they spread out and become surrounded by solvent molecules. Distinction between solvation, dissolution and solubility By an IUPAC definition, ref GoldBookRef title solvation file S05747 ref solvation ... chemistry complexed by solvent molecules. The concept of the solvation interaction can also be applied to an insoluble material, for example, solvation of functional groups on a surface of ion exchange resin . Solvation is, in concept, distinct from Dissolution chemistry dissolution and solubility ... be mol kg. Liquefaction accompanied by an irreversible chemical change is also distinct from solvation ... a solvation shell or hydration shell in the case of water . Water is the most common and well studied ... such as salts. Solvation involves different types of intermolecular interactions hydrogen bonding ... only in ionic solvents. The solvation process will be thermodynamically favored only if the overall .... The Conductivity electrolytic conductivity of a solution depends on the solvation of its ions. Thermodynamic considerations For solvation to occur, energy is required to release individual ions .... Energy released in this form is called the free energy of solvation . The enthalpy of solution ... solvation, this does not stand up to scrutiny for ions like iron III or lanthanide s and actinide ..., not solvated. Enthalpy of solvation can help explain why solvation occurs with some ionic lattices ... that solvation will not occur. It is possible that an ion will dissolve even if it has a positive enthalpy ... will dissolve or not. A quantitative measure for solvation power of solvents is given by donor ... et al. eds. year 1985 88 title The Chemical Physics of Solvation edition 3 vols. publisher Elsevier ... simple Solvation sr sh Solvatacija sv Solvatisering uk zh ... more details
File Na H2O.svg thumb right The first solvation shell of a sodium ion dissolved in water A Solvation shell is a shell of any chemical species acting as a solvent , surrounding a Solution solute species. When the solvent is water it is often referred to as a hydration shell or hydration sphere. A classic example is water molecules solvating a metal ion. The electronegative oxygen atom contained in the water molecule attracts electrostatically to the positive charge on the metal ion. The result is a solvation shell of water molecules surrounding the ion. This shell can be several molecules thick, dependent on the charge of the ion. Hydration Shells of Proteins The hydration shell also sometimes called hydration layer that forms around proteins is of particular importance in biochemistry. This interaction of the protein surface with the surrounding water is often referred to as protein hydration and is fundamental to the activity of the protein. ref name Mapping hydration dynamics cite doi 10.1073 pnas.0707647104 ref The hydration layer around a protein has been found to have dynamics distinct from the bulk water to a distance of 1 nm with effects on the surrounding water network extending beyond 2 nm. ref cite doi 10.1073 pnas.0709207104 ref The duration of contact of a specific water molecule with the protein surface may be in the subnanosecond range while molecular dynamics simulations suggest the time water spends in the hydration shell before mixing with the outside bulk water could be in the femtosecond to picosecond range. ref name Mapping hydration dynamics With other solvents and solutes, varying steric and kinetic factors can also affect the solvation shell. See also Water model Poisson Boltzmann equation References references External links http www1.lsbu.ac.uk water protein.html London South Bank University pages on protein hydration Chemical solutions DEFAULTSORT Solvation Shell Category Solutions physical chemistry stub fr Couche de solvatation it Sfera ... more details
Implicit solvation sometimes known as continuum solvation is a method of representing solvent as a continuous ... of drugs across biological membrane s. The implicit solvation model is justified in liquids, where ... as media with specific solvation or dielectric properties. These media are continuous but not necessarily ... 0084 6589 ref This method operates directly with free energy of solvation , unlike molecular mechanics ... surface area based method Main Accessible surface area The free energy of solvation of a solution ... ASA i math where math ASA i math is accessible surface area of atom i , and math sigma i math is solvation parameter of atom i , i.e. a contribution to the free energy of solvation of the particular atom i per surface unit area. The required solvation parameters for different types of atoms carbon ... 