scholarly journals Protonation sequence of linear aliphatic polyamines from intramolecular atomic energies and charges

2011 ◽  
Vol 966 (1-3) ◽  
pp. 213-219 ◽  
Author(s):  
Ignacy Cukrowski ◽  
Chérif F. Matta
Keyword(s):  
Protonation Sequence

Two-dimensional n.m.r. investigation of the protonation sequence in spermidine

1983 ◽  
pp. 43 ◽  
Author(s):  
David A. Aikens ◽  
Stanley C. Bunce ◽  
O. Frederick Onasch ◽  
Herbert M. Schwartz ◽  
Charles Hurwitz
Keyword(s):  
Two Dimensional ◽  
Protonation Sequence

The protonation reactions of catechin, epicatechin and related compounds

1984 ◽  
Vol 37 (4) ◽  
pp. 885 ◽  
Author(s):  
JA Kennedy ◽  
MHG Munro ◽  
HKJ Powell ◽  
LJ Porter ◽  
LY Foo
Keyword(s):  
Time Scale ◽  
Protocatechuic Acid ◽  
Equilibrium Constants ◽  
Basic Solution ◽  
Ionic Mechanism ◽  
Model Compounds ◽  
Specific Solvation ◽  
Experimental Time ◽  
Protonation Sequence ◽  
Related Compounds

The protonation reactions for catechin and epicatechin have been studied at 25�C, I 0.10M (KCl). Equilibrium constants Kn for the protonation steps of the anions L4- have been determined from potentiometric and/or spectrophotometric measurements. The logKn values for the epimers differed significantly only for logKl and logK4 (values for catechin 13.26 � 0.05, 11.26 � 0.06, 9.41 � 0.02, 8.64 � 0.01, and epicatechin 13.40 � 0.05, ll.23 � 0.06, 9.49 � 0.02, 8.72 � .01, n = 1-4 respectively). These differences are ascribed to specific solvation effects or ion associations between K+ and the ligand anions. Epimerization was studied by h.p.l.c., and was found to be minimal over the experimental time scale at pH c. 13.5. The ring on which each stepwise protonation occurs was elucidated by reference to log Kn values measured for the model compounds catechol, 4-methylbenzene-1,2-diol, protocatechuic acid and 3',4'-di-O-methylcatechin. The protonation sequence is B ring, A ring, B ring and A ring. In contrast to earlier results, it has been established that the epimerization of catechin or epicatechin at C2, and the formation of catechinic acid in basic solution, may proceed through a radical rather than ionic mechanism.

Protonation Sequence Study of the Solution Structure of DTPA by1H NMR

1995 ◽  
Vol 28 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Thomas J. Manning ◽  
Eddie D. Gravley
Keyword(s):  
Solution Structure ◽  
Protonation Sequence ◽  
Sequence Study

ChemInform Abstract: Synthesis, Protonation Sequence, and NMR Studies of Polyazamacrocyclic Methylenephosphonates.

ChemInform ◽  
1989 ◽  
Vol 20 (49) ◽  
Author(s):  
C. F. G. C. GERALDES ◽  
A. D. SHERRY ◽  
W. P. CACHERIS
Keyword(s):  
Nmr Studies ◽  
Protonation Sequence
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