{"id":5429,"date":"2021-03-08T16:58:12","date_gmt":"2021-03-08T14:58:12","guid":{"rendered":"https:\/\/akki.ut.ee\/?p=5429"},"modified":"2022-04-08T20:13:09","modified_gmt":"2022-04-08T18:13:09","slug":"acidity-scale-in-acetonitrile-231-pka-values-spanning-30-orders-of-magnitude","status":"publish","type":"post","link":"https:\/\/akki.ut.ee\/en\/acidity-scale-in-acetonitrile-231-pka-values-spanning-30-orders-of-magnitude\/","title":{"rendered":"Acidity scale in acetonitrile: 231 pKa values spanning 30 orders of magnitude"},"content":{"rendered":"<p><a href=\"https:\/\/analytical.chem.ut.ee\/wp-content\/uploads\/2021\/09\/Strengths-of-Acids-in-Acetonitrile-09-2021.pdf\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-5432 alignleft\" src=\"https:\/\/akki.ut.ee\/wp-content\/uploads\/2021\/03\/Acid-pKa-08032021-300x258.png\" alt=\"\" width=\"333\" height=\"286\" srcset=\"https:\/\/akki.ut.ee\/wp-content\/uploads\/2021\/03\/Acid-pKa-08032021-300x258.png 300w, https:\/\/akki.ut.ee\/wp-content\/uploads\/2021\/03\/Acid-pKa-08032021-768x662.png 768w, https:\/\/akki.ut.ee\/wp-content\/uploads\/2021\/03\/Acid-pKa-08032021.png 961w\" sizes=\"auto, (max-width: 333px) 100vw, 333px\" \/><\/a>The equilibrium acidity scale (p<i>K<\/i><sub>a<\/sub> scale) in acetonitrile (MeCN) has been supplemented by numerous new compounds and new \u0394p<i>K<\/i><sub>a<\/sub> measurements and has been published in <a href=\"https:\/\/doi.org\/10.1002\/ejoc.202001649\"><i>Eur. J. Org. Chem<\/i>. <strong>2021<\/strong>, 1407\u20131419 (Open access)<\/a>. The p<i>K<\/i><sub>a<\/sub> scale\u00a0now contains altogether 231 acids \u2013 over twice more than published previously \u2013 linked by 566 \u0394p<i>K<\/i><sub>a<\/sub> measurements and spans between the p<i>K<\/i><sub>a<\/sub> values of hydrogen iodide (2.8) and indole (32.57), covering close to 30 orders of magnitude. The acids have wide structural variety, ranging from common families &#8211; phenols (e.g. picric acid, alizarin, polyhalogenophenols), carboxylic acids (e.g. acetic, benzoic, retinoic and sorbic acid), sulfonic acids, hydrogen halides) to highly special molecules (chiral BINOL catalysts, bis(benzoxazole-2-<span class=\"GramE\">yl)<span class=\"SpellE\">methanes<\/span><\/span>, polyfluorinated\u00a0<span class=\"SpellE\">compounds<\/span>) and superacids (fluorinated sulfonimides, cyanoform, tetracyanopropenes).<\/p>\n<p>Measurement results acquired over the last 15 years were added to the scale and new least squares treatment was carried out. The treatment yielded revised p<i>K<\/i><sub>a<\/sub> values for the compounds published previously, with the root mean square difference between revised and previous values 0.04, demonstrating very good stability of the scale.<\/p>\n<p>Correlation equations were developed for estimating p<i>K<\/i><sub>a<\/sub> values for the studied types of compounds in water, DMSO, DMF and 1,2-dichloroethane on the basis of p<i>K<\/i><sub>a<\/sub> values in acetonitrile. These equations enable predicting p<i>K<\/i><sub>a<\/sub> values with an average error around or less than 1 p<i>K<\/i><sub>a<\/sub> unit, which is a sufficient accuracy for many applications.<\/p>\n<p>The scale is expected to be a useful tool for the widest possible research areas in organic chemistry, electrochemical power sources, catalysis, etc.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The equilibrium acidity scale (pKa scale) in acetonitrile (MeCN) has been supplemented by numerous new compounds and new \u0394pKa measurements and has been published in Eur. J. Org. Chem. 2021,&#8230;<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[54],"tags":[],"class_list":{"0":"post-5429","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-news"},"_links":{"self":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/5429","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/comments?post=5429"}],"version-history":[{"count":5,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/5429\/revisions"}],"predecessor-version":[{"id":5701,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/5429\/revisions\/5701"}],"wp:attachment":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/media?parent=5429"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/categories?post=5429"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/tags?post=5429"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}