3525 format Free full text ref It is noteworthy that solvation energy is free energy required to transfer a solute molecule from a solvent to vacuum gas phase . This solvation energy can supplement ... solvation parameters were initially derived from water gas partition data. ref name pmid3472198 ... author Eisenberg D, McLachlan AD title Solvation energy in protein folding and binding journal Nature ... two condensed media or the difference of two solvation energies. Poisson Boltzmann Main Poisson Boltzmann ... 1990 title Semianalytical treatment of solvation for molecular mechanics and dynamics journal J Am ... issn 0006 3495 bibcode 2003BpJ....85.2900I ref Ad hoc fast solvation models Another possibility is to use ad hoc quick strategies to estimate solvation free energy. A first generation of fast implicit ... of atom types, a different parameter scales its contribution to solvation ASA based model described above . ref name pmid1304905 cite journal author Wesson L, Eisenberg D title Atomic solvation ... on a Gaussian shaped solvent exclusion. The solvation free energy is math Delta G i solv Delta G i ref sum j int Vj f i r dr math The reference solvation free energy of i corresponds to a suitably ... more details
Image Pentaacrylat.png thumb COSMO surface of a pentaacrylate molecule red negative, green positive equilibrium layer . COSMO is the abbreviation for CO nductor like S creening MO del , a calculation method for determining the electrostatic interaction of a molecule with a solvent . In COSMO the solvent is treated as a continuum with a permittivity &epsilon , and therefore belongs to the continuum solvation group of models. As in all these models COSMO approximates the solvent by a dielectric continuum, surrounding the solute molecules outside of a molecular cavity. The details of the cavity construction differ in different COSMO implementations. In most cases it is constructed as an assembly of atom centered spheres with radii approximately 20 larger than the Van der Waals radius . For the actual calculation the cavity surface is approximated by segments, e.g., hexagons, pentagons, or triangles. In difference to other continuum solvation models, COSMO derives the polarization charges of the continuum, caused by the polarity of the solute, from a scaled conductor approximation. If the solvent were an ideal conductor the electric potential on the cavity surface must disappear. If the distribution of the electric charge in the molecule is known, e.g. from quantum chemistry, then it is possible to calculate the charge q on the surface segments. For solvents with finite dielectric constant this charge q is lower by approximately a factor &fnof &epsilon math q f varepsilon q . math The factor &fnof &epsilon is approximately math f varepsilon frac varepsilon 1 varepsilon x , math where the value of x is set to 0.5 based on theoretical arguments. Some re implementations of COSMO use x 0. From the thus determined solvent charges q and the known charge distribution of the molecule, the energy of the interaction between the solvent and the solute molecule can be calculated. The COSMO method can be used for all methods in theoretical chemistry where the charge dist ... more details
The polarizable continuum model PCM is a commonly used method in computational chemistry to model solvation effects. If it were necessary to consider each solvent molecule as a separate molecule, the computational cost of modeling a solvent mediated chemical reaction would grow prohibitively high. Modeling the solvent as a polarizable continuum, and not as individual molecules, makes ab initio computation feasible. Two types of PCMs have been popularly used dielectric PCM D PCM which deals the continuum as a polarizable dielectrics and conductor like PCM C PCM which deals the continuum as a conductor like picture similar to COSMO Solvation Model . ref name Tomasi2005 Jacopo Tomasi, Benedetta Mennucci, and Roberto Cammi 2005 . Quantum Mechanical Continuum Solvation Models. Chem. Rev. 105 8 2999 3094. http dx.doi.org 10.1021 cr9904009 ref ref Maurizio Cossi, Nadia Rega, Giovanni Scalmani, Vincenzo Barone 2003 . Energies, structures, and electronic properties of molecules in solution with the C PCM solvation model. J. Comput. Chem. 24 6 669 681. http dx.doi.org 10.1002 jcc.10189 ref The molecular Gibbs free energy free energy of solvation is computed as the sum of three terms G sub sol sub G sub es sub G sub dr sub G sub cav sub G sub es sub electrostatic G sub dr sub dispersion repulsion G sub cav sub cavitation