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7700797 
Journal Article 
Strengths of Acids in Acetonitrile 
Kutt, A; Tshepelevitsh, S; Saame, J; Lokov, M; Kaljurand, I; Selberg, S; Leito, Ivo; , 
2021 
Yes 
European Journal of Organic Chemistry
ISSN: 1434-193X
EISSN: 1099-0690 
WILEY-V C H VERLAG GMBH 
WEINHEIM 
2021 
9 
1407-1419 
English 
WOS:000618369900001 
The equilibrium acidity scale (pK(a) scale) in acetonitrile has been supplemented by numerous new compounds and new Delta pK(a) measurements. It now contains altogether 231 acids - over twice more than published previously - linked by 569 Delta pK(a) measurements and spans between the pK(a) values of hydrogen iodide (2.8) and indole (32.57), covering close to 30 orders of magnitude. 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 pK(a) 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. Correlation equations were developed for estimating pK(a) values for the studied types of compounds in water, DMSO, DMF, and 1,2-dichloroethane on the basis of pK(a) values in acetonitrile. These equations enable predicting pK(a) values with an average error around or less than 1 pK(a) unit, which is a sufficient accuracy for many applications. The scale is expected to be a useful tool for the widest possible research areas in organic chemistry, electrochemical power sources, catalysis, etc. 
Acetonitrile; Acidity; Non-aqueous solvents; pKa values; Solvent effects