Hydrate anions

Quinazoline [253-82-7] M 130.2, m 48.0-48.5 , b 120-121 /17-18mm, pK, -4.51 (aq H2SO4, anhydrous dication), pK 2.01 (anhydrous monocation), pK3 4.3 (equilibrium with 3,4-hydrated species), PK4 12.1 (hydrated anion). Purified by passage through an activated alumina column in benzene or pet ether (b 40-60°). Distd under reduced pressure, sublimed under vacuum and crystd from pet ether. [Armarego 7 Chem 1170 1961.]... 

Unstable) anhydrous neutral molecule (Stable) anhydrous anion (Stable) hydrated neutral molecule (Unstable) hydrated anion... 

Figure 9. Adsorption of intermediate layer (metal-ion complex) in anodic metal dissolution. A (aq), hydrated anion M2+(M), metal adion MA+(ad), adsorbed metal-ion complex MA (aq), hydrated metal-ion complex.

The rate constant k t for the dehydrated adsorption of hydrated anions does not depend on the coverage, whereas the rate constant for... 

The second term dominates and is characterised by p = +1.30 (using a-meta constants), E = 10.8 kcal.mole , dS = —22.8 eu and k jko > 1-8. experiments show the major source of oxygen in the acid produced is the solvent, which suggests the hydrate anion is the reactive form, viz. 

Less uncertainty surrounds the structure of hydrated anions the hydrogen atoms are almost collinear with the oxygen atoms and the centres of the ions (Briant Burton, 1976). Monte-Carlo calculations have shown that F is surrounded by four hydrogen atoms each 0-17 nm away (Watts, dementi Fromm, 1974). 

In the present analyses [49], 34 ions are classified into five groups (1) hydrated cations, (2) nonhydrated cations, (3) hydrated anions, (4) nonhydrated anions, and (5) polyanions. Here, the term hydrated or nonhydrated means that the ion is associated with some water molecules in the O phase or not, respectively. 

Calculated using Eqs. (45), (49), (46), (50), and (51) for hydrated cations, nonhydrated cations, hydrated anions, nonhydrated anions, and polyanions, respectively. 

Let us now extend the long-period hydronium ice-like model for the IHP on Pt(lll) to explain the observations in electrolytes other than sulphate. In acid chloride, both the observations and the model carry-over directly from the case of sulphate. In fluoride, perchlorate, bicarbonate and hydroxide, in Which the anomalous features shift considerably in both potential and appearance (especially in the basic media) from sulphate, another model is needed. Both (bi)sulphate and chloride are large weakly hydrated anions, and in the double-layer model of Figures 4-5, they interact strongly with both the hydronium ions and the Pt surface. The contact adsorption... 

Chemisorption of anions at the electrode interface involves dehydration of hydrated anions followed by adsorption of dehydrated anions which, then, penetrate into the compact double layer to contact the interface directly, this result is called the contact adsorption or specific adsorption. The plane of the contact adsorption of dehydrated anions is occasionally called the inner Helmholtz plane... 

Hg/OH on which the standard electrochemical free enthalpy of anion adsorption is positive AGli > 0), only the ph3 ical adsorption of hydrated anions occurs at the OHP whereas, the chemisorption of anions takes place at the IHP on those electrodes whose standard electrochemical free enthalpy of anion adsorption is negative < 0). 

Fig. 5-96. Effects of concentration of hydrated anions on critical potential, t, beyond which transformation of interfacial lattice (5 x 20) (1 x 1) occurs on gold electrodes with...

Fig. 5-60. Interfacial hydroxyl groups and their dissociation on semiconductor electrodes (a) dissociation of hydroxjd group of the add-Qi>e, (b) dissociation of hydroxyl group of the base-lype. K", = hydrated cation A = hydrated anion. [Prom Tamura-Furuidii, 1991.]...

For hydration of an o -aminotetrahydropyranone, and the hydrate and hydrate anion of a,a,a-trifluoroacetophenone, see under Acetals and Aldols above, respectively. 

The overall change of enthalpy represents the enthalpy of formation of the hydrated anion, X (aq), and has a value as given in Table 2.2 for particular cases. The value consists of contributions from enthalpy of atomization of element M and its electron attachment energy, and the enthalpy of hydration of the gaseous ion. It also includes the enthalpy of ionization of the hydrogen atom, the enthalpy of atomization of dihydrogen and the enthalpy of hydration of the proton. The enthalpy of formation of the anion is estimated by the equation ... 

The value of K is fairly constant between e=8 and e=128, but it increases with still greater dilutions, possibly owing to an increase in the strength of the acid formation of more complex molecules. The conductivity measurements do not decide whether periodic acid is to be regarded as a binary electrolyte with anions 10/ or hydrated anions H2I05 or H4IO/. 

On the other hand, LDH structure consists of the stacking of brucite-like layers, Mg(OH)2, where some divalent cations are substituted by trivalent ones, giving rise to a positive residual charge. To neutralise such charges an appropriate number of hydrated anions is placed between the layers. The general formula that can represent LDHs is ... 

Scheme 1. The anhydrous neutral species (11), the hydrated neutral species (12), and the hydrated anion of 3,8-dimethyllumazine Ama, 394, 308, and 306 nm, respectively.

Neutralization of an alkaline solution of 3,8-dimethyllumazine produced the (unstable) hydrated form of the neutral species (12) with a UV maximum at 308 nm, quite close to that of the hydrated anion (306 nm). On standing at room temperature, this neutral form quickly became converted into the anhydrous starting material (11) which has... 

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