Common anions

Hydroxy-7-methylpteridine (neutral species) is hydrated in the 7,8-position, but it is transformed by hot, dilute acid into what appears to be an isomer in which water occupies the 3,4-position the water is liberated by alkali from the latter isomer at a measurable rate to give the anhydrous anion common to both species. ... 

There is only one simple anion commonly found in soil, and that is chloride (Cl ). Chloride is an essential nutrient for plants but is typically present in sufficiently high concentrations that deficiencies are never observed. If other halogens are present, they will also be present as simple anions. Most soils do contain small amounts of bromide as the second most common simple anion. In some cases, significant levels of fluoride and iodide may be present, although this is rare. These anions are generally soluble in water and tend to exist as the simple anion. However, they can combine with other components and exist as other species. For instance, halogens are present in organic compounds such as solvents, insecticides, and herbicides, which can be soil contaminants. There are also other nonionic species of these elements that may be present [20],... 

The most frequently encountered representative of the KSOsO" close of leaving groups is probably the toluene-p-eulfonote anion (commonly abbreviated to toeylate ), but others are occasionally employed aa well. The latter include the methylaulfonatc ( mesylate ) end the p-bromobenzenesulfbaate ( brosylate ) ankme. 

The affinity of a strong-base resin for various anions commonly present in uranium process solutions can be ranked as follows U07(S04)34- > U02(S04)22- > NO, > Cl- > HS04 > Fe(S04)2- > SO4-. 

Radical anions generated from ketones (or aldehydes) are referred to as ketyl anions. Common methods for generation of >C=0 are summarized in Figure 1. 

Oxy)(hydr)oxide compounds Nonsilicate, crystalline, or amorphous solids that contain oxide (O2-), hydroxide (OH-), or oxyhydroxide (OOH3-) as the major anion. Common cations include aluminum, iron(II), iron(III), or manganese. 

Figure 3.10 Cations and anions commonly found in low-melting ionic liquids...

The early transition metals (V, Nb, Ta, Mo, W) in their highest oxidation states are able to form metal-oxygen clnster anions, commonly referred to as polyoxoanions or polyoxometalatesd In the gigantic family, the Keggin... 

In contrast to the above systems, lanthanide metal vapor reactions with unsaturated substrates not readily convertible to stable organic anions common as ligands generate some of the most unusual organolanthanide... 

Figure 6.1 Some of the cations and anions commonly used to prepare room temperature ionic liquids (RTILs).

Polyhedral hydroborate anions (commonly referred to as polyhedral borane anions in the current literature) of generic formula have assumed an unusual status in inorganic chemistry within recent years, not only because of their high thermal and hydrolytic stability, but also because of the wide range of geometries which the boron atom skeletons in compounds of the series (n = 6-12) can adoptd Convenient syntheses... 

Common Strong Acids and Their Anions Common Strong Acids Anions of These Strong Acids... 

Esters are named as "organic salts" that is, the alkyl name comes first, followed by the name of the carboxylate anion, (common abbreviation — COOR)... 

Eluent strength. Anion eluents vary considerably in their ability to elute sample anions. Several anions commonly used for IC with suppressed conductivity detection are listed in Table 6.5. An anion of higher charge, such as carbonate, has greater eluting strength than an eluent containing a monovalent anion. 

Fig. 1 Examples of cations and anions commonly used for the formation of NAILs and relative anion coordination ability towards transition metal complexes.

After they are generated by dissolution reactions such as those outlined previously, both Fe " and Mn " can reprecipitate as oxides upon exposure to O2 or, under anoxic conditions, form insoluble phases with anions commonly produced during anaerobic metabolism. Some geologically likely reduced-metal carbonate and sulfide phases, together with their solubility products are listed in Table IV (see reviews of Nriagu and Dell, 1974 Rickard, 1969 Berner, 1970 Troup, 1974 Holdren, 1977) representative Fe, Mn-phosphate compounds are listed in Table VI of Part I. (p. 308). 

In Mg-Al calcined hydrotalcites the weak basic sites are proposed to be the surface OH" groups, while the medium strength sites are related to Mg -0 , but also to Al -O pairs [11-13]. Isolated O anions, common in pure oxides, are also responsible for the strong basic sites in calcined hydrotalcites [14,15]. 

This case has additional convenience in the possibility of using colored anion (commonly picrate), which is useful for monitoring distribution but is inert with respect to complexation. This technique allowed the determination of a large body of association constants, thus providing a basis for further structure-stability correlations, and Cram s picrate method became a de facto standard. (One experienced in metal ion extraction may note that this approach evidently parallels the well-known distribution method for determining chelate stability constants [34. )... 

A simple and fast flow injection fluorescence quenching method for the determination of low levels of iron(III) in water has been developed. For this purpose, a preconcentration minicolumn consisting of cation-exchange resin was coupled to the FIA system. The use of mini-column in the system provided an improvement in sensitivity and the developed FIA method was successfully applied to the on-line determination of low levels of iron in real samples without the pre-concentration process. Fluorimetric determination was based on the measurement of the quenching effect of iron on salicylic acid fluorescence. An emission peak of salicylic acid in aqueous solution occurs at 409 nm with excitation at 299 nm. The effect of interferences from various metals and anions commonly present in water was also studied. The method was successfully applied to the determination of low levels of iron in real samples (river, sea, and spring waters). 

In contrast to anionics, common nonionic surfactants have appreciable solubility in hydrocarbons. As a result, when mixtures of individual nonionic surfactants are present, as inevitably is the case for commercial products, or when anionic and nonionic surfactants are mixed, diff ntial partitioning occurs and the composition of the surfactant films in the microranulsions formed depends on both the total surfactant concentration and the wateroil ratio. For instance, an increase in surfactant concentration while maintaining a fixed overall ratio of anionic to nonionic surfactant produces a reduced ratio of the two species in the surfactant films. The result is to increase v /a/ and reduce the PIT for the typical case where the nonionic surfactant has the higher value of v /aZ. Methods for relating the PIT or optimal conditions to surfactant concentration and the relative amoimts of oil and water present have been developed (Kunieda and Ishikawa, 1985 Kunieda and Shinoda, 1985). 

Apatite was at one time confused with other hexagonal minerals and was so named from the Greek word apate meaning deceit. Although many cations and anions commonly substitute for Ca + and (P04) in mineral apatites, the degree of substitution is often insufficient to warrant naming a separate mineral species. 

As long as the cations and the anions commonly occupy compact locations and respectively the interstitials structures. Rule 1 indicates, shortly, how, from the cations radii ratio of (r ) with the one of anions (r) there... 

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