{"id":50229,"date":"2023-11-13T12:14:56","date_gmt":"2023-11-13T06:29:56","guid":{"rendered":"https:\/\/thechemistrynotes.com\/?p=50229"},"modified":"2023-11-13T12:14:59","modified_gmt":"2023-11-13T06:29:59","slug":"meta-directors-reactivity-orientation","status":"publish","type":"post","link":"https:\/\/thechemistrynotes.com\/meta-directors-reactivity-orientation\/","title":{"rendered":"Meta Directors: Definition, Reactivity, Orientation"},"content":{"rendered":"\n<figure class=\"wp-block-image size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1205\" height=\"631\" src=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/Meta-directors.jpg\" alt=\"Meta directors\" class=\"wp-image-50234\" style=\"width:697px;height:auto\" srcset=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/Meta-directors.jpg 1205w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/Meta-directors-300x157.jpg 300w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/Meta-directors-1024x536.jpg 1024w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/Meta-directors-768x402.jpg 768w\" sizes=\"(max-width: 1205px) 100vw, 1205px\" \/><\/figure>\n\n\n\n<p><strong>Meta directors<\/strong>&nbsp;are deactivating groups on benzene that direct the electrophile E to the meta position. In comparison to hydrogen, deactivating groups slow down the rate of electrophilic aromatic substitution. Substituents that pull electron density away from nearby carbocations (e.g., CF<sub>3<\/sub>, NO<sub>2<\/sub>) will avoid leading E to the ortho- or para-position, resulting in the formation of the meta-product.<\/p>\n\n\n\n<p>Example of meta directos include: -NO<sub>2<\/sub>, -CHO, -COOH, CONH<sub>2<\/sub>, CONHR, -SO<sub>3<\/sub>H, -COR, -COOR, -CN.<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_64 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title \" >Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #0a0a0a;color:#0a0a0a\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #0a0a0a;color:#0a0a0a\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/thechemistrynotes.com\/meta-directors-reactivity-orientation\/#what-are-meta-directors\" title=\"What are meta directors?\">What are meta directors?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/thechemistrynotes.com\/meta-directors-reactivity-orientation\/#meta-directing-nature-of-electron-withdrawing-group\" title=\"Meta-directing nature of electron withdrawing group\">Meta-directing nature of electron withdrawing group<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/thechemistrynotes.com\/meta-directors-reactivity-orientation\/#ortho-para-directing-nature-of-halogens\" title=\"Ortho\/ Para directing nature of halogens\">Ortho\/ Para directing nature of halogens<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/thechemistrynotes.com\/meta-directors-reactivity-orientation\/#references\" title=\"References\">References<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"what-are-meta-directors\"><\/span><strong>What are meta directors?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>Meta directors<\/strong> are substituents present on the benzene ring that favor electrophilic attack at the\u00a0meta position In electrophilic substitution reaction. The reaction occurs in the meta position because these meta directors deactivate the ortho and para positions by taking the electron cloud from them via electron displacement effects, resulting in increased electron density or cloud at the meta position, which allows the coming electrophile to attach to it during the electrophilic substitution reaction.<\/p>\n\n\n\n<p>Electron-withdrawing\u00a0groups function as deactivators and therefore act\u00a0as Meta directors. Meta directors are the already-present group on benzene that extracts electrons from the ring either directly through induction or indirectly through resonance.<\/p>\n\n\n\n<p>Species with full positive charges, such as the nitro group or ammonium salts, are found in strongly deactivating groups. Our carbonyls, carboxylic acid derivatives, and related groups are weakly deactivating. Finally, halogens are weakly deactivating groups.<\/p>\n\n\n\n<p>where two positive charges are right next to each other on adjacent atoms. This is a highly unstable and unfavorable thermodynamic condition. As a result, the overall o\/p-contributors will be less stable than the meta one. Because they are less stable, they have more energy and form more slowly.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"975\" height=\"204\" src=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-54.png\" alt=\"\" class=\"wp-image-50232\" style=\"width:545px;height:auto\" srcset=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-54.png 975w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-54-300x63.png 300w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-54-768x161.png 768w\" sizes=\"(max-width: 975px) 100vw, 975px\" \/><\/figure><\/div>\n\n\n<p>So, electron-withdrawing groups raise activation energy in all places on the benzene ring, but more so in the ortho and para positions than in the meta position.&nbsp; The majority of the products will be meta-substituted&nbsp;because meta-substitution&nbsp;is substantially faster.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"meta-directing-nature-of-electron-withdrawing-group\"><\/span><strong>Meta-directing nature of electron withdrawing group<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Electron withdrawing groups\u00a0bind\u00a0electronegative atoms next to the It system and\u00a0deactivate the aromatic ring by lowering the electron density on the ring via a resonance withdrawing effect. The resonance effect only reduces electron density in the ortho- and para-positions. As a result, these sites are\u00a0less nucleophilic.