Complicated Mixture Of Products Research Articles

Water-soluble metal complexes and catalysts

Abstract A stereospecific synthesis of both enantiomers of the new axially chiral diphosphine ligand 2,2′-bis(diphenylphosphinomethyl)-4,4′,6,6′-tetrachloro-1,1′-biphenyl 5 called BIPHLOPHOS, starting from the readily available pure enantiomers of 4,4′,6,6′-tetrachlorodiphenic acid, was developed. The (−)-enantiomer was then tested in the homogeneous rhodium-catalyzed asymmetric hydroformylation of styrene. The ligand was used to prepare the complex IrH(CO)(PPh3)L2 (L2=5) 6, the crystal structure of which was determined and compared with the related complex RhH(CO)(PPh3)(BISBI). Additionally, ligand 5 was sulfonated by classical methods to yield a uniform reaction product. This is in sharp contrast to the analogous ligands BISBI and NAPHOS, where sulfonation yields a complicated mixture of products. The sulfonated ligand is excellently water-soluble and shows activities and regioselectivities in the hydroformylation of styrene comparable to the well-investigated ligand BISBI.

Reaction of N-Phtalylamino Acid Chlorides with Trialkyl Phosphites

Reaction of N-blocked amino acid chlorides with trialkyl phosphites is a first step in the synthesis of 2-amino-l-hydroxyalkylphosphonates. Quite surprisingly a very purl trialkyl phosphite is required m order to obtain the desired N-blocked 2-amino-1-oxoalkylphosphonate. Thus, the use of commercially rvailrble phosphites prolongation of the reaction time, or attempts for chromatographic purification of the formed oxophosphonate resulted m quite complicated mixture of products. We haw found that these products arise as a consequence of rearrangements of 1oxo-2. phtalylnmmoalLylphosphonates in a series of reactions which are promoted by that presence of dialkyl phosphite (standard impurity present m commercially availablt trialkyl phosphites) in the reaction medium.

A bulky phosphite‐modified rhodium catalyst for the hydroformylation of unsaturated fatty acid esters

AbstractA series of hydroformylation experiments was performed with a high‐grade and a technical‐grade‐derived methyl oleate (MO) and a rhodium catalyst modified by the bulky tris(2‐tert‐butyl‐4‐methylphenyl)phosphite. In the hydroformylation of pure methyl oleate, relatively high turnover numbers were obtained (400–500 mol/mol/h) under mild conditions (molar ratio MO/Rh=910, 80–100°C and 20 bar; CO/H2=1:1, solvent toluene), leading to about 95% conversion in 3 h. Fast isomerization occurs under these conditions to produce the trans oleate. Trans oleate reacts more slowly than cis oleate. At temperatures below 50°C, isomerization does not occur. The use of technical‐grade methyl oleate, containing 14% 9,12 diene, methyl linoleate (ML), results in lower reaction rates because dienes form stable π‐allylic intermediates, which slowly undergo hydroformylation. More severe conditions were applied to obtain higher rates. The rate varied from 50 to 400 mol/mol/h, depending on conditions (molar ratio MO/Rh=910, T=50–120°C, P = 50–80 bar; CO/H2=1:1–1:6, solvent, toluene). Several isomers of ML were formed during the reaction. Subsequent hydroformylation of these isomers results in a complicated mixture of products. The product mixture consists predominantly of methyl formylstearate, methyl formyloleate, methyl diformylstearate, and some yet unidentified side products. A comparison of the classic triphenylphosphine‐modified catalyst and the bulky phosphite‐modified catalyst has shown that the latter is several times more active.

