Acetoxylations carbonylations

Apart from acetoxylation, carbonyl compounds undergo a variety of transformations with DIB in combination with alkali and methanol or trimethyl orthoformate. The nature of the substrates is often critical in determining the outcome of a reaction. 

The production of 1,4-butanediol (1,4-BDO) from propylene via the carbonylation of allyl acetate is noted in Chapter 8. 1,4-Butanediol from maleic anhydride is discussed later in this chapter. An alternative route for the diol is through the acetoxylation of butadiene with acetic acid followed by hydrogenation and hydrolysis. 

The back recombination of the pair of acetoxyl radicals with the formation of parent diacetyl peroxide was observed in special experiments on the decomposition of acetyl peroxide labelled by the lsO isotope on the carbonyl group [78,79]. The reaction of acetyl peroxide with NaOCH3 produces methyl acetate and all lsO isotopes are contained in the carbonyl... 

Support for the above view comes from NMR studies of the binding of phenyl and nitrophenyl acetates to a-CD (Komiyama and Hirai, 1980). These indicate that the nitro groups are located in the CD cavity and that the acetoxyl groups of the esters are held outside, more or less close to the secondary hydroxyls of the CD. It was calculated that the distance between the ester carbonyl carbon and the secondary hydroxyls decreases as p-nitro > phenyl > m-nitrophenyl, consistent with the observed order of rate acceleration (Komiyama and Bender, 1984). 

A number of reactions, principally of olefinic substrates, that can be catalyzed by supported complexes have been studied. These include hydrogenation, hydrosilylation, hydroformylation, polymerization, oxidative hydrolysis, acetoxylation, and carbonylation. Each of these will be considered in turn together with the possibility of carrying out several reactions consecutively using a catalyst containing more than one kind of metal complex. 

Oxidation of p-toluenesulfonylhydrazones.1 Carbonyl compounds can be regenerated in good yield from the tosylhydrazones by treatment with 1 equivalent of Tl(OAc), in HOAc. Room temperature suffices in the case of aldehydes, whereas reflux temperatures are used for ketones. The other product is T1(0S02C6H4CH3). This method is less useful for oxidative cleavage of semicarbazones long reflux periods are necessary, and acetoxylation is a side reaction. 

Alkenes can be transformed to carbonyl compounds through the oxidation of the vinylic carbon atom. A special case of vinylic oxidation is acetoxylation of alkenes and dienes. 

Acetoxylation. Transformations of Carbonyl Compounds. Phenolic Oxidation. Oxidation of Nitrogen Compounds. Hypervalent iodine Reagents in Combination with Azido Compounds. DIB and Sodium Azide in Combination with Other Reagents. Transformations of Alkynes Involving Thiophenols and Diphenyl Diselenide. Miscellaneous Reactions. 

The anodic a-acetoxylation or a-medioxylation of ketones has been shown to be a powerful tool for the 1,2-transposition of the carbonyl group. The overall process is described by equation (24). ... 

N03)j, a newcomer to the arena of oxidants, is useful for the acetoxylation of aromatic side chains in benzylic positions [415, 416] and for the oxidation of methylene or methyl groups that are adjacent to aromatic rings to carbonyl groups [238, 415, 417]. The reagent also oxidizes alcohols to aldehydes [418, 419, 420, 421] and phenols to quinones [422, 423], cleaves vicinal diols to ketones and a-hydroxy ketones to acids [424, 425], and converts diaryl sulfides into sulfoxides [426]. A specialty of ammonium cerium nitrate is the oxidative recovery of carbonyl compounds from their oximes and semicarbazones [422, 427] and of carboxylic acids from their hydrazides [428] under mild conditions. 

A. Olefinic compounds Acetylenic compounds Aromatic compounds Carbonyl compounds F/c-Oxygen compounds Nitrogen compounds Sulfur compounds Halogen compounds Other heteroatom compounds Organometallic compounds Stereoselective and Stereospecific Electrooxidation A. Carboxylic acids Acetoxylation Methoxylation Acetamidation... 

Acetoxylations (oxyacylations) have to be seen in context with olefin oxidation to carbonyl compounds (Wacker process, Section 2.4.1). With the lowest olefin, ethylene, acetaldehyde is formed. In water-free acetic acid no reaction takes place. Only in the presence of alkali acetates - the acetate ion shows higher nu-cleophilicity than acetic acid - ethylene reacts with palladium salts (eq. (1)) to give vinyl acetate, the expected product, as first reported by Moiseev et al. [1]. Stem and Spector [2] independently used [HP04] as base in a mixture of isooctane and acetic acid. This reaction could be exploited for a commercial process to produce vinyl acetate and closed the last gap replacing acetylene by the cheaper ethylene, a petrochemical feed material, for the production of large-tonnage chemical intermediates. 

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