{"id":6205,"date":"2012-02-04T13:39:50","date_gmt":"2012-02-04T13:39:50","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=6205"},"modified":"2021-05-10T17:39:04","modified_gmt":"2021-05-10T16:39:04","slug":"the-e2-elimination-reaction-an-nbo-orbital-analysis","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205","title":{"rendered":"An orbital analysis of the stereochemistry of the E2 elimination reaction"},"content":{"rendered":"
\n

The so-called E2 elimination<\/strong> mechanism is another<\/a> one of those mainstays of organic chemistry. It is important because it introduces the principle that anti-periplanarity of the reacting atoms is favoured over other orientations such as the syn-periplanar form; Barton<\/a> used this principle to great effect in developing the theory of conformational analysis. Here I explore its origins.<\/p>\n

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

The transition state for this reaction is readily calculated (\u03c9B97XD\/6-311+G(d,p)\/SCRF=acetone). The app<\/a> form is calculated to be 4.3 kcal\/mol lower<\/strong> in free energy than the spp<\/a> form.<\/p>\n\n\n\n\n
Anti-periplanar<\/th>\nSyn-periplanar<\/th>\n<\/tr>\n
\"\"

antiperiplanar E2 transition state. Click for 3D.<\/p><\/div><\/td>\n

\"\"

syn-periplanar E2 transition state. Click for 3D.<\/p><\/div><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The concerted bimolecular nature of the elimination (E2) is revealed by the intrinsic reaction coordinate<\/a> (IRC). Notice the peculiar goings on for the spp<\/em> geometry at IRC = -15, during which the initial gauche<\/em> conformation of the chloroethane rotates into an eclipsed<\/em> orientation to allow the synperiplanar transition state to develop. The app isomer has no need to do this.<\/p>\n\n\n\n
\"\"<\/a><\/td>\n\"\"<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n
\"\"<\/a><\/td>\n\"\"<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Time to explain what is going on. This will be done by obtaining a form of localised bond orbital known as the NBO. In fact, a pair of them, one bonding, the other antibonding. The former is known as the donor, and the latter the acceptor. Such a take was used in an earlier pos<\/a>t to explain why 1,2-difluoroethane adopts a gauche rather than antiperiplanar conformation. Such localised orbitals are useful to probe specific bonds in a molecule, and why they might be reacting in the way that they do. The theory behind this is shown below. Basically an occupied (donor) orbital can interact (be perturbed by) an empty (acceptor) orbital, the result being a stabilisation energy E2<\/strong>. This energy depends on two specific factors; the energy gap between the donor and acceptor orbitals (the smaller the gap the better) and the overlap between the two orbitals (the larger the overlap the better).<\/p>\n

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

For chloroethane, these two criteria are satisfied by virtue of the C-Cl bond being a good acceptor (due to the electronegative chlorine) whilst the C-H bond is a reasonable donor. The overlap is shown below (click on the image to get a rotatable model). The colour scheme is purple\/orange<\/strong> for the two phases of the donor orbital, which derives from the H-C bond, and blue\/red<\/strong> for the acceptor orbital, which derives from the C-Cl bond. The colours can be equivalenced; purple=blue, and orange=red, meaning that any overlap between purple and blue or orange and red is positive and stabilising, and the larger this overlap, the larger is E2. At the start of the reaction (IRC=9), E2 = 7.0 cal\/mol.<\/p>\n

\"\"

Donor-acceptor interaction in the E2 reactants. Click for 3D.<\/p><\/div>As the reaction proceeds, so E2 gets slowly bigger. At IRC +6, E2 has climbed to 11 kcal\/mol, by IRC +2.5 it is 31 and at IRC =0 (the transition state) it is 111 kcal\/mol<\/strong>. This is induced by the action of the base (Cl–<\/sup>in this case) making the C-H a better donor and the increasing overlap between the donor and acceptor orbitals. At the transition state, the two overlapping orbitals are morphing from C-H and C-Cl* \u03c3-type orbitals into one \u03c0-type orbital of the product alkene. At the product I(IRC= -15) the \u03c0-\u03c0 overlap is complete and now corresponds to a fully fledged bond.<\/p>\n\n\n\n
\"\"

Donor-acceptor interaction in the app E2 transition state. Click for 3D.<\/p><\/div><\/td>\n

