{"id":3732,"date":"2018-07-16T18:46:03","date_gmt":"2018-07-16T18:46:03","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/?post_type=chapter&#038;p=3732"},"modified":"2018-07-31T05:32:41","modified_gmt":"2018-07-31T05:32:41","slug":"4-2-how-to-test-for-chirality","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/chapter\/4-2-how-to-test-for-chirality\/","title":{"raw":"4.2. How to test for chirality","rendered":"4.2. How to test for chirality"},"content":{"raw":"You will often be asked to look at a chemical structure, and determine if it is chiral or not. Don't be fooled by the fact that a structure may be drawn with wedged and dashed bonds!\u00a0 In cases where you have only one carbon with four different substituents - thus one chiral carbon - then it is clearly a chiral molecule.\u00a0 If you have more than one chiral center, then there are some useful ways to check quickly to see if a molecule is chiral:\r\n<div class=\"textbox shaded\">\r\n\r\nTests for chirality\r\n<ul>\r\n \t<li>(a) (Most reliable) Check to see if the molecule has a pair of non-superimposable mirror image forms.<\/li>\r\n \t<li>(b) (Nearly always works) Look for a mirror plane; if no mirror plane, the molecule is nearly always chiral<\/li>\r\n \t<li>(c) Look for chiral centers \u2013 tetrahedral atoms (usually carbon) with four different groups attached. As long as these don\u2019t mirror each other, the molecule is chiral.<\/li>\r\n<\/ul>\r\n<\/div>\r\nMethod (a) will always give the correct answer, but it may be difficult to do quickly unless you have a model of both enantiomers to work with.\r\n\r\nThe second method (b) is very useful as a quick test, and in this course you will never come across molecules where this test leads to a wrong answer.\u00a0 However, you should be careful to ensure that you are looking at the most symmetrical form you can draw or make, otherwise you may be misled.\r\n\r\nMethod (c) is quick and very helpful for almost every case you will see in this class.\u00a0 As with (b), you will need to take care to try and make the molecule as symmetrical as possible.\u00a0 If you have a meso form, the two chiral centers will be reflections of each other and the molecule will (overall) be achiral.\r\n\r\nThere are some special cases:\r\n<ul>\r\n \t<li>Uncharged nitrogens with a lone pair are achiral, but an N<sup>+<\/sup> with four different attached groups will be chiral.<\/li>\r\n \t<li>When looking at cyclohexanes, you can treat them as flat, and look for symmetry.<\/li>\r\n<\/ul>\r\n&nbsp;","rendered":"<p>You will often be asked to look at a chemical structure, and determine if it is chiral or not. Don&#8217;t be fooled by the fact that a structure may be drawn with wedged and dashed bonds!\u00a0 In cases where you have only one carbon with four different substituents &#8211; thus one chiral carbon &#8211; then it is clearly a chiral molecule.\u00a0 If you have more than one chiral center, then there are some useful ways to check quickly to see if a molecule is chiral:<\/p>\n<div class=\"textbox shaded\">\n<p>Tests for chirality<\/p>\n<ul>\n<li>(a) (Most reliable) Check to see if the molecule has a pair of non-superimposable mirror image forms.<\/li>\n<li>(b) (Nearly always works) Look for a mirror plane; if no mirror plane, the molecule is nearly always chiral<\/li>\n<li>(c) Look for chiral centers \u2013 tetrahedral atoms (usually carbon) with four different groups attached. As long as these don\u2019t mirror each other, the molecule is chiral.<\/li>\n<\/ul>\n<\/div>\n<p>Method (a) will always give the correct answer, but it may be difficult to do quickly unless you have a model of both enantiomers to work with.<\/p>\n<p>The second method (b) is very useful as a quick test, and in this course you will never come across molecules where this test leads to a wrong answer.\u00a0 However, you should be careful to ensure that you are looking at the most symmetrical form you can draw or make, otherwise you may be misled.<\/p>\n<p>Method (c) is quick and very helpful for almost every case you will see in this class.\u00a0 As with (b), you will need to take care to try and make the molecule as symmetrical as possible.\u00a0 If you have a meso form, the two chiral centers will be reflections of each other and the molecule will (overall) be achiral.<\/p>\n<p>There are some special cases:<\/p>\n<ul>\n<li>Uncharged nitrogens with a lone pair are achiral, but an N<sup>+<\/sup> with four different attached groups will be chiral.<\/li>\n<li>When looking at cyclohexanes, you can treat them as flat, and look for symmetry.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-3732\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Original<\/div><ul class=\"citation-list\"><li><strong>Authored by<\/strong>: Martin Walker. <strong>Provided by<\/strong>: SUNY Potsdam. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/directory.potsdam.edu\/?function=user=walkerma\">http:\/\/directory.potsdam.edu\/?function=user=walkerma<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA: Attribution-ShareAlike<\/a><\/em><\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":96103,"menu_order":2,"template":"","meta":{"_candela_citation":"[{\"type\":\"original\",\"description\":\"\",\"author\":\"Martin Walker\",\"organization\":\"SUNY Potsdam\",\"url\":\"http:\/\/directory.potsdam.edu\/?function=user=walkerma\",\"project\":\"\",\"license\":\"cc-by-sa\",\"license_terms\":\"\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"How to test for chirality","pb_subtitle":"","pb_authors":["martin-walker"],"pb_section_license":"cc-by-sa"},"chapter-type":[],"contributor":[54],"license":[57],"class_list":["post-3732","chapter","type-chapter","status-publish","hentry","contributor-martin-walker","license-cc-by-sa"],"part":76,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/3732","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/wp\/v2\/users\/96103"}],"version-history":[{"count":5,"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/3732\/revisions"}],"predecessor-version":[{"id":4403,"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/3732\/revisions\/4403"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/pressbooks\/v2\/parts\/76"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/3732\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/wp\/v2\/media?parent=3732"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/pressbooks\/v2\/chapter-type?post=3732"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/wp\/v2\/contributor?post=3732"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry\/wp-json\/wp\/v2\/license?post=3732"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}