Tris rhodium chloride preparation

Many catalysts, certainly those most widely used such as platinum, palladium, rhodium, ruthenium, nickel, Raney nickel, and catalysts for homogeneous hydrogenation such as tris(triphenylphosphine)rhodium chloride are now commercially available. Procedures for the preparation of catalysts are therefore described in detail only in the cases of the less common ones (p. 205). Guidelines for use and dosage of catalysts are given in Table 1. 

Reduction of the double bond only was achieved by catalytic hydrogenation over palladium prepared by reduction with sodium borohydride. This catalyst does not catalyze hydrogenation of the aldehyde group [31]. Also sodium borohydride-reduced nickel was used for conversion of cinnamaldehyde to hydrocinnamaldehyde [31]. Homogeneous hydrogenation over tris(triphenylphosphine)rhodium chloride gave 60% of hydrocinnamaldehyde and 40% of ethylbenzene [5(5]. Raney nickel, by contrast, catalyzes total reduction to hydrocinnamyl alcohol [4S. Total reduction of both the double... 

Preparation of the Catalyst Tris(triphenylphosphine)rhodium Chloride [57]... 

Previous work has shown that the electronic characteristics of the benzene substituent in triarylphosphine chlororhodium complexes have a marked influence on the rate of olefin hydrogenation catalyzed by these compounds. Thus, in the hydrogenation of cyclohexene using L3RhCl the rate decreased as L = tri-p-methoxyphenylphosphine > triphenylphosphine > tri-p-fluorophenylphosphine (14). In the hydrogenation of 1-hexene with catalysts prepared by treating dicyclooctene rhodium chloride with 2.2-2.5 equivalents of substituted triarylphosphines, the substituent effect on the rate was p-methoxy > p-methyl >> p-chloro (15). No mention could be found of any product stereochemistry studies using this type of catalyst. 

The tris(triphenylphosphine)rhodium chloride catalyst was prepared according to the procedure of G. Wilkinson and co-workers.4... 

Reduction of the amide (123 R1 = R2 = OMe) with sodium aluminium hydride gave a mixture of the bases (125 R1 = R2 = OMe), (127), and (130),165 and the last of these lost carbon monoxide when heated with tris(tri-phenylphosphine)rhodium chloride in benzene to give the dimethyl ketal of 14/3-methylcodeinone, which could be hydrolysed to 14j8-methylcodeinone, the 7,8-dihydro-derivative of which proved to be identical with material previously prepared by a different route (see Volume 9, p. 116). The corresponding morphinone and dihydromorphinone have been prepared.164... 

Materials. The ultraviolet initiator Darocur 1173 (2-hydroxy-2-methyl-l-phenyl-propan-1-one) was purchased from EM Science and was used as received. Dimethylacrylamide (DMA), methacryloyl chloride (MC), allyloxytrimethylsilane and (tris(triphenylphosphine)rhodium)chloride were purchased from Aldrich Chemical Co. DMA and MC were distilled under nitrogen prior to use. 1,3-Tetramethyldisiloxane, methacryloylpropyltrichlorosilane, and 1,3-tetramethyldisiloxane platinum complex (2 % platinum in xylenes) were purchased from Gelest, The fluorinated allylic ether, allyloxy octafluoropentane, was prepared by the phase transfer catalyzed reaction of allyl bromide with octafluoropentanol using tetrabutylammonium hydrogen sulfate, tetrahydrofuran and 50% (w/w) NaOH (11). The fluorinated side-chain methacrylate end-capped siloxane (FSi) was prepared according to a literature procedure. All other solvents and reagents were used as received. 

The tritium labelled V.fischeri AHL 31 was prepared with a specific activity of 45-55 Ci/mmol by the tritiation of the corresponding unsaturated precursor, AT-(3-oxo-4-hexenoyl)-L-HSL 30 in the presence of a homogeneous Wilkinson s catalyst, tris(triphenylphosphine)rhodium[I] chloride (Scheme 13) [71]. 

Methods for the preparation of tris(ethylenediamine)rhodium-(III) chloride hydrate and for its resolution by means of the diastereoisomer Ii (—)D-lRh(en)s] (- -)-tart 2 3H20 are presented. The resolution of tris(ethylenediamine)chromium(III) chloride by means of an analogous diastereoisomeric compound is also described. 

Tris(ethylenediamine)rhodium(III) chloride, first reported by Werner,1 was prepared by the reaction of sodium hexachloro-rhodate(III) dodecahydrate with ethylenediamine monohydrate. The reaction product, however, contained sodium chloride, which could not be removed by recrystallization,1 probably because of the formation of a double salt. J Jaeger2,8 prepared the compound from rhodium (III) chloride trihydrate and 50 % aqueous ethylenediamine. Gillard, Osborn, and Wilkinson4 carried out the reaction of rhodium(III) chloride... 

The complexes are prepared simply by heating the diyne with tris(triphenyl-phosphine)rhodium(i) chloride, abbreviated RhLjCI, in an inert solvent. For example, the complex 246 is obtained in 98% yield by heating the reactants in xylene for 30 min. 