\u00a0 So,\u00a0the system tends to react with electrophiles at the meta\u00a0sites.<\/p>\n\n\n\n<p><strong>Example: Trifluoromethyl benzene<\/strong><\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"822\" height=\"617\" src=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-53.png\" alt=\"\" class=\"wp-image-50231\" style=\"width:502px;height:auto\" srcset=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-53.png 822w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-53-300x225.png 300w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-53-768x576.png 768w\" sizes=\"(max-width: 822px) 100vw, 822px\" \/><\/figure><\/div>\n\n\n<p>Because the positive charge is positioned on the ring carbon that contains the electron-withdrawing group, the resonance structures for the arenium ion coming from ortho and para attack that one contributing structure is particularly unstable relative to all the others. In the arenium ion resulting from metaattack, we do not observe any such extremely unstable resonance configuration. This implies that the meta-attack&nbsp;arenium ion should be the most stable of the three.<\/p>\n\n\n\n<p>Halogen substituents are unique in that they are deactivating while still directing the incoming electrophile in the&nbsp;ortho-Para direction. The reason for this is that they both exert -I&nbsp;&nbsp;(electronegativity) and&nbsp;+R&nbsp;(lone pair donation) effects. The inductive effect reduces reactivity, whereas the resonance effect controls regiochemistry due to the stability of the intermediates.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"ortho-para-directing-nature-of-halogens\"><\/span><strong><a href=\"https:\/\/thechemistrynotes.com\/ortho-para-directors-reactivity-orientation\/\">Ortho\/ Para <\/a>directing nature of halogens<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Although halogens (F, Cl, Br, and I) are ortho, para directing, they deactivate the benzene ring, making additional <a href=\"https:\/\/thechemistrynotes.com\/electrophilic-substitution-reaction\/\">electrophilic substitutions<\/a> difficult. This is due to the existence of two opposing effects, namely the + R (or + M) and \u2014I effects.<\/p>\n\n\n\n<p>They are deactivators because they extract electrons from the ring inductively more strongly than they supply electrons via resonance. Inductive electron withdrawal deactivates all ring locations, however,\u00a0electron donation by resonance partially compensates for this deactivation at the ortho and para positions. The meta is the most inactive state since it cannot benefit from resonance electron donation. As a result, the halogens act as ortho\/para directors and deactivators.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"975\" height=\"259\" src=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-52.png\" alt=\"\" class=\"wp-image-50230\" srcset=\"https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-52.png 975w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-52-300x80.png 300w, https:\/\/thechemistrynotes.com\/wp-content\/uploads\/2023\/11\/image-52-768x204.png 768w\" sizes=\"(max-width: 975px) 100vw, 975px\" \/><\/figure><\/div>\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"references\"><\/span><strong>References<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul>\n<li>Morrison R. T. &amp; Boyd R. N. (1983).&nbsp;<em>Organic chemistry<\/em>&nbsp;(4th ed.). Allyn and Bacon.<\/li>\n\n\n\n<li>Smith M. &amp; March J. (2001).&nbsp;<em>March\u2019s Advanced Organic Chemistry: Reactions Mechanisms and Structure<\/em>&nbsp;(5th ed.). Wiley.<\/li>\n\n\n\n<li>Ghosh, S.K.,&nbsp;<em>Advanced General Organic Chemistry<\/em>, Second Edition, New Central Book Agency Pvt. Ltd., Kolkatta, 2007.<\/li>\n\n\n\n<li>Bahl, B.S., A., Advanced Organic Chemistry, S. Chand and Company Ltd, New Delhi, 1992. production of polyesters, polyurethanes, and alkaline resins.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Meta directors&nbsp;are deactivating groups on benzene that direct the electrophile E to the meta position. In comparison to hydrogen, deactivating groups slow down the rate of electrophilic aromatic substitution. Substituents &#8230; <a title=\"Meta Directors: Definition, Reactivity, Orientation\" class=\"read-more\" href=\"https:\/\/thechemistrynotes.com\/meta-directors-reactivity-orientation\/\" aria-label=\"Read more about Meta Directors: Definition, Reactivity, Orientation\">Read more<\/a><\/p>\n","protected":false},"author":4,"featured_media":50234,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[21],"tags":[3054,3055],"_links":{"self":[{"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/posts\/50229"}],"collection":[{"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/comments?post=50229"}],"version-history":[{"count":2,"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/posts\/50229\/revisions"}],"predecessor-version":[{"id":50235,"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/posts\/50229\/revisions\/50235"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/media\/50234"}],"wp:attachment":[{"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/media?parent=50229"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/categories?post=50229"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thechemistrynotes.com\/wp-json\/wp\/v2\/tags?post=50229"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}