Acidity constants of cefetamet, cefotaxime and ceftriaxone; the effect of the substituent at C3 position
Само за регистроване кориснике
2005
Чланак у часопису (Објављена верзија)
Метаподаци
Приказ свих података о документуАпстракт
Ionization constants of three cephalosporin antibiotics, cefetamet (CEF), cefotaxime (CFX) and ceftriaxone (CFTR) are determined using pH-potentiometric titrations at I= 0.1 M (NaCl) and t = 25 degrees C. Cefetarnet and cefotaxime have three ionization groups: carboxylic, amide and aminothiazole. Besides those three, ceftriaxone possesses an hydroxytriazi none group as new and additional ionization center. In acid medium two overlapping acid-base processes are occuring with acidity constants being: pK(1) 2.93 (COOH) and PK2 3.07 (amin nothiazole) for cefetamet, and pK(1) 2.21 (COOH) and pK(2) 3.15 (aminothiazole) for cefotaxime. In the case of ceftriaxone the situation is even more complicated, three overlapping processes coexist with pK(1) 2.37 (COOH), pK(2) 3.03 (aminothiazole) and pK(3) 4.21 (hydroxytriazinone). Protolysis of amide group is happening in the alkaline medium as completely separated process from those in acid medium. The acidity constants which correspond to amide grou...p are pK(3) 10.65 (CEF), pK(3) 10.87 (CFX) and pK(4) 10.74 (CFTR). The influence of the C3 substituent on the dissociation process of the neighboring ionization group, particularly carboxylic group, was considered. The differences in acidity of CEF, CFX and CFFR pK(1): 2.93, 2.21 and 2.37, respectively) are likely to be caused by the stereoelectronic properties of substituents in the P-position to the carboxylic group due to the combined inductive, hyperconjugative and resonance effects.
Кључне речи:
cephalosporins / cefetamet / ceftriaxone / cefotaxime / acidity constants / potentiometryИзвор:
Journal of Pharmaceutical and Biomedical Analysis, 2005, 39, 3-4, 752-756Издавач:
- Elsevier Science BV, Amsterdam
DOI: 10.1016/j.jpba.2005.04.033
ISSN: 0731-7085
PubMed: 15967622
WoS: 000232209700057
Scopus: 2-s2.0-23944515541
Институција/група
PharmacyTY - JOUR AU - Aleksić, Mara AU - Savić, Vladimir AU - Popović, Gordana AU - Burić, Nikola AU - Kapetanović, Vera PY - 2005 UR - https://farfar.pharmacy.bg.ac.rs/handle/123456789/616 AB - Ionization constants of three cephalosporin antibiotics, cefetamet (CEF), cefotaxime (CFX) and ceftriaxone (CFTR) are determined using pH-potentiometric titrations at I= 0.1 M (NaCl) and t = 25 degrees C. Cefetarnet and cefotaxime have three ionization groups: carboxylic, amide and aminothiazole. Besides those three, ceftriaxone possesses an hydroxytriazi none group as new and additional ionization center. In acid medium two overlapping acid-base processes are occuring with acidity constants being: pK(1) 2.93 (COOH) and PK2 3.07 (amin nothiazole) for cefetamet, and pK(1) 2.21 (COOH) and pK(2) 3.15 (aminothiazole) for cefotaxime. In the case of ceftriaxone the situation is even more complicated, three overlapping processes coexist with pK(1) 2.37 (COOH), pK(2) 3.03 (aminothiazole) and pK(3) 4.21 (hydroxytriazinone). Protolysis of amide group is happening in the alkaline medium as completely separated process from those in acid medium. The acidity constants which correspond to amide group are pK(3) 10.65 (CEF), pK(3) 10.87 (CFX) and pK(4) 10.74 (CFTR). The influence of the C3 substituent on the dissociation process of the neighboring ionization group, particularly carboxylic group, was considered. The differences in acidity of CEF, CFX and CFFR pK(1): 2.93, 2.21 and 2.37, respectively) are likely to be caused by the stereoelectronic properties of substituents in the P-position to the carboxylic group due to the combined inductive, hyperconjugative and resonance effects. PB - Elsevier Science BV, Amsterdam T2 - Journal of Pharmaceutical and Biomedical Analysis T1 - Acidity constants of cefetamet, cefotaxime and ceftriaxone; the effect of the substituent at C3 position VL - 39 IS - 3-4 SP - 752 EP - 756 DO - 10.1016/j.jpba.2005.04.033 ER -
@article{ author = "Aleksić, Mara and Savić, Vladimir and Popović, Gordana and Burić, Nikola and Kapetanović, Vera", year = "2005", abstract = "Ionization constants of three cephalosporin antibiotics, cefetamet (CEF), cefotaxime (CFX) and ceftriaxone (CFTR) are determined using pH-potentiometric titrations at I= 0.1 M (NaCl) and t = 25 degrees C. Cefetarnet and cefotaxime have three ionization groups: carboxylic, amide and aminothiazole. Besides those three, ceftriaxone possesses an hydroxytriazi none group as new and additional ionization center. In acid medium two overlapping acid-base processes are occuring with acidity constants being: pK(1) 2.93 (COOH) and PK2 3.07 (amin nothiazole) for cefetamet, and pK(1) 2.21 (COOH) and pK(2) 3.15 (aminothiazole) for cefotaxime. In the case of ceftriaxone the situation is even more complicated, three overlapping processes coexist with pK(1) 2.37 (COOH), pK(2) 3.03 (aminothiazole) and pK(3) 4.21 (hydroxytriazinone). Protolysis of amide group is happening in the alkaline medium as completely separated process from those in acid medium. The acidity constants which correspond to amide group are pK(3) 10.65 (CEF), pK(3) 10.87 (CFX) and pK(4) 10.74 (CFTR). The influence of the C3 substituent on the dissociation process of the neighboring ionization group, particularly carboxylic group, was considered. The differences in acidity of CEF, CFX and CFFR pK(1): 2.93, 2.21 and 2.37, respectively) are likely to be caused by the stereoelectronic properties of substituents in the P-position to the carboxylic group due to the combined inductive, hyperconjugative and resonance effects.", publisher = "Elsevier Science BV, Amsterdam", journal = "Journal of Pharmaceutical and Biomedical Analysis", title = "Acidity constants of cefetamet, cefotaxime and ceftriaxone; the effect of the substituent at C3 position", volume = "39", number = "3-4", pages = "752-756", doi = "10.1016/j.jpba.2005.04.033" }
Aleksić, M., Savić, V., Popović, G., Burić, N.,& Kapetanović, V.. (2005). Acidity constants of cefetamet, cefotaxime and ceftriaxone; the effect of the substituent at C3 position. in Journal of Pharmaceutical and Biomedical Analysis Elsevier Science BV, Amsterdam., 39(3-4), 752-756. https://doi.org/10.1016/j.jpba.2005.04.033
Aleksić M, Savić V, Popović G, Burić N, Kapetanović V. Acidity constants of cefetamet, cefotaxime and ceftriaxone; the effect of the substituent at C3 position. in Journal of Pharmaceutical and Biomedical Analysis. 2005;39(3-4):752-756. doi:10.1016/j.jpba.2005.04.033 .
Aleksić, Mara, Savić, Vladimir, Popović, Gordana, Burić, Nikola, Kapetanović, Vera, "Acidity constants of cefetamet, cefotaxime and ceftriaxone; the effect of the substituent at C3 position" in Journal of Pharmaceutical and Biomedical Analysis, 39, no. 3-4 (2005):752-756, https://doi.org/10.1016/j.jpba.2005.04.033 . .