Protolytic equilibria of bromazepam
Protolitičke ravnoteže bromazepama
Abstract
The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in homogeneous and heterogeneous systems were studied in the pH range 0-14 at 25 degreesC and at ionic strength of 0.1 mol/dm(3) (NaCl). On the basis of C-13-NMR spectra, the protonation site was predicted - in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity constants of bromazepam were determined spectrophotometrically (pK(a1) 2.83 and pK(a2) 11.60) and potentiometrically (pk(a1) 2.99). In the heterogeneous system the following equilibrium constants were determined: K-s0 = [HA] (pK(s0) 3.44), K-s1 = [H(2)A(+)]/[H3O+] (pK(s1) 0.61), and K-s2 = [A(-)][H3O+] (pK(s2) 15.04).
Proučavane su protolitičke ravnoteže bromazepama, amfolita iz klase 1,4-benzodiazepina, slabo rastvornog u vodi. Ispitivanja su vršena u homogenom i heterogenom sistemu u pH intervalu 0–14, na temperaturi 25ºC i pri jonskoj sili 0,1 mol/dm3 (NaCl). Na osnovu 13C-NMR spektara pretpostavljeno je da do protonovanja u molekulu bromazepama dolazi na piridinskom atomu azota. Kiselinske konstante određene su spektrofotometrijski (pKa1 2.83 and pKa2 11.60) i potenciometrijski (pKa1 2,99). U heterogenom sistemu određene su sledeće ravnotežne konstante Ks0 =[HA](pKs0 3.44), Ks1=[H2A+]/[H3O+](pKs1 0.61), and Ks2 =[A-][H3O+](pKs2 15.04).
Keywords:
bromazepam / 1,4-benzodiazepines / 1,4-benzodiazepines / acidity constants / acidity constants / heterogeneous equilibria / heterogeneous equilibriaSource:
Journal of the Serbian Chemical Society, 2002, 67, 3, 187-195Publisher:
- Serbian Chemical Soc, Belgrade
DOI: 10.2298/JSC0203187P
ISSN: 0352-5139
WoS: 000174611800005
Scopus: 2-s2.0-0036335136
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Hemijski fakultet / Faculty of ChemistryTY - JOUR AU - Pfendt, Lidija B. AU - Popović, Gordana V. AU - Damjanović, Tatjana Ž. AU - Sladić, Dušan PY - 2002 UR - https://cherry.chem.bg.ac.rs/handle/123456789/484 AB - The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in homogeneous and heterogeneous systems were studied in the pH range 0-14 at 25 degreesC and at ionic strength of 0.1 mol/dm(3) (NaCl). On the basis of C-13-NMR spectra, the protonation site was predicted - in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity constants of bromazepam were determined spectrophotometrically (pK(a1) 2.83 and pK(a2) 11.60) and potentiometrically (pk(a1) 2.99). In the heterogeneous system the following equilibrium constants were determined: K-s0 = [HA] (pK(s0) 3.44), K-s1 = [H(2)A(+)]/[H3O+] (pK(s1) 0.61), and K-s2 = [A(-)][H3O+] (pK(s2) 15.04). AB - Proučavane su protolitičke ravnoteže bromazepama, amfolita iz klase 1,4-benzodiazepina, slabo rastvornog u vodi. Ispitivanja su vršena u homogenom i heterogenom sistemu u pH intervalu 0–14, na temperaturi 25ºC i pri jonskoj sili 0,1 mol/dm3 (NaCl). Na osnovu 13C-NMR spektara pretpostavljeno je da do protonovanja u molekulu bromazepama dolazi na piridinskom atomu azota. Kiselinske konstante određene su spektrofotometrijski (pKa1 2.83 and pKa2 11.60) i potenciometrijski (pKa1 2,99). U heterogenom sistemu određene su sledeće ravnotežne konstante Ks0 =[HA](pKs0 3.44), Ks1=[H2A+]/[H3O+](pKs1 0.61), and Ks2 =[A-][H3O+](pKs2 15.04). PB - Serbian Chemical Soc, Belgrade T2 - Journal of the Serbian Chemical Society T1 - Protolytic equilibria of bromazepam T1 - Protolitičke ravnoteže bromazepama VL - 67 IS - 3 SP - 187 EP - 195 DO - 10.2298/JSC0203187P ER -
@article{ author = "Pfendt, Lidija B. and Popović, Gordana V. and Damjanović, Tatjana Ž. and Sladić, Dušan", year = "2002", abstract = "The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in homogeneous and heterogeneous systems were studied in the pH range 0-14 at 25 degreesC and at ionic strength of 0.1 mol/dm(3) (NaCl). On the basis of C-13-NMR spectra, the protonation site was predicted - in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity constants of bromazepam were determined spectrophotometrically (pK(a1) 2.83 and pK(a2) 11.60) and potentiometrically (pk(a1) 2.99). In the heterogeneous system the following equilibrium constants were determined: K-s0 = [HA] (pK(s0) 3.44), K-s1 = [H(2)A(+)]/[H3O+] (pK(s1) 0.61), and K-s2 = [A(-)][H3O+] (pK(s2) 15.04)., Proučavane su protolitičke ravnoteže bromazepama, amfolita iz klase 1,4-benzodiazepina, slabo rastvornog u vodi. Ispitivanja su vršena u homogenom i heterogenom sistemu u pH intervalu 0–14, na temperaturi 25ºC i pri jonskoj sili 0,1 mol/dm3 (NaCl). Na osnovu 13C-NMR spektara pretpostavljeno je da do protonovanja u molekulu bromazepama dolazi na piridinskom atomu azota. Kiselinske konstante određene su spektrofotometrijski (pKa1 2.83 and pKa2 11.60) i potenciometrijski (pKa1 2,99). U heterogenom sistemu određene su sledeće ravnotežne konstante Ks0 =[HA](pKs0 3.44), Ks1=[H2A+]/[H3O+](pKs1 0.61), and Ks2 =[A-][H3O+](pKs2 15.04).", publisher = "Serbian Chemical Soc, Belgrade", journal = "Journal of the Serbian Chemical Society", title = "Protolytic equilibria of bromazepam, Protolitičke ravnoteže bromazepama", volume = "67", number = "3", pages = "187-195", doi = "10.2298/JSC0203187P" }
Pfendt, L. B., Popović, G. V., Damjanović, T. Ž.,& Sladić, D.. (2002). Protolytic equilibria of bromazepam. in Journal of the Serbian Chemical Society Serbian Chemical Soc, Belgrade., 67(3), 187-195. https://doi.org/10.2298/JSC0203187P
Pfendt LB, Popović GV, Damjanović TŽ, Sladić D. Protolytic equilibria of bromazepam. in Journal of the Serbian Chemical Society. 2002;67(3):187-195. doi:10.2298/JSC0203187P .
Pfendt, Lidija B., Popović, Gordana V., Damjanović, Tatjana Ž., Sladić, Dušan, "Protolytic equilibria of bromazepam" in Journal of the Serbian Chemical Society, 67, no. 3 (2002):187-195, https://doi.org/10.2298/JSC0203187P . .