{"id":10689,"date":"2017-05-05T16:19:48","date_gmt":"2017-05-05T20:19:48","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=10689"},"modified":"2025-05-07T22:06:58","modified_gmt":"2025-05-08T03:06:58","slug":"the-pi-molecular-orbitals-of-benzene","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2017\/05\/05\/the-pi-molecular-orbitals-of-benzene\/","title":{"rendered":"The Pi Molecular Orbitals of Benzene"},"content":{"rendered":"

The Pi Molecular Orbitals of Benzene<\/strong><\/p>\n

Today, let’s go through how to draw out the molecular orbitals of benzene. We’ll compare them with the molecular orbitals for (linear) hexatriene. The\u00a0big takeaway is that from contrasting the molecular orbitals of these two 6-electron pi systems, we will unlock the deep, mysterious\u00a0riddle\u00a0of why\u00a0benzene is so unusually stable.<\/p>\n

Quick spoiler. Here’s of what the molecular orbitals of benzene look like.<\/p>\n

\"pi<\/p>\n

The rest of this post will describe how we came up with this drawing and what it means.<\/p>\n

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

    \n
  1. Quickie Review: How To Draw Pi Molecular Orbitals For A Given Pi System<\/a><\/li>\n
  2. Building The Pi Molecular Orbital Diagram For Benzene: Hexatriene and Benzene Each Have Six Pi Molecular Orbitals<\/a><\/li>\n
  3. The Lowest-Energy Molecular Orbitals Of Hexatriene And Benzene Have Zero Nodes<\/a><\/li>\n
  4. The “Penthouse” Of The M.O. Diagram\u00a0 (Highest Energy Level) Has The Maximum Number Of Nodes<\/a><\/li>\n
  5. Benzene Has Nodal Planes<\/i>. The Maximum Energy Level Has 3 Nodal Planes<\/a><\/li>\n
  6. Where Do We Place The Nodes In The Intermediate Energy Levels Of Benzene?<\/a><\/li>\n
  7. The Benzene Molecular Orbital Diagram: Putting It All Together<\/a><\/li>\n
  8. Filling Out The Rest of The Picture For Benzene<\/a><\/li>\n
  9. Why Is Benzene More Stable Than Hexatriene?<\/a><\/li>\n
  10. Notes<\/a><\/li>\n
  11. Quiz Yourself!<\/a><\/li>\n
  12. (Advanced) References and Further Reading<\/a><\/li>\n<\/ol>\n
    \n

    <\/a>1. Quickie Review: How To Draw Pi Molecular Orbitals For A Given Pi System<\/h2>\n

    Previously we’ve looked at the molecular orbitals of the allyl system, and of butadiene<\/a>. We learned some key lessons for drawing out the molecular orbitals of (linear) pi systems<\/a> that I will quickly rehash here.<\/p>\n

    Think of drawing out the pi orbitals as a bit like constructing an apartment building, albeit with some strange municipal building codes and quirky tenant behaviour.<\/p>\n