Salts organic , with metal ions

Salts (organic), (a) With metal ions Water-soluble salts are best purified by preparing a concentrated aqueous solution to which, after decolorising with charcoal and filtering, ethanol or acetone is added so that the salts crystallise. They are collected, washed with aqueous ethanol or aqueous acetone, and dried. In some cases, water-soluble salts can be recystallised satisfactorily from alcohols. Water-insoluble salts are purified by Soxhlet extraction, first with organic solvents and then with water, to remove soluble contaminants. The purified salt is recovered from the thimble. 

Their most common impurities are sulphonyl chlorides (neutral) or the sulphinic acid or disulphide from which they are 

Thiolsulphonates decompose slowly in dilute, or rapidly in strong, alkali to form disulphides and sulphonic acids. 

Thiolsulphonates also decompose on distillation but they can be steam distilled. The solid members can be 

Handbook of Preparative Inorganic Chemistry, 2nd edn, Vol 1 (1963) and vol 2 (1965), Academic Press, NY. 

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The bile acids undergo the reactions that might be expected at their various functional groups. The carboxyl group may be esterified, reduced, subjected to salt formation with metal ions, alkaloids, or organic bases and converted to the amide. 

Known as crown ethers because of their crown-like shape, these ethers contain cavities that are ideal for forming complexes with metal ions. It is this property that allows ordinary salts to dissolve in organic solvents. For example, potassium permanganate is usually insoluble in benzene, but readily dissolves in benzene if [18]-crown-6 ether is added. This solution is useful because it allows oxidation with potassium permanganate to be carried out in organic solvents. The potassium ion (shown in green) is just the right size to fit into the cavity in the crown ether. 

Solubility differences of fatty acid salts In 1828, Gusserow introduced a method that lead salts or soaps of fatty acids in ether can be separated depending on the solubility differences. Saturated and unsaturated fatty acids form salts with metallic ions (e.g., Li) whose solubihties in water and organic solvents vary with the nature of the metallic ion and the chain length, degree of unsaturation, and other characteristics of the acid radicals. Substitution of ethanol for diethyl ether (113) allows better separation. 

Inorganic salts, which contain metal ions, do not dissolve in organic solvents such as benzene. However, by surrounding the metal ion with a chelate called a crown ether the desired solution can be made. The mining industry uses cyanide ions to dissolve gold out of the quartz rocks in which it is often found. The cyanide ligands are removed in subsequent chemical steps. 

Metal complex formation can be used to stabilize an otherwise reactive or unstable organic developer, such as hydroquinone or p-phenylenediamine, to permit its incorporation into silver halide emulsion layers or adjacent layers. For example, catechols and hydroquinones can be mixed with several metal salts of lead(II), cadmium or barium and incorporated into emulsion layers. Treating the film with an activator solution containing an anion that forms an insoluble salt of the metal ion (S04 , liberates the organic developer.The structures of the complexes... 

Typical soils exhibiting distinctive layers with increasing depth are called horizons (Fig. 9.7). The top layer, normally several centimetres in thickness, is known as the A horizon, or topsoil. This is the layer of maximum biological activity in the soil and it contains most of the soil organic matter. Metal ions and clay particles in the A horizon are subject to considerable leaching. The next layer is the B horizon, or subsoil. It receives material such as organic matter, salts, and clay particles leached from the topsoil. The C horizon is composed of weathered parent rocks from which the soil originated [1]. 

If the acid or base group of a compound participates in a salt formation, the absorption spectra and in some cases the color intensity or appearance of the parent compound will be affected. Same behavior is seen when a compound participates in a complex formation with a metal, and this is widely used in determining metal ions with the aid of organic color reagents. The same effect can, however, also be the cause of unintended interference in cases were a test solution or reagent solution in a color reaction is contaminated with metal ions. 

This section contains metal-organic compounds, ammonium and metal derivatives of organic alcohols, amines and carboxylic acids (salts), as well as ionophores that form complexes with metal ions. Note that there is a large number of metal-organic catalysts, and reagents for preparing some of these catalysts, in Chapter 6, and can be considered as an extension of this section. (For Introduction see p 555.)... 

Acids also dissolve basic organic compounds such as amines and aniline. Chelating agents, such as dissolved ethylenediaminetetraacetate (EDTA, HY ), dissolve insoluble metal salts by forming soluble species with metal ions ... 

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