Synthesis of highly chiral multisubstituted binaphthyl compounds as potential new biaxial nematic and NLO materials

Abstract A number of multi substituted binaphthalene compounds were synthesized in an attempt to obtain a highly chiral biaxial nematic (Nb) phase or a good NLO material. Introduction of two pairs of substituents into the binaphthalene molecule with one of these being a nitrile group and R = C10 was successful but neither this compound nor the above esters showed any mesophases. Introduction of additional pairs of substituents proved to be difficult. Friedel-Crafts acylation to add a third pair through a ketone gave complicated mixtures of products obtained by cleavage of the ether followed by acylation. Bromination, which could lead to either the necessary nitrile substituent or esters via the acid obtained from the nitrile generally gave mixtures of bromides as expected. Some of these could be separated by chromatography and successfully converted to the nitrile. However, attempts to hydrolyze these nitrile groups usually gave mixtures of various products of incomplete hydrolysis producing compounds tha...

Metal complexes of carbohydrates: isolation and characterisation of cobalt(III) complexes containing N-substituted glycosylamine ligands derived from ethane-1,2-diamine and glucosamine

Reaction between cis- or trans-[Co(en)2CI2]+(en = ethane-1,2-diamine) and D-glucosamine (2-amino-2-deoxy-D-glucopyranose) in neutral aqueous solution results in a very complicated product mixture including as a major component several isomeric complex ions in which the co-ordination sphere is formally made up of two ethane-1,2-diamine units and one sugar unit. Separation of these complexes by ion-exchange chromatography, and subsequent spectroscopic and structural studies have shown that they are diastereomeric forms in which the co-ordination sphere actually contains one bidentate ethane-1,2-diamine chelate and a multidentate ligand which is an N-(2′-aminoethyl)amino-substituted glycosylamine derived from glucosamine, fructosamine or mannosamine. The presence of the fructosamine moiety reveals that the complex formation reaction is accompanied by the Amadori rearrangement of glucosamine, while the presence of the mannosamine moiety indicates that this rearrangement may be reversible and possibly stereospecific in particular diastereoisomers. Crystal structure determinations have definitively characterised eight of the reaction products as: 1 a complex of the 1-N-(2′-aminoethyl)amino-substituted glucosamine in which the sugar, although chelated to the metal as part of a tridentate ligand, is in its open-chain form and in which the four nitrogen atoms derived from the original two ethane-1,2-diamine units are essentially coplanar; 2 a complex of tridentate 1-N-(2′-aminoethyl)amino-substituted glucosamine in which the sugar has its pyranose form and the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 3 a complex of 1-N-(2′-aminoethyl)amino-substituted glucosamine in which the sugar is in its open-chain form and the ligand is bound in a quadridentate manner, with the chelate edges spanned by the original ethane-1,2-diamine units in the Δ configuration; 4 a complex of 1-N-(2′-aminoethyl)amino-substituted mannosamine in which the sugar has a furanose form and is part of a quadridentate ligand, and the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 5 a complex of quadridentate 1-(2′-aminoethylamino)-1-deoxy-fructopyranosylamine in which the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 6 a complex of quadridentate 1-(2′-aminoethylamino)-1-deoxy-fructopyranosylamine in which the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 7 the same complex as 6 but in the form where its co-ordinated sugar hydroxyl group is deprotonated; and 8 a complex of 1-(2′-aminoethylamino)-1-deoxyfructopyranosylamine in which the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration.

Phenylpalladium(IV) Chemistry: Selectivity in Reductive Elimination from Palladium(IV) Complexes and Alkyl Halide Transfer from Palladium(IV) to Palladium(II)

