Hydrogen halide solids

In order to elucidate the causes of the increased stability of the hydrolyzed cluster ions compared with the unhydrolyzed ions, further studies were made of the behaviour of [Te2X8]3 (where X = Cl,Br, or I) in solutions of hydrogen halides [43,52,80,87]. The studies were performed mainly in relation to the most stable and most readily synthesized [Tc2C18]3- ion (Fig. la) kinetic methods with optical recording were employed. The identity of the reaction products was in most cases confirmed by their isolation in the solid phase. The studies showed that the stability of the [Tc2X8]3 ions (where X = Cl, Br, or I) in aqueous solutions is determined by the sum of competing processes acid hydrolysis complex formation with subsequent disproportionation and dissociation of the M-M bonds, and oxidative addition of atmospheric oxygen to the Tc-Tc multiple bond. 

The reactions of the halide salts, in the solid state, with concentrated sulphuric acid vary in relation to the reducing power of the hydrogen halides produced. 

The Dohrmann DX 20B system is based on combustion of the sample to produce the hydrogen halide, which is then swept into a microcoulometric cell and estimated. It is applicable at total halide concentrations up to lOOOpl-10 with a precision of 2% at the lOpg L-1 level. The detection limit is about 0.5pg L-1. Analysis can be performed in 5 min. A sample boat is available for carrying out analysis of solid samples. The instrument has been applied to waste waters, soils and sediments. 

Some halo-substituted anilines are of limited thermal stability, tending to eliminate hydrogen halide which may catalyse further decomposition. To avoid decomposition during distillation, this should be conducted in the presence of solid alkali or magnesium oxide at minimum temperature (under relatively high vacuum) and/or with exclusion of air by inert gas. Individually indexed compounds are 4-Bromoaniline, 2296... 

When some straight and branched-chain aliphatic alcohols, such as n-propanol, n-butanol and isopropanol, are subjected to high temperatures, dehydrogenation products predominate over dehydration (51). Presumably the eliminations take place via a six-membered transition state and are catalyzed by hydrogen halides in the homogeneous phase (52) to produce olefins. On the other hand, gas phase dehydration over solid catalysts is a valuable process for the preparation of olefins and ethers. 

Very little is yet known about the specific chemistry of 1,3,2-diaza-boracycloalkanes. At room temperature, these compounds add hydrogen halide readily in a 1 2 molar ratio 1>. In a similar manner, boron trihalide is added at low temperatures 13>. The solid addition products of the latter reaction decompose near room temperature with cleavage of the original B—N linkages presumably leading to linear products (Eq. 9). 

These compounds are liquids or low melting solids with characteristic foul and persistent odors. They can be stored under an inert atmosphere in the refrigerator for long periods without decomposition. At 20° they decompose slowly to diorgano ditellurium derivatives while in air, tellurium is deposited. Protic agents such as water, hydrogen halides, and alcohols cleave the tellurium-group TV element bond. 

B-Halo-9-borabicyclo[3.3.1]nonene (B-X-9-BBN, X = Cl, Br, 1). These derivatives can be prepared most simply by reaetion of 9-BBN with the halogens (75-80% yield) or with the hydrogen halides (80-85% yield). They are all liquids, but form solid complexes with S(CH,)2. ... 

Experimental measurements confirm many of the conclusions reached by the calculations. Combination of a hydrogen halide with an amine produces an ion pair in the gas phase for only the strongest acid/base pairs. In concert with spectral information obtained in solid matrix, the transition from neutral to ion pair appears to be a gradual one as the strengths of the acid and base reach threshold values. There are a number of systems examined which do not fall neatly into either the pure neutral or ion pair category, but are better described as having a broad minimum in their proton transfer potential the bottom of this well occurs... 

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