Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Carbonylation manganese-catalyzed

F. Calderazzo, The Manganese-Catalyzed Carbonylation of Amines, Inorg. Chem. 4, 293-296 (1965). [Pg.121]

In the presence of dioxygen, the carbon radical R- produced by reactions (201) and (202) ar transformed into alkylperoxy radicals ROO, reacts with Co or Mn species to regenerate th Co " or Mn " oxidants, and produce primary oxygenated products (alcohol, carbonyl compounds which can be further oxidized to carboxylic acids. This constitutes the basis of several Industrie processes such as the manganese-catalyzed oxidation of n-alkenes to fatty acids, and the cobal catalyzed oxidation of butane (or naphtha) to acetic acid, cyclohexane to cyclohexanol-on mixture, and methyl aromatic compounds (toluene, xylene) to the corresponding aromatic monc or di-carboxylic acids. ... [Pg.374]

The a-heteroaryl carbonyl structure has stimulated interest in organic synthesis because it is a highly prevalent motif in pharmaceuticals and natural products. In the year 2014, a manganese-catalyzed intermolecular C-H/C-H coupling of carbonyls and heteroarenes was developed (14CC4105).The presence of NaI04 is necessary for the catalytic reaction. These new reaction conditions allow gram-scale synthesis of a-heteroaryl carboxylic acids. [Pg.153]

Finally, manganese carbonyl complexes also show potential for effecting interesting phase transfer catalyzed carbonylation reactions. Alkynes react with carbon monoxide and methyl iodide in methylene chloride, using 5N NaOH as the aqueous phase, benzyl-triethylammonium chloride as the phase transfer catalyst, and either bromopentacarbonylmanganese or dimanganese decacarbonyl to afford... [Pg.13]

Hydrogen transfer reactions from an alcohol to a ketone (typically acetone) to produce a carbonyl compound (the so-caUed Oppenauer-type oxidation ) can be performed under mild and low-toxicity conditions, and with high selectivity when compared to conventional methods for oxidation using chromium and manganese reagents. While the traditional Oppenauer oxidation using aluminum alkoxide is accompanied by various side reactions, several transition-metal-catalyzed Oppenauer-type oxidations have been reported recently [27-29]. However, most of these are limited to the oxidation of secondary alcohols to ketones. [Pg.108]

The spectroscopic and kinetic data from this reaction indicated the existence of a long sought catalytic reaction topology, bimetallic catalytic binuclear elimination. The kinetic data provided a linear-bilinear form in organometallics [95]. One term represented the classic unicyclic rhodium catalyzed hydroformylation and the other represented the attack of manganese hydride carbonyl on an acyl rhodium tetracarbonyl species. A representation of the interconnected topology is shown in Figure 4.12. [Pg.183]

Figure F shows some acetylene insertion reactions. These, too, are similar to the olefin insertion reactions. The manganese and cobalt hydrocarbonyls again add. Chloronickelcarbonyl hydride, which I believe is an intermediate in many of the nickel carbonyl-catalyzed reactions, adds to olefins. Diborane and the aluminum hydrides also add. Figure F shows some acetylene insertion reactions. These, too, are similar to the olefin insertion reactions. The manganese and cobalt hydrocarbonyls again add. Chloronickelcarbonyl hydride, which I believe is an intermediate in many of the nickel carbonyl-catalyzed reactions, adds to olefins. Diborane and the aluminum hydrides also add.
Ojima and co-workers first reported the RhCl(PPh2)3-catalyzed hydrosilylation of carbonyl-containing compounds to silyl ethers in 1972.164 Since that time, a number of transition metal complexes have been investigated for activity in the system, and transition metal catalysis is now a well-established route for the reduction of ketones and aldehydes.9 Some of the advances in this area include the development of manganese,165 molybdenum,166 and ruthenium167 complex catalysts, and work by the Buchwald and Cutler groups toward extension of the system to hydrosilylations of ester substrates.168... [Pg.250]

Neither the palladium nor nickel catalyst described will promote the carbonylation of saturated aliphatic halides as noted above. However, this reaction can be catalyzed with cobalt (17) or iron (77) and probably with manganese (18) carbonyl anion salts. These carbonyl anions are strongly nucleophilic species and readily displace halide or other good leaving groups from primary or secondary positions giving alkyl metal carbonyl complexes. [Pg.330]

