{"id":10405,"date":"2017-02-01T12:02:27","date_gmt":"2017-02-01T17:02:27","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=10405"},"modified":"2026-04-17T21:07:13","modified_gmt":"2026-04-18T02:07:13","slug":"assigning-rs-to-newman-projections-and-converting-newman-to-line-diagrams","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2017\/02\/01\/assigning-rs-to-newman-projections-and-converting-newman-to-line-diagrams\/","title":{"rendered":"Assigning R\/S To Newman Projections (And Converting Newman To Line Diagrams)"},"content":{"rendered":"

Determining R and S Configurations of Newman Projections<\/strong><\/p>\n

How do you determine\u00a0R<\/em> and\u00a0S<\/em> configurations on Newman projections?<\/p>\n

The key is to be able to quickly convert Newman projections into line diagrams<\/strong>, and then use the familiar CIP rules<\/strong> to determine R\/S on the line diagrams.<\/strong><\/p>\n

So how do<\/em> you convert Newman projections to line diagrams? That’s what we’re going to cover in this article.<\/p>\n

\"\"<\/a><\/p>\n

Table of Contents<\/strong><\/p>\n

    \n
  1. Determining (R) <\/em>and (S)<\/em> On Newman Projections: A Good Thing To Know For A Stereochemistry Exam<\/a><\/li>\n
  2. Most People Are Actually OK At Visualizing Familiar Things In 3-D. The Problem For Beginners In Organic Chemistry Is That Molecules Are Not Familiar<\/a><\/li>\n
  3. Cats Are Familiar. So Let’s Draw The “Newman Projection” Of A Cat<\/a><\/li>\n
  4. The Newman Projection: Eclipsed and Staggered Conformations<\/a><\/li>\n
  5. Eclipsed And Staggered Conformations Are Interconverted By Rotation Of 60\u00b0 Along The Central C-C Bond<\/a><\/li>\n
  6. How To Convert A Newman Projection \u00a0To A Line Diagram<\/span><\/span><\/a><\/li>\n
  7. A Cheat Sheet For Going From A Newman To A Line Diagram: There Are Only 4 Templates To Consider<\/a><\/li>\n
  8. Determining R and S Configuration On Newman Projections: Example #1<\/a><\/li>\n
  9. Determining R and S Configuration On Newman Projections: Example #2<\/a><\/li>\n
  10. Determining R and S On A Newman With An Eclipsed Conformation: Example #3.<\/a><\/li>\n
  11. Conclusion: Determining R and S Configurations In Newman Projections<\/a><\/li>\n
  12. Notes<\/a><\/li>\n
  13. Quiz Yourself!<\/a><\/li>\n<\/ol>\n
    \n

    <\/a>1. Determining (R) <\/em>and (S)<\/em> On Newman Projections<\/h2>\n

    In two recent posts we discussed how to use the Cahn-Ingold-Prelog (CIP) rules to assign (R\/S) to configurations of chiral carbons in a variety of situations, both simple<\/a> and more complex<\/a>.<\/p>\n

    So far, all the questions have asked you to assign (R\/S) on molecules drawn as bond-line diagrams, such as the molecule shown bottom left.<\/p>\n

    This is fine.\u00a0But every once in awhile – like on an exam, for instance, hint hint<\/strong> – you might find yourself thrown for a loop. For example, how do you determine R\/S when the molecule is drawn as a Newman? (bottom right)<\/p>\n

    \"determine-r-s-designations-for-chiral-centers-on-a-newman-projection\"<\/p>\n

    The trick is to\u00a0convert the Newman projection to the bond-line diagram and then assign R\/S.<\/p>\n

    This post explains how to do that.<\/p>\n

    \n

    This post was co-authored with Matt Pierce of\u00a0Organic Chemistry Solutions<\/a>.\u00a0 Ask Matt about scheduling an online tutoring session\u00a0here<\/a>.<\/strong><\/p>\n

    \n

    <\/a>2. Most People Are Actually Pretty Good At Visualizing Familiar Things In 3-D. The Problem For People Starting Organic Chemistry Is That Molecules Are Not Familiar<\/h2>\n

    One common thing I hear from students about why organic chemistry\u00a0is\u00a0hard is that they say they have “a hard time visualizing things in 3D”.<\/p>\n

    I actually don’t think this is true.<\/p>\n

    I think most people are fine visualizing things in 3D.<\/p>\n

    The problem is that visualizing molecules is\u00a0unfamiliar.\u00a0<\/strong><\/p>\n

    Given this hypothesis, let’s take something that is<\/strong> familiar and do some visualization exercises.<\/p>\n

    Here’s a picture of a hungry Jerusalem street cat.<\/p>\n

    \"Image-of-a-jerusalem-street-cat\"<\/p>\n

    Could you visualize what it would look like from the side?<\/p>\n

    Almost certainly, because you are very familiar with how cats look from most angles.<\/p>\n

    If you had to make a drawing (stick figures are fine) it would probably\u00a0look something like this:<\/p>\n

    \"side-drawing-of-a-cat-line-diagram-wedges-and-dashes\"<\/p>\n

    Note we took some liberties. The legs facing us are drawn as wedges<\/strong> and the ones pointing away are dashes<\/strong>.<\/p>\n

    [Here, I drew the two wedges on the “inside” relative to the dashes, but drawing them on the outside (or even alternating) is OK, since it amounts to the same thing]<\/em><\/span><\/p>\n

    <\/a>3. The “Newman Projection” Of A Cat<\/h2>\n

    Now let’s do the same kind of exercise, but in reverse.<\/p>\n

    Let’s take that\u00a0the stick figure we just drew and try to picture what it would look like from the front (i.e. look from the left) and from the back (look from the right).<\/p>\n

    For reasons that will soon become apparent, we’ll add a bit of detail: let’s give the cat\u00a0some\u00a0colored “socks” (orange and blue).<\/p>\n

    \"imagine-looking-at-cat-line-diagram-from-the-front-what-do-we-see-newman\"<\/p>\n

    [You might ask: what’s that weird looking symbol? \u00a0It’s the Side-Eye of the Illuminanti, the symbol of the underground secret society of chemists that rules the world<\/del>\u00a0just a symbol that says,\u00a0\u00a0“imagine looking at this thing from this direction”]<\/em><\/span><\/p>\n

    Because you likely have a\u00a0very good 3-D mental model of a cat<\/strong>, you shouldn’t have found exercise this too hard.<\/p>\n

    Hopefully you got\u00a0something like this, below.\u00a0For simplicity, I omitted drawing in the eyes [2 in the front view, 1 in the back view (heh)]<\/em><\/span><\/p>\n

    \"two<\/a><\/p>\n

    The circle represents the cat’s body, since the front and back hips block each other.<\/p>\n

    Maybe you noticed this helpful correspondence:<\/p>\n