Wacker reaction oxidation

Four common aromatic olefins as well as two aliphatic counterparts could be converted to the desired methyl ketones in good to excellent yields and selectivity through Wacker oxidation reaction as shown in Scheme 3.4. 

Athawale, A. A., Bhagwat, S. V. Synthesis and characterization of novel copper/polyaniline nanocomposite and application as a catalyst in the Wacker oxidation reaction. J. Appl. Polym. Sci. 2003, 89, 2412-2417. 

The Wacker-Smidt process—hereafter known simply as the Wacker oxidation, reaction, or process—enjoyed considerable success, yet its use has declined dramatically over the past 10 years for at least two reasons.49 First, manufacturing plants are expensive to build and maintain because they must be constructed to withstand a corrosive environment. Second, another procedure that yields acetic acid directly from synthesis gas was developed and now supplants the Wacker-Smidt process. This newer route also uses homogeneous catalysis involving Rh and Ir complexes and will be described in Section 9-5. 

The applications reported for polymer-supported, soluble oxidation catalysts are the use of poly(vinylbenzyl)trimethylammonium chloride for the autooxidation of 2,6-di-tert-butylphenol [8], of copper polyaniline nanocomposites for the Wacker oxidation reaction [9], of cationic polymers containing cobalt(II) phthalocyanate for the autooxidation of 2-mercaptoethanol [10] and oxidation of olefins [11], of polymer-bound phthalocyanines for oxidative decomposition of polychlorophenols [12], and of a norbornene-based polymer with polymer-fixed manganese(IV) complexes for the catalytic oxidation of alkanes [13], Noncatalytic processes can also be found, such as the use of soluble polystyrene-based sulfoxide reagents for Swern oxidation [14], The reactions listed above will be described in more detail in the following paragraphs. 

The redox interaction between transition metals and redox-active ligands is likely to permit a smooth reversible redox cycle in the transition metal-catalyzed oxidation reactions. Actually, the Wacker oxidation reaction of a terminal olefin proceeds catalytically only in the presence of a catalytic amount of polyaniline or polypyrrole derivative as a cocatalyst in acetonitrile-water under oxygen atmosphere to give 2-alkanone (Scheme Copper-free catalytic systems are... 

Organopalladium derivatives containing Pd(II) can serve as sources of carbocationic species. Both alkene-Pd Tr-complexes and oxypalladated intermediates in the Wacker oxidation reactions can therefore generate carbocationic intermediates, which may then undergo anionotropic rearrangements (Scheme 6). In fact, it is rather remaikable that, despite the well-known involvanent of alkene-Pd Tr-complexes and oxypalladated intermediates, the Wacker-type oxidation of alkenes is relatively free from various possible rearrangement reactions. 

Oxidation ofTerminal Alkenes to Methyl Ketones. An aerobic variant of the classic Wacker oxidation reaction has been described and is believed to involve a paUadium(II) hydroperoxide as the key intermediate. ... 

Scheme 3.11 The Wacker oxidation reaction using palladium(II)-iedox-active hgand hybrid catalyst...

The following procedure may prove to be one of the largest advances in the field of MDMA chemistry since the perfection and dissemination of the Wacker oxidation procedure for producing MDP2P. This reaction is based on a published process that somehow has escaped discovery by underground chemistry until... 

These reactions constitute the cycle their sum gives the stoichiometry of the Wacker oxidation ... 

Whereas this reaction was used to oxidize ethylene (qv) to acetaldehyde (qv), which in turn was oxidized to acetic acid, the direct carbonylation of methanol (qv) to acetic acid has largely replaced the Wacker process industrially (see Acetic acid and derivatives). A large number of other oxidation reactions of hydrocarbons by oxygen involve coordination compounds as detailed elsewhere (25). 

W-Heterocyclic Carbene Complexes in Oxidation Reactions Table 10.8 Enantioselective aza-Wacker cycUsations [43]... 

Wacker olefin oxidation, which is depicted in its simplest form in Eq. (6.33), contains palladium( 11)-catalyzed hydration of olefin in its important step (Eq. 6.34) and is discussed extensively [62]. In this review article we introduce two asymmetric Wacker type reactions. 

Under the conditions of the Wacker oxidation, 4-trimethylsilyl-3-alkyn-l-ols give 7 -lactones. Similarly, A-carbamoyl or A-acetyl 4-trimethylsilyl-3-alkynamines cyclize to y -lactams. Formulate a mechanism for these reactions. (Hint In DzO,... 

The most important reaction based on Pdn-catalysis is the Wacker oxidation [171], which is used industrially for the synthesis of acetaldehyde, starting from ethane. This process can be combined with a Heck reaction and has been used by Tietze and coworkers [172] for an efficient enantioselective synthesis of vitamin E (6/1-... 

The latest example of a Pdn-catalyzed Wacker/Heck methodology was published by Rawal and coworkers. During the total synthesis of mycalamide A, an inter-molecular Wacker oxidation with methanol acting as nucleophile and a subsequent ring closure via Heck reaction led to a tetrahydropyran moiety in a 5.7 1 diastereom-eric mixture [184]. 

Wacker cyclization has proved to be one of the most versatile methods for functionalization of olefins.58,59 However, asymmetric oxidative reaction with palladium(II) species has received only scant attention. Using chiral ligand 1,1 -binaphthyl-2,2 -bis(oxazoline)-coordinated Pd(II) as the catalyst, high enantioselectivity (up to 97% ee) has been attained in the Wacker-type cyclization of o-alkylphenols (66a-f) (Scheme 8-24). 

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