A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides
An attempt has been made to determine potentiometrically (1) acid dissociation constants of cations obtained by protonation of nine trisubstituted pyridine N-oxides, namely 2-halo(Cl, Br and I)-4-nitropicoline N-oxides with the methyl group at positions 3, 5, and 6, as well as (2) the cationic homoc...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
1999-03-01
|
| Series: | Molecules |
| Subjects: | |
| Online Access: | http://www.mdpi.com/1420-3049/4/4/94/ |
| _version_ | 1811238583764254720 |
|---|---|
| author | Lech Chmurzynski Jadwiga Lorenc Aniela Puszko Ewa Kaczmarczyk |
| author_facet | Lech Chmurzynski Jadwiga Lorenc Aniela Puszko Ewa Kaczmarczyk |
| author_sort | Lech Chmurzynski |
| collection | DOAJ |
| description | An attempt has been made to determine potentiometrically (1) acid dissociation constants of cations obtained by protonation of nine trisubstituted pyridine N-oxides, namely 2-halo(Cl, Br and I)-4-nitropicoline N-oxides with the methyl group at positions 3, 5, and 6, as well as (2) the cationic homoconjugation constants of these cationic acids with conjugated N-oxides in acetonitrile. On the basis of the substitution effect, variations of the acid dissociation constants of the trisubstituted pyridine N-oxide cations are discussed. The determined pKa values of the protonated 2-halo-4-nitropicoline N-oxides are compared with the previously determined equilibrium constants of the cationic acids conjugated with the mono- and disubstituted pyridine N-oxides in acetonitrile. Further, based on the pKa values of the protonated 2-halo-4-nitropicoline N-oxides in acetonitrile, supplemented with correlations between pKa’s of the protonated mono- and disubstituted pyridine N-oxides in acetonitrile and water, the pKa's of the acids conjugated with the trisubstituted N-oxides studied in aqueous solutions have been estimated. Moreover, it has been concluded that the cationic homoconjugation constants cannot be determined by potentiometric titration in acetonitrile solutions of the 2-halo-4-nitropicoline N-oxide systems. |
| first_indexed | 2024-04-12T12:45:16Z |
| format | Article |
| id | doaj.art-a7f6b8c442094a1ca70f4001cd87cd47 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-04-12T12:45:16Z |
| publishDate | 1999-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-a7f6b8c442094a1ca70f4001cd87cd472022-12-22T03:32:38ZengMDPI AGMolecules1420-30491999-03-01449410310.3390/40400094A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxidesLech ChmurzynskiJadwiga LorencAniela PuszkoEwa KaczmarczykAn attempt has been made to determine potentiometrically (1) acid dissociation constants of cations obtained by protonation of nine trisubstituted pyridine N-oxides, namely 2-halo(Cl, Br and I)-4-nitropicoline N-oxides with the methyl group at positions 3, 5, and 6, as well as (2) the cationic homoconjugation constants of these cationic acids with conjugated N-oxides in acetonitrile. On the basis of the substitution effect, variations of the acid dissociation constants of the trisubstituted pyridine N-oxide cations are discussed. The determined pKa values of the protonated 2-halo-4-nitropicoline N-oxides are compared with the previously determined equilibrium constants of the cationic acids conjugated with the mono- and disubstituted pyridine N-oxides in acetonitrile. Further, based on the pKa values of the protonated 2-halo-4-nitropicoline N-oxides in acetonitrile, supplemented with correlations between pKa’s of the protonated mono- and disubstituted pyridine N-oxides in acetonitrile and water, the pKa's of the acids conjugated with the trisubstituted N-oxides studied in aqueous solutions have been estimated. Moreover, it has been concluded that the cationic homoconjugation constants cannot be determined by potentiometric titration in acetonitrile solutions of the 2-halo-4-nitropicoline N-oxide systems.http://www.mdpi.com/1420-3049/4/4/94/acidic dissociationcationic homoconjugation2-halogeno(ClBrI)-4-nitro- (356)-picoline N-oxidespotentiometric titrationacetonitrile |
| spellingShingle | Lech Chmurzynski Jadwiga Lorenc Aniela Puszko Ewa Kaczmarczyk A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides Molecules acidic dissociation cationic homoconjugation 2-halogeno(Cl Br I)-4-nitro- (3 5 6)-picoline N-oxides potentiometric titration acetonitrile |
| title | A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides |
| title_full | A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides |
| title_fullStr | A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides |
| title_full_unstemmed | A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides |
| title_short | A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides |
| title_sort | study of acid base equilibria in acetonitrile systems of 2 halo cl br i 4 nitropicoline 3 5 6 n oxides |
| topic | acidic dissociation cationic homoconjugation 2-halogeno(Cl Br I)-4-nitro- (3 5 6)-picoline N-oxides potentiometric titration acetonitrile |
| url | http://www.mdpi.com/1420-3049/4/4/94/ |
| work_keys_str_mv | AT lechchmurzynski astudyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides AT jadwigalorenc astudyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides AT anielapuszko astudyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides AT ewakaczmarczyk astudyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides AT lechchmurzynski studyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides AT jadwigalorenc studyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides AT anielapuszko studyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides AT ewakaczmarczyk studyofacidbaseequilibriainacetonitrilesystemsof2haloclbri4nitropicoline356noxides |