Carbonyl group anhydrides Carboxylic acids Esters Ketones

Carboxylic acids, esters, ketones, and aldehydes. These compounds, along with acid anhydrides, acid halides, amides, and others, all possess a double bond between carbon and oxygen, C=0, called a carbonyl group. The IR spectra of these compounds are easily recognized from the very strong C O stretching band between 1650 and 1850 cm The position of this band is very characteristic of the class of compound. 

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 ... 

Consequently, aldehydes and ketones are not as reactive as carbonyl compounds in which Y is a very weak base (acyl halides and acid anhydrides), but are more reactive than carbonyl compounds in which Y is a relatively strong base (carboxylic acids, esters, and amides). A molecular orbital explanation of why resonance electron donation decreases the reactivity of the carbonyl group is given in Section 17.15. 

In this chapter, we will be discussing the chemistry of carboxylic acids, esters, acyl halides, anhydrides, and amides. This is dominated by substitution, where one group is exchanged with another. Substitution is NOT possible for aldehydes and ketones, as you can t displace H or — they are hopeless leaving groups. First, let s review some nomenclature. The suffix for carboxylic acids is -oic acid and the carbonyl of the acid is always numbered as C-1. The acid takes precedence over most other functional groups. Some examples are shown in Figure 15.1. Notice that when we have both a ketone and an acid in the molecule, it is named as a carboxylic acid, and the ketone is described as oxo. ... 

The chemistry of the carbonyl group is probably the single most important aspect of organic chemical reactivity Classes of compounds that contain the carbonyl group include many derived from carboxylic acids (acyl chlorides acid anhydrides esters and amides) as well as the two related classes discussed m this chapter aldehydes and ketones... 

Note The frequencies given for the C=0 stretching vibrations for anhydrides, acid chlorides, esters, lactones, aldehydes, ketones, carboxylic acids and amides refer to the open chain or unstrained functional group in a nonconjugated system. If the carbonyl group is conjugated with a double bond or an aromatic ring, the frequency is 30 cm less. If it is... 

The major classes of carbonyl compounds include aldehydes, ketones, carboxamides, esters, carboxylic acids and anhydrides, and carbonyl halides (acyl halides). These groups differ in the identity of the substituent X on the carbonyl group. At this point we concentrate on these examples, but a number of other carbonyl derivatives have important roles in synthetic and/or biological reactions. These other compounds include acyl cyanides, acyl azides, A-acylimidazoles, 0-aryl esters, and thioesters. The carbonyl compounds are arranged below in the order of the increasing reactivity toward nucleophilic addition. 

Electrophilic substitution of the carbonyl compounds occurs the more easily the less the carbonyl group is stabilized by mesomerism. It is increasingly difficult in the series ketone — acid chloride — acid anhydride — ester, carboxylic acid — carboxyamide.546 This gradation can be illustrated by, for instance, the bromination of levulic acid (4-oxovaleric acid) with 2 moles... 

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