which of the following compounds won't rotate plane polarised light
« Reply #2 on: September 17, 2018, 05:32:41 AM »
Wait a minute...2 and 4 are conformers, aren't they?

Offline sjb

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 3652
  • Mole Snacks: +222/-42
  • Gender: Male
Re: Which of the following compounds won't rotate plane polarised light
« Reply #3 on: September 17, 2018, 08:07:47 AM »
I think so...

Offline Babcock_Hall

  • Chemist
  • Sr. Member
  • *
  • Posts: 5592
  • Mole Snacks: +319/-22
Re: Which of the following compounds won't rotate plane polarised light
« Reply #4 on: September 25, 2018, 08:54:44 PM »
Meso compounds are not chiral.  Is one of your drawings a meso form?

Offline Vidya

  • Full Member
  • ****
  • Posts: 839
  • Mole Snacks: +46/-62
  • Gender: Female
  • Online Chemistry and Organic Chemistry tutor
    • Online Chemistry Tutor
Re: Which of the following compounds won't rotate plane polarised light
« Reply #5 on: September 27, 2018, 03:16:14 AM »
Convert all newman projections into Fisher Projections and from there you can easily figure out which one is meso and not chiral.

Sponsored Links