Deuterium Oxide Solvent Isotope Effects on Fast Reactions of Substituted Malonic Acids1

1966 ◽  
Vol 70 (11) ◽  
pp. 3490-3493 ◽  
Author(s):  
Melvin H. Miles ◽  
Edward M. Eyring ◽  
William W. Epstein ◽  
Michael T. Anderson
Keyword(s):  
Deuterium Oxide ◽  
Isotope Effects ◽  
Fast Reactions ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

The Hydrolysis of Disubstituted Alkyl Phosphorochloridates and N,N,N′,N′-Tetra-stibstituted Phosphorodiamidic Chlorides in Water and Deuterium Oxide: Heat Capacity of Activation and Kinetic Solvent Isotope Effects

1973 ◽  
Vol 51 (4) ◽  
pp. 597-603 ◽  
Author(s):  
E. C. F. Ko ◽  
R. E. Robertson
Keyword(s):  
Heat Capacity ◽  
Thermodynamic Parameters ◽  
Alkyl Group ◽  
Deuterium Oxide ◽  
Isotope Effects ◽  
Potential Relationship ◽  
Mechanism Of Reaction ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Solvent Isotope Effects

The pseudo-thermodynamic parameters, ΔH≠, ΔS≠, and ΔCp≠ and the kinetic solvent isotope effects have been determined for the three alkyl-phosphorochloridates, where the alkyl group is ethylisopropyl and n-propyl; for tetra-methyl and tetra-ethyl phosphorodiamidic chlorides; the di-n-propyl and di-isopropyl analog, the di(isopropylmethylcarbinyl)phosphorochloridate and the tetra-ethylthiophosphorodiamidic chloride. These compounds have a potential relationship to compounds used as insecticides and as polymers. The mechanism of reaction is discussed on the basis of these data.

Solvent isotope effects in the oxidation of dipeptides by aqueous chlorine

1999 ◽  
Vol 77 (5-6) ◽  
pp. 997-1004 ◽  
Author(s):  
X L Armesto ◽  
M Canle L. ◽  
V García ◽  
J A Santaballa
Keyword(s):  
Isotope Effect ◽  
Deuterium Oxide ◽  
Isotope Effects ◽  
Second Step ◽  
Solvent Isotope Effect ◽  
General Base ◽  
Peptide Oxidation ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Solvent Isotope Effects

A kinetic study of the mechanism of oxidation of Ala-Gly and Pro-Gly by aqueous chlorine has been carried out. Among other experimental facts, the deuterium solvent isotope effects were used to clarify the mechanisms involved. In a first stage, N-chlorination takes place, and then the (N-Cl)-dipeptide decomposes through two possible mechanisms, depending on the acidity of the medium. The initial chlorination step shows a small isotope effect. In alkaline medium, two consecutive processes take place: first, the general base-catalyzed formation of an azomethine (β ca. 0.27), which has an inverse deuterium solvent isotope effect (kOH-/kOD- ~ 0.8). In a second step, the hydrolysis of the azomethine intermediate takes place, which is also general base-catalyzed, without deuterium solvent isotope effect, the corresponding uncatalyzed process having a normal deuterium solvent isotope effect (kH2O/kD2O ~ 2). In acid medium, the (N-Cl)-dipeptide undergoes disproportionation to a (N,N)-di-Cl-dipeptide, the very fast decomposition of the latter in deuterium oxide preventing a reliable estimation of the solvent isotope effect.Key words: chlorination, deuterium isotope effects, fractionation factors, peptide oxidation, water treatment.

Studies in solvolysis. Part I. The neutral hydrolysis of some alkyl trifluoroacetates in water and deuterium oxide

1968 ◽  
Vol 46 (18) ◽  
pp. 2887-2894 ◽  
Author(s):  
June G. Winter ◽  
J. M. W. Scott
Keyword(s):  
Deuterium Oxide ◽  
Isotope Effects ◽  
Activation Process ◽  
Rate Data ◽  
Methyl Ethyl ◽  
Light Water ◽  
Carbonium Ion ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Solvent Isotope Effects

The temperature dependence of the rates of neutral hydrolysis of a series of alkyl trifluoroacetates (CF3COOR; R = methyl, ethyl, s-propyl, t-butyl) has been determined in both light and heavy water. From these studies the thermodynamic parameters (ΔH≠, ΔS≠) which characterize the activation process have been calculated. Sufficient rate data have been obtained in the case of the ethyl ester to calculate the heat capacity of activation (ΔCP≠) for the hydrolysis of this compound in light water. Both the entropies and enthalpies of activation as well as the solvent isotope effects are consistent with the proposal that the primary and secondary esters react by an acyl–oxygen BAc2 mechanism, in contrast to the tertiary ester, which appears to react either by a carbonium ion (SN1) process or by a route which combines both the BAc2 and SN1 paths.

