Carbonyl compounds Aldehydes Amides Carboxylic acid

The carbonyl group consists of a carbon atom double-bonded to an oxygen atom. It occurs in the organic compounds known as ketones, aldehydes, amides, carboxylic acids, and esters. 

Many compounds contain more than one functional group Prostaglandin Ei a hormone that regulates the relaxation of smooth muscles con tains two different kinds of carbonyl groups Classify each one (aldehyde ketone carboxylic acid ester amide acyl chloride or acid anhydride) Identify the most acidic proton in prostaglandin Ei and use Table 1 7 to estimate its pK ... 

The zwitterion (6) can react with protic solvents to produce a variety of products. Reaction with water yields a transient hydroperoxy alcohol (10) that can dehydrate to a carboxyUc acid or spHt out H2O2 to form a carbonyl compound (aldehyde or ketone, R2CO). In alcohoHc media, the product is an isolable hydroperoxy ether (11) that can be hydrolyzed or reduced (with (CH O) or (CH2)2S) to a carbonyl compound. Reductive amination of (11) over Raney nickel produces amides and amines (64). Reaction of the zwitterion with a carboxyUc acid to form a hydroperoxy ester (12) is commercially important because it can be oxidized to other acids, RCOOH and R COOH. Reaction of zwitterion with HCN produces a-hydroxy nitriles that can be hydrolyzed to a-hydroxy carboxyUc acids. Carboxylates are obtained with H2O2/OH (65). The zwitterion can be reduced during the course of the reaction by tetracyanoethylene to produce its epoxide (66). 

The epoxide can be prepared from an alkene and the amide from a carboxylic acid. The new target. 2-ethyl-2-hexenoic acid, has a CC double bond in conjugation with the carbonyl group of the carboxylic acid. Whenever a compound with an ,/3-unsaturated carbonyl group is encountered, it is worthwhile to consider the possibility of using an aldol condensation (see Section 20.5) or a related reaction to prepare it. To examine this possibility, the aldehyde that will provide the carboxylic acid upon oxidation is disconnected at the double bond. Because both fragments produced by this disconnection are the same, it is apparent that an aldol condensation of butanal can be employed to prepare this compound. The synthesis was accomplished as shown in Figure 23.5. 

Further kinetic evidence for the importance of enols comes from work on the base-catalyzed condensations of carbonyl-containing compounds. There are a number of such reactions characteristic of aldehydes, ketones, carboxylic acids, esters, amides, etc. Of these the most elementary appear to be the aldol condensations, which are prototypes of the others. These reactions can be represented by the equation... 

The a bromination of carbonyl compounds by in acetic acid is limited tc aldehydes and ketones because acids, esters, and amides don t enolize to a suffi cient extent. Carboxylic acids, however, can be a brominated bv a mixture of Br and PH13 in the Hell-Volharcl-Zelinskii (UVZ) reaction. 

Chapters 20 through 24 of this text discuss carbonyl compounds—aldehydes, ketones, acid halides, esters, amides, and carboxylic acids. The carbonyl group is perhaps the most important Functional group in organic chemistry, because its electron-deficient carbon and easily broken 7t bond make it susceptible to a wide variety of useful reactions. 

Draw and identify the structures of carbonyl compounds including aldehydes, ketones, carboxylic acids, esters, and amides. 

Another important part of Organic II is carbonyl chemistry. We look at the basics of the carbonyls in Chapter 9. It s like a family reunion where I (John, one of your authors) grew up in North Carolina — everybody is related. You meet aldehydes, ketones, carboxylic acids, acyl chlorides, esters, amides, and on and on. It s a quick peek, because later we go back and examine many of these in detail. For example, in Chapter 10 you study aldehydes and ketones, along with some of the amines, while in Chapter 11 we introduce you to other carbonyl compounds, enols and enolates, along with nitroalkanes and nitriles. 

Lithium aluminium hydride is a more powerful reducing agent than sodium borohydride and reduces most of the commonly encountered organic functional groups (see Table 7.3). It reacts readily with water and other compounds that contain active hydrogen atoms and must be used under anhydrous conditions in a non-hydroxylic solvent diethyl ether and THF are commonly employed. Lithium aluminium hydride has found widespread use for the reduction of carbonyl compounds. Aldehydes, ketones, esters, carboxylic acids and lactones can all be reduced smoothly to the corresponding alcohols under mild conditions. Carboxylic amides are converted into amines or aldehydes, depending on the conditions and on the... 

The classical Ugi four-component reaction (U-4CR) originally described by Ugi et al. [1] consists in the reaction of a primary amine, a carbonyl compound (aldehyde or ketone), an isocyanide, and a carboxylic acid to afford a-acylamino amides 36 (Scheme 7.14) [31, 32], Rapidly, other components or adducts were found to give the Ugi-4CR—that is, ammonia, hydroxylamine, or hydrazine as amine component or thiosulfates [33], thiocarboxylic acids [34], isothiocyanic acids [35], hydrazoic acid [36], or carbonic acid monoesters... 

In an aldol reaction, an enolizable carbonyl compound reacts with another carbonyl compound that is either an aldehyde or a ketone. The enolizable carbonyl compound, which must have at least one acidic proton in its a-position, acts as a nucleophile, whereas the carbonyl active component has electrophilic reactivity. In its classical meaning the aldol reaction is restricted to aldehydes and ketones and can occur between identical or nonidentical carbonyl compounds. The term aldol reaction , in a more advanced sense, is applied to any enolizable carbonyl compounds, for example carboxylic esters, amides, and carboxylates, that add to aldehydes or ketones. The primary products are always j5-hydroxycarbonyl compounds, which can undergo an elimination of water to form a,j5-unsaturated carbonyl compounds. The reaction that ends with the j5-hydroxycarbonyl compound is usually termed aldol addition whereas the reaction that includes the elimination process is denoted aldol condensation . The traditional aldol reaction [1] proceeds under thermodynamic control, as a reversible reaction, mediated either by acids or bases. 

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