Methyl iodide, benzyl bromide, and benzyl iodide react with PdMePh(bpy) (bpy = 2,2'- bipyridyl) in acetone at 0 °C to form the isolable fuc-triorganopalladium(1V) complexes PdIMez- Ph(bpy) (3) and PdXMePh(CHzPh)(bpy) [X = Br (4), I (5)l. Complex 3 occurs as a mixture of isomers in a cu. 1:l ratio, involving the phenyl group in a position trans either to bpy (3a) or to iodine (3b), while complexes 4 and 5 are obtained as one isomer which, most likely, has the benzyl group trans to the halogen. The selectivity of reductive elimination from a metal bonded to three different groups could be studied for the first time. The complexes undergo facile reductive elimination in (CD3)zCO at 0 °C, in which PdIMezPh(bpy) gives a mixture of ethane and toluene in a 4:l molar ratio together with PdIR(bpy) (R = Ph, Me), whereas PdXMePh- (CHzPh)(bpy) (X = Br, I) gives exclusively toluene and PdX(CHZPh)(bpy). The analogous tmeda complex, PdMePh(tmeda) (tmeda = N,N,N',N'-tetramethylethylenediamine), reacts more slowly than PdMePh(bpy1 with alkyl halides. Methyl iodide reacts cleanly with PdMePh- (tmeda) at 0 °C in (CD3)zC0 to form ethane and PdIPh(tmeda), but the expected palladium(1V) intermediate could not be detected. Benzyl bromide does not react with PdMePh(tmeda) below the decomposition temperature of the latter under these conditions (50 °C, (CD&CO), while benzyl iodide reacts at 40 °C to give a complicated mixture of products of which ethane, diphenylmethane, ethylbenzene, toluene, and PdIR(tmeda) (R = Me, Ph) could be identified. Benzyl iodide reacts with PdMez(tmeda) at -30 °C in (CD3)zCO to form PdIMez(CHzPh)- (tmeda), for which lH NMR spectra showed the benzyl group to be trans to one of the N-donor atoms. However, PdIMez(CHzPh) (tmeda) is unstable and undergoes facile reductive elimination to form ethane and PdI(CH2Ph)(tmeda). Transfer of alkyl and halide groups from palladium- (IV) to palladium(I1) complexes occurs in (CD3)zCO at low temperatures for several reaction systems in which the resulting palladium(1V) complex is known to be more stable than the palladium(1V) reagent. There is a strong preference for benzyl group transfer from PdXMePh- (CHZPh)(bpy) to PdMez(L2) (X = Br, I; LZ = bpy, phen). The mechanism of the transfer reactions is discussed in terms of the mechanism suggested earlier for alkyl halide transfer from palladium(1V) to platinum(II), palladium(I1) to palladium(O), cobalt(II1) to cobalt(I), and rhodium(II1) to rhodium(1). These reaction systems involve nucleophilic attack by the lower oxidation state reagent at an alkyl group attached to the higher oxidation state reagent.

Reaktive E=C(p–p)π-Systeme, XXXVI [1] Darstellung, Reaktivität und Ligandeneigenschaften des Trifluormethyl-1,3-diphosphans tBu(H)PCF2P(H)CF3 / Reactive E=C(p—p)π Systems, XXXVI [1]. Synthesis, Reactivity and Ligand Properties of the Trifluoromethyl-1,3-diphosphane tBu(H)PCF2P(H)CF3

Trifluoromethyl-1,3-diphosphane tBu(H)PCF2P(H)CF3 (2) is formed regioselectively in almost quantitative yield by addition of tert-butylphosphane to perfluoro-2-phosphapropene F3CP=CF2 (1) as a 1:1 mixture of two diastereomers 2 a and 2b. 2 reacts with nickel tetracarbonyl to give the binuclear complex [tBu(H)PCF2P(H)CF3Ni(CO)2]2 (3) as the only isolable product. The mixture contains four of the eight possible isomers; one of them (3 a) could be isolated in pure form by crystallization from n-pentane solution. Attempts to generate the phosphaalkene tBu(H)PC(F)=PCF3 or the 1,3-diphosphaallene tBuP=C=PCF3 by HF elimination from 2 with NEt3, HNMe2 or HNEt2 lead to complicated mixtures of products. On the other hand, reaction of 3 a with isopropylamine affords the binuclear complex [(CO)Ni(F3CP=CFP(H)tBu)Ni(CO)2tBu(H)PCFHP(CF3)NHiPr] (4) with both a 16 eand an 18 e-nickel(O) fragment and a side-on coordinated F3CP=CF group. The new compounds were characterized by spectroscopic investigations, 3 a and 4 by an X-ray diffraction study.

