Hydration series

In systems such as the 2- and 6-hydroxypteridine series, rapid potentiometric or spectrophotometric pA determinations on neutral solutions usually give values near to the acidic pA of the hydrated series. (Exceptions include 2-hydroxy-4,6,7-trimethyl-, 6-hydroxy-7-methyl-, and 4,6-dihydroxy-pteridine, where the neutral solution contains comparable amounts of hydrated and anhydrous species. In such cases, rapid potentiometric titrations show two well-defined and separated curves, one for the hydrated, the other for the anhydrous, species.) Similarly, from solutions of the anion, an approximate pA value for the anhydrous species is obtained. For convenience, the anhydrous molecule is referred to as HX, its anion as X , the hydrated neutral molecule as HY, and its anion as Y, and the two equilibrium constants are defined as follows ... 

Johnson, A.H., Max, M.D., Dillon, W.P., Economic Geology of Natural Gas Hydrates, Series Coastal Systems and Continental Margins, 9, Springer (2006). 

Central atom Isomorphous hydrate series Cation M +2... 

In systems such as the 2- and 6-hydroxypteridine series, rapid potentiometric or spectrophotometric p determinations on neutral solutions usually give values near to the acidic pA of the hydrated series. (Exceptions include 2-hydroxy-4,6,7-trimethyl-, 6-hydroxy-... 

Detailed information on the proton hydrate series in the solid state is available, and the reader is referred to articles reviewing structural studies and vibrational spectroscopic studies of proton hydrates , but also general overviews the most recent being the comprehensive review of 1986. ... 

We observe a complete hydration series for the TE+ system (Ti + [HjO], where n = 1-4, unpublished data). These hydrated ions increase in relative abundance as the temperature is lowered, then disappear from the spectrum when the temperature of the drift gas is reduced below the freezing point of water, 273 K. 

Van Oss and Good [148] have compared solubilities and interfacial tensions for a series of alcohols and their corresponding hydrocarbons to determine the free energy of hydration of the hydroxyl group they find -14 kJ/mol per —OH group. 

Fig. 6. Free energies of hydration calculated, for a series of polar and non-polar solute molecules by extrapolating using (3) from a 1.6 ns trajectory of a softcore cavity in water plotted against values obtained using Thermodynamic Integration. The solid line indicates an ideal one-to-one correspondence. The broken line is a line of best fit through the calculated points.

The reaction corresponds to a proton transfer and not to a net formation of ions, and thus the AS is of minor importance in the whole series, especially for the two t-Bu derivatives. This last effect is believed to be due to a structure-promoting effect of the bulky alkyl groups in the disordered region outside the primary hydration sphere of the thiazolium ion (322). 

Group 13 (IIIA) Perchlorates. Perchlorate compounds of boron and aluminum are known. Boron perchlorates occur as double salts with alkah metal perchlorates, eg, cesium boron tetraperchlorate [33152-95-3] Cs(B(C104)4) (51). Aluminum perchlorate [14452-95-3] A1(C104)2, forms a series of hydrates having 3, 6, 9, or 15 moles of water per mole of compound. The anhydrous salt is prepared from the trihydrate by drying under reduced pressure at 145—155°C over P2O5 (32). 

Antimony trioxide is insoluble in organic solvents and only very slightly soluble in water. The compound does form a number of hydrates of indefinite composition which are related to the hypothetical antimonic(III) acid (antimonous acid). In acidic solution antimony trioxide dissolves to form a complex series of polyantimonic(III) acids freshly precipitated antimony trioxide dissolves in strongly basic solutions with the formation of the antimonate ion [29872-00-2] Sb(OH) , as well as more complex species. Addition of suitable metal ions to these solutions permits formation of salts. Other derivatives are made by heating antimony trioxide with appropriate metal oxides or carbonates. 

Barium is a member of the aLkaline-earth group of elements in Group 2 (IIA) of the period table. Calcium [7440-70-2], Ca, strontium [7440-24-6], Sr, and barium form a closely aUied series in which the chemical and physical properties of the elements and thek compounds vary systematically with increa sing size, the ionic and electropositive nature being greatest for barium (see Calcium AND CALCIUM ALLOYS Calcium compounds Strontium and STRONTIUM compounds). As size increases, hydration tendencies of the crystalline salts increase solubiUties of sulfates, nitrates, chlorides, etc, decrease (except duorides) solubiUties of haUdes in ethanol decrease thermal stabiUties of carbonates, nitrates, and peroxides increase and the rates of reaction of the metals with hydrogen increase. 

Borate salts or complexes of virtually every metal have been prepared. For most metals, a series of hydrated and anhydrous compounds maybe obtained by varying the starting materials and/or reaction conditions. Some have achieved commercial importance. 

Zinc Borates. A series of hydrated 2inc borates have been developed for use as fire-retardant additives in coatings and polymers (59,153). Worldwide consumption of these 2inc salts is several thousand metric tons per year. A substantial portion of this total is used in vinyl plastics where 2inc borates ate added alone or in combination with other fire retardants such as antimony oxide or alurnina trihydrate. 

Positionalisomeri tion occurs most often duting partial hydrogenation of unsaturated fatty acids it also occurs ia strongly basic or acidic solution and by catalysis with metal hydrides or organometaUic carbonyl complexes. Concentrated sulfuric or 70% perchloric acid treatment of oleic acid at 85°C produces y-stearolactone from a series of double-bond isomerizations, hydration, and dehydration steps (57). 

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