The Catalysis of Proton Exchange in Creatinine by General Acids and General Bases

1975 ◽  
Vol 53 (2) ◽  
pp. 224-231 ◽  
Author(s):  
R. Srinivasan ◽  
Ross Stewart
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Central Peak ◽  
Proton Exchange ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Acidity Function ◽  
Hydroxide Ion ◽  
Factors Affecting

The rate of exchange of methylene protons in creatinine has been followed in D2O by means of proton magnetic resonance spectroscopy over a range of acidity from pD 12.22 to DA –4.24. A plot of the logarithm of the rate against acidity function is in the form of a "W", one wing of which involves reaction of neutral creatinine with hydroxide ion, and the other diprotonated creatinine with water. The central peak represents reaction of protonated creatinine with a molecule of creatinine acting as base. The reaction is subject to catalysis by buffers.The activation of exchange produced by protonating the substrate is designated protonactivatingfactor, p.a.f., and factors affecting its size are discussed in terms of structure.

Metal – Aminopolycarboxylic Acid Complexes. II. Studies of Triethylenetetraaminehexaacetic Acid and its Lead(II) Complexes in Aqueous Solution by Proton Magnetic Resonance Spectroscopy

1971 ◽  
Vol 49 (12) ◽  
pp. 2086-2095 ◽  
Author(s):  
P. Letkeman ◽  
J. B. Westmore
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Equilibrium Constants ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Carboxylate Groups ◽  
Triethylenetetraaminehexaacetic Acid ◽  
Nitrogen Bonds ◽  
Aminopolycarboxylic Acid

Nuclear magnetic resonance (n.m.r.) spectroscopy was used to determine the preferred protonation sites in TTHA. For its 1:1 complex with Pb(II) the following equilibrium constants for protonation were obtained (triethylenetetraaminehexaacetic acid ≡ H6A)[Formula: see text]The non-protonated complex is considered to have four coplanar (or nearly coplanar) metal–nitrogen bonds with the center carboxylate groups coordinated above and below this plane, and with the terminal carboxylate groups playing only a small part in the coordinate bonding. The first and second protonations of the complex occur preferentially at the terminal and center nitrogen atoms, respectively, on the same side of the complex, accompanied by breaking of the respective metal–nitrogen bonds. This causes partial unwrapping of the complex from one side. Rapid interconversion between configurations in which unwrapping and rewrapping occurs first from one side of the molecule and then from the other leads to simplified n.m.r. spectra.

Conformations, configurations, and proton reactions of colbalt(III) complexes

1967 ◽  
Vol 20 (2) ◽  
pp. 257 ◽  
Author(s):  
DA Buckingham ◽  
L Durham ◽  
AM Sargeson
Keyword(s):  
Amino Acid ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Proton Exchange ◽  
Resonance Spectroscopy ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans

Proton magnetic resonance spectroscopy allows the cis and trans isomers of [CoX2 en2] complexes to be distinguished. Some information has been obtained concerning the rate of chelate conformational interchange for cobalt-ethylenediamine, propylenediamine, N-methylethylenediamine, and malonate rings. For [Co(amino acid)en2]2+ complexes the diastereoisomeric pairs can be differentiated and the relative rates of CH and NH proton exchange have been observed for a variety of chelate rings including cobalt-amino acid, acetylacetonato, ethylenediamine, and malonato.

General-base-catalyzed Proton Exchange in Glycocyamidiniom Ions: A Comparison of Activation by Protonation and by Alkylation

1975 ◽  
Vol 53 (19) ◽  
pp. 2906-2910 ◽  
Author(s):  
Ross Stewart ◽  
R. Srinivasan
Keyword(s):  
Exchange Rate ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Proton Exchange ◽  
Resonance Spectroscopy ◽  
Methyl Groups ◽  
General Base ◽  
Satisfactory Model ◽  
Conjugate Acid

The rates of exchange of methylene protons in seven glycocyamidinium ions in formate and chloroacetate buffers were measured in D2O by means of proton magnetic resonance spectroscopy. When protonation and methylation of glycocyamidines occur at the same site the methyated products react faster than the protonated products by factors of 1.8–1.9. Replacing ring protons in glycocyamidinium ions by methyl groups causes small increases in the méthylène exchange rate whereas corresponding substitution at the exocyclic nitrogen causes small rate decreases. It is concluded that in this reaction a quaternary ion ZR+ can serve as a satisfactory model for the analogous conjugate acid ZH+.

scholarly journals Imaging intelligence with proton magnetic resonance spectroscopy

Intelligence ◽  
2009 ◽  
Vol 37 (2) ◽  
pp. 192-198 ◽  
Author(s):  
Rex E. Jung ◽  
Charles Gasparovic ◽  
Robert S. Chavez ◽  
Arvind Caprihan ◽  
Ranee Barrow ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy

Disulfiram Determination by Proton Magnetic Resonance Spectroscopy and by Colorimetry

1973 ◽  
Vol 56 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Eric B Sheinin ◽  
Walter R Benson ◽  
Myron M Smith
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Colorimetric Method ◽  
Drug Substance ◽  
Resonance Spectroscopy ◽  
Pmr Spectroscopy ◽  
Label Claim ◽  
Tablet Excipients

Abstract Disulfiram was determined in disulfiram drug substance and tablets by proton magnetic resonance (PMR) spectroscopy at the 100–480 mg level and by a colorimetric technique involving cuprous iodide at the 50 mg level. The tablet excipients do not interfere in the analysis. The average result for disulfiram in a tablet composite was 100.8±1.4% of label claim by PMR and 100.7±0.4% by the colorimetric method.

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