Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water media
The acid-base properties of 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-one (L1) and 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-thione (L2) were investigated potentiometrically at an ionic strength of 0.10M(LiCl) in 19.8, 33.6 and 55.9 % (v/v) methanolâwater mixtures at 25.0 ± 0.1 ºC. The apparent...
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| Format: | Article |
| Language: | English |
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Serbian Chemical Society
2006-01-01
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| Series: | Journal of the Serbian Chemical Society |
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| Online Access: | http://www.shd.org.yu/HtDocs/SHD/Vol71/No1/JSCS_V71_No1-05.pdf |
| _version_ | 1818162670295056384 |
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| author | HASAN KILIÇ BİROL ER |
| author_facet | HASAN KILIÇ BİROL ER |
| author_sort | HASAN KILIÇ |
| collection | DOAJ |
| description | The acid-base properties of 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-one (L1) and 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-thione (L2) were investigated potentiometrically at an ionic strength of 0.10M(LiCl) in 19.8, 33.6 and 55.9 % (v/v) methanolâwater mixtures at 25.0 ± 0.1 ºC. The apparent dissociation constants (psKa) were calculated for the di-protonated form (L1H2+2 and L2H2+2) of pyrimidine bases, using a software package TITFIT, which were then extrapolated to pure water to derive the dissociation constants in aqueous solution (pKa). The aqueous pKa constants were found to be: L1, pKa1 = 3.76 and pKa2 = 6.95; L2, pKa1 = 3.57 and pKa1 = 6.90. At pH 2.00, the dominant species in solution were the protonated form of the amino group substituted at the 1-position, while at a pH around 5.00, they were the protonated form of the pyrimidine ring nitrogen at the 3-position. An effect of intramolecular hydrogen bonding on the psKa values was observed with L1 but not L2. The effects ofmolecular structure and solvent medium on the psKa values are also discussed. |
| first_indexed | 2024-12-11T16:37:21Z |
| format | Article |
| id | doaj.art-e57a2ef536c0492aae8851a83ae88f48 |
| institution | Directory Open Access Journal |
| issn | 0352-5139 |
| language | English |
| last_indexed | 2024-12-11T16:37:21Z |
| publishDate | 2006-01-01 |
| publisher | Serbian Chemical Society |
| record_format | Article |
| series | Journal of the Serbian Chemical Society |
| spelling | doaj.art-e57a2ef536c0492aae8851a83ae88f482022-12-22T00:58:25ZengSerbian Chemical SocietyJournal of the Serbian Chemical Society0352-51392006-01-017114354Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water mediaHASAN KILIÇBİROL ERThe acid-base properties of 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-one (L1) and 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-thione (L2) were investigated potentiometrically at an ionic strength of 0.10M(LiCl) in 19.8, 33.6 and 55.9 % (v/v) methanolâwater mixtures at 25.0 ± 0.1 ºC. The apparent dissociation constants (psKa) were calculated for the di-protonated form (L1H2+2 and L2H2+2) of pyrimidine bases, using a software package TITFIT, which were then extrapolated to pure water to derive the dissociation constants in aqueous solution (pKa). The aqueous pKa constants were found to be: L1, pKa1 = 3.76 and pKa2 = 6.95; L2, pKa1 = 3.57 and pKa1 = 6.90. At pH 2.00, the dominant species in solution were the protonated form of the amino group substituted at the 1-position, while at a pH around 5.00, they were the protonated form of the pyrimidine ring nitrogen at the 3-position. An effect of intramolecular hydrogen bonding on the psKa values was observed with L1 but not L2. The effects ofmolecular structure and solvent medium on the psKa values are also discussed.http://www.shd.org.yu/HtDocs/SHD/Vol71/No1/JSCS_V71_No1-05.pdfdissociation constantpKapotentiometrypyrimidine derivativesprotonated aminesnitrogen-protonated pyrimidine basesintramolecular hydrogen bonding |
| spellingShingle | HASAN KILIÇ BİROL ER Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water media Journal of the Serbian Chemical Society dissociation constant pKa potentiometry pyrimidine derivatives protonated amines nitrogen-protonated pyrimidine bases intramolecular hydrogen bonding |
| title | Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water media |
| title_full | Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water media |
| title_fullStr | Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water media |
| title_full_unstemmed | Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water media |
| title_short | Potentiometric investigation of acid-base equilibria of two newv pyrimidine derivatives in various methanol–water media |
| title_sort | potentiometric investigation of acid base equilibria of two newv pyrimidine derivatives in various methanol water media |
| topic | dissociation constant pKa potentiometry pyrimidine derivatives protonated amines nitrogen-protonated pyrimidine bases intramolecular hydrogen bonding |
| url | http://www.shd.org.yu/HtDocs/SHD/Vol71/No1/JSCS_V71_No1-05.pdf |
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