{"id":25270,"date":"2022-06-22T18:27:40","date_gmt":"2022-06-22T17:27:40","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=25270"},"modified":"2022-08-08T10:34:25","modified_gmt":"2022-08-08T09:34:25","slug":"dioxane-tetraketone-an-acs-molecule-of-the-week-with-a-mystery","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=25270","title":{"rendered":"Dioxane tetraketone – an ACS molecule of the week with a mystery."},"content":{"rendered":"
\n

I have long been fascinated by polymers of either carbon dioxide,\u2020<\/sup> or carbon monoxide, or combinations of both.\u00a0One such molecule, referred to as dioxane tetraketone when it was featured on the ACS molecule-of-the-week site<\/a> and also known as the anhydride of oxalic acid, or more formally 1,4-dioxane-2,3,5,6-tetraone, has been speculated upon for more than a century.[1]<\/a><\/span><\/p>\n

\"\"<\/p>\n

The history of chemistry has many molecules whose existence has been speculated upon, but where attempted syntheses have failed and for which sound theoretical reasons often only emerged many years later.[2]<\/a><\/span><\/p>\n

The synthesis of dioxane tetraketone was finally achieved in 1998[3]<\/a><\/span> at low temperatures (243K), although it was noted that in CDCl3<\/sub>\/Et2<\/sub>O solutions at 273K it quickly decomposed to give equal quantities of carbon monoxide and dioxide. The characterisation was by 13<\/sup>C NMR, for which a single signal at 144.9 ppm was observed. The predicted value using\u00a0the ACD\/CNMR\u00a0Predictor 2.0 Program (a so-called additive rule-based method) was 154 ppm (the value obtained using a similar tool available in Chemdraw is 150.9 ppm). The monomer oxirane-2,3-dione was also eliminated because of its predicted 13<\/sup>C shift using the same method of 167 ppm (155.3 using Chemdraw). Here I thought I would check these chemical shifts using a DFT-based method and also look at the barrier to the decomposition to see if it corresponds to a facile reaction at 273K (FAIR\u00a0Data DOI: 10.14469\/hpc\/10619<\/a>).<\/p>\n

Firstly the NMR, using eg \u03c9B97XD\/aug-cc-pvdz\/SCRF=chloroform. The calculated value of 148.2 ppm compares well with the observed value of 144.9 ppm. The value calculated for oxirane-2,3-dione was 156.6 ppm, rather lower than the ACD\/Predictor method but in agreement with the Chemdraw implementation. The predicted IR spectrum (not reported) is shown below, should it ever be measured for this species.<\/p>\n

\"\"<\/p>\n

Next, the reaction energy profile, this time calculated using \u03c9B97XD\/Def2-TZVPP for the reaction mechanism shown below.<\/p>\n

\"\"<\/p>\n

The IRC reveals that the mechanism (black arrows) is followed, in a concerted process that reveals absolutely no sign of any ionic intermediate (red) which could then lead to oxirane-2,3-dione (blue). The barrier\u00a0\u0394G\u2021<\/sup> is 36.9 kcal\/mol (it is lower than the total energy inferred below because the entropy is very positive, one molecule being converted to four during the reaction) which is far to high to correspond to a reaction that easily occurs at 273K. The value in water as solvent is very similar, again indicating that the ionic route is not enhanced by a polar solvent.\u00a0The transition state has another feature of interest.\u00a0It has\u00a0C2<\/sub> chiral symmetry, typical of a pericyclic reaction with M\u00f6bius topology<\/strong>, as indeed would be appropriate for an eight electron process.<\/p>\n

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

So what about that mystery then? Well, experimentally dioxane tetraketone decomposes at 273K, which would correspond to a free energy barrier of around 14-15 kcal\/mol. The calculated value is far higher, too high to be simply an error in the DFT method. So here is a suggestion. CDCl3<\/sub>, unless very carefully purified, contains HCl, which could very easily catalyse the reaction. So if another solvent were to be tried, lets say acetonitrile in which any trace of acid has been removed, would solutions of dioxane tetraketone then persist at room temperatures for far longer? \u00a0An experiment perhaps to be tried!<\/p>\n

\n

\u2020<\/sup>Perhaps the most fascinating is the cyclic trimer of carbon dioxide, which arguably has pretensions to be aromatic. It has very recently been synthesized.[4]<\/a><\/span>,[5]<\/a><\/span><\/p>\n

