Influence of solvent

Mavri, J., Berendsen, H.J.C., Van Gunsteren, W.F. Influence of solvent on intramolecular proton transfer in hydrogen malonate. Molecular dynamics study of tunneling by density matrix evolution and nonequilibrium solvation. J. Phys. Chem. 97 (1993) 13469-13476. 

The influence of solvent can be incorporated in an implicit fashion to yield so-called langevin modes. Although NMA has been applied to allosteric proteins previously, the predictive power of normal mode analysis is intrinsically limited to the regime of fast structural fluctuations. Slow conformational transitions are dominantly found in the regime of anharmonic protein motion. 

This is a question of reaction prediction. In fact, this is a deterministic system. If we knew the rules of chemistry completely, and understood chemical reactivity fully, we should be able to answer this question and to predict the outcome of a reaction. Thus, we might use quantum mechanical calculations for exploring the structure and energetics of various transition states in order to find out which reaction pathway is followed. This requires calculations of quite a high degree of sophistication. In addition, modeling the influence of solvents on... 

The understanding and simulation of chemical reactions is one of the great challenges of chemoinformatics. Each day millions of reactions are performed, sometimes with rather poor results because of our limited understanding of chemical reactivity and the influence of solvents, catalysts, temperature, etc. This problem has to be tackled by both deductive and inductive learning methods. 

Focuses on force field calculations for understanding the dynamic properties of proteins and nucleic acids. Provides a useful introduction to several computational techniques, including molecular mechanics minimization and molecular dynamics. Includes discussions of research involving structural changes and short time scale dynamics of these biomolecules, and the influence of solvent in these processes. 

Use a solvent or water bath to capture the influence of solvent on the solute. Use the fewest shells of water/solvent possible, but no fewer than two, if resources are scarce. Use a formal "box" of water, if possible, to reduce the influence of edge effects. 

Rizzuti et al. [Chem. Eng. Sci, 36, 973 (1981)] examined the influence of solvent viscosity upon the effective interfacial area in packed columns and concluded that for the systems studied the effective interfacial area a was proportional to the kinematic viscosity raised to the 0.7 power. Thus, the hydrodynamic behavior of a packed absorber is strongly affected by viscosity effects. Surface-tension effects also are important, as expressed in the work of Onda et al. (see Table 5-28-D). 

The value of current of the addition peak on concentration of dye and metal, ionic strength of the solution, influence of solvent and temperature were investigated. 

Influence of solvent on viscosity and tack of polychloroprene adhesives... 

Table 3-1 illustrates the influence of solvent polarity on the amount of 6W-product e.g. 10) formed from hydrogenation of octalone (9), testo-sterone and cholestenone. The product composition is determined by the amount of 1,2 and 1,4 adsorption of the substrate. 

The marked influence of solvent and temperature on product composition is illustrated by results obtained with 3 5-hydroxy-5a-androstan-17-one (5), which yields in addition to the 3a-fluoro derivative (6) the elimination... 

The influence of solvent polarity on the rate of quatemization is well known and recent measurements have supported the general view that the more polar solvents produce a faster reaction. Fuoss and his colleagues determined the rate of reaction in a number of solvents and discovered that the process was twice as fast in... 

At times, selectivity changes drastically with a change in solvent, providing one of the best means available for controlling selectivity. The powerful influence of solvent is insufficiently appreciated and its efficacy often overlooked. There are many examples, so many that it is difficult to make encompassing generalities. 

It is well known that the choice of solvent can have a dramatic effect upon a chemical reaction [1]. As early as 1862 the ability of solvents to decelerate the reaction between acetic acid and ethanol had been noted [2]. Thirty years later the influence of solvents on reaction equilibria was demonstrated for the first time [3]. 

The proton transfer mechanism described previously was confirmed somewhat by the influence of solvent polarity on polymerization. The rate of photopo-... 

Figure 13 The dependence of probability of the reaction proceeding on the position of active center in chain on different chain-solvent influence. The active center after the reaction proceeding has a lower local rigidity than the initial chain a = influence of solvent on deflection of reacted and unreacted place of the same chain b = influence of solvent on deflection is compensated by the influence of the local rigidity c influences of solvent and local rigidities on deflection are equal, but have opposite directions of action, d = influence of solvent on the deflection is stronger than the influence of the local rigidity.

The solubility of most inorganic compounds is reduced by the addition of organic solvents, such as methanol, ethanol, propan-l-ol, acetone, etc. For example, the addition of about 20 per cent by volume of ethanol renders the solubility of lead sulphate practically negligible, thus permitting quantitative separation. Similarly calcium sulphate separates quantitatively from 50percent ethanol. Other examples of the influence of solvents will be found in Chapter 11. 

Kamachi, M. Influence of Solvent on Free Radical Polymerization of Vinyl Compounds. Vol. 38, pp. 55-87. 

Any understanding of the kinetics of copolymerization and the structure of copolymers requires a knowledge of the dependence of the initiation, propagation and termination reactions on the chain composition, the nature of the monomers and radicals, and the polymerization medium. This section is principally concerned with propagation and the effects of monomer reactivity on composition and monomer sequence distribution. The influence of solvent and complcxing agents on copolymerization is dealt with in more detail in Section 8.3.1. 

In conclusion, it is very likely that the influence of solvents on the change from the heterolytic mechanism of dissociation of the C —N bond in aromatic diazonium ions to homolytic dissociation can be accounted for by a mechanism in which a solvent molecule acts as a nucleophile or an electron donor to the P-nitrogen atom. This process is followed by a one- or a two-step homolytic dissociation to an aryl radical, a solvent radical, and a nitrogen molecule. In this way the unfavorable formation of a dinitrogen radical cation 8.3 as mentioned in Section 8.2, is eliminated. 

Scheme 49 Total syntheses of epo490 (240d) and epoD (237d) by diene-ene RCM between CIO and Cl 1 favorable influence of solvent toluene or unprotected hydroxy groups in metathesis substrates 239 [113]...

Scheme 1.4 Asymmetric hydrolysis of dihydropyridine diesters influence of solvent on lipase stereochemical preference.

Le Beau, D.S., Basic reactions occurring during rubber reclaiming. II. The influence of solvent naphtha, storage of reclaim and aging of scrap prior to reclaiming, and infrared spectra of natural rubber reclaim. Rubber Chem. TechnoL, 22, 560, 1949. 

Kagan H, Namy JL (1999) Influence of Solvents or Additives on the Organic Chemistry... 

FIGURE 4.5 The influence of solvent viscosity on migration characteristics on preparative plates (a) Nonviscous solvent (acetonitrile) (b) Viscous solvent (methanol). (Adapted from Botz, L., Nyiredy, S., and Sticher, O., J. Planar Chromatogr.,3,10-14,1990. With permission.)... 

As BH dissociates into H+ and the uncharged base B, the dielectric constant can exert only a minor effect on the mutual coulombic attraction, so that even in water (e = 78.5) the pKa values of aliphatic amines do not differ much from the above picture of the influence of solvent basicity. That piiTa(water) lies between ptfa(m.cresoi) and p a(acetlc acid) instead of between the latter and p.Ka(pyridine) may be ascribed to effects of solvation however, the p a(Water) values of the aromatic amines are low owing to effects of mesomerism. 

TABLE 1.3 Influence of Solvent on Hydrogenation of an exo Double Bond... 

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