Boiling point tetrachloride

It follows that liquids of high boiling point should not be distilled from drying agent systems which have appreciable vapour pressures. An extreme case of this action is the dehydration of oxalic acid dihydrate by distillation over toluene or over carbon tetrachloride. 

Selection of solvents. The choice of solvent will naturally depend in the first place upon the solubility relations of the substance. If this is already in solution, for example, as an extract, it is usually evaporated to dryness under reduced pressure and then dissolved in a suitable medium the solution must be dilute since crystallisation in the column must be avoided. The solvents generally employed possess boiling points between 40° and 85°. The most widely used medium is light petroleum (b.p. not above 80°) others are cycZohexane, carbon disulphide, benzene, chloroform, carbon tetrachloride, methylene chloride, ethyl acetate, ethyl alcohol, acetone, ether and acetic acid. 

Repeat the boiling point determination with the following pure liquids (a) carbon tetrachloride, A.R. (77°) (6) ethylene dibromide (132°) or chlorobenzene (132°) (c) aniline, A.R. (184-6°) and (d) nitrobenzene, A.R. (211°). An air condenser should be used for (c) and (d). Correct the observed boiling points for any appreciable deviation from the normal pressure of 760 mm. Compare the observed boiling points with the values given in parentheses and construct a calibration curve for the thermometer. Compare the latter with the curve obtained from melting point determinations (Section 111,1). 

Other mixtures which may be employed are carbon tetrachloride (b.p. 77°) and toluene (b.p. 110-111°) chloroform (b.p. 61°) and toluene methyl alcohol (b.p. 65°) and water (b.p. 100°). The last example is of interest because almost pure methyl alcohol may be isolated no constant boiling point mixture (or azeotropic mixture) is formed (compare ethyl alcohol and water, Sections 1,4 and 1,5). Attention is directed to the poisonous character of methyl alcohol the vapour should therefore not be inhaled. 

Determination of boiling points. Distillation method (Fig. II, 12, 1) for carbon tetrachloride (25 nil. distillation flask and small water condenser), and SiwoloboflF s method (Fig. II, 12, 2) for carbon tetrachloride, aniline and nitrobenzene. Calibration curve for thermometer. Determination of b.p. of unknown liquid. 

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... 

By-products from EDC pyrolysis typically include acetjiene, ethylene, methyl chloride, ethyl chloride, 1,3-butadiene, vinylacetylene, benzene, chloroprene, vinyUdene chloride, 1,1-dichloroethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane [71-55-6] and other chlorinated hydrocarbons (78). Most of these impurities remain with the unconverted EDC, and are subsequendy removed in EDC purification as light and heavy ends. The lightest compounds, ethylene and acetylene, are taken off with the HCl and end up in the oxychlorination reactor feed. The acetylene can be selectively hydrogenated to ethylene. The compounds that have boiling points near that of vinyl chloride, ie, methyl chloride and 1,3-butadiene, will codistiU with the vinyl chloride product. Chlorine or carbon tetrachloride addition to the pyrolysis reactor feed has been used to suppress methyl chloride formation, whereas 1,3-butadiene, which interferes with PVC polymerization, can be removed by treatment with chlorine or HCl, or by selective hydrogenation. 

Carbon tetrachloride (as well as a number of other halogen compounds) greatly accelerates the reaction between magnesium and alcohol. If anhydrous alcohol is used the reaction will start in the course of some time without heating, whereas 99.5 per cent alcohol has to be heated nearly to the boiling point before the evolution of hydrogen becomes rapid. 

It is clear that when the formation of a higher chloride, by the interaction between a lower chloride and chlorine is difficult, the reverse reaction, i.e., the decomposition of the higher chloride to a lower chloride and chlorine, occurs easily. For example, vanadium tetrachloride decomposes, on heating at its boiling point (148.5 °C) to the trichloride and chlorine ... 

A mixture containing equal parts by mass of carbon tetrachloride and toluene is to be fractionated to give an overhead product containing 95 mass per cent carbon tetrachloride, a bottom product of 5 mass per cent carbon tetrachloride, and a sidestream containing 80 mass per cent carbon tetrachloride. Both the feed and sidestream may be regarded as liquids at their boiling points. 

Young, H.D. and Nelson, O.A. Binary system carbon tetrachloride-ethylene dichloride their boiling points and specific gravities as aids in analysis, Ind. Eng. Chem. Anal Ed., 4(l) 67-69, 1932. 

Elemental composition Os 74.82%, 0 25.18%. The compound can be identified by its physical properties, such as, odor, color, density, melting-, and boiling points. Its acrid odor is perceptible at concentrations of 0.02 mg/hter in air. The oxide also produces an orange color when a small amount of the compound or its aqueous solution is mixed with an aqueous solution of ammonia in KOH (see Reactions). Aqueous solution of the tetroxide may be analyzed for osmium by AA or ICP spectrometry (see Osmium). Vapors of the tetroxide may be purged from an aqueous solution by helium, adsorbed over a trap, and desorbed thermally by helium onto a GC. Alternatively, a benzene or carbon tetrachloride solution may be injected onto the GC and the compound peak identified by mass spectrometry. The characteristic mass ions for its identification should be 190 and 254. 

---