\"\"

Donor-acceptor interaction in the spp E2 transition state. Click for 3D.<\/p><\/div><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The syn-periplanar transition state in contrast shows a smaller value of E2 = 63 kcal\/mol<\/strong> at the transition state due to a smaller positive overlap of the donor\/acceptor orbitals at this geometry.<\/p>\n

To conclude, the relatively small and subtle bond\/antibond orbital overlaps that are used in conformational analysis to explain the equilibrium conformations of species such as 1,2-difluoroethane also apply to considering the transition states involving elimination. The overlap of the donor orbital (with two electrons) with an (empty) acceptor orbital directly morphs as the reaction proceeds into a new orbital in the product.<\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

The so-called E2 elimination mechanism is another one of those mainstays of organic chemistry. It is important because it introduces the principle that anti-periplanarity of the reacting atoms is favoured over other orientations such as the syn-periplanar form; Barton used this principle to great effect in developing the theory of conformational analysis. Here I explore […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":5,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"","footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[4],"tags":[17,373],"ppma_author":[2661],"class_list":["post-6205","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry","tag-conformational-analysis","tag-tutorial-material"],"yoast_head":"\nAn orbital analysis of the stereochemistry of the E2 elimination reaction - Henry Rzepa's Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"An orbital analysis of the stereochemistry of the E2 elimination reaction - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"The so-called E2 elimination mechanism is another one of those mainstays of organic chemistry. It is important because it introduces the principle that anti-periplanarity of the reacting atoms is favoured over other orientations such as the syn-periplanar form; Barton used this principle to great effect in developing the theory of conformational analysis. Here I explore […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2012-02-04T13:39:50+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2021-05-10T16:39:04+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/E2.svg\" \/>\n<meta name=\"author\" content=\"Henry Rzepa\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Henry Rzepa\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"4 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"An orbital analysis of the stereochemistry of the E2 elimination reaction - Henry Rzepa's Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205","og_locale":"en_GB","og_type":"article","og_title":"An orbital analysis of the stereochemistry of the E2 elimination reaction - Henry Rzepa's Blog","og_description":"The so-called E2 elimination mechanism is another one of those mainstays of organic chemistry. It is important because it introduces the principle that anti-periplanarity of the reacting atoms is favoured over other orientations such as the syn-periplanar form; Barton used this principle to great effect in developing the theory of conformational analysis. Here I explore […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205","og_site_name":"Henry Rzepa's Blog","article_published_time":"2012-02-04T13:39:50+00:00","article_modified_time":"2021-05-10T16:39:04+00:00","og_image":[{"url":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/E2.svg","type":"","width":"","height":""}],"author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"4 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"An orbital analysis of the stereochemistry of the E2 elimination reaction","datePublished":"2012-02-04T13:39:50+00:00","dateModified":"2021-05-10T16:39:04+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205"},"wordCount":720,"commentCount":4,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/E2.svg","keywords":["conformational analysis","Tutorial material"],"articleSection":["Interesting chemistry"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205","name":"An orbital analysis of the stereochemistry of the E2 elimination reaction - Henry Rzepa's Blog","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/E2.svg","datePublished":"2012-02-04T13:39:50+00:00","dateModified":"2021-05-10T16:39:04+00:00","author":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"breadcrumb":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#primaryimage","url":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/E2.svg","contentUrl":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/E2.svg"},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6205#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"An orbital analysis of the stereochemistry of the E2 elimination reaction"}]},{"@type":"WebSite","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/","name":"Henry Rzepa's Blog","description":"Chemistry with a twist","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-GB"},{"@type":"Person","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281","name":"Henry Rzepa","image":{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g370be3a7397865e4fd161aefeb0a5a85","url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","caption":"Henry Rzepa"},"description":"Henry Rzepa is Emeritus Professor of Computational Chemistry at Imperial College London.","sameAs":["https:\/\/orcid.org\/0000-0002-8635-8390"],"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?author=1"}]}},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pDef7-1C5","jetpack-related-posts":[{"id":6279,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6279","url_meta":{"origin":6205,"position":0},"title":"E2 