ref name uni cite web url http www.cup.uni muenchen.de oc zipse the polarizable continuum model pcm.html author Hendrik Zipse title The Polarizable Continuum Model PCM date 09.02.2004 accessdate January 25, 2009 ref Charge transfer effect is also considered as a part of solvation in cases. ref name Tomasi2005 The PCM solvation model is available for calculating energies ... version of the PCM ref. 4 in the 2002 paper . PCM is also used to model outer solvation layers in multi layered solvation approach. ref Mark S. Gordon CLUSTER BASED APPROACHES TO SOLVATION Iowa State University, Ames Laboratory. http www.msg.ameslab.gov tutorials solvation.pdf ref See also COSMO Solvation ... more details
wiktionarypar solvent solvency Solvent may refer to Solvent , a liquid that dissolves another material Solvent producer , the stage name of electronic musician Jason Amm Solvency , a company s capability to meet its financial obligations See also Solvation Solvent cabinet Solvent exposure Solvent extraction Disambig de Solvent th Solvent ... more details
Unreferenced date December 2007 A quantum solvent is essentially a superfluid aka a Quantum hydrodynamics quantum liquid used to solvation dissolve another chemical species . Any superfluid can theoretically act as a quantum solvent, however in practice the only viable superfluid medium that can currently be used is Helium Isotopes helium 4 , and it has been successfully accomplished in controlled conditions. Such solvents are currently under investigation for use in spectroscopy spectroscopic techniques in the field of analytical chemistry , due to their superior kinetic properties. Any matter dissolved or otherwise suspended in the superfluid will tend to aggregate together in clumps, encapsulated by a quantum solvation shell . Due to the totally frictionless nature of the superfluid medium, the entire object then proceeds to act very much like a nanoscopic ball bearing, allowing effectively complete rotational freedom of the solvated chemical species . A quantum solvation shell consists of a region of non superfluid helium 4 atoms that surround the molecule s and exhibit adiabatic following around the centre of gravity of the solute. As such, the kinetics of an effectively gaseous molecule can be studied without the need to use an actual gas which can be impractical or impossible . It is necessary to make a small alteration to the Rotational spectroscopy Classification of molecules based on rotational behavior rotational constant of the chemical species being examined, in order to compensate for the higher mass entailed by the quantum solvation shell. Quantum solvation has so far been achieved with a number of organic, inorganic and organometallic compounds, and it has been speculated that as well as the obvious use in the field of spectroscopy , quantum solvents could be used as tools in nanoscale chemical engineering, perhaps to manufacture components for use in nanotechnology . References reflist Category Condensed matter physics Category Nanotechnology Catego ... more details
wiktionary hydration Hydration may refer to Hydration reaction , a chemical addition reaction where a hydroxyl group and proton are added to a compound Mineral hydration , an inorganic chemical reaction where water is added to the crystal structure of a mineral Solvation , the clustering of solvent water molecules around a solute particle Tissue hydration , the supply and retention of adequate water in biological tissues See also Dehydration disambig es Hidrataci n ko ... more details
Unreferenced stub auto yes date December 2009 Pregnant Leach Solution PLS is acid ic metal laden water generated from stockpile leaching and heap leaching . Pregnant Leach Solution is used in the SX EW process. The portion of an original liquid that remains after other components have been solvation dissolved by a solvent is called raffinate . DEFAULTSORT Pregnant Leach Solution Category Metallurgical processes Industry stub ... more details
