Aldehydes, Ketones, and Carboxylic Acids

It is also possible to convert carbonyl groups into oxirane rings with cenain carbenoid synthons. The classical Darzens reaction, which involves addition of anions of a-chloroacetic esters, has been replaced by the addition of sulfonium ylides (R. Sowada, 1971 C.R. Johnson, 1979). 

An interesting aspect of this reaction is the contrasting stereoselective behaviour of the dimethyisulfonium and dimethyloxosuifonium methylides in reactions with cyclic ketones (E.J. Corey, 1963 B, 1965 A C.E. Cook, 1968). The small, reactive dimethyisulfonium ylide prefers axial attack, but with the larger, less reactive oxosulfonium ylide only the thermodynamically favored equatorial addition is observed. 

The most general synthetic route to ketones uses the reaction of carboxylic acids (or their derivatives) or nitriles with organometallic compounds (M.J. Jorgenson, 1970). Lithium car-boxylates react with organolithium compounds to give stable gem-diolates, which are decom- 

For aromatic hydrocarbons some very efficient formytation and acylation procedures are known (e.g. Friedel-Crafts, Vilsmeier, Gattermann-Koch), They are treated in introductory text books. 

Carboxyl and nitrile groups are usually introduced in synthesis with commercial carboxylic acid derivatives, nitriles, or cyanide anion. Carbanions can be carboxylated with carbon dioxide (H.F. Ebel, 1970) or dialkyl carbonate (J. Schmidlin, 1957). 

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Reduction of Aldehydes, Ketones, and Carboxylic Acid Derivatives... 

All carbonyl-containing compounds have intense IR absorptions in the range 1650 to 1850 cm-1. As shown in Table 21.3, the exact position of the absorption provides information about the specific kind of carbonyl group. For comparison, the IR absorptions of aldehydes, ketones, and carboxylic acids are included in the table, along with values for carboxylic acid derivatives. 

For a review of methods of synthesis of aldehydes, ketones and carboxylic acids by coupling reactions, see Martin, S.F. Synthesis, 1979, 633. 

Aldehydes, ketones, and carboxylic acids containing a hydrogens can be sulfo-nated with sulfur trioxide. The mechanism is presumably similar to that of 12-4. Sulfonation has also been accomplished at vinylic hydrogen. 

Recently, great advancement has been made in the use of air and oxygen as the oxidant for the oxidation of alcohols in aqueous media. Both transition-metal catalysts and organocatalysts have been developed. Complexes of various transition-metals such as cobalt,31 copper [Cu(I) and Cu(II)],32 Fe(III),33 Co/Mn/Br-system,34 Ru(III and IV),35 and V0P04 2H20,36 have been used to catalyze aerobic oxidations of alcohols. Cu(I) complex-based catalytic aerobic oxidations provide a model of copper(I)-containing oxidase in nature.37 Palladium complexes such as water-soluble Pd-bathophenanthroline are selective catalysts for aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic... 

In organic chemistry, reduction is defined as a reaction in which a carbon atom forms fewer bonds to oxygen, O, or more bonds to hydrogen, H. Often, a C=0 bond or C=C bond is reduced to a single bond by reduction. A reduction that transforms double C=C or C=0 bonds to single bonds may also be classified as an addition reaction. Aldehydes, ketones, and carboxylic acids can be reduced to become alcohols. Alkenes and alkynes can be reduced by the addition of H2 to become alkanes. 

Aldehydes, ketones and carboxylic acids are widespread in plants and animal kingdom. They play an important role in biochemical processes of life. They add fragrance and flavour to nature, for example, vanillin (from vanilla beans), salicylaldehyde (from meadow sweet) and cinnamaldehyde (from cinnamon) have veiy pleasant fragrances. 

The steroid may be bifunctionalized with any of the functional groups participating in the Ugi reaction, i.e., isonitrile, amine, aldehyde (ketone), and carboxylic acid, and having two different functionalities on one steroid building block even increases the possibilities. 

Aromatic aldehydes, ketones, and carboxylic acids and esters can be halogenated and reduced in one operation (e g., ArCHO —> ArCH2Br), by treatment with LiAlH4 followed by HBr.248... 

The DoM reaction of amino substituted heterocycles leads to versatile ortho-amino aldehydes, ketones, and carboxylic acids synthons that may be available only by lengthy and tedious classical routes. 

This reaction can be used for quantitative analysis of malonic acid by heating a sample in 4 M 11CI04 with excess standard Ce41 and back-titrating unreacted Ce4+ with Fe2+. Analogous procedures are available for many alcohols, aldehydes, ketones, and carboxylic acids. 

In a similar manner, carbonyl carbons in a, /f-unsaturated aldehydes, ketones and carboxylic acids are shielded by about 10 ppm when compared with those of corresponding saturated carbonyl compounds [73] ... 

Carbonyl carbon-13 shifts of aldehydes, ketones and carboxylic acids, including all derivatives, occur between 150 and 220 ppm [281]. Within this range, carboxy carbons are shielded (150-180 ppm) relative to carbonyl carbons in aldehydes and ketones (190-220 ppm). This is attributed to an electron releasing effect of the additional hetero... 

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