{"id":7104,"date":"2013-03-12T16:33:32","date_gmt":"2013-03-12T20:33:32","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=7104"},"modified":"2024-12-19T15:06:21","modified_gmt":"2024-12-19T21:06:21","slug":"common-mistakes-drawing-tetrahedral-carbons","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2013\/03\/12\/common-mistakes-drawing-tetrahedral-carbons\/","title":{"rendered":"Wedge And Dash Convention For Tetrahedral Carbon"},"content":{"rendered":"

How To Properly Draw Tetrahedral Carbons – And The Many Ways To Screw It Up<\/strong><\/p>\n

There is a knack to drawing proper tetrahedrons. And some very common pitfalls that might not be immediately obvious.<\/p>\n

One of the challenges that has faced chemists since the days of Van’t Hoff’s controversial (for the 1870’s!) proposal that carbons attached to four substituents can adopt a tetrahedral geometry is that of trying to depict three-dimensional structures on a two dimensional page.<\/p>\n

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

    \n
  1. Wedges And Dashes: Items In The Foreground Have High Contrast; Items In The Background Are Low Contrast<\/a><\/li>\n
  2. The “Industry Standard” Way To Draw Tetrahedral Carbon<\/a><\/li>\n
  3. A Rotated Version Of The Same Thing<\/a><\/li>\n
  4. How To Screw Up Drawing Tetrahedral Carbon, Part 1<\/a><\/li>\n
  5. A Second Way To Screw Up Drawing Tetrahedral Carbon<\/a><\/li>\n
  6. Summary: How To Draw Tetrahedral Carbon (And How Not To)\u00a0<\/a><\/li>\n
  7. Notes<\/a><\/li>\n<\/ol>\n
    \n

    <\/a>1. Wedges And Dashes: Items In The Foreground Have High Contrast; Items In The Background Are Low Contrast<\/strong><\/h2>\n

    The way it’s done in chemistry is with heavy “wedges” to depict bonds in the foreground (pointing out of the page) and light “dashes” to depict bonds in the background (behind the page). Think of artists’ depictions of a mountain range: the further away they are, the more faintly they are drawn. [Fun link – look how many movie posters resemble this painting]<\/a><\/em><\/span><\/p>\n

    \"300px-Caspar_David_Friedrich_032_The_wanderer_above_the_sea_of_fog\"<\/p>\n

    <\/a>2. The “Industry Standard” Way To Draw Tetrahedral Carbon<\/strong><\/h2>\n

    Although there are several permissible ways to depict a tetrahedral carbon on a flat page using dashes and wedges, the most intuitive to grasp is the one which shows one bond on a “wedge”, one on a “dash”, and two that are “flat” (that is, in the plane of the page). Here is what you might call the “industry standard” version, since it will easily allow us to add chains going off to the left and right (more on that later).<\/p>\n

    Here, note that it actually\u00a0doesn’t matter<\/strong> if the “wedged” bond (C) is drawn to the left or to the right of the “dashed” bond – they depict the same molecule!<\/strong><\/p>\n

    \"standard-way-to-draw-tetrahedral-carbon-where-bonds-in-plane-of-page-have-obtuse-angle-and-dash-wedge-have-acute-angle\"<\/p>\n

    Here’s a quick movie showing that these depictions actually represent the same 3-D object.<\/p>\n