Binary acids are certain molecular compounds in which hydrogen is combined with a second nonmetal lic chemical element element . Citation needed date September 2009 Examples HF HCl HBr HI Their strengths depend on the solvation of the initial acid, the H X bond energy , the electron affinity energy of X, and the solvation energy of X. Citation needed date September 2009 Observed trends in acidity correlate with bond energies, the weaker the H X bond, the stronger the acid. For example, there is a weak bond between hydrogen and iodine in hydroiodic acid , making it a very strong acid . Citation needed date September 2009 Binary Acids are one of two classes of acids, the second being the oxoacid s, which consist of a hydrogen, oxygen, and some other element. Citation needed date September 2009 The names of binary acids begin with hydro followed by the name of the other element modified to end with ic . Citation needed date September 2009 Some texts contrast two types of acids. 1. binary acids or hydracids and 2. oxoacids that contain oxygen. Citation needed date September 2009 References Hill Petrucci McCreary Perry. General Chemistry, Fourth Edition. New Jersey, Pearson Prentice Hall. 2005 See also Acid Oxoacid Category Acids inorganic compound stub ... more details
Unreferenced date December 2009 The conductivity factor CF of solvation dissolved salt s in a given solution is a measurement of Conductivity electrolytic conductivity . Using the electrical conductivity between two electrode s in a water solution, the level of Total dissolved solids dissolved solids in that solution can be measured. Measurements can then be used to dosing dose the solution with the necessary nutrients in the case of hydroponics . Conductivity measurements are also used in ecology and environmental sciences to assess the level of nutrients in lakes and rivers. For a discussion of conductivity in this context, see Total dissolved solids . See also EC meter TDS meter DEFAULTSORT Conductivity Factor Category Measurement Category Electricity ... more details
Image Abalone molecular modelling 300.png thumb DNA model on Abalone Abalone is a general purpose molecular dynamics and molecular graphics program for simulations of bio molecules in a periodic boundary conditions in explicit water Flexible SPC water model Flexible SPC ref cite journal title Molecular dynamics study of atomic motions in water author Toukan K and Rahman A journal Physical Review B volume 31 year 1985 pages 2643 2648 doi 10.1103 PhysRevB.31.2643 bibcode 1985PhRvB..31.2643T issue 5 ref or in Implicit solvation implicit water models. ref cite journal author Still WC, Tempczyk A, Hawley RC, Hendrickson T journal J Am Chem Soc volume 112 year 1990 pages 6127 6129 doi 10.1021 ja00172a038 title Semianalytical treatment of solvation for molecular mechanics and dynamics issue 16 ref Mainly designed to simulate the protein folding proteins folding and DNA ligand Complex chemistry complexes in AMBER Force field chemistry force field . The key features 3D molecular graphics Building and editing chemical structures Library of building blocks Force field chemistry Force Fields AMBER 94, 96, 99SB, 03 OPLS Geometry optimization Molecular dynamics with multiple time step integrator Hybrid Monte Carlo Replica exchange ref cite journal doi 10.1016 S0009 2614 99 01123 9 author Y. Sugita and Y. Okamoto year 1999 title Replica exchange molecular dynamics method for protein folding journal Chemical Physics Letters volume 314 pages 141 151 bibcode 1999CPL...314..141S ref Molecular modeling on GPU GPU accelerated molecular dynamics See also columns list 3 Molecular modelling Molecular design software MDynaMix TINKER NAMD GROMACS References references External links http www.biomolecular modeling.com Abalone index.html Home page DEFAULTSORT Abalone Molecular Mechanics Category Molecular modelling software Category Molecular dynamics software Category Monte Carlo software ... more details
Dissolution or dissolve may refer to Dissolution law , in law, means to end a legal entity or agreement such as a marriage, adoption, or corporation Dissolution chemistry , or solvation , in chemistry, the process of dissolving a solid substance into a solvent to make a solution Dissolution of parliament , in politics, the dismissal of a legislature so that fresh elections can be held, sometimes ahead of schedule Dissolution of the Parliament of the United Kingdom Dissolution of the Monasteries , in British history, the formal process during the English Reformation by which Henry VIII confiscated the property of the monastic institutions in England, Wales and Ireland between 1538 and 1541 Dissolution of the Monasteries, England and Wales List of monasteries dissolved by Henry VIII of England Dissolution of the Lesser Monasteries Act 1535 Tudor conquest of Ireland Dissolution novel Dissolution novel , a 2002 fantasy novel by Richard Lee Byers Dissolution Sansom novel , a 2003 historical novel by C. J. Sansom Dissolve filmmaking , in film and video editing , a transition between scenes Decadence , moral degeneracy disambig fr Dissolution it Dissolution simple Dissolve ... more details
