{"id":13802,"date":"2015-04-10T08:47:33","date_gmt":"2015-04-10T07:47:33","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=13802"},"modified":"2023-09-16T18:20:17","modified_gmt":"2023-09-16T17:20:17","slug":"a-better-model-for-the-mechanism-of-lithal-lah-reduction-of-cinnamaldehyde","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802","title":{"rendered":"A better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde?"},"content":{"rendered":"
\n

Previously on this blog<\/a>: modelling the reduction of cinnamaldehyde using one molecule of lithal shows easy reduction of the carbonyl but a high barrier at the next stage, the reduction of the double bond. Here is a quantum energetic exploration of what might happen when a second LAH is added to the brew (the usual \u03c9B97XD\/6-311+G(d,p)\/SCRF=diethyl ether).<\/p>\n

\"LAH1\"<\/a>
\n<\/a>
\nIn a comment<\/a> at the end of the first post on this theme, I had noted some crystal structures containing in effect Hx<\/sub>Al.Li(OR)y<\/sub> units (x=3,4; y=0-3), noting the variety of structural motifs. The current exploration does not even attempt to cover this range of possibilities, but it is informed by the types of weak interaction that these structures reveal. I will nevertheless accept that whatever pathway is revealed here is likely to represent an energetic upper bound and recognise that lower energy pathways may well exist but are yet to be explored.<\/p>\n

    \n
  1. At the I12<\/strong> stage, a second AlH4<\/sub>–<\/sup>.Li(OMe)2<\/sub> is added and hydride transfer occurs antiperiplanar<\/em> across the C=C bond (TS34-1<\/strong>). The computed free energy barrier \u0394G298<\/sub>\u2020<\/sup> is ~24 kcal\/mol. The magnitude of this barrier corresponds to a relatively slow reaction occurring around room temperatures or slightly higher.
    \n
  2. A transient shallow intermediate I34-1<\/b> is formed in which the benzylic anion is stabilised by an adjacent solvated Li centre. The energy of this species (Table below) needs some explanation.‡<\/sup> Can its free energy really be 1.5 kcal\/mol higher than that of the preceding transition state? Yes, because its entropy is lower! The transition state is located on a total energy surface, which does not include thermal and entropic corrections; these are always applied AFTER the stationary points are located. If one inspects these total energies, I34-1<\/b> emerges as 1.2 kcal\/mol lower than the preceding transition state. This sort of result serves to remind us of the dynamic nature of a potential energy surface, and that static energies may on occasion lead to odd results. Its geometry is shown below, and this too has an interesting feature. The C-H bond just created from the LAH is antiperiplanar<\/i> to the benzylic anion (locked anti<\/i> by the Li) and the resulting stereoelectronic effect reduces its C-H calculated[1]<\/a><\/span> stretching wavenumber from the normal value of ~3100 cm-1<\/sup> to 2231 cm-1<\/sup>, a remarkable reduction.
    \n
    \"Click

    I34-1. Click for 3D<\/p><\/div><\/li>\n

  3. The C-O-AlH3<\/sub>.Li(OMe)2<\/sub> ligand now needs to rotate to I34-2<\/b> so that metal exchange on the benzylic carbon can occur, with Al displacing Li at that position. As with I34-1<\/b>, the free energy of this species is actually slightly higher than that of TS34-1<\/b>. Two AlH3<\/sub> groups now exist at this stage (each of them formed by hydride donation as part of the reduction process, see below). A hydride transfer metathesis between them (H2<\/sub>Al-H-Al3<\/sub> is actually a stable bridged species) will generate an AlH2<\/sub> as part of the 5-ring aluminate ester in P34<\/b> and regenerate a molecule of LAH. Transition states for these processes (i.e.<\/i> TS34-2) proved difficult to locate;†<\/sup> it may be that the ligand rotation and the hydride metathesis are part of the same concerted process but that is not proven yet.
    \n
    \"Click