The copper(II)-promoted hydrolysis of glycylglycine has been studied in some detail.120 Copper(II) ions catalyze the hydrolysis of glycylglycine in the pH range 3.5 to 6 at 85 °C.120 The pH rate profile has a maximum at pH 4.2, consistent with the view that the catalytically active species in the reaction is the carbonyl-bonded complex. The decrease in rate at higher pH is associated with the formation of a catalytically inactive complex produced by ionization of the peptide hydrogen atom. This view has subsequently been confirmed by other workers,121 in conjunction with an IR investigation of the structures of the copper(II) and zinc(II) complexes in D20 solution.122 Catalysis by cobalt(II),123 and zinc(II), nickel(II) and manganese(II) has also been studied.124-126... [Pg.425]

In a thorough study it was determined that the Barbier coupling of allylic halides 69a to aldehydes, ketones, or a,p-unsaturated carbonyl compounds 68 catalyzed by Cp2TiCl2 47a in the presence of manganese as the terminal reducing agent proceeds most likely via a radical mechanism (Fig. 21) [149,150], The active titanocene(III)... [Pg.143]

Cobalt-, Manganese- and Iron-catalyzed Cross-coupling Reactions 9.4.2.1 Carbonylations and acylations... [Pg.485]

There is evidence that the enol mechanism of manganese-ion catalyzed oxidation of carbonyl compounds is also active to some extent in the oxidation of... [Pg.534]

Many other metal ions have been reported as catalysts for oxidations of paraffins or intermediates. Some of the more frequently mentioned ones include cerium, vanadium, molybdenum, nickel, titanium, and ruthenium [21, 77, 105, 106]. These are employed singly or in various combinations, including combinations with cobalt and/or manganese. Activators such as aldehydes or ketones are frequently used. The oxo forms of vanadium and molybdenum may very well have the heterolytic oxidation capability to catalyze the conversion of alcohols or hydroperoxides to carbonyl compounds (see the discussion of chromium, above). There is reported evidence that Ce can oxidize carbonyl compounds via an enol mechanism [107] (see discussion of manganese, above). Although little is reported about the effectiveness of these other catalysts for oxidation of paraffins to acetic acid, tests conducted by Hoechst Celanese have indicated that cerium salts are usable catalysts in liquid-phase oxidation of butane [108]. [Pg.540]

In the nickel(ll)-catalyzed NHK reaction, the first step is the reduction of Ni " to Ni that inserts into the halogen-carbon bond via an oxidative addition. The organonickel species transmetallates with Cr " to form the organochromium(lll) nucleophile, which then reacts with the carbonyl compound. To make the process environmentally benign, a chromium-catalyzed version was developed where a chlorosilane was used as an additive to silylate the chromium alkoxide species in order to release the metal salt from the product. The released Cr " is reduced to Cr " with manganese powder. [Pg.318]

One aspect which sets oxidation apart from other reactions, e.g. hydrogenation and carbonylation is the fact that there is almost always a reaction (free radical chain autoxidation) in the absence of the catalyst (Reactions 1-3). Moreover, (transition) metal ions which readily imdergo a reversible one-electron valence change, e.g. manganese, cobalt, iron, chromium, and copper, catalyze this process by generating alkoxy and alkylperoxy radicals from RO2H (Reactions 4-6). [Pg.153]

Another reaction of type 3 is the formation of sym-dialkylureas from primary amines and CO catalyzed by manganese carbonyl complexes ... [Pg.470]

The likely mechanism of the CA[Mn]-catalyzed epoxidation of olefins is similar to that proposed by Burgess for free manganese involving peroxycarbonate as the key intermediate [41, 43 5], CA[Mn] forms a stable manganese-bicarbonate complex in the active-site [60], Hydrogen peroxide may add to carbonyl of this bicarbonate complex and displace water thereby forming a peroxycarbonate, which then may epoxidize a bound olefin. In contrast, heme peroxidases catalyze epoxidations either by a radical mechanism or by a ferryl-oxygen transfer mechanism [55]. [Pg.57]


See other pages where Carbonylation manganese-catalyzed is mentioned: [Pg.548]    [Pg.374]    [Pg.164]    [Pg.478]    [Pg.199]    [Pg.239]    [Pg.48]    [Pg.299]    [Pg.424]    [Pg.1735]    [Pg.73]    [Pg.56]    [Pg.172]    [Pg.434]    [Pg.436]    [Pg.424]    [Pg.267]    [Pg.535]    [Pg.29]    [Pg.289]    [Pg.51]    [Pg.467]    [Pg.48]    [Pg.108]    [Pg.313]   
See also in sourсe #XX -- [ Pg.165 ]




SEARCH



Carbonylation catalyzed

Carbonylation, manganese

Catalyzed Carbonylations

Manganese carbonyl carbonylation

Manganese carbonyls

© 2024 chempedia.info