Ion Vibration Current Potential IVI is an electric signal that arises when an acoustic wave propagates through a Homogeneous chemistry homogeneous fluid. Historically, the IVI is the first known electroacoustic phenomena . It was predicted by Debye in 1933. ref Debye.P. A method for the determination of the mass of electrolyte ions J. Chem. Phys., 1,13 16,1933 ref He pointed out that the difference in the effective mass or friction coefficient between anion and cation would result in different displacement amplitudes in a longitudinal wave . This difference creates an alternating electric potential between various points in sound wave. This effect was extensively used in 1950 s and 1960 s for characterizing ion solvation. These works are mostly associated with names of Zana and Yaeger, who published a review of their studies in 1982. ref Zana.R. and Yeager. E. Ultrasonic Vibration Potentials Mod.Aspects of Electrochemsitry, 14, 3 60, 1982 ref References references Category Interface and Colloid Science Category Chemical mixtures Category Colloidal chemistry Category Condensed matter physics Category Matter Category Soft matter ... more details
cleanup date May 2011 The aniline point of an oil is defined as the temperature at which equal volumes of aniline chem C 6 H 5 NH 2 and the desired oil are completely miscible . The value gives an indication of the aromatic content of the oil, since aniline is an aromaticity aromatic compound which is solvation dissolve d on heat ing by the aromatics in the oil. The greater the aniline point, the lower the aromatics in the oil. A higher aniline point also indicates a higher proportion of paraffin . It is an indication of the possible deterioration of the oil in contact with rubber seals since aromatic hydrocarbons present in oil have a tendency to dissolve natural rubber and some synthetic rubber. Determination of aniline point Equal volumes of aniline and oil are stirred continuously in a test tube and heated until the two merge into a homogeneous solution. Heating is stopped and the tube is allowed to cool. The temperature at which the two phases separate out is recorded as aniline point. References Gupta, O.P. Fuels, Furnaces, Refractories. chem stub Category Chemical properties pl Punkt anilinowy ... more details
a rigid matrix of counterions attached to the protein surface. The adjacent solvation layer, which ... can have a similar effect. Water forms a solvation layer around hydrophilic surface residues of a protein ... proteins. gallery Image IonicSolvationLayerNew.jpg Ionic Solvation Layer Image HydrationLayerNew.jpg ... electrostatic interactions with acidic residues on another protein. However, solvation by ions in an electrolytic ... of a neutral salt, such as ammonium sulfate , compresses the solvation layer and increases protein ... becomes associated with the ions. As a result, less water is available to partake in the solvation ... change upon precipitation, T Absolute temperature. When water molecules in the rigid solvation ... which promote the dissipation of water from the solvation layer around a protein. Hydrophobic patches ..., have the opposite effect of Kosmotropes. These salts promote an increase in the solvation layer ... in the solution to precipitate. The solvation layer around the protein will decrease as the organic ... isoelectric precipitation. These polymers in solution attract water molecules away from the solvation ... more details
confusing date May 2009 expert subject multiple Chemistry Computing date May 2009 MacroModel is a computer program for molecular modelling of organic compound s and biopolymer s. It features various force field chemistry force field s coupled with energy minimization algorithms for the prediction of molecular geometry geometry and relative conformational isomerism conformational energies of molecules. ref name Mohamadi 1990 cite journal author Mohamadi F, Richard NGJ, Guida WC, Liskamp R, Lipton M, Caufield C, Chang G, Hendrickson T, Still WC title MacroModel an Integrated Software System for Modeling Organic and Bioorganic Molecules Using Molecular Mechanics journal J. Comput. Chem. year 1990 month May volume 11 issue 4 pages 440 467 doi 10.1002 jcc.540110405 ref MacroModel is maintained by Schr dinger company Schr dinger, Inc. It carries out simulations in the framework of classical mechanics the so called molecular mechanics . MacroModel also has the ability to perform molecular dynamics simulations to model systems at finite temperatures using stochastic dynamics and mixed Monte Carlo method Monte Carlo algorithms. MacroModel supports Microsoft Windows Windows , Linux , Silicon Graphics