Incorporation of solvent

Mechanism I was ruled out by an isotopic labeling experiment. The mixed anhydride of salicylic acid and acetic acid is an intermediate if nucleophilic catalysis occurs by mechanism 1. This molecule is known to hydrolyze in water with about 25% incorporation of solvent water into the salicylic acid. 

Few cases of incorporation of solvent fragments following hydrogen abstraction have become known. 

During continuous redox cycling, the first cycle usually differs from the following ones. This effect is referred as break-in. In poly(vinylferrocene), PVF, films this has been related to the incorporation of solvent and ions into the film, decreasing its resistivity [132]. This effect has been observed for several polyelectrolyte and polymer-modified electrodes, for example, polyaniline [155]. 

Perez, C., Pastor, M., Ortiz, A.R., and Gago, F. Comparative binding energy analysis of HIV-1 protease inhibitors incorporation of solvent effects and validation as a powerful tool in receptor-based drug design. /. Med. Chem. 1998, 41, 836-852. 

The ciystal habit of sucrose and adipic add crystals were calculated from their intern structure and from the attachment energies of the various crystal faces. As a first attempt to indude the role of the solvent on the crystal habit, the solvent accessible areas of the faces of sucrose and adipic add and were calculated for spherical solvent probes of difierent sizes. In the sucrose system the results show that this type of calculation can qualitatively account for differences in solvent (water) adsorption hence fast growing and slow growing faces. In the adipic add system results show the presence of solvent sized receptacles that might enhance solvent interadions on various fares. The quantitative use of this type of data in crystal shape calculations could prove to be a reasonable method for incorporation of solvent effeds on calculated crystal shapes. 

Incorporation of Solvent Effects in Crystal Habit Calculations... 

In view of these recent studies, it appears that (1) incorporation of solvent molecules into the lattice of the Fe(R2Dtc)3 complexes can be as effective as temperature or pressure changes in shifting the spin-state equilibria, and (2) some of the magnetic data in the literature on the Fe(R2 Dtc)3 complexes may well be misleading owing to the presence of different types and quantities of solvents in the lattice. 

O. Takahashi, H. Sawahata, Y. Ogawa and O. Kikuchi, Incorporation of solvent effects into ab initio molecular orbital calculations by the generalized Born formula. Formulation, parameterization, and applications, J. Mol. Struct. (THEOCHEM), 393 (1997) 141-150. 

Compositional modification frequently, by ligand exchange and incorporation of solvent possible with volatiles, frequently with compounds by thermochemical reduction... 

The Records Conservation Section has five years of satisfactory experience treating a variety of unique works with Wei To solutions. A survey of conservators and scientists in other institutions verified the chemistry was sound and the results were aesthetically acceptable. The problems to be resolved were mechanical, involving equipment choice rather than the chemistry of the treatment (11). The hazards inherent to the system could be isolated and controlled at the treatment site. The solvent, approximately 90% dichlorodifluoromethane and 10% methanol by volume, has a maximum allowable concentration of 982 ppm in air (12), a level many times more than expected in workroom air. Incorporation of solvent recovery equipment not only reduces unit treatment cost but avoids a potential detrimental effect on the ozone layer in the upper atmosphere by dichlorodifluoromethane. 

Incorporation of solvent hydrogen into the substrate does not rule out its transfer as hydride if the source of hydride is dithiol, as in the ribonucleotide reductases. In the most understood enzyme of this type, from Lactobacillus leichmannii, the function of the dithiol (45) is to reduce the cobamide coenzyme (46) and provide a source... 

In the (ET) Re04 salts the conductivity varies (8, 57). The 2 1 salt, which becomes superconducting under pressure, has a sharp metal-insulator transition at 81 K whereas the 3 2 salt has a broader transition at a similar temperature. In the 2 1 salt (where j indicates incorporation of solvent molecule of THF per formula unit) there is no indication of a transition from the conductivity data. 

Since a vast majority of NMR experiments are performed in solution, incorporation of solvent within the computation is a reasonable expectation. One might anticipate inclusion of solvent using a continuum method as described in Section 1.4.2. In a consistent manner, the molecular geometry should be optimized with the solvent field, and the chemical shifts computed with this geometry and with the solvent field. As will be demonstrated below, optimization in the solvent field turns out to oftentimes be unnecessary and the gas-phase geometry will suffice. 

Skeletal rearrangements which either furnish isomeric ketones capable of further photoisomerization, or products formed on incorporation of solvent molecules. 

For some compounds, suitable crystals simply can not be obtained and all attempts are frustrated. The reasons are not well understood. In some cases, repeated attempts with varied conditions always produce multiple or twinned crystals. Trying a range of different solvents is the most obvious approach. It is not just that the crystal quality may vary with the solvent used incorporation of solvent in the crystal structure generates a different crystalline form (a solvate), which will probably have quite different crystal growth characteristics. In most cases the nature of the solvent is unimportant in the quest for a definitive crystal structure analysis. However, the study of different solvates (and different polymorphs) of the same compound can itself be of interest, with significant changes in molecular structure resulting from different intermolecular interactions. 

Andzelm, J., Kolmel, C., Klamt, A. Incorporation of solvent effects into density-functional calculations of molecular energies and geometries. J. Chem. Phys. 1995,103(21), 9312-20. 

Electron Transfer Processes - A single electron-transfer mechanism is involved in the cycloaddition of alkenes, such as 2-methylpropene, to 1,2-dicyanonaphthalene. Reaction of the alkene radical cation with the radical anion of the sensitiser results in the products shown in the Scheme 1. Incorporation of solvent to give (55) occurs as one of the main products in addition to what are essentially photo-NOCAS products (56). 

Burnett et al.63,64 observed an anomalous rate increase in the polymerization of methyl methacrylate in halobenzene. Although the experimental data did not indicate any solvent effect on the rate of decomposition of azobisisobutyronitrile, the efficiency of initiation varied with solvents. Since an enhanced rate of incorporation of initiator fragments and incorporation of solvent fragments into the polymer were not observed, a mechanism describing the increase in the initiator efficiency through the participation of an initiator-solvent-monomer complex was postulated [Eq. (2.4)]. Henrici-Olive et al.65) reported, however, that the rate of the azobisisobutyronitrile decomposition at 50 °C, measured spectroscopically, is higher in halo-benzene than in benzene. Burnett et al.66) found a similar enhanced rate effect of halobenzenes with other initiators, supporting his mechanism. 

Pseudopolymorphs are not strictly polymorphs because they differ from each other in the solid crystalline phase, such as through the incorporation of solvents (solvates) or water (hydrates). Pseudopolymorphsmay also be suitable for development and should be identified and evaluated during solid form screening activities. 

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