Rhodium trichloride

Acetyl chlotide is reduced by vatious organometaUic compounds, eg, LiAlH (18). / fZ-Butyl alcohol lessens the activity of LiAlH to form lithium tti-/-butoxyalumium hydtide [17476-04-9] C22H2gA102Li, which can convert acetyl chlotide to acetaldehyde [75-07-0] (19). Triphenyl tin hydtide also reduces acetyl chlotide (20). Acetyl chlotide in the presence of Pt(II) or Rh(I) complexes, can cleave tetrahydrofuran [109-99-9] C HgO, to form chlorobutyl acetate [13398-04-4] in about 72% yield (21). Although catalytic hydrogenation of acetyl chlotide in the Rosenmund reaction is not very satisfactory, it is catalyticaHy possible to reduce acetic anhydride to ethylidene diacetate [542-10-9] in the presence of acetyl chlotide over palladium complexes (22). Rhodium trichloride, methyl iodide, and ttiphenylphosphine combine into a complex that is active in reducing acetyl chlotide (23). 

A solution of rhodium trichloride trihydrate (2 g) in hot ethanol (70 ml) is added to a solution of freshly recrystallized triphenylphosphine (12 g) in hot... 

Rhodium trichloride and other soluble salts, 115 Rhone-Poulenc, See Aventis (France), 159 Rhone-Poulenc Agro France, See Aventis (France), 159 Richards Bay Minerals, 200, 207 RichardsApex hic., 245... 

Rhodium trichloride oxidises ethylene in dimethylacetamide solution to a... 

Many compounds of rhodium (III) may readily be obtained by this general catalytic procedure. Rhodium(III) bromide may be substituted for the rhodium trichloride, and weakly basic nitrogenous ligands (2,2 -bipyridine, o- (or l,10-)phen-anthroline, or dioximes) for the pyridine. The products all have the halogen atom in trans positions. 

It has been repored (86) that these same three isomeric aldehydes were formed from allyl acetate by a reaction catalyzed by rhodium trichloride and iron pentacarbonyl. Reaction proceeded at 135°C under 300 atm of H2/CO, but the product composition was not specified. 

The dichlororuthenium arene dimers are conveniently prepared by refluxing ethanolic ruthenium trichloride in the appropriate cyclohexadiene [19]. The di-chloro(pentamethylcyclopentadienyl) rhodium dimer is prepared by refluxing Dewar benzene and rhodium trichloride, whilst the dichloro(pentamethylcyclo-pentadienyl)iridium dimer is prepared by reaction of the cyclopentadiene with iridium trichloride [20]. Alternatively, the complexes can be purchased from most precious-metal suppliers. It should be noted that these ruthenium, rhodium and iridium arenes are all fine, dusty, solids and are potential respiratory sensitizers. Hence, the materials should be handled with great care, especially when weighing or charging operations are being carried out. Appropriate protective clothing and air extraction facilities should be used at all times. 

In the example of Fig. 7.15 [43j rhodium particles have been deposited by spin coat impregnation of a Si02/Si substrate with an aqueous solution of rhodium trichloride. After drying, the particles were reduced in hydrogen. The images show samples prepared at three different rotation speeds in the spin coating process, but with concentrations adjusted such that each sample contains about the same amount of rhodium atoms. The particles prepared at high rotation speeds are smaller, which... 

Surprisingly, there are only a few catalysts known capable of hydrogenating ketones in fully or largely aqueous systems. For example, most of the water-soluble rhodium, mthenium and indium phosphine complexes preferentially hydrogenate the C=C bonds in unsaturated ketones, as does the solvated ion pair formed from aqueous rhodium trichloride and Aliquat-336 [206]. 

Cycloisomerization of 1,6-diene 25 is effected by a number of transition metal catalysts. For example, both rhodium trichloride [22, 23] and Wilkinson s catalyst [24, 25] promote this reaction efficiently to give methylenecyclopentane 26 (Scheme 7.12). In the latter case, the active catalyst species is beheved to be [Rh(PPh3)2HCl2]. A mechanism proposed for this cycloisomerization is shown in Scheme 7.13. Coordination of a diene to [Rh(PPh3)2HCl2] and insertion of one of the olefin moieties of the diene into the [Rh]-H bond gives complex II.3a. Carbocychzation affords alkyl-[Rh] intermediate II.3i,. Subsequent reductive ehmination of the methylenecyclopentane regenerates the active catalyst species. 