Studies in Solvolysis. Part IV. Substituent and Solvent Isotope Effects in the Solvolysis of a Series of Benzyl Trifluoroacetates

1972 ◽  
Vol 50 (12) ◽  
pp. 1886-1890 ◽  
Author(s):  
June G. Winter ◽  
J. M. W. Scott
Keyword(s):  
Isotope Effect ◽  
Deuterium Oxide ◽  
Isotope Effects ◽  
The Other ◽  
Solvent Isotope Effect ◽  
Other Hand ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Solvent Isotope Effects

The rates of neutral hydrolysis of a series of 4-substituted benzyl trifluoroacetates 4-X-C6H4CH2OCOCF3, X = NO2, Cl, H, CH3, and OCH3 have been studied in water and deuterium oxide, both solvents containing 0.012 mol fraction of acetone. The alteration of the rates with the nature of the 4-substituent and the kinetic solvent isotope effect (k(H2O)/k(D2O)) are consistent with the proposal that the esters with X = NO2, Cl, H, and CH3 all react by an acyl–oxygen BAc2 mechanism. On the other hand, the same mechanistic criteria indicate that the 4-methoxybenzyl ester reacts by both the BAc2 and the SN1 alkyl–oxygen fission paths in equal amounts.

Deuterium Oxide Solvent Isotope Effects in the Nucleophilic Reactions of Phenyl Esters

1962 ◽  
Vol 84 (4) ◽  
pp. 595-599 ◽  
Author(s):  
Myron L. Bender ◽  
Edward J. Pollock ◽  
Maurice C. Neveu
Keyword(s):  
Deuterium Oxide ◽  
Isotope Effects ◽  
Nucleophilic Reactions ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

Solvent Isotope Effects in Atomic Force Spectroscopy

2001 ◽  
Vol 7 (S2) ◽  
pp. 856-857
Author(s):  
Jeffrey G. Forbes ◽  
John P. Santos
Keyword(s):  
Deuterium Oxide ◽  
Isotope Effects ◽  
Protein Ligand Interactions ◽  
Atomic Force ◽  
Single Protein ◽  
Ligand Interactions ◽  
Solvent Isotope ◽  
Functionalized Tips ◽  
Glass Surfaces ◽  
Solvent Isotope Effects

The utility of the atomic force microscope (AFM) for measuring forces is now well established. The AFM is capable of measuring forces from tens of piconewtons to tens of nanonewtons. Systems ranging from the adhesion of clean or functionalized tips interacting with different surface, to singlemolecule measurements of the force required to rupture protein-ligand interactions, to the forced unfolding of single protein molecules have been studied. The adhesion of a clean silicon nitride tip to a clean glass surface is one of the simplest systems to study and was the first system to demonstrate quantized adhesion. AFM cantilevers will adhere to glass surfaces in the presence of water and the force required to separate the surfaces is on the order of 1-6 nN at low pH. The adhesion mechanism is believed to be due to hydrogen bonds formed between the silanol groups present on both the glass and AFM tip. Deuterium oxide (D2O) has physical properties significantly different from that of H2O; the density, melting temperature and heat capacity are all greater than that of water. These and the differences between H2O and D2O can be attributed to the lower vibrational frequency of the OD bond and the fact that O-D…O bonds are about lkJ/mol stronger than O-H…O bonds.

scholarly journals Location of deuterium oxide solvent isotope effects in the glutamate dehydrogenase reaction.

1975 ◽  
Vol 250 (13) ◽  
pp. 5243-5246
Author(s):  
A H Colen ◽  
R R Wilkinson ◽  
H F Fisher
Keyword(s):  
Glutamate Dehydrogenase ◽  
Deuterium Oxide ◽  
Isotope Effects ◽  
Dehydrogenase Reaction ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

SOLVOLYSIS IN HYDROGEN AND DEUTERIUM OXIDE: IV. HALIDES WITH NEIGHBORING GROUPS

1961 ◽  
Vol 39 (11) ◽  
pp. 2155-2162 ◽  
Author(s):  
P. M. Laughton ◽  
R. E. Robertson
Keyword(s):  
Deuterium Oxide ◽  
Isotope Effects ◽  
Solvation Shell ◽  
Hydroxyl Group ◽  
Activation Process ◽  
Anchimeric Assistance ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Related Compounds ◽  
Solvent Isotope Effects

Rate data for the hydrolysis of a series of halohydrins and related compounds in light and heavy water are reported. The solvent isotope effects [Formula: see text] from these measurements fall into three groups compared with those of simple halides. Thus the presence of a hydroxyl group in proximity to the seat of reaction may lead to increased, decreased, or normal solvent isotope ratios. The abnormal ratios can be interpreted in terms of the effect of anchimeric assistance on the solvation shell in the activation process.

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