Isolation and characterization of a vanadium ethylidyne complex. The crystal structure of [(Cy2N)2Li(µ3-O)(µ2,η1:η1CMe) an unusual V2LiO cluster

Reaction of VCI2(TMEDA)2[TMEDA =N,N,N′,N′-tetramethylenediannine] with Cy2NH [Cy = cyclohexyl] and BunLi in tetrahydrofuran led to the formation of a complicated mixture of products from which a dinuclear ethylidyne complex [(Cy2N)2V]2(µ3η1-O)(µ2,η1:η1-CMe)1was isolated

An unexpected reaction of CF 3SCl with n-pentane

Studies on the reaction of various open-chain and cyclic ethers with trifluoromethylsulphenyl chloride in n-pentane in the presence of pyridine showed that the only fluorinated product of these reactions was a mixture of CF 3S-substituted n-pentane derivatives. Therefore the reaction of CF 3SCl with n-pentane was carefully investigated that resulted in the following conclusion: both substances react only when pyridine is used as HCl trapping agent. Under these conditions a mixture of 2-SCF 3 and 3-SCF 3 substituted n-pentane derivatives in molar ratio 1.9 : 1 is formed: ▪ It was proved by elemental analysis, 1H, 19F and 13C NMR, IR as well as MS data. CF 3SCl reacts also with n-hexane in the presence of pyridine giving, however, a more complicated mixture of products. It shows that CF 3SCl generally reacts with hydrocarbons, that are frequently used as solvents. Moreover, the reaction investigated proves, in accordance with the element displacement principle [1], the analogous reactivity of CF 3SCl and Cl 2 towards hydrocarbons in substitution reaction.

The substitution of 5-halo-1,2,3-triazines with electrolytically generated superoxide

Electrolytically generated superoxide reacted with 5-halo-1,2,3-triazines 1 to afford 5-hydroxy-1,2,3-triazines 2. Reaction of 1 with hydroxide anion or potassium superoxide resulted in complicated mixture of products, therefore the reaction was specific for electrogenerated superoxide. The reaction mechanism was investigated with electrochemical methods, and it was revealed that one electron transfer from superoxide to 1 initialized the reaction.

Reaktive EC ( p—p) π-Systeme : XXV. Isolierung und Molekülstruktur eines ungewöhnlichen Dirhodiumkomplexes: [(η 5-C 5Me 5)(CO)Rh I(F 3CPCF 2) 2RH III(CO)(η 5-C 5Me 5)

Perfluoro-2-phosphapropene F 3CPCF 2 ( 1) reacts with Rh 2(μ-CO) 2(η 5-C 5Me 5) 2 ( 2) at −78°C in dichloromethane yielding a complicated mixture of products containing F 3CPCF 2 and Rh(CO)(C 5Me 5) units. One of the main products (ca. 40% of the mixture) can be isolated by column chromatography. Composition and structure of this compound 3 have been determined by analytical (C, H) and specroscopic investigations (IR, MS, 1H-, 19F-, 31P-NMR) as well as by an X-ray diffraction study. The product turnsout to be a novel dirhodium complex 3C (structure in Introduction) which is also produced by the reaction of 2 with the trans-diphosphetane (F 3CPCF 2) 2 ( 4) under the conditions mentioned above.

Synthesis of 5,1′-alkynyl- and 5,1′-alkenyl-1,3-cyclohexadiene-tricarbonyliron complexes using aluminum reagents

Dimethylaluminum acetylides react with (η 5-cyclohexadienyl)tricarbonyliron fluoroborate ( 1) to give the corresponding C(5) alkynyl substituted complexes in high yields without competing reduction products. Using this method, phenylethynyl and trimethylsilylethynyl groups have been added to the cationic complex at C(5). In the latter case, the yield can be improved substantially if tris(trimethylsilylethynyl)-aluminum is used instead. Desilylation of this complex yields the 5-ethynyl complex. Hydrogenation with Lindlar's catalyst yields the corresponding alkenyl complex. Oxidative removal of the Fe(CO) 3 moiety yields the organic ligand in near quantiative yields. Use of aluminum reagents as alkynyl anion synthons in reactions with 1 is a far superior method compared to the use of either lithium acetylides which give complicated mixtures of products or 1-trimethylsilylalkynes which are unreactive.