The first example involving a rhodium catalyst in an ene reaction was reported by Schmitz in 1976. An intramolecular cyclization of a diene occurred to give a pyrrole when exposed to rhodium trichloride in isobutanol (Eq. 2) [15]. Subsequently to this work, Grigg utilized Wilkinson s catalyst to effect a similar cycloisomerization reaction (Eq. 3) [16]. Opplozer and Eurstner showed that a n -allyl-rhodium species could be formed from an allyl carbonate or acetate and intercepted intramolecularly by an alkene to afford 1,4-dienes (Eq. 4). Hydridotetrakis(triphenylphosphine)rhodium(l) proved to be the most efficient catalyst for this particular transformation. A direct comparison was made between this catalyst and palladium bis(dibenzylidene) acetone, in which it was determined that rhodium might offer an additional stereochemical perspective. In the latter case, this type of reaction is typically referred to as a metallo-ene reaction [17]. 

Principal Compounds Rhodium trichloride rhodium trioxide rhodium (II) acetate rhodium nitrate rhodium potassium sulfate rhodium sulfate rhodium sulfite... 

The LDso for rhodium trichloride in rabbits by intravenous injection was 215 mg/kg the clinical signs presented shortly after injection were increasing lethargy and waning respiration. There were no abnormal findings at autopsy, but the rapid onset of death suggested central nervous system effects. 

A solution of rhodium trichloride in the eye of a rabbit gave a delayed injurious reaction 0.1 mg of solution adjusted to pH 7.2 with ammonium hydroxide was placed for 10 minutes in a rabbit eye after the corneal epithelium had been removed an orange coloration of the cornea occurred that faded to faint yellow within 8 weeks. During the first 2-3 weeks, the cornea was slightly hazy in the third week, white opacities gradually developed and, finally, there was extensive opacification and vascularization. 

Lifetime exposure to 5 ppm rhodium trichloride in the drinking water caused a minimally significant increase in malignant tumors... 

Landholt RR, Berk HW, Russell HT Studies on the toxicity of rhodium trichloride in rats and rabbits. Toxicol ApplPharmacol 21 589-590, 1972... 

Formula RhCE MW 209.26 forms a trihydrate RhCl3 3H20 Synonyms rhodium trichloride rhodium(III) chloride... 

Rhodium trichloride is prepared by heating rhodium with chlorine gas at... 

Also, the chloride salt may be obtained by treating the yellow hydrous oxide, Rh203 5H20, with hydrochloric acid. The solution is carefully evaporated to form a dark red and water-soluble salt, rhodium trichloride tetrahy-drate, RhCl3 4H20. Heating the tetrahydrate in a stream of hydrogen chloride gas at 180°C forms the anhydrous salt, RhCR. 

Di-/i-chloro-bis(7)4-1,5-cyclooctadiene)dirhodium(l), [RhCl(l,5-C8Hi2)]2, has been prepared in 60% yield by reducing rhodium trichloride hydrate in the presence of excess olefin in aqueous ethanol.1 In the present preparation the yield has been greatly increased (to 94%). Two related complexes, [RhCl(l,5-C6Hio)]22 and [RhCl(C6H12)2]2, are similarly prepared in high yield from 1,5-hexadiene and 2,3-dimethyl-2-butene, respectively. 

Dimethylformamide (99.8%), 2-methylpropanethiol (99%), triphenylphosphine (99%), and triphenylphosphite (99- -%) were purchased from Aldrich and used as received. Rhodium trichloride hydrate was a generous loan from Engelhard-CLAL, and iridium iodide was purchased from Johnson Matthey as a mixture of M3 and M4 of several formula M3 4. The trisodium salt of tris(3-sulfonatophe-nyl)phospine (TPPTS) was a gift from Hoechst. 

The first compound of the ammino-rhodium series examined was chloro-pentammino-rhodium chloride, [Rh(NH3)5Cl]Cl2, which vras prepared by treating rhodium trichloride with ammonia. Claus 1 investigated the composition of the substance and prepared from it, by means of moist silver oxide, a strongly basic substance, which proved to be the corresponding hydroxide, [Rh(NH3)5Cl](OH)2. 

The only alkane used in the study using rhodium trichloride as a catalyst (6) is cyclohexane. This system is intermediate in Stability between that of Ir(III) and Pt(II), and the exchange rate is slower. The distribution of deuterium in the side chain of alkyl aromatics is as found on the other catalysts, and the rate of cyclohexane exchange is very much slower than that of benzene. 

Itaconic acid (Eastman) and 2-acetamidoacrylic acid (Fluka) were CP grade a tropic acid was prepared according to the literature (53). Ruthenium and rhodium trichlorides were obtained as trihydrates from Johnson Matthey Limited. (+)Diop was obtained from Strem Chemicals a literature synthesis provided (-)diop (7). Racemic methyl phenyl sulfoxide was a K K product. 

---