Magnesium chloride, cation reactions

The running of parallel reactions of hydrolysis, ammonolysis and depolymerization of apple pectin in aqueous solution of ammonia (IM) at 25 C were investigated. It was examined the effects of monovalent cations (Na, K", NH4 ) and divalent cations (Ca, Mg ) when they were added as chloride salts. It was found that the relative rates of the above mentioned reactions, depend on the nature and concentration of the added salts as well. The chlorides of sodium, potassium and calcium accelerate hydrolysis and depolymerization, while magnesium chloride delays these reactions. Ammonolysis was increased in cases of ammonium chloride addition. 

The purification of some enzymes inactivates them because substances essential for their activity but not classed as a prosthetic group are removed. These are frequently inorganic ions which are not explicit participants in the reaction. Anionic activation seems to be non-specific and different anions are often effective. Amylase (EC 3.2.1.1), for example, is activated by a variety of anions, notably chloride. Cationic activation is more specific, e.g. magnesium is particularly important in reactions involving ATP and ADP as substrates. In cationic activation it seems very likely that the cation binds initially to the substrate rather than to the enzyme. 

A part of the throughfall flux of sulfur, calcium, magnesium, and potassium is due to the deposition of sea-salt particles. Ion fluxes in bulk and stand precipitation can be corrected for the contribution of sea-salt particles, using sodium or chloride as sea-salt tracers. Sea-salt contributions between 8% (Europe) and 45% (coastal sites) of the total sulfur in stand precipitation were found. Deposited sea-salts are neutral salts, and these do not contribute to either acidic (in the case of sulfur) or alkaline (in the case of base cations) reactions in the forest soil (Biittner et al. 1986). 

In Section 14.1, we learned that acids dissolve metals, or more precisely, that acids react with metals in a way that causes metals to go into solution. The reaction between an acid and a metal usually produces hydrogen gas and a dissolved salt containing the metal ion as the cation. For example, hydrochloric acid reacts with magnesium metal to form hydrogen gas and magnesium chloride. 

More conclusive evidence for the intermediacy of benzocyclopropenyl cations was obtained upon chloride/fluoride exchange of 22 with AgF in acetonitrile, which led to the chloro-fluoro derivative 278 and, ultimately, to the difluoro compound 279 in almost quantitative yield. Reaction of 22 with LiAlH AlClj afforded 2,5-diphenylbenzocyclopropene (264), while that with ethyl magnesium bromide lead to the diethyl derivative 280. Phenylmagnesium bromide and methylmagne-... 

A further synthesis of metal complexes containing two six-membered aromatic rings, which was limited to chromium, was based on the interaction of phenyl magnesium bromide and chromic chloride, and subsequent hydrolysis of the reaction mixture to the [Cr(C8He)2] cation (107, m, m). 

In these reactions within the acidic gastric milieu, the remaining cations (aluminum, magnesium, calcium) combine principally with chloride ions. 

Binary ionic compounds Thousands of compounds contain ionic bonds. Many ionic compounds are binary, which means that they contain only two different elements. Binary ionic compounds contain a metallic cation and a nonmetallic anion. Sodium chloride (NaCl) is a binary compound because it contains two different elements, sodium and chlorine. Magnesium oxide (MgO), the reaction product shown in Figure 7.5b, is also a binary ionic compound. 

Chloride ions attack oxide layers on iron, aluminum, and magnesium. Subsequently, the metal is electrochemically dissolved. The hydration of Fe " ", AP" ", or Mg " " releases protons and thereby leads to an acidification of the tip of the filament. At the cathodic site, the primary cathodic reaction, the reduction of oxygen to hydroxyl ions takes place. In between the anode and the cathode a potential gradient is estahhshed, which forces anions to migrate to the front and cations to the back. As the distance from the anode increases, the pH also increases on the basis of the dilution of hydronium ions and the migration of hydroxyl ions from the cathodic site. When favorable conditions are reached, the corresponding hydroxides of the cations are formed as gels. As the head advances, these hydrated corrosion products lose their water and convert to the dry corrosion products that fill the tail see Ref. [168] and references therein. 

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