Anhydrous Chromium III Chloride

KohlschOtteb Z. physik. Chem., A170, 307 (1934) Z. anorg. dUgem. 

CrCU (violet) + 6H2O Cr203 + 6HC1 + 9H2O 

Anhydrous chromium(III) chloride is usually prepared by passing a chlorinating agent such as chlorine, sulfur chloride, carbon tetrachloride, phosgene, or hydrogen chloride and carbon disulfide over hot chromium(III) oxide (about 600°) or an oxide-carbon mixture. In the latter case, the chloride is separated from excess carbon by sublimation. 

The apparatus shown in Fig. 22 is constructed. The furnace E may be any suitable commercially available crucible furnace closed with several layers of sheet asbestos perforated for the neck of the flask and covered with a 1-in. layer of insulating material. A homemade furnace of 600 watts that will serve equally well may be constructed 

Caution. Since phosgene is formed in this preparation, the efflmnt gas is led to a hood or outdoors. A water suction pump will not dispose of phosgene because this gas is not hydrolyzed rapidly. 

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A series of chromium(III) amidinates containing additional pyrazolato, triazolato, or tetrazolato ligands have recently been reported. Treatment of anhydrous chromium(III) chloride with 2 or 3 equivalents of LilMeCfNBu l or Li[MeC(NPr )2] in THF at room temperature afforded [MeC(NBu02]2CrCl(THF) and [MeC(NPr )2]3Cr in 78 and 65% yields, respectively (Scheme 120). ... 

The synthesis of [Cr(NH3)6]Cl3 from anhydrous chromium(III) chloride and liquid ammonia in the presence of catalytic quan-... 

This is prepared by passing dry hydrogen chloride over chromium, or hydrogen over anhydrous chromium(III) chloride. It is a white solid. If pure chromium is dissolved in dilute hydrochloric acid in the absence of air, a blue solution of the hydrated chloride, containing the hexaaquo-ion [Cr(H20)6]2+. is obtained. The same solution is also obtained by reduction of the + 6 oxidation state (through the + 3) using a solution of a dichromate(VI) and reducing with zinc and hydrochloric acid ... 

The anhydrous chromium (III) chloride may be obtained by heating the hydrated salt CrCls 6H2O with SOCI2 and subliming the product in a stream of chlorine at 600°C. Alternatively, the red-violet anhydrous chloride can be obtained by passing chlorine gas over a mixture of chromic oxide and carbon ... 

Preparation of Anhydrous Chromium(III) Chloride. Perform the experiment in a fume cupboard Grind 5 g of charcoal into a fine powder in a mortar, mix it with 12.5 g of chromium(III) oxide, add a thick starch size or a dextrin solution in cold water, and make beads about 5 mm in diameter from the mixture. Put the beads onto a clay dish and dry them in a drying cabinet at 110-120 °C. Next put them into an iron crucible, cover them with the charcoal powder and a lid, and roast them. 

Assemble an apparatus (see Fig. 61). Place the dry beads into a porcelain or quartz tube and perform chlorination at 750-800 °C during one hour. Ghromium(III) chloride can sublime, therefore see that the tube outlet is not clogged by the product. Cool the apparatus in a stream of chlorine. Extract the beads from the tube and mechanically separate the chromium chloride formed on their surface from the unreacted charcoal. In what other ways can anhydrous chromium(III) chloride be obtained ... 

Preparation of Chromium(III) Nitride. Work in a fume cupboard Assemble an apparatus for preparing nitrides (see Fig. 84). Put 0.5-1 g of anhydrous chromium(III) chloride into a boat. Put the latter into a tubular furnace. Displace the air from the apparatus with a stream of dry ammonia and then heat the furnace to 600 °C. Continue the heating in an ammonia stream for one hour, next switch off the furnace and cool the apparatus without stopping the stream of gas. Extract the boat and weigh the product. Write the equation of the reaction. Calculate the yield in per cent. 

