Oxygen-containing functionalities

Since the concept of acidic and basic surface oxides was introduced by Steen-berg in 1944 [86], research on carbon chemistry has attracted a lot of attention 

The basicity of activated carbon has been discussed extensively by Montes-Moran and co-workers [90]. Using experimental and theoretical resnlts, they snggest that oxygen functional gronps, and the existence of pyrone-type structnres on the edges of the polyaromatic layers, are the main contributors to overall surface basicity. On the other hand, the basicity of the k-electron density of the basal planes is considered to be weak. 

By applying the concept of hard and soft acids and bases to the interpretation of the adsorption of metal ions onto activated carbons, Alffara and co-workers 

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This chapter is a transitional one It ties together much of the material encountered earlier and sets the stage for our study of other oxygen containing functional groups m the chapters that follow... 

The next several chapters deal with the chemistry of various oxygen-containing functional groups. The interplay of these important classes of compounds—alcohols, ethers, aldehydes, ketones, carboxylic acids, and derivatives of carboxylic acids— is fundfflnental to organic chemistry and biochemistry. 

Upon removal of the auxiliary, an enantioenriched product could be obtained. The application of chiral auxiliary-based methods to Simmons-Smith cyclopropanation not only provided a useful synthetic strategy, but it also served to substantiate earlier mechanistic hypotheses regarding the directing influence of oxygen-containing functional groups on the zinc reagent [6dj. 

Table 1 Range of Di.stribution of Oxygen-Containing Functional Groups in Humic and Fulvic Acids Isolated from Soils of Widely Different Climatic Zones (in mEq/lOO g)...

In the compound with water, continuous layers of water alternate with bilayers of host molecules, defining two distinct regions in the solid (Fig. 7). Within the bilayers, the structure is stabilized mainly by dipolar interactions between the C-Cl groups turning inward. All the oxygen-containing functions of the host point outward on both sides of the bilayer, and are linked efficiently to the adjacent hydration layers. 

The cationic Pd(II) catalysts exhibit effective copolymerizations of ethylene and other a-olefins with polar-functionalized comonomers, with the majority of insertions occurring at the ends of branches. Among the best tolerated monomers are those bearing fluorine or oxygen-containing functionalities, such as esters, ketones, and ethers. The copolymerization of ethylene and acrylates, attractive because the monomers are inexpensive and the copolymers exhibit unique physical properties, has been well-studied mechanistically [27,69], Examples of copolymerizations of ethylene and a-olefins with methyl acrylate are shown in Table 4. In general, the amount of comonomer incorporation varies linearly with its reaction concentration and... 

The same is true of rhenium catalysts rhenium heptoxide [42], rhenium heptasulfide [5i] and rhenimn heptaselenide [54] all require temperatures of 100-300° and pressures of 100-300 atm. Rhenium heptasulfide is not sensitive to sulfur, and is more active than molybdenum and cobalt sulfides in hydrogenating oxygen-containing functions [55,55]. 

Alcohols are at a fairly low oxidation level compared to other oxygen-containing functional groups and consequently are readily prepared by reduction. Large numbers of reductive methods have been reported for the preparation of alcohols. Carboxylic acids and esters react vigorously with lithium aluminum hydride (LAH) to produce primary alcohols. Carboxylic acids, but not esters, are also reduced easily by borane, which is die only reducing agent diat reacts faster widi carboxylic acids dian widi esters or odier acid derivatives. 

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