    I34-2. Click for 3D<\/p><\/div>\n<\/li>\n

  4. The final product prior to hydrolysis is appropriately exoenergic.<\/li>\n
  5. I would also remark that many aspects of this reaction remain unexplored. For example, AlH4<\/sub> can deliver up to four hydrides, becoming progressively substituted as Al(OR)n<\/sub>Hy<\/sub> and in the process loosing Al-H…Li weak interactions. What influence this has on the barriers remains unknown.\n<\/li>\n<\/ol>\n\n\n\n\n\n\n\n\n
    Species<\/th>\nRelative \u0394G298<\/sub>, kcal\/mol<\/th>\nFAIR Data<\/a>-DOI<\/th>\n<\/tr>\n
    I12<\/td>\n0.0<\/td>\n[2]<\/a><\/span><\/td>\n<\/tr>\n
    TS34-1<\/td>\n24.1<\/td>\n[3]<\/a><\/span><\/td>\n<\/tr>\n
    I34-1<\/td>\n25.5‡<\/sup><\/td>\n[1]<\/a><\/span><\/td>\n<\/tr>\n
    I34-2<\/td>\n25.0‡<\/sup><\/td>\n[4]<\/a><\/span><\/td>\n<\/tr>\n
    P34<\/td>\n-8.8<\/td>\n[5]<\/a><\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    In summary, the first step in the reduction of cinnamaldehyde to cinnamyl alcohol requires just one molecule of “LiAlH4<\/sub>” as reductant and has a very low barrier to reaction. To construct a reasonable model to account for the slower further reduction of the C=C bond requires adding a further LiAlH4<\/sub>, the key feature being the availability of a lithium centre to stabilise out the forming benzylic carbanion. No doubt even better models might include the effects of adding e.g.<\/i> a third molecule of LAH, and a much more extensive exploration of the various conformational options. But I think the present model might be good enough to augment the apparently relatively limited mechanistic speculations found in text books on the topic.<\/p>\n

    \n

    †<\/sup>You sometimes see this phrase in articles reporting transition state location. What is means it that I tried a half-dozen what I thought were reasonable possibilities, and none of them satisfactorily converged. This semi-random exploration of the potential energy surface revealed a very flat energy potential, with lots of conformational possibilities. At this point, you have to decide whether it is worth the time to continue hunting.<\/p>\n

    \n

    Acknowledgments<\/h4>\n

    This post has been cross-posted in PDF format at Authorea<\/a>.<\/p>\n

    References<\/h2>\n
    1. H.S. Rzepa, and H.S. Rzepa, \"C 17 H 40 Al 2 Li 2 O 5\", 2015. https:\/\/doi.org\/10.14469\/ch\/191178<\/a>\n\n<\/li>\n
    2. H.S. Rzepa, and H.S. Rzepa, \"C 17 H 40 Al 2 Li 2 O 5\", 2015. https:\/\/doi.org\/10.14469\/ch\/191172<\/a>\n\n<\/li>\n
    3. H.S. Rzepa, and H.S. Rzepa, \"C 17 H 40 Al 2 Li 2 O 5\", 2015. https:\/\/doi.org\/10.14469\/ch\/191177<\/a>\n\n<\/li>\n
    4. H.S. Rzepa, and H.S. Rzepa, \"C 17 H 40 Al 2 Li 2 O 5\", 2015. https:\/\/doi.org\/10.14469\/ch\/191181<\/a>\n\n<\/li>\n
    5. H.S. Rzepa, and H.S. Rzepa, \"C 17 H 40 Al 2 Li 2 O 5\", 2015. https:\/\/doi.org\/10.14469\/ch\/191171<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