The tris and bis complexes of acetylacetone (2,4-pentanedione) (167) with chromium(III) have been known for many years (168,169).739 The tris compound is generally prepared by the reaction of an aqueous suspension of anhydrous chromium(III) chloride with acetylacetone, in the presence of urea.740 Recently a novel, efficient synthesis of tris(acetylacetonato)chromium-(III) from Cr03 in acetylacetone has been reported.741 The crystal structure of the tris complex has been determined.744 A large anisotropic motion was observed for one of the chelate rings, attributed to thermal motion, rather than a slight disorder in the molecular packing. 

Five grains of anhydrous chromium (III) chloride (No. 14) are placed in a combustion tube which is left completely... 

Anhydrous chromium (III) chloride (No. 14) is boiled for 15-30 minutes with 2N hydrochloric add and then washed well with water, methanol, and ether in that order. The salt is ground fine in a mortar and dried at 105-120°C for two hours. 

Seven-tenths gram (0.026 mol) of aluminum powder, 6 g. (0.031 mol) of powdered anhydrous chromium(III) chloride, 12 g. (0.09 mol) of sublimed and quickly ground aluminum chloride, and 25 ml. of dry and pure benzene are placed in a sealed tube of approximately 60 ml. volume. After cleaning the neck of the tube, a stopcock is attached to it by means of a short piece of rubber tubing. The tube is carefully evacuated, and benzene is allowed to boil off for some minutes at room temperature. Then the stopcock is closed and the tube is sealed in vacuo. The contents are... 

The zinc catalyst probably functions by generating kinetically labile chromium(II) species. The present observation is reminiscent of several others, notably (1) the ready dissolution of anhydrous chromium(III) chloride in water and other solvents only in the presence of chromium(II) ion or reducing agents,... 

A mixture of 1 g. of zinc dust and 20 g. (0.13 mol) of anhydrous chromium(III) chloride is placed in the thimble of a Soxhlet extraction apparatus. Approximately 218 ml. (2.7 mols) of tetrahydrofuran (freshly distilled from calcium hydride) is placed in a 300-ml. round-bottomed flask and attached to the extraction apparatus a calcium chloride drying tube is fitted to the reflux condenser. At the end of 4 hours of reflux the reaction is stopped and an additional gram of zinc dust is placed in the thimble. The reflux is then resumed and continued for 8 hours (or until the recycling liquid is colorless). The tetrahydrofuran solution... 

An ethereal solution of a Grignard reagent reacts readily with CO in the presence of anhydrous chromium(III) chloride (Job, 1927). One of the products is the ether-soluble Cr(CO)g. If the CrClg is replaced by MoClg orWClg the hexacarbonyl of molybdenum or tungsten is formed. 

Aquopentammine- or acidopentamminechromium(III) salts have been prepared by the reaction of liquid ammonia with anhydrous chromium (III) chloride 1 by the oxidation... 

Pfeiffer prepared trichloro(tripyridine)chromium(III) from anhydrous chromium(III) chloride and from dichloro-tetraaquochromium(III) chloride 2-hydrate (the common hydrated chromic chloride of commerce), but neither details of the preparations nor yields were reported. The reaction of [Cr(H20)4Cl2]Cl-2H20 with pyridine gives [Cr(C6H6N)3-CI3] with a yield of about 4%. In the procedure described here, the complex can be prepared in about 90% yield when anhydrous chromium(III) chloride is used as the starting material. 

Twenty-six and four-tenths grams (0.16 mol) of anhydrous chromium(III) chloride and 79.1 g (1 mol) of anhydrous pyridine and a stirring magnet are placed in a 1-1. round-bottomed flask which has a standard taper opening. 

Anhydrous chromium (III) chloride forms violet-colored greasy scales, which sublime at 950° and begin to dissociate above 1300°. The vapor density at temperatures where there is no dissociation is in agreement with the formula CrCU. Anhydrous chromium(III) chloride remains in contact with cold water for some time without dissolving or reacting. This is possibly due to the fact that the... 

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