Carboxylic acid Carbonyl compounds

Carboxylic acids. Carbonyl compounds undergo a-cleavage on exposure to NaOCl under microwave conditions. 

With certain reactants isocyanides undergo three-component condensation and with others four-component condensation.32 1 Three-component addition occurs when isocyanides react with the combinations carboxylic acid-carbonyl compound, hydrogen, azide-carbonyl compound, tropylium salt-water, or two molecules of hydrogen thiocyanate. 

It is particularly interesting, that some titanium and tantalum carbene complexes olefinate derivatives of carboxylic acids. These reagents are, moreover, much less basic than phosphorus ylides, and thus enable the olefination of strongly C-H acidic carbonyl compounds. 

Carboxylic acids aren t the only acidic carbonyl compounds. Acidity can occur in other ways for example, hydrogen atoms attached to a carbon adjacent to the carbonyl group (the a hydrogen atoms only, not the (i hydrogens)... 

As in all of these more complex syntheses, other routes to the target compound are possible. This route was chosen because the Grignard reaction introduces a double bond without removing functionality at carbon 3. Dehydration occurs in the desired direction to produce a double bond conjugated with the carboxylic acid carbonyl group. 

A MW-assisted protocol for the synthesis of azides, thiocyanates, and sulfones has been developed (Scheme 12) that has proved to be a useful alternative, as the use of environmentally deterimental volatile chlorinated hydrocarbons is avoided.All the reactions with these readily available halides or tosylates have shown significant increase in reactivity, thus reducing the reaction times with substantial improvement in the yields. Various functional groups such as ester, carboxylic acid, carbonyl, and hydroxyl were unaffected under the mild reaction conditions employed. This method involves simple experimental procedures and product isolation which avoids the use of phase-transfer catalysts, and is expected to contribute to the development of greener strategy for the preparation of various azides, thiocyanates, sulfones, and other useful compounds. 

Figure 3.45 shows the NMR spectra for an amide, a class of compounds with — NH2 substituted for the hydroxyl group of a carboxylic acid. The compound here is propiona-mide, CH3CH2CONH2. There are three unique carbon atoms, the carbonyl carbon in the amide and two alkyl carbons. From Fig. 3.39, the carbonyl carbon in an amide is expected to absorb in the 165-175 ppm range the peak occurs at 177 ppm in this spectrum. The methyl carbon is located at 10 ppm, while the methylene carbon appears at 29 ppm. The proton spectrum was discussed earlier, but it is worth noting again the two small broad peaks due to the nonequivalent amide protons at 6.3 and 6.6 ppm. 

Smoking is a slow process and it is not easy to control the process. Smoke contains phenolic compounds, adds, and carbonyls and smoke flavor is primarily due to the volatile phenolic compound [10,20,34]. Wood smoke is extranely complex and more than 400 volatiles have been identified [43]. Guillen and Manzanos [26] identified around 140 compounds in liquid smoke prepared from Thymus vulgaris wood. Polycyclic aromatic hydrocarbons are ubiquitous in the environment as pyrolysis products of organic matter. Their concentrations in smoked food can reach levels hazardous for human health, especially when the smoking procedure is carried out under uncontrolled conditions [46]. Wood smoke contains nitrogen oxides, polycyclic aromatic hydrocarbons, phenolic compounds, furans, carbonylic compounds, aliphatic carboxylic acids, tar compounds, carbohydrates. 

Primary and secondary alcohols (e.g., cyclohexanol) add to the carbon of the carbonyl of carboxylic acids and compounds derived from carboxyUc acids to form... 

Closely related to the carboxylic acids and nitriles discussed in the previons chapter are the carboxylic acid derivatives, compounds in which an acyl group is bonded to an electronegative atom or snbstituent that can act as a leaving group in the nucleophilic acyl substitution reaction that we saw briefly in the Preview of Carbonyl Chemistry ... 

Besides carboxylic acids, carbonylation can give their derivatives or ketones if other nucleophiles were used to cleave the acylpalladium complex. Thus, esters and amides are formed with alcohols and amines, while ketones can be obtained in the presence of such carbanion synthons as organometallic compounds. Certainly, these processes leave a small margin for the intervention of water in any form, as in the presence of water the competition between the different nucleophiles would lower the selectivity, as, for example, in the... 

These substances, as well as the parent compound, are p-keto esters and undergo hydrol3rtio cleavage in two directions. One type of cleavage, ketonlc hydrolysis, is effected by the action of dilute caustic alkali in the cold, followed by acidification and boiling the free acetoacetic acid produced has a carboxyl and carbonyl group on the same carbon atom and therefore readily undergoes decarboxylation to yield a ketone, for example ... 

Supplement 1952 2666-3031 Carbonyl compounds Ethylene carbonate, 100. Piperonal, 116. Thioindigo, 177. Fluorescein, 222. Carboxylic acids Piperonylic acid, 269. Amines, 328. Three Cyclic Oxygens, 381. Four Cyclic Oxygens, 433. Fiite Cyclic Oxygens, 459.. . . ... 

Supplement 1953 3242-3457 Hydroxy-carboxylic acids, 190 In i doxylic acid, 226. Carbonyl-carboxylic acids, 284. i Sulphonic acids, 386 Quinoline sul-phonic acid, 390. Amines, 419 2-Aminopyridine, 428. Amino-carboxylic acids, 541 Tryp- tophane, 545. Hydrazines, 563. Azo. compounds, 572. Diazo compounds, 590. ... 

Formation of carboxylic acids ami their derivatives. Aryl and alkenyl halides undergo Pd-catalyzed carbonylation under mild conditions, offering useful synthetic methods for carbonyl compounds. The facile CO insertion into aryl- or alkenylpalladium complexes, followed by the nucleophilic attack of alcohol or water affords esters or carboxylic acids. Aromatic and a,/ -unsaturated carboxylic acids or esters are prepared by the carbonylation of aryl and alkenyl halides in water or alcohols[30l-305]. 

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 ... 

Two aldehydes two ketones or one aldehyde and one ketone may be formed Let s recall the classes of carbonyl compounds from Table 4 1 Aldehydes have at least one hydrogen on the carbonyl group ketones have two carbon substituents—alkyl groups for example—on the carbonyl Carboxylic acids have a hydroxyl substituent attached to the carbonyl group... 

Oxidation of an alcohol yields a carbonyl compound Whether the resulting carbonyl compound is an aldehyde a ketone or a carboxylic acid depends on the alcohol and on the oxidizing agent... 

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