{"id":11452,"date":"2018-03-19T12:36:57","date_gmt":"2018-03-19T16:36:57","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=11452"},"modified":"2026-02-06T12:32:32","modified_gmt":"2026-02-06T18:32:32","slug":"eas-disubstituted-benzenes","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2018\/03\/19\/eas-disubstituted-benzenes\/","title":{"rendered":"Disubstituted Benzenes: The Strongest Electron-Donor “Wins”"},"content":{"rendered":"

Having gone through the mechanism<\/a> of electrophilic aromatic substitution, explored\u00a0activating and deactivating substituents<\/a>, and seen the importance of\u00a0directing groups<\/a>, let’s now take the opportunity to use these concepts to answer some slightly thornier questions.<\/p>\n

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

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

    \n
  1. Electrophilic Aromatic Substitution With Two Directing Groups: Which Group “Wins” ?<\/span><\/a><\/li>\n
  2. An Easy One: p<\/i>-Nitroanisole<\/span><\/a><\/li>\n
  3. When Two Or More Substituents Are Present, The Directing Group Will Be The Most Activating Substituent.<\/span><\/a><\/li>\n
  4. If Attack At Two Or More Positions Is Possible, Pick The Least Sterically Hindered One<\/span><\/a><\/li>\n
  5. Nothing Says “Steric Effects” Quite Like A t-Butyl Group<\/span><\/span><\/a><\/li>\n
  6. Summary: Electrophilic Aromatic Substitution on Disubstituted Benzenes<\/a><\/li>\n
  7. Notes<\/a><\/li>\n
  8. Quiz Yourself!<\/a><\/li>\n
  9. (Advanced) References and Further Reading<\/a><\/li>\n<\/ol>\n
    \n

    <\/a>1. Electrophilic Aromatic Substitution With Two Directing Groups: Which Group “Wins” ?<\/h2>\n

    Here’s a thorny question: What happens when we perform an electrophilic aromatic substitution reaction when there are two<\/em> substituents on benzene?<\/strong><\/p>\n

    And say that one of them is an\u00a0ortho-, para-\u00a0<\/em>director and one is a\u00a0meta-\u00a0<\/em>director, and they “direct” electrophiles to different carbons on the ring?<\/p>\n

    Which directing group “wins?”.<\/p>\n

    \"how<\/p>\n

    <\/a>2. An Easy One: p<\/em>-Nitroanisole<\/h2>\n

    Let’s start with\u00a01-methoxy-4-nitrobenzene, which also goes by the name,\u00a0p<\/em>-nitroanisole<\/a>.\u00a0 Say we try to perform an electrophilic aromatic substitution reaction. Where does the electrophile react? What’s the directing group, OCH3<\/sub> or NO2\u00a0<\/sub>?<\/p>\n

    \u00a0[Note that I’ve used “chlorination” as an example of an electrophilic aromatic substitution reaction, but the principles we will learn in this post apply to\u00a0all electrophilic aromatic substitution reactions].<\/em><\/span><\/p>\n

    \"example<\/p>\n

    The first thing to do is to analyze each substituent individually.<\/p>\n