      Previously on this blog: modelling the reduction of cinnamaldehyde using one molecule of lithal shows easy reduction of the carbonyl but a high barrier at the next stage, the reduction of the double bond. Here is a quantum energetic exploration of what might happen when a second LAH is added to the brew (the usual […]<\/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":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1086],"tags":[1376,24,863,835,1375,40,1123,1377,74,142,691,1378],"ppma_author":[2661],"class_list":["post-13802","post","type-post","status-publish","format-standard","hentry","category-reaction-mechanism-2","tag-computed-free-energy-barrier","tag-energy","tag-energy-surface","tag-final-product","tag-flat-energy-potential","tag-free-energy","tag-lower-energy-pathways","tag-metal-exchange","tag-pence","tag-potential-energy-surface","tag-reduction","tag-yes"],"yoast_head":"\nA better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde? - 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=13802\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde? - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"Previously on this blog: modelling the reduction of cinnamaldehyde using one molecule of lithal shows easy reduction of the carbonyl but a high barrier at the next stage, the reduction of the double bond. Here is a quantum energetic exploration of what might happen when a second LAH is added to the brew (the usual […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2015-04-10T07:47:33+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-09-16T17:20:17+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/04\/LAH11.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":"A better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde? - 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=13802","og_locale":"en_GB","og_type":"article","og_title":"A better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde? - Henry Rzepa's Blog","og_description":"Previously on this blog: modelling the reduction of cinnamaldehyde using one molecule of lithal shows easy reduction of the carbonyl but a high barrier at the next stage, the reduction of the double bond. Here is a quantum energetic exploration of what might happen when a second LAH is added to the brew (the usual […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802","og_site_name":"Henry Rzepa's Blog","article_published_time":"2015-04-10T07:47:33+00:00","article_modified_time":"2023-09-16T17:20:17+00:00","og_image":[{"url":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/04\/LAH11.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=13802#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"A better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde?","datePublished":"2015-04-10T07:47:33+00:00","dateModified":"2023-09-16T17:20:17+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802"},"wordCount":890,"commentCount":0,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/04\/LAH11.svg","keywords":["computed free energy barrier","energy","energy surface","final product","flat energy potential","free energy","lower energy pathways","metal exchange","pence","potential energy surface","reduction","Yes"],"articleSection":["reaction mechanism"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802","name":"A better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde? - 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=13802#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/04\/LAH11.svg","datePublished":"2015-04-10T07:47:33+00:00","dateModified":"2023-09-16T17:20:17+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=13802#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802#primaryimage","url":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/04\/LAH11.svg","contentUrl":"http:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/04\/LAH11.svg"},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13802#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"A better model for the mechanism of Lithal (LAH) reduction of cinnamaldehyde?"}]},{"@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\/pDef7-3AC","jetpack-related-posts":[{"id":13688,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13688","url_meta":{"origin":13802,"position":0},"title":"Mechanism of the Lithal (LAH) reduction of cinnamaldehyde.","author":"Henry Rzepa","date":"April 1, 2015","format":false,"excerpt":"The reduction of cinnamaldehyde by lithium aluminium hydride (LAH) was reported in a classic series of experiments,, dating from 1947-8. The reaction was first introduced into the organic chemistry laboratories here at Imperial College decades ago, vanished for a short period, and has recently been reintroduced again.\u2021 The experiment is\u2026","rel":"","context":"In "reaction mechanism"","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":13899,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=13899","url_meta":{"origin":13802,"position":1},"title":"The mechanism of borohydride reductions. Part 1: ethanal.","author":"Henry Rzepa","date":"April 12, 2015","format":false,"excerpt":"Sodium borohydride is the tamer cousin of lithium aluminium hydride (LAH). It is used in aqueous solution to e.g. reduce aldehydes and ketones, but it leaves acids, amides and esters alone. Here I start an exploration of why it is such a different reducing agent. Initially, I am using Li,\u2026","rel":"","context":"In "reaction mechanism"","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":8508,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=8508","url_meta":{"origin":13802,"position":2},"title":"The mechanism of the Birch reduction. Part 2: a transition state model.","author":"Henry Rzepa","date":"December 3, 2012","format":false,"excerpt":"I promised that the follow-up to on the topic of Birch reduction would focus on the proton transfer reaction between the radical anion of anisole and a proton source, as part of analysing whether the mechanistic pathway proceeds O or M. To add some context, Hammond's postulate\u00a0\u00a0states that \"the structure\u2026","rel":"","context":"In \"Birch reduction\"","block_context":{"text":"Birch reduction","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=birch-reduction"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/12\/birch-mts.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":8540,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=8540","url_meta":{"origin":13802,"position":3},"title":"The mechanism of the Birch reduction. Part 3: reduction of benzene","author":"Henry Rzepa","date":"December 4, 2012","format":false,"excerpt":"Birch reduction of benzene itself results in 1,4-cyclohexadiene rather than the more stable (conjugated) 1,3-cyclohexadiene. Why is this? The mechanism, as elaborated in the previous two posts, involves a one-electron transfer from a sodium atom to form the radical anion, which is then protonated in a second step, and this\u2026","rel":"","context":"In \"Birch reduction\"","block_context":{"text":"Birch reduction","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=birch-reduction"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/12\/birch-ip.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":27784,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=27784","url_meta":{"origin":13802,"position":4},"title":"Mechanism of the Masamune-Bergman reaction. Part 4. Why was the DFT energy barrier too high for the Calicheamicin reaction?","author":"Henry Rzepa","date":"October 29, 2024","format":false,"excerpt":"Michael in a comment here on the mechanism of the Masamune-Bergman reaction notes that when it occurs as part of the Calicheamicin (an antibody-drug conjugate or ADC) version of this mechanism, a pre-step is first necessary. As discussed in this review article, the trisulfide linkage is reduced and the resulting\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":"","width":0,"height":0},"classes":[]},{"id":5114,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=5114","url_meta":{"origin":13802,"position":5},"title":"Mechanism of the reduction of a carboxylic acid by borane: revisited and revised.","author":"Henry Rzepa","date":"October 16, 2011","format":false,"excerpt":"I asked a while back\u00a0whether blogs could be considered a serious form of scholarly scientific communication (and so has Peter Murray-Rust more recently). A case for doing so might be my post of about a year ago, addressing why borane reduces a carboxylic acid, but not its ester, where I\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":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2011\/10\/acyloxy1-page001.svg","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\/13802","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=13802"}],"version-history":[{"count":67,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/13802\/revisions"}],"predecessor-version":[{"id":26465,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/13802\/revisions\/26465"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13802"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13802"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13802"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=13802"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}