SGI IRIX and IBM AIX . Key features columns list 2 Implicit solvation GB SA continuum solvation model ref name Still 1990 cite journal author Still WC, Tempczyk A, Hawley RC, Hendrickson T year 1990 title Semianalytical treatment of solvation for molecular mechanics and dynamics journal J Am Chem Soc volume 112 issue 16 pages 6127 6129 doi 10.1021 ja00172a038 ref ref name pmid18422307 cite journal author Guimar es CR, Cardozo M title MM GB SA rescoring of docking poses in structure based lead optimization journal J Chem Inf Model volume 48 issue 5 pages 958 70 year 2008 month May pmid 18422307 doi 10.1021 ci800004w url issn ref Force field chemistry MM2 , Force field chemistry MM3 , AMBER , Merck Molecular Force Field MMFF , OPLS Force field chemistry Force Fields Molecular Dynam ... more details
O sub n sub sup z sup . The solvation number, n , determined by a variety of experimental methods is 4 ... and actinide aqua ions have solvation number of 8 and 9. The strength of the bonds between the metal ion and water molecules in the primary solvation shell increases with the electrical charge, z .... The aqua ion is associated, through hydrogen bond ing with other water molecules in a secondary solvation shell. Water molecules in the first hydration shell exchange with molecules in the second solvation ... File Secondary solvation.svg thumb First and second solvation shells of an octahedral aqua ion. Up ..., or primary, solvation shell. The bond between a water molecule and the metal ion is a dative ... ions the high charge on the cation polarizes the water molecules in the first solvation shell to such an extent ... Water molecules in the first and second solvation shells can exchange places. The rate of exchange ... in solution by solvated anions, but much less is known about anion solvation than about cation solvation. ref Burgess, chapter 11. ref Understanding of the nature of aqua ions is helped by having ... give separate peaks for molecules in the first solvation shell and for other water molecules. The solvation ... in the first solvation shell. Molecules in the second solvation shell exchange rapidly with solvent ... style text align center Solvation numbers determined by NMR ref Burgess, p. 53. ref ion number nucleus ... charge some information is obtained about the second solvation shell. ref cite book last1 Sykes first1 ... scattering has been used to characterize the second solvation shell with trivalent ions such as Cr sup ... Cl isotopes to yield a very detailed picture of cation and anion solvation. ref name nickelchloride ... for some of the variation of solvation number with concentration even if there is no contact ion ... solvation shells. The measured solvation number is a time averaged value for the solution as a whole. When a measured primary solvation number is fractional there are two or more species ... more details
, the ions retain most of their solvation shell. The nature of this solvation shell is generally not known ... by between four and nine solvent molecules in the primary solvation shell , ref name Burgess cite ... Chapter 5, Solvation numbers . ref but the nature of solvation of anions is mostly unknown. An alternative ..., as does the energy of displacing a solvent molecule from the solvation shell of the cation .... The entropy term is similar for electrolytes of the same type, with minor differences due to solvation ... &minus sup have six water molecules in the primary solvation shell at ambient temperatures a 5 M ... in aqueous solution primary solvation sphere of the cation. This energy decreases with the size of the cation ... more details
of the transition state theory . In essence, the reaction rates are influenced by differential solvation ... state then the reaction proceeds slower. However, such differential solvation requires rapid reorientational ... state theory breaks down. In such cases involving strongly dipolar, slowly relaxing solvents, solvation ..., J. Chem. Soc., 244 255 1935 . ref Using a simple solvation model that considered only pure electrostatic ... that could be made about the extent of solvation to be expected in these situations increasing magnitude of charge will increase solvation increasing delocalization will decrease solvation loss of charge will decrease solvation more than the dispersal of charge ref name reichardt The applicable ... different, as the lack of solvation on the nucleophile increases the rate of an S sub N sub 2 reaction ... transition metal complexes cationic or anionic are dramatically influenced by solvation, especially ... more details