The photolysis and subsequent reactions of bis(triaryl phosphite) complexes of iron(0), trans-[Fe(CO)3{P(OAr)3}2

On photolysis in solution,trans-[Fe(CO)3{P(OAr)3}2] complexes (Ar = Ph and o- and p-MeC6H4) lose CO to give red products. These cannot be isolated, but react in situ with various ligands, L (e.g. CO, phosphines, phosphites, isocyanides, CS2, SO2, tetracyanoethylene, and acetylenes) to give [Fe(CO)2{P(OAr)3}2(L)] derivatives, and with various compounds X–Y (e.g. H–H, D–D, H–Cl, and Cl–SnCl3) to form [FeII(CO)2{P(OAr)3}2(X)(Y)] compounds. These reactions are often not simple and complicated mixtures of products may be obtained. Carbon tetrachloride and N-bromosuccinimide convert the red intermediate to a mixture of [Fe(CO)2{P(OAr)3}2(X)(Y)] and [Fe(CO)2-{P(OAr)3}2X](X = Y = Cl or Br). It is suggested that the latter contain o-metallated phosphite ligands and that the red intermediate compound is related to them and is best formulated as [Fe{P(OC6H3Z)(OAr)2}{P(OAr)3}-(CO)2H] rather than [Fe(CO)2{P(OAr)3}2](Z = H or Me).

Mechanism of free radical formation by Mo(CO)6+CCl4

The mechanism of free-radical formation in the system molybdenum carbonyl+carbon tetra-chloride in the presence of methyl methacrylate, ethyl acetate and dioxan has been studied in greater detail. For each carbonyl molecule decomposed under conditions of “high”[CCl4] in methyl methacrylate solution one polymer molecule is formed and one chlorine atom is incorporated into the resulting molybdenum derivatives. In the above solvents the rate of carbon monoxide evolution for [CCl4]= 0 is equal to the rate of radical formation at high [CCl4], in agreement with earlier suggestions that the primary process is the displacement of a molecule of carbon monoxide by a solvent molecule. A second molecule of carbon monoxide is liberated on reaction with CCl4. A mechanism involving the interaction of two intermediates is proposed to account for the inhibition of polymerization observed at high carbonyl concentrations. With a very active halide such as ethyl trichloracetate the concentration of one intermediate is very small and inhibition is negligible. In systems containing monomer the ˙CCl3 radical generated from CCl4 is believed to add to the double bond of the monomer molecule already co-ordinated to the metal. With ethyl acetate and dioxan as solvents this cannot occur and radical attack on the solvents leads to a complicated mixture of products, some of which act as ligands and displace further molecules of carbon monoxide. A total of five molecules of CO are then evolved as CO from each Mo(CO)6, the remaining one appearing as phosgene.

Interaction of N-alkyl-N-nitrosourethanes with thiols

1. The interaction at room temperature of thiols (cysteine and certain of its derivatives, and glutathione) with N-alkyl-N-nitrosourethanes and with diazomethane gave complicated mixtures of products. 2. S-Methylcysteine and S-ethoxycarbonylcysteine, the main products of the reaction between cysteine and N-methyl-N-nitrosourethane, were isolated and unequivocally identified. Paper-chromatographic and other evidence was used for the identification of several other components of the mixtures of products obtained. 3. S-Methyl derivatives and their methyl esters were the common products formed from the thiol compounds with both N-methyl-N-nitrosourethane and with diazomethane. 4. The esters were unstable and hydrolysed readily. 5. S-Ethoxycarbonyl derivatives, the primary products of the reaction of the thiols with N-alkyl-N-nitrosourethanes, isomerized to the respective N-ethoxycarbonyl derivatives when the pH increased above 7.0; the migration of the ethoxycarbonyl group from S to N was particularly easy with cysteine, probably owing to the spatial proximity of the amino group. 6. It is suggested that the non-enzymic reactions in vitro of thiols with both N-methyl-N-nitrosourethane and diazomethane may represent models for events in vivo and might help in the studies of the carcinogenic process.