Dehydrohalogenation Benzyltrimethylammonium mcsitoate. r-Butylamine. Calcium carbonate. j Uidine. Diazabicyclo[3.4.0]nonene-5. N.N-Dimethylaniline (see also Ethoxy-acetylene, preparation). N,N-Dimelhylformamide. Dimethyl sulfoxide-Potassium r-but-oxide. Dimethyl sulfoxide-Sodium bicarbonate. 2,4-Dinitrophenylhydrazine. Ethoxy-carbonylhydrazine. Ethyldicyclohexylamine. Ethyidiisopropylamine. Ion-exchange resins. Lithium. Lithium carbonate. Lithium carbonate-Lithium bromide. Lithium chloride. Methanolic KOH (see DimethylTormamide). N-PhenylmorphoKne. Potassium amide. Potassium r-butoxide. Pyridine. Quinoline. Rhodium-Alumina. Silver oxide. Sodium acetate-Acetonitrile (see Tetrachlorocyclopentadienone, preparation). Sodium amide. Sodium 2-butylcyclohexoxide. Sodium ethoxide (see l-Ethoxybutene-l-yne-3, preparation). Sodium hydride. Sodium iodide in 1,2-dimethoxyethane (see Tetrachlorocyclopentadienone, alternative preparation) Tetraethylammonium chloride. Tri-n-butylamine. Triethylamine. Tri-methyiamine (see Boron trichloride). Trimethyl phosphite. 

O-Methylation of mandelic acid leads to the enantiomers of a-methoxy-M-phcnylacetic acid (10), which are also commercially available. This methylation without noticeable racemiza-tion was achieved with diazomethane, using aluminum tris(tert-butanoate) as catalyst8. Alternatively, dimethyl sulfate/ sodium hydroxide has been used15, as described in detail for the racemic compound10. The acids have been used for the construction of quite sophisticated chiral auxiliaries, e.g., a rhodium cyclopentadienyl complex (Section 7.2.2.), and for chiral dienes applied in both normal and inverse Diels-Alder reactions (Section D.1.6.1.1.1.). Chiral dienes, e.g., 1, for normal Diels -Alder reactions were prepared by pyrolysis (460 C) of a tricyclic precursor cstcrified with (S)-O-methylmandeloyl chloride or with the free acid and dicyclohexylcarbodiimide/4-dimethylaminopyridine11 -13. 

Alkylation of the Uthium salt of TMSCHN2 (TMSC(Li)N2) gives a -trimethylsLlyl diazoalkanes which are useful for the preparation of vinylsilanes and acylsilanes. Decomposition of a-tri-methylsilyl diazoalkanes in the presence of a catalytic amount of Copper(I) Chloride gives mainly ( )-vinylsilanes (eq 12), while replacement of CuCl with rhodium(II) pivalate affords (Z)-vinylsilanes as the major products (eq 12). Oxidation of a-trimethylsilyl diazoalkanes with m-Chloroperbenzoic Acid in a two-phase system of benzene and phosphate buffer (pH 7.6) affords acylsilanes (a-keto silanes) (eq 12). ... 

Koneko et al. (1999) developed a synthesis for 6-[ F]FDOPA (O Fig. 42.29b). The 4-[ F] fluorocatechol was prepared by nucleophilic aromatic substitution of the nitro group on 6-nitroveratryl aldehyde followed by decarbonylation with tris(triphenylphosphine) rhodium(I) chloride and hydrolysis (9.2% yield). 6-[ F]FDOPA was then prepared from the 4-[ F] fluorocatechol by a P-tyrosinase catalyzed reaction in the presence of ammonium, pyruvate, and ascorbate in an ethanolic Tris-HCl buffer within 5 min in about 60% radiochemical yield without any isomers. 

Wollaston continued his investigation of the aqua regia solution of platinum in 1803. He then discovered an additional metal in the following way. An aqua regia solution was partially neutralized with sodium hydroxide. Platinum was precipitated with ammonium chloride in the usual way and palladium with mercury cyanide. The common precipitates of chloroplatinate and palladium cyanide were removed by filtering. Hydrochloric add was added to the filtrate and the solution was evaporated to dryness. Wollaston tried to dissolve the residue in alcohol but a beautiful dark-red powder remained undissolved. It proved to be a double chloride of sodium and a new element Wollaston called the new metal rhodium because of the rose colors of its salts. The metal itself was prepared by hydrogen reduction and washing away the sodium chloride with water. 

This reaction is catalysed by metals of Group VIII and their complexes. The preparation of triethylpropanoyloxysilane [271] (95% b.p. 188°C) from trieth-ylsilane apd propanoic acid (30 min at 70 °C) depends on a small amount of tris(triphenylphosphine)-rhodium(I)chloride as catalyst. 

Tris(triphenylphosphine)rhodium(I) chloride is a catalyst for the reaction of triethylsilane with thiophenol [352] and nickel catalyses the reaction of diethyldi-hydrosilane with some alkane thiols [353]. Chlorodihydrophenylsilane reacts with dimethyldisulphide at — 80°C to form chlorobis(methylthio)phenylsilane [354] (77 %). Phenylselenotrimethylsilane [355,356] (b.p. 70°C at 266 Pa = 2 m Hg) can be prepared in excellent yield from phenylselenol or by a reductive silylation of diphenyldisilenide (Scheme 3.13) ... 

In addition to the methods described above, prenol (51) can be prepared from methyl-butynol (43) by rearrangement to prenal (52) using a titanium alkoxide/copper chloride catalyst [69, 70] followed by selective hydrogenation using a ruthenium rhodium tris( 7-sulfonatoyl)phosphine trisodium salt (TPPTS) catalyst [71, 72]. However, it is more usual to prepare the prenyl esters by nucleophilic substitution of a carboxylate anion on prenyl chloride [503-60-6] (56) which, in turn, is available through hydrochlorination of isoprene [78-79-5] (1). This hydrochlorination often employs copper ions as catalysts. These processes are shown in Fig. 8.14. 

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