elimination vs ring contraction: anti-periplanarity in action.","author":"Henry Rzepa","date":"February 20, 2012","format":false,"excerpt":"The anti-periplanar principle permeates organic reactivity. Here I pick up on an example of the antiperiplanar E2 elimination (below, blue) by comparing it to a competing reaction involving a [1,2] antiperiplanar migration (red). The relative rates of these two processes will depend on several factors such as the ability of\u2026","rel":"","context":"In \"conformational analysis\"","block_context":{"text":"conformational analysis","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=conformational-analysis"},"img":{"alt_text":"","src":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/Ring.svg","width":350,"height":200},"classes":[]},{"id":6262,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6262","url_meta":{"origin":6205,"position":1},"title":"An exothermic E2 elimination: an unusual intrinsic reaction coordinate.","author":"Henry Rzepa","date":"February 6, 2012","format":false,"excerpt":"The previous post explored why E2 elimination reactions occur with an antiperiplanar geometry for the transition state. Here I have tweaked the initial reactant to make the overall reaction exothermic rather than endothermic as it was before. The change is startling. The exothermicity is of course due to the aromatisation\u2026","rel":"","context":"In \"conformational analysis\"","block_context":{"text":"conformational analysis","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=conformational-analysis"},"img":{"alt_text":"","src":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/02\/E2-benzo.svg","width":350,"height":200},"classes":[]},{"id":4030,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=4030","url_meta":{"origin":6205,"position":2},"title":"Updating a worked problem in conformational analysis. Part 1: the question.","author":"Henry Rzepa","date":"May 13, 2011","format":false,"excerpt":"Conformational analysis comes from the classical renaissance of physical organic chemistry in the 1950s and 60s. The following problem is taken from\u00a0E. D. Hughes and J. Wilby J. Chem. Soc., 1960, 4094-4101, DOI: 10.1039\/JR9600004094, the essence of which is that Hofmann elimination of a neomenthyl derivative (C below) was observed\u2026","rel":"","context":"In \"chair\"","block_context":{"text":"chair","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=chair"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/05\/menthyl.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":1663,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=1663","url_meta":{"origin":6205,"position":3},"title":"Conformational analysis of cyclotriborazane","author":"Henry Rzepa","date":"February 14, 2010","format":false,"excerpt":"In an earlier post, I re-visited the conformational analysis of cyclohexane by looking at the vibrations of the entirely planar form (of D6h symmetry). The method also gave interesting results for the larger cyclo-octane ring. How about a larger leap into the unknown? Let us proceed as follows. One fun\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2010\/02\/B3N3H12.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":4038,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=4038","url_meta":{"origin":6205,"position":4},"title":"Updating a worked problem in conformational analysis. Part 2: an answer.","author":"Henry Rzepa","date":"May 17, 2011","format":false,"excerpt":"The previous post set out a problem in conformational analysis. Here is my take, which includes an NCI (non-covalent interaction) display as discussed in another post. The lowest energies of the four diastereomers A-D, each in two conformations (1\/2) were calculated at the \u03c9B97D\/6-311G(d,p)\/SCRF=ethanol level, and are shown here relative\u2026","rel":"","context":"In \"conformational analysis\"","block_context":{"text":"conformational analysis","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=conformational-analysis"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/05\/problem_sheet_answer42.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":248,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=248","url_meta":{"origin":6205,"position":5},"title":"Conformational analysis and enzyme activity: models for amide hydrolysis.","author":"Henry Rzepa","date":"April 12, 2009","format":false,"excerpt":"The diagram below summarizes an interesting result recently reported by Hanson and co-workers (DOI: 10.1021\/jo800706y. At ~neutral pH, compound 13 hydrolyses with a half life of 21 minutes, whereas 14 takes 840 minutes. Understanding this difference in reactivity may allow us to understand why some enzymes can catalyze the hydrolysis\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"Models for peptide cleavage.","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/04\/amide-cleavage.png?resize=350%2C200","width":350,"height":200},"classes":[]}],"jetpack_likes_enabled":false,"authors":[{"term_id":2661,"user_id":1,"is_guest":0,"slug":"admin","display_name":"Henry Rzepa","avatar_url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6205","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6205"}],"version-history":[{"count":43,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6205\/revisions"}],"predecessor-version":[{"id":23748,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6205\/revisions\/23748"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6205"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6205"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6205"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=6205"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}