File Voltametro a rame.png thumb 200px Copper coulometer The copper coulometer is a one of the common application of the copper copper II sulfate electrode . Such a coulometry coulometer consists of two identical copper electrodes immersed in slightly acidic buffer solution pH buffered solution of copper II sulfate . Passing of current electricity current through the element leads to the anodic solvation dissolution of the metal on anode and simultaneous Deposition chemistry deposition of copper ions on the cathode . These reactions have 100 efficiency over a wide range of the current densities. Calculation Amount of the quantity of electricity passed through the cell can be easily calculated by mass changes of any of the electrodes math Q frac Delta m 2 F 63.546 math , where Q is the quantity of electricity coulombs math Delta m math is the mass transported gm 63.546 is the atomic weight of copper the factor 2 is due to the transport of divalent ions F is the Faraday constant 96485.3383 Although from a theoretical and historical point of view this apparatus is interesting, present day electronic measurement of time and electrical current provide in their multiplication the amount of passed coulomb s much easier, with greater precission, and in a shorter period of time than is possible by weighing the electrodes. See also Mercury coulometer Coulometry References references unreferenced date October 2008 Category Physical chemistry Category Electroanalytical chemistry devices Category Copper Coulometer Category Coulometers physical chemistry stub de Kupfercoulometer nl Kopercoulometer ... more details
or hydrophobic molecular groups, but the water molecules that form the cage or solvation shell have restricted mobilities. In the solvation shell of small nonpolar particles, the restriction amounts ... the reorientational and translational motion of the water molecules in the solvation shell may ... temperature because of the reduced mobility of water molecules in solvation shell of the non polar ... of water water hydrogen bonds in the solvation shell, apparently due to the reduced mobility ... more details
in the cage or solvation shell is strongly restricted. This leads to significant losses in translational ... ref A . Ben Naim, Biopolymers 29 1990 567. ref In addition, the role of self solvation makes using .... Biol. 105 1976 1. ref Accessible surface area methods main Implicit solvation Hydrophobicity scales ... by the Implicit solvation Accessible surface area based method empirical solvation parameters for the corresponding ... the solvation free energy. ref D . Eisenberg, A.D. McLachlan, Nature 319 1986 199 ref The solvation ... solvation parameter. Results indicate the solvation free energy lowers by an average of 1 Kcal ... more details
In chemistry the intimate ion pair concept introduced by Saul Winstein describes the interactions between a cation , anion and surrounding solvent molecules . ref cite journal last Winstein first S. coauthors Clippinger, E. Fainberg, A. H. Heck, R. RobinsonG. C. year 1956 title Salt Effects and Ion Pairs in Solvolysis and Related Reactions. III.1 Common Ion Rate Depression and Exchange of Anions during Acetolysis volume 78 issue 2 pages 328 335 issn DOI 10.1021 ja01583a022 doi 10.1021 ja01583a022 journal Journal of the American Chemical Society ref In ordinary aqueous solutions of inorganic salts an ion is completely solvated and shielded from the counterion. In less Chemical polarity polar solvents two ions can still be connected to some extent. In a tight or intimate or contact ion pair there are no solvent molecules between the two ions. When solvation increases, ionic bonding decreases and a loose or solvent shared ion pair results. The ion pair concept explains stereochemistry in solvolysis . The concept of intimate ion pairs is used to explain the slight tendency for inversion of stereochemistry during an SN1 reaction . It is proposed that solvent or other ions in solution may assist in the removal of a leaving group to form a carbocation which reacts in an SN1 fashion similarly, the leaving group may associate loosely with the cationic intermediate. The association of solvent or an ion with the leaving group effectively blocks one side of the incipient carbocation, while allowing the backside to be attacked by a nucleophile. This leads to a slight excess of the product with inverted stereochemistry, whereas a purely SN1 reaction should lead to a racemic product. See also Ion association References reflist Category Chemical bonding ... more details
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