{"id":13618,"date":"2015-03-15T18:53:22","date_gmt":"2015-03-15T18:53:22","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=13618"},"modified":"2015-03-15T18:53:22","modified_gmt":"2015-03-15T18:53:22","slug":"ionizing-ultra-strong-acids-with-water-molecules","status":"publish","type":"post","link":"https:\/\/www.rzepa.net\/blog\/?p=13618","title":{"rendered":"Ionizing ultra-strong acids with water molecules."},"content":{"rendered":"
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My previous posts<\/a> have covered the ionization by a small number of discrete water molecules of the series of halogen acids, ranging from HI (the strongest, pKa -10) via<\/em> HF (weaker, pKa 3.1) to the pseudo-halogen HCN (the weakest, pKa 9.2). Here I try out some even stronger acids to see what the least number of water molecule needed to ionize these might be.<\/p>\n

Firstly what must surely be the ultimate acid H(CHB11<\/sub>Cl11<\/sub>), discovered by Christopher Reed[1]<\/a><\/span> in 2006. This is so strong that it appears that it can even largely ionize itself; the form on the right (below) is the cationic acid, the form on the left is its anionic base. The proton itself is bridged[2]<\/a><\/span> between the two in a manner similar to the structure of one form of HCl.4H2<\/sub>O reported in the earlier post <\/a>on the topic.<\/p>\n

\"Click

Click for 3D<\/p><\/div>\n

So it comes as no surprise‡<\/sup> to find[3]<\/a><\/span> that just one water molecule can also ionize H(CHB11<\/sub>Cl11<\/sub>) to the anionic form (CHB11<\/sub>Cl11<\/sub>)–<\/sup>.<\/p>\n

\"Click

Click for 3D<\/p><\/div>\n

How about triflic acid, CF3<\/sub>SO2<\/sub>OH, pKa -16), which is also a fair bit more acidic than HI? Here, only three waters are needed (\u03c9B97XD\/6-311++G(2d,2p) prediction) to ionise to triflate anion.[4]<\/a><\/span><\/p>\n

\"Click

Click for 3D<\/p><\/div>\n

So, if there a system which is ionised by precisely two water molecules I will record it here.<\/p>\n

\n

‡<\/sup>Perhaps also no surprise is that one H2<\/sub>S molecule can also perform this ionisation.[5]<\/a><\/span> This leads us into another exploration, using molecules other than water to perform these ionisations.<\/p>\n

References<\/h2>\n
  1. E.S. Stoyanov, S.P. Hoffmann, M. Juhasz, and C.A. Reed, \"The Structure of the Strongest Br\u00f8nsted Acid:\u2009 The Carborane Acid H(CHB<sub>11<\/sub>Cl<sub>11<\/sub>)\", Journal of the American Chemical Society<\/i>, vol. 128, pp. 3160-3161, 2006. https:\/\/doi.org\/10.1021\/ja058581l<\/a>\n\n<\/li>\n
  2. Stoyanov, E.S.., Hoffmann, S.P.., Juhasz, M.., and Reed, C.A.., \"CCDC 606170: Experimental Crystal Structure Determination\", 2006. https:\/\/doi.org\/10.5517\/ccnbrwl<\/a>\n\n<\/li>\n
  3. H.S. Rzepa, \"C 1 H 4 B 11 Cl 11 O 1\", 2015. https:\/\/doi.org\/10.14469\/ch\/191134<\/a>\n\n<\/li>\n
  4. H.S. Rzepa, \"C 1 H 7 F 3 O 6 S 1\", 2015. https:\/\/doi.org\/10.14469\/ch\/191129<\/a>\n\n<\/li>\n
  5. H.S. Rzepa, \"C 1 H 4 B 11 Cl 11 S 1\", 2015. https:\/\/doi.org\/10.14469\/ch\/191135<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

    My previous posts have covered the ionization by a small number of discrete water molecules of the series of halogen acids, ranging from HI (the strongest, pKa -10) via HF (weaker, pKa 3.1) to the pseudo-halogen HCN (the weakest, pKa 9.2). Here I try out some even stronger acids to see what the least number of water […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_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,"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}},"categories":[6],"tags":[1321,636,287],"class_list":["post-13618","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry","tag-christopher-reed","tag-ohio","tag-pence"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p1gPyz-3xE","jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/13618","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=13618"}],"version-history":[{"count":0,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/13618\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13618"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13618"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rzepa.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13618"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}