Chromic chloride complexes

Stearamphopropylsulfonate. See Sodium stearoamphohydroxypropylsulfonate Stearate PEG 1000. See PEG-21 stearate Stearato chromic chloride Stearato-chromic chloride complex Stearatochromium chloride. See Stearatochromium chloride complex Stearatochromium chloride complex CAS 15242-96-3 UN 1993... 

Synonyms Chrome complex of stearic acid Chromic chloride stearate Octadecanoato chromic chloride hydroxide (1 2 4 1) Stearato chromic chloride Stearato-chromic chloride complex... 

Chromium(IH) chloride, chromic chloride, CrClj. Violet solid (Cr plus CI2, hydrate plus SOCI2) only soluble in water in presence of Cr. Forms many complexes including the hydrates [Cr(H20)6]Cl3 - violet, [Cr(H20)jCl]Cl2,H20 - green, [Cr(H20)4Cl2]Cl,2H20 - green. 

Sihcone products dominate the pressure-sensitive adhesive release paper market, but other materials such as Quilon (E.I. du Pont de Nemours Co., Inc.), a Werner-type chromium complex, stearato chromic chloride [12768-56-8] are also used. Various base papers are used, including polyethylene-coated kraft as well as polymer substrates such as polyethylene or polyester film. Sihcone coatings that cross-link to form a film and also bond to the cellulose are used in various forms, such as solvent and solventless dispersions and emulsions. Technical requirements for the coated papers include good release, no contamination of the adhesive being protected, no blocking in roUs, good solvent holdout with respect to adhesives appHed from solvent, and good thermal and dimensional stabiUty (see Silicon COMPOUNDS, silicones). 

Chromium has a maximum co-ordination number of six the chromium atom, therefore, may combine with, at most, six monovalent atoms or groups, over and above its ordinary valency value, with formation of a complex radicle. Hence chromic chloride is capable of associating with, or adding on, six molecules of ammonia with formation of the derivative, [Cr(NH3)8]Cl3. Ammonia may be replaced by a substituted ammonia group or some other basic group, such as alkyl amine, pyridine, or ethylenediamine. 

Potassium Tetrathiocyanato-dipyridino-chromium, [Cr py2 (SCN)4]K.2H,0, is prepared by heating potassium ehromithiocyanate with anhydrous pyridine. The melt is reerystallised from a little wTater, and on cooling a stable red powder separates. The thiocyanato-groups are all within the complex, and the salt in solution therefore gives no coloration with ferric chloride. It is decomposed by chlorine in presence of cold water with formation of tetraquo-dipyridino-chromic chloride. If crystallised in the dry state from pyridine it forms transparent red crystals of the addition compound, [Cr py2(SCN)JK.4py, which quickly effloresce in air. 

It has been found4 that a good yield may be obtained rapidly by allowing the commercially available green chromic chloride, CrCl8-6H20, in methanol to boil under reflux with ethylenedi-amine in the presence of metallic zinc. The product, hydrated tris(ethylenediamine)chromium(III) chloride, is obtained as a solid and is readily purified. An exactly similar procedure may be used for the complex of 1,2-propanediamine. 

Formation of the atropisomeric o-kexaphenylenes. When the chromium ate complex (2), prepared from 2,2 -dilithiumdiphcnyl and chromic chloride, is treated with a transition metal halide (CoClj, FcClj), the atropisomers of o-hexaphenylene (3a) and (3b) are formed ... 

Chromic chloride, C l3 6H20, forms several kinds of crystals, varying in color from violet to green, the solutions of which have similar colors. These diflEerent colors are due to the formation of stable complex ions (Fig. 25-3) ... 

The sesquioxide, Cr Oa, containing trivalent chromium, is an amphoteric oxide. It yields chromic salts, such as chromic chloride, CrCla, and sulphate, Cr2(S04)a, which are very stable and show great similarity to the ferric salts and to salts of aluminium as, for example, in the formation of alums. Since, however, chromic oxide functions as a weaker base than chromous oxide, the latter having a lower oxygen content, the chromic salts are more liable to hydrolysis than the chromous salts. This is well marked in the case of the chlorides. Again, in spite of the stability of chromic salts, only a slight tendency to form simple Cr " ions is exhibited, whilst complex ions are formed much more readily, not only complex anions, as in the case of iron and aluminium, but also complex cations, as in the extensive chromammine series. In this respect chromium resembles cobalt and platinum. 

A further synthesis of metal complexes containing two six-membered aromatic rings, which was limited to chromium, was based on the interaction of phenyl magnesium bromide and chromic chloride, and subsequent hydrolysis of the reaction mixture to the [Cr(C8He)2] cation (107, m, m). 

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. 

The chromium may be used to prepare anhydrous chromic chloride, from which certain complexes of chromium can be made the manganese may be used in the electrolytic preparation of potassium permanganate (see Experiment 52). 

Magnanini studied the absorption spectrum and A. Speransky found that the electrical conductivity of aq. soln. shows that only a small proportion of the salt is ionized. The soln. of the violet modification conducts electricity three times better than that of the green. G. Gore electrolyzed a cone. soln. of chromic fluoride acidified with hydrofluoric and hydrochloric acids, and found that the liquid became hot no gas was liberated at the cathode, but chlorine and ozone were liberated at the platinum anode which was not corroded. C. Poulenc showed that the salt is reduced by hydrogen at dull redness. The heat of formation is 230-95 Cals, per mol—vide infra, the dichloride. Steam transforms chromic fluoride into chromic oxide. Chromic fluoride is insoluble in water, and alcohol hydrogen chloride transforms it into chromic chloride hot hydrochloric, sulphuric, and nitric acids attack chromic fluoride only a little hydrogen sulphide converts it into black sulphide and molten alkali nitrate or carbonate converts it into chromate. A. Costachescu prepared complex pyridine salts. 

---