{"id":6236,"date":"2024-09-10T20:28:47","date_gmt":"2024-09-10T18:28:47","guid":{"rendered":"https:\/\/akki.ut.ee\/?p=6236"},"modified":"2024-09-10T20:29:43","modified_gmt":"2024-09-10T18:29:43","slug":"how-to-make-maximum-use-of-the-available-pka-data-in-non-aqueous-solvents","status":"publish","type":"post","link":"https:\/\/akki.ut.ee\/en\/how-to-make-maximum-use-of-the-available-pka-data-in-non-aqueous-solvents\/","title":{"rendered":"How to make maximum use of the available pKa data in non-aqueous solvents?"},"content":{"rendered":"

\"\"At the recent Balticum Organicum Syntheticum<\/a> conference Ivo Leito made a presentation titled How to make maximum use of the available pKa data in non-aqueous solvents?<\/a> (Photo on the left)<\/p>\n

The presentation<\/a> started with how acid and base strengths, typically expressed as pK<\/i>a<\/sub> values (acids) or pK<\/i>aH<\/sub> values (bases), depend on solvation of the proton, as well as of the neutral and ionized forms of the acid\/base. Every solvent has different solvation properties. Thus, the pK<\/i>a<\/sub> values for the same acid\/base in different solvents are also different (often dramatically different).<\/p>\n

In principle, whenever using pK<\/i>a<\/sub> values for predicting or rationalizing chemical processes, the pK<\/i>a<\/sub> values determined in the same solvent should be used. In some solvents, e.g. water, DMSO or acetonitrile large bodies of pK<\/i>a<\/sub> data exist, while in most solvents either very few pK<\/i>a<\/sub> values are available or none at all. This leads to the frequent need of estimating pK<\/i>a<\/sub> values in one solvent from the data in other solvent(s)<\/strong> (Picture on the right). An additional consideration is the (often problematic) quality of pK<\/i>a<\/sub> data in the literature.<\/p>\n

\"\"When estimating pK<\/i>a<\/sub> values in one solvent based on the data in another solvent it is important to clearly define the aim. Is it needed to have the absolute pK<\/i>a<\/sub> value or is it rather necessary to have the acidity\/basicity differences (or acidity\/basicity order) within a set of compounds? Perhaps the question is just “can base B deprotonate acid A in solvent S”? If absolute pK<\/i>a<\/sub> value is needed then what accuracy is necessary? Depending on the aim, there are different possibilities of estimating pK<\/i>a<\/sub> and pK<\/i>aH<\/sub> values in a solvent on the basis of data in other solvents<\/a>.<\/p>\n

The presentation gave an overview to what extent such estimates can be usefully done, highlighting both successes and failures, as well as how to recognize clearly erroneous pK<\/i>a<\/sub> data. The presentation also highlighted the IUPAC project Critical compilation of acid pKa values in polar aprotic solvents<\/strong><\/a> that is nearing completion. The critically evaluated pK<\/i>a<\/sub> data of acids in dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, pyridine, acetone, propylene carbonate, tetrahydrofuran are available from Ivo Leito on request.<\/p>\n

The presentation turned out to be highly interesting for the participants, receiving a large amount of questions<\/strong>, which extended well into the coffee break!<\/p>\n","protected":false},"excerpt":{"rendered":"

At the recent Balticum Organicum Syntheticum conference Ivo Leito made a presentation titled How to make maximum use of the available pKa data in non-aqueous solvents? (Photo on the left)…<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[54],"tags":[],"class_list":{"0":"post-6236","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\/6236","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\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/comments?post=6236"}],"version-history":[{"count":2,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/6236\/revisions"}],"predecessor-version":[{"id":6238,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/6236\/revisions\/6238"}],"wp:attachment":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/media?parent=6236"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/categories?post=6236"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/tags?post=6236"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}