References<\/h2>\n
  1. H. Staudinger, \"Oxalylchlorid\", Berichte der deutschen chemischen Gesellschaft<\/i>, vol. 41, pp. 3558-3566, 1908. https:\/\/doi.org\/10.1002\/cber.19080410335<\/a>\n\n<\/li>\n
  2. H.M. Perks, and J.F. Liebman, \"Paradigms and Paradoxes: Aspects of the Energetics of Carboxylic Acids and Their Anhydrides\", Structural Chemistry<\/i>, vol. 11, pp. 265-269, 2000. https:\/\/doi.org\/10.1023\/a:1009270411806<\/a>\n\n<\/li>\n
  3. P. Strazzolini, A. Gambi, A.G. Giumanini, and H. Vancik, \"The reaction between ethanedioyl (oxalyl) dihalides and Ag2C2O4: a route to Staudinger\u2019s elusive ethanedioic (oxalic) acid anhydride\", Journal of the Chemical Society, Perkin Transactions 1<\/i>, pp. 2553-2558, 1998. https:\/\/doi.org\/10.1039\/a803430c<\/a>\n\n<\/li>\n
  4. M.J. Rodig, A.W. Snow, P. Scholl, and S. Rea, \"Synthesis and Low Temperature Spectroscopic Observation of 1,3,5-Trioxane-2,4,6-Trione: The Cyclic Trimer of Carbon Dioxide\", The Journal of Organic Chemistry<\/i>, vol. 81, pp. 5354-5361, 2016. https:\/\/doi.org\/10.1021\/acs.joc.6b00647<\/a>\n\n<\/li>\n
  5. H. Takeuchi, \"Geometry Optimization of Carbon Dioxide Clusters (CO<sub>2<\/sub>)<sub><i>n<\/i><\/sub> for 4 \u2264 <i>n<\/i> \u2264 40\", The Journal of Physical Chemistry A<\/i>, vol. 112, pp. 7492-7497, 2008. https:\/\/doi.org\/10.1021\/jp802872p<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    I have long been fascinated by polymers of either carbon dioxide,\u2020 or carbon monoxide, or combinations of both.\u00a0One such molecule, referred to as dioxane tetraketone when it was featured on the ACS molecule-of-the-week site and also known as the anhydride of oxalic acid, or more formally 1,4-dioxane-2,3,5,6-tetraone, has been speculated upon for more than a […]<\/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":[2648],"ppma_author":[2661],"class_list":["post-25270","post","type-post","status-publish","format-standard","hentry","category-reaction-mechanism-2","tag-interesting-chemistry"],"yoast_head":"\nDioxane tetraketone - an ACS molecule of the week with a mystery. - 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=25270\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Dioxane tetraketone - an ACS molecule of the week with a mystery. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"I have long been fascinated by polymers of either carbon dioxide,\u2020 or carbon monoxide, or combinations of both.\u00a0One such molecule, referred to as dioxane tetraketone when it was featured on the ACS molecule-of-the-week site and also known as the anhydride of oxalic acid, or more formally 1,4-dioxane-2,3,5,6-tetraone, has been speculated upon for more than a […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=25270\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2022-06-22T17:27:40+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2022-08-08T09:34:25+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2022\/06\/dioxane-tetraone.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=\"3 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Dioxane tetraketone - 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So here I chart one example of such connectivity over a period of\u2026","rel":"","context":"In "Hypervalency"","block_context":{"text":"Hypervalency","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=7"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":28233,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=28233","url_meta":{"origin":25270,"position":2},"title":"Molecules of the Year 2024: Molecular shuttle in a box.","author":"Henry Rzepa","date":"January 25, 2025","format":false,"excerpt":"This is another in the C&E News list of candidates for the Molecule of the Year, Molecular shuttle in a box Mirror-image cyclodextrin Molecular shuttle in a box Rule-bending strained alkene First soluble promethium complex Single-electron carbon-carbon bond Hot MOF for capturing carbon The molecule shown below inside the cavity\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":2046,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=2046","url_meta":{"origin":25270,"position":3},"title":"Chemistry with a super-twist: A molecular trefoil knot, part 1.","author":"Henry Rzepa","date":"May 31, 2010","format":false,"excerpt":"Something important happened in chemistry for the first time about 100 years ago. A molecule was built (nowadays we would say synthesized) specifically for the purpose of investigating a theory. It was cyclo-octatetraene or (CH)8, and it was made by Willst\u00e4tter and Waser to try to find out if benzene,\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\/05\/metallatrefoil.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":17063,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=17063","url_meta":{"origin":25270,"position":4},"title":"The largest C-C-C angle?","author":"Henry Rzepa","date":"November 1, 2016","format":false,"excerpt":"I am now inverting the previous question by asking what is the largest angle subtended at a chain of three connected 4-coordinate carbon atoms? Let's see if further interesting chemistry can be unearthed. Specifying only angles > 130\u00b0, the following distribution is obtained. Note the maximum at ~138\u00b0. This is\u2026","rel":"","context":"In "crystal_structure_mining"","block_context":{"text":"crystal_structure_mining","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1745"},"img":{"alt_text":"vajhap","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2016\/10\/VAJHAP.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":16758,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=16758","url_meta":{"origin":25270,"position":5},"title":"What’s in a name? Carbenes: a reality check.","author":"Henry Rzepa","date":"September 11, 2016","format":false,"excerpt":"To quote from Wikipedia: in chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The most ubiquitous type of carbene of recent times is the one shown below as 1, often referred to as a resonance stabilised or\u2026","rel":"","context":"In "crystal_structure_mining"","block_context":{"text":"crystal_structure_mining","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1745"},"img":{"alt_text":"","src":"","width":0,"height":0},"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\/25270","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=25270"}],"version-history":[{"count":21,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/25270\/revisions"}],"predecessor-version":[{"id":25299,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/25270\/revisions\/25299"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25270"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25270"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25270"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=25270"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}