The kinetics of base hydrolysis of the peptide bond in the glycylglycine methyl ester complex of β-(triethylenetetramine)cobalt(III)

1969 ◽  
Vol 0 (20) ◽  
pp. 1208-1209 ◽  
Author(s):  
R. W. Hay ◽  
P. J. Morris
Keyword(s):  
Methyl Ester ◽  
Peptide Bond ◽  
Base Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

Reactivity of base catalysed hydrolysis of 2-pyridinylmethylene-8-quinolinyl-Schiff base iron(II) iodide complexes: solvent effects

2013 ◽  
Vol 67 (4) ◽  
Author(s):  
Ahmad Mohamad ◽  
Mohamed Adam
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Solvent Effects ◽  
Base Hydrolysis ◽  
Iodide Ions ◽  
Ligand Structure ◽  
Solvation Parameters ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Direct Condensation

AbstractThree ligands of 2-pyridinylmethylene-8-quinolinyl (L1), methyl-2-pyridinylmethylene-8-quinolinyl (L2), and phenyl-2-pyridinylmethylene-8-quinolinyl (L3), Schiff bases were synthesised by direct condensation of 8-aminoquinoline with 2-pyridinecarboxaldehyde, 2-acetylpyridine, or 2-benzoylpyridine. They coordinated to Fe(II) ion in a 1: 2 mole ratio followed by treatment with iodide ions affording complexes with a general formula [Fe(L)2]I2·2H2O, (L = L1, L2, or L3). Spectrophotometric evaluation of the kinetics of base catalysed hydrolysis of these complex cations was carried out with an aqueous solution of NaOH in different ratios of water/methanol binary mixtures. Kinetics of the hydrolysis followed the rate law (k 2[OH−] + k 3[OH−]2)[complex]. Reactivity trends and their rate constants were compared and discussed in terms of ligand structure and solvation parameters. The methanol ratio affects the hydrolysis as a co-solvent which was analysed into initial and transition state components. The increase in the rate constant of the base hydrolysis of Fe(II) complexes, as the ratio of methanol increases, is predominantly caused by the strong effect of the organic co-solvent on the transition states.

ChemInform Abstract: Kinetics of Base Hydrolysis of Cyanogen and 1-Cyanoformamide.

ChemInform ◽  
1987 ◽  
Vol 18 (47) ◽  
Author(s):  
Y. L. WANG ◽  
H. D. LEE ◽  
M. W. BEACH ◽  
D. W. MARGERUM
Keyword(s):  
Base Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

Synthesis and Base Hydrolysis of the Pentaammine(dimethyl sulfide)cobalt(III) Ion

1992 ◽  
Vol 45 (12) ◽  
pp. 2049 ◽  
Author(s):  
A Ellis ◽  
A Fultz ◽  
R Hicks ◽  
T Morgan ◽  
L Parsons ◽  
...  
Keyword(s):  
Linear Dependence ◽  
Reaction Rate ◽  
Dimethyl Sulfide ◽  
Activation Parameters ◽  
Base Hydrolysis ◽  
Basic Solution ◽  
Acidic Solutions ◽  
Temperature Range ◽  
Kinetics Of ◽  
Hydrolysis Of

The synthesis of the trifluoromethanesulfonate salt of the pentaarnmine (dimethy1 sulfide)-cobalt(III) ion, [NH3)5Co-S(CH3)2]3+, is described along with the kinetics of its hydrolysis in basic and acidic solutions. The synthesis proceeds in 44% yield from the reaction of [(NH3)5Co-OSO2CF3] (CF3SO3)2 with CH3SCH3 in tetramethylene sulfone at 80�C. The salt has been characterized by elemental analysis, visible-U.V. spectroscopy, and 1H n.m.r. In basic solution the complex decomposes by Co-S cleavage to yield [(NH3)5CO-OH]2+ and non-coordinated CH3SCH3. The kinetics of this reaction were studied in phosphate buffers ranging from pH 8.50 to 11.67 ( �= 1.0 M); a linear dependence of the reaction rate on [OH-] was observed. At 25�C, kOH = 8.8 � 0.2 dm3 mol-1 s-1. Activation parameters, determined over a temperature range from 15 to 44�C, were ΔH‡ = 152 � 3 kJ mol-1 and Δ S‡ = 286 � 9 J K-1 mol-1. In 0.01 M HClO4 ( � = 1.0 M, 25�C), the cobaltsulfur bond is cleaved at a rate of 1.6×10-6 s-l. Activation parameters, determined over a temperature range from 25 to 60�C, were ΔH‡ = 106 � 5 kJ mol-1 and ΔS‡= -2 � 16 J K-1 mol-1.

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