Bromides, acid properties

Ceroplastic acid, physical properties, 5 30t Cerotic acid, physical properties, 5 30t Cerous bromide, physical properties of, 4 328... 

Cyclophanes, 24 37-38 Cyclopropanes, 13 654 26 654 Cyclopropenyl acids, 5 28 Cyclopropylamine (CPA) in nevirapine synthesis, 15 741-742 physical properties of, 2 498t Cyclopropyl bromide, physical properties of, 4 350t... 

In this current work, cerium-modified MCM-41 mesoporous molecular sieve was synthesized using heptahydrated cerium chloride, colloidal fumed-silica, sodium hydroxide, cethyltrimethylammonium bromide and water. The incorporation of cerium to MCM-41 improved the quality, stability and acid properties of the resulting ordered mesoporous material. Its surface and structural properties were extensively studied by nitrogen adsorption and high-resolution thermogravimetry. 

Condensation between phenol and selenium oxychloride in ether or chloroform solution produces two isomeric selenonium chlorides, [(HO.CeH4)3Se]Cl, each containing chlorine precipitable as silver chloride and replaceable by other acid radicals. The three phenolic hydroxyl groups of the complex cation impart acidic properties to the chlorides, causing them to be soluble in aqueous caustic alkali. From such solutions carbonic or acetic acid precipitates the amphoteric oxide [(H0.C6H4)8Se]20, which redissolves in alkalis and reacts with acids to give a bromide, nitrate, sulphate and chloroplatinate. The following scheme shows the compounds obtained ... 

Blanda, M. T., Horner, J. H., Newcomb, M., Macrocycles containing tin - preparation of macrobicyclic Lewis acidic hosts containing 2 tin atoms and Sn-119 Nmr-studies of their chloride and bromide binding-properties in solution. J. Org. Chem. 1989,54,4626-4636. 

In addition to these three classes of Lewis acids, certain compounds (notably halides) in which the central atom may hold more than an octet of electrons may show acidic properties. Typical of these are tin(IV) chloride, titanium(IV) bromide, and molecular iodine. In such acids, the acidic atom is always beyond the first eight-membered group in the periodic table. 

The change of halide ion results in weaker acidic properties for LnCl3 as compared with LnF3. This means that equilibrium (1.1.41) with the participation of alkali metal halide should be shifted to the left as compared with the fluoride complexes. That is, lithium chloride does not react with chlorides of the rare-earth elements with the formation of any compounds the binary phase diagrams are characterized by one simple eutectic. The same situation is observed for the binary diagrams for lithium- and rare-earth bromides. 

The same was found by comparing the acidic properties of bromides within one period... 

Janz and Danyluk referred to liquids such as nitrobenzene as nonbasic, although that compound was described as polar. The weakly acidic properties of the nitro group were said to limit the utility of nitrobenzene and nitromethane as ionizing media for the hydrogen halides. It was also stated that hydrogen chloride and hydrogen bromide are very weak electrolytes in acetic acid. 

The presence of chloric(I) acid makes the properties of chlorine water different from those of gaseous chlorine, just as aqueous sulphur dioxide is very different from the gas. Chloric(I) acid is a strong oxidising agent, and in acid solution will even oxidise sulphur to sulphuric acid however, the concentration of free chloric(I) acid in chlorine water is often low and oxidation reactions are not always complete. Nevertheless when chlorine bleaches moist litmus, it is the chloric(I) acid which is formed that produces the bleaching. The reaction of chlorine gas with aqueous bromide or iodide ions which causes displacement of bromine or iodine (see below) may also involve the reaction... 

Niobic Acid. Niobic acid, Nb20 XH2O, includes all hydrated forms of niobium pentoxide, where the degree of hydration depends on the method of preparation, age, etc. It is a white insoluble precipitate formed by acid hydrolysis of niobates that are prepared by alkaH pyrosulfate, carbonate, or hydroxide fusion base hydrolysis of niobium fluoride solutions or aqueous hydrolysis of chlorides or bromides. When it is formed in the presence of tannin, a volurninous red complex forms. Freshly precipitated niobic acid usually is coUoidal and is peptized by water washing, thus it is difficult to free from traces of electrolyte. Its properties vary with age and reactivity is noticeably diminished on standing for even a few days. It is soluble in concentrated hydrochloric and sulfuric acids but is reprecipitated on dilution and boiling and can be complexed when it is freshly made with oxaHc or tartaric acid. It is soluble in hydrofluoric acid of any concentration. 

Two approaches that have been investigated recently for disinfection are mixtures of bromine and chlorine, and mixtures containing bromide or iodide salts. Some evidence exists that mixtures of bromine and chlorine have superior germicidal properties than either halogen alone. It is believed that the increased bacterial activity of these mixtures can be attributed to the attacks by bromine on sites other than those affected by chlorine. The oxidation of bromide or iodide salts can be used to prepare interhalogen compounds or the hypollalous acid in accordance with the following reaction ... 

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