Oxychlorides, volatilization

The oxide dichloride, b.p. 351 K, is separated from the less volatile phosphorus oxychloride by a fractional distillation. 

Reaction with Meta/ Oxides. The reaction of hydrogen chloride with the transition-metal oxides at elevated temperatures has been studied extensively. Fe202 reacts readily at temperatures as low as 300°C to produce FeCl and water. The heavier transition-metal oxides require a higher reaction temperature, and the primary reaction product is usually the corresponding oxychlorides. Similar reactions are reported for many other metal oxides, such as Sb202, BeO, AI2O2, andTi02, which lead to the formation of relatively volatile chlorides or oxychlorides. 

After firing, the powder is washed in water typically with a small amount of complexing agent such as ethylenediarninetetraacetic acid (EDTA), sodium EDTA, or a weak acid such as citric acid to remove the excess chloride, volatile antimony oxychlorides which have recondensed on the phosphor during cooling, and manganese compounds which are not incorporated in the halophosphate lattice. The powder is then ready for suspension. 

The volatile chlorides ate collected and the unreactedsohds and nonvolatile chlorides ate discarded. Titanium tetrachloride is separated from the other chlorides by double distillation (12). Vanadium oxychloride, VOCl, which has a boiling point close to TiCl, is separated by complexing with mineral oil, reducing with H2S to VOCI2, or complexing with copper. The TiCl is finally oxidized at 985°C to Ti02 and the chlorine gas is recycled (8,11) (see also... 

Oxychlorides are less prolific, apart from the red-brown OsOCl4 (m.p. 32°C). This probably has a molecular structure in the solid state as the IR spectra of the solid, matrix-isolated and gas-phase molecules are very similar, and the volatility is consonant with this [30]. Syntheses include heating osmium in a stream of oxygen/chlorine ( oxychlorination ) and by ... 

The above reaction shows that the oxychloride decomposes at the sublimation temperature into the volatile tetrachloride and the nonvolatile oxide. Reduction starts as soon as the chloride vapour contacts the molten magnesium, and this exothermic reaction raises the temperature of the reaction mixture. The temperature of the reduction crucible is maintained in the range of 800 to 875 °C. The process is carefully controlled by matching the sublimation rate of zirconium tetrachloride with the reduction rate. The conclusion of the reduction is indicated by a fall in temperature and pressure. 

In the production of titanium, the chlorination of rutile generates approximately 0.12 tons of waste for every ton of titanium tetrachloride produced. If ilmenite is directly chlorinated, the amount of waste is 1.5 tons for every ton of titanium tetrachloride. Large amounts of ferric chloride are produced along with volatile chlorides and oxychlorides (e.g., aluminum trichloride, silicon tetrachloride, carbon oxychloride, tin tetrachloride, vanadium tetrachloride, vanadium oxychloride) these can be removed by selective distillation. In flu-idized-bed chlorination, the build-up of liquid calcium chloride and magnesium chloride in the fluid bed interferes with the process of fluidization and hence these must be removed. 

In many cases the solid, more active and much less volatile pentar chloride is used instead of phosphorus trichloride. Then it is necessary to use a whole mole of PC15 for each mole of alcohol since the reaction leads to the formation of the much more -sluggish phosphorus oxychloride, e.g. 

The contaminants in commercial boron trichloride usually are HCI and COCI2, as well as oxychlorides which have some volatility. The oxyhalides are readily removed by one or two trap-to-trap distillations in a clean vacuum system. Most of the HCl can be removed by holding the BCI3 at — 78°C and pumping away the volatiles for a brief period (some BCI3 is sacrificed in the process). Phosgene, which may be detected by its gas-phase infrared absorption at 850 cm"1, is very difficult to remove. Liquid boron tribromide is generally supplied in sealed ampules. If it is straw colored, dibromine is a likely impurity, and this... 

Acid Chlorides.—Another class of double oxides and chlorides exists, most of which are easily volatile, and which therefore are of known molecular weight. These are the so-called acid chlorides —oxychlorides of those elements which form acids. These are related to acids, in as much as by replacement of their chlorine by hydroxyl,... 

There is some indication that the phosphorus oxychloride formed in the preparation of the acid chloride interferes with the cyclization when aluminum chloride is used. Thus, the cyclization of a/y-diphenylbutyrio acid was effected in 94% yield only after the volatile phosphorus compounds had been removed from the reaction mixture -otherwise the yield was only 77%.114 By removing the phosphorus oxychloride under reduced pressure before introduction of the aluminum chloride,114 115 114 seven acids have been cyclized in yields of 85% or better. No single set of directions can be given which is entirely general. The following description of the cyclization of a/y-diphenylbutyric acid is a typical example of the form of procedure. The critical phase of the reaction is during the aluminum chloride treatment the optimum time and temperature may vary for each add. 

Calcium fluoride has also been used in metathetical reactions. Usually, heat is required to promote reactions of this type. Booth and Dutton4 passed vapors of a volatile halide [phosphorus(V) oxychloride] over a bed of heated calcium fluoride to produce the chlorofluoride and fluoride derivatives. Sodium fluoride, potassium fluoride, titanium (IV) fluoride, and zinc fluoride have been used in similar metathetical fluorination reactions. 

Eichler, B., Gaggeler, H.W. "Stability and "Volatility" of Element 104 Oxychloride". In Labor fur Radio- und Umweltchemie Annual Report 2000, Villigen (2001) 33. 

For over 20 years, 263Sg with a half-life of 0.9 s was the longest-lived known Sg isotope. In addition to the minute production rates, this short half-life effectively prevented a chemical identification of Sg. In 1992 S. Timokhin et al. from Dubna studied the chemical identification of Sg as a volatile oxychloride making use of an on-line thermochromatography method [25], This claim was substantiated by ancillary experiments [26, 27] and further studies of the behavior of homologues elements Mo and W [28], Shortly thereafter, an international collaboration of chemists conducted on-line... 

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