Hydrates hydration

M (s) M+ M+ Ionic radius Hydration hydration Hydrated mobilities... 

Hybridisierungsinkubator hybridization oven Hybridisierungsofen hydrate Hydrat hydration (solvation) Hydratation, Hydratisierung, Solvation (Wassereinlagerung, W asseranlagerung) hydration shell Hydrathtllle,... 

The cation of 4,4 -biquinazolinyl and its 2,2 -dimethyl derivative readily add water across the 3,4- and 3, 4 -double bonds, but the cation of 2,2 -biquinazolinyl is not hydrated. Hydration in the 4,4 -isomers has been attributed to restricted rotation about the 4,4 -bond, a steric effect which is relieved by hydration. The ultraviolet spectrum of 2,2 -biquinazolinyl (neutral species and cation) shows that there is considerable conjugation between the quinazoline groups. Covalent hydration is absent from the latter compound because it would otherwise destroy the extended conjugation present. 

The rate-acidity profile for pyrimidin-2-one indicated reaction on the free base but since the derived second-order rate coefficient is 104 times greater than that for 2-pyridone, and the acidity dependence in the H0 region was also greater, the slope of log kt versus —H0 plot being 0.45, cf. 0.15 for 2-pyridone reaction was, therefore, postulated as occurring via a covalent hydrate, hydration taking place at the 4 position. Methyl substitution increased the rate as expected and N-methyl substitution produced a larger effect than 4,6-dimethyl substitution and this may be due to alteration of the amount of covalent hydration at equilibrium. The data... 

The same applies to the historic gas-hydrates (hydrate clathrates, Fig. 5)17,18). However, on principle, only such molecules are suited for inclusion into the complicated H-bridge networks of gas-hydrates which do not interfere with the H-bridges of water, but have a hydrophobic nature. More recent hosts related to this inclusion principle are given in Chapter 3 of this book. 

KEYWORDS CH4 hydrate hydrate kinetics, hydrate stability, C02 sequestration numerical simulation... 

Properties and extraction processes At high pressures and low temperatures, water and gas form an ice-like mixture, called gas hydrate, also known as clathrate or simply hydrate. Hydrates are a crystalline, solid substance composed largely of water... 

Predicting the outcome of electrophilic additions to alkynes from an extension of alkene reactivity usually works well, and can be applied to halogenations and hydrations. Hydration of an alkyne has a subtle twist, however the product is a ketone This can still be rationalized quite readily, though. 

Synonyms bismuth hydrate hydrated bismuth oxide. 

Synonyms cupric hydroxide copper hydrate hydrated copper oxide... 

The work in Table 1.2 illustrates one of the early research difficulties that is still present—namely, the direct measurement of the water to gas ratio in hydrates (hydration number, n = water molecules per guest). Whereas many solids... 

Micromechanical force measurement apparatus (Taylor, 2006 Taylor et al., 2007) Particle adhesive forces Yes Adhesive forces vs. time (min) 15 psi >5 pm Adhesive forces between hydrate—hydrate particles, hydrate particle-surface... 

Hydrate Hydrate denuding of CH4 and C3H8 from condensates or crudes Reference Verma et al. (1974)... 

Both catalyst activity and tar formation are directly affected by the state of hydration of the phosphoric acid-kieselguhr type of catalyst. At the higher temperature it is more difficult to maintain proper hydration. Hydration control is required because the catalyst has an optimum water content which determines the activity and selectivity of the catalyst. The water-vapor pressure varies at different catalyst temperatures and it is important to keep the water content of the hydrocarbon in equilibrium with that of the catalyst. In those units where water of saturation in the feed is insufficient, additional water must be injected into the feed as catalyst requirements dictate. The solid phosphoric acid type of catalyst contains the proper amount of water when manufactured and the art of catalyst hydration has reached such a point that catalyst in properly operated polymerization units no longer fails from coke formation or loss of activity. 

Comparative Studies of the Changes in Dynamic Friction Coefficient (/n) with Increasing Hydration (Hydration) and Decreasing Hydration (Dryness)... 

For example, many ionic compounds crystallize from a water solution with water molecules incorporated into their crystal structure, forming a hydrate. Hydrates have a specific number of water molecules chemically bonded to each formula unit. A chemist may know the formula of the ionic part of the hydrate but not how many water molecules are present for each formula unit. 

Copper(II) sulfate pentahydrate is a hydrate. Hydrates are ionic compounds that have a specific amount of water molecules associated with each ion pair. 

FIGURE 6 Various possibilities that arise from dehydration of hydrate. A hydrate can dehydrate reversibly into various solid-state forms. It can dehydrate to form an anhydrous form of the drug or to a lower hydrate. Hydrate can also dehydrate to form an isomorphic desolvate where the crystal lattice is retained except for the absence of water. The crystal structure may also collapse on dehydration to form an amorphous form. Hydrates on dehydration can also result in different polymorphs. 

Another consequence of the presence of water in natural gas and acid gas is the formation of solid compounds called hydrates. Hydrates are important because they form at conditions where a solid phase would not otherwise be expected. In addition, hydrates are notorious for plugging production and processing facilities. In this chapter, we will examine hydrates as they relate to acid gas injection. 

The mass rado h is commonly used in describing protein hydration. Hydration, however, should depend more closely on protein surface than on volume or mass. Most of the data described in this review are for small globular proteins, for which weight and surface-based measures should be similar. Comparisons of proteins of much different size may need to take into account surface area, compactness, and domain size. 

Fig. 18. Temperature and hydration dependence of NMR relaxation. Variation with temperature of the proton spin-lattice relaxation time, T, at 60 MHz of polycrystalline lysozyme with various degrees of hydration. —, hydration with HjO 0—0, hydration with D2O. From Andrew (1985).

In completion it may be remarked that we have arrived in two different ways at the conclusion that the lowering of the melting point of hydrated calcium chloride by addition of water or calcium chloride is less than normal. Both arguments proceed essentially from the same fundamental assumption the first from the partial dissociation of the hydrate for equilibrium in the fused state the second on the existence of a pressure of water vapour for the fused hydrate, which is intimately bound up with the partial dissociation of the hydrate. Hydrates, therefore, that when melted have no vapour pressure of water must give the normal lowering of melting point on addition of cither component that is very approximately the case for bodies like sulphuric acid, and completely so for the carbohydrates. 

Fig. 16 Real time monitoring of the phase changes during the freeze-drying of sodium nafcillin by in situ XRD. The disappearance of sodium nafcillin hydrate ( Hydrate ) and the appearance of sodium nafcillin hemihydrate ( Hemi-hydrate ) were simultaneously quantified. The curves were drawn to assist in visualizing the trends. (From Ref. . )...

The digestion and absorption of organic and inorganic nutrients, as well as all other biochemical processes in living organisms, are influenced by the unique properties of water. Water is an interactive liquid or solvent. Its chemical interactions with solutes are called hydration. Hydration involves weak associations of water molecules with other molecules or ions, such as Na+, Cl , starch, or protein. Because hydration bonding is weak and transitory, the number of water molecules associated with an ion or molecule at any particular moment is approximate and difficult to measure. However, typical indicated hydration numbers are Na", 1-2 K+, 2 Mg2+, 4-10 4r-8 Zn2+, 4-10 Fe, 10 Q- 1 and F-, 4 (Conway, 1981). 

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