Carboxylic acid anhydrides, carbonylation

The O acylation of phenols with carboxylic acid anhydrides can be conveniently catalyzed m either of two ways One method involves converting the acid anhydride to a more powerful acylatmg agent by protonation of one of its carbonyl oxygens Addi tion of a few drops of sulfuric acid is usually sufficient... 

Step 2 Structurally O acylisoureas resemble carboxylic acid anhydrides and are powerful acylatmg agents In the reaction s second stage the amine adds to the carbonyl group of the O acylisourea to give a tetrahedral intermediate... 

Similar additions have been successfully carried out with carboxylic acids, anhydrides, acyl halides, carboxylic esters, nitriles, and other types of compounds. These reactions are not successful when the alkene contains electron-withdrawing groups such as halo or carbonyl groups. A free-radical initiator is required, usually peroxides or UV light. The mechanism is illustrated for aldehydes but is similar for the other compounds ... 

An extensive nmr study of the protonation of acyclic carboxylic acid anhydrides in HSO3F—SbFs—SO2 solution at —70°C has proved the formation of carbonyl-protonated anhydrides [206],... 

Carboxylic acid anhydrides cleave immediately when protonated even in HSC F-SbFs solution at low temperature (—80°C).541 569 Monoprotonated anhydrides 291, however can easily be generated reacting oxocarbenium ions (acyl cations) with carboxylic acids in SO2 solution. Rapid intramolecular proton transfer between the carbonyl groups was observed by NMR. 

Theoretically, the Karl Fischer reagent can be used for the determination of any organic functional group that will undergo a quantitative and stoichiometric reaction to produce or consume water under conditions that do not interfere with the titration. These include alcohols, carboxylic acids, acid anhydrides, carbonyl compounds, primary and secondary amines, nitriles, and peroxides. 

In those Instances where coupling Is observed In basic salt-initiated polymerizations (66) It may be explained by reaction of a portion of the Initiator with the 2-carbonyl of an NCA. This would generate a carboxylic acid salt that can react with an NCA to yield a carbamate Ion that contains a carboxylic acid anhydride function. 

PROBLEM 2.1 Many compounds contain more than one functional group. The structure of prostaglandin fj, a hormone that regulates the relaxation of smooth muscles, contains two different kinds of carbonyl groups. Classify each one (aldehyde, ketone, carboxylic acid, ester, amide, acyl chloride, or carboxylic acid anhydride). 

Carbon suboxide, 52 Carbonylation, 148, 149, 216 Carbonyl chlorofluoride, 48, 54 Carbonyl cyanide, 60-61 N,N -Carbonyldiimidazole, 61 1,1-Carbonyldi-l,2,4-triazole, 61 N-Carbonylsulfamic acid chloride (N-Carbonylsulfamyl chloride), 61 Carboxamides, 270 Carboxamine-N-sulfochlorides, 70 p-Carboxybenzenediazonium chloride, 62 p-Carboxybenzenesulfonazide, 62 Carboxylation, 15, 16 Carboxylic acid anhydrides, 133 Carboxylic acid N,N-dimethylamines, 153 Carboxylic anhydrides, 409-410 p-Carboxyphenylhydrazones, 62 Cardenolides, 130, 131 (S-Carotene, 19 /-Carvone, 451, 452 i//-Caryophyllene, 149, 150 Catechol, 65, 233 Catechol amines, 159 Catechyl phosphorus tribromide, 63 Catechyl phosphorus trichloride, 63 Cis-Cecropia juvenile hormone, 261 Cedrene, 234, 235 a-Cedrene, 349 /3-Cedrene, 349 Cendranoxide, 234, 235 Cephalosporin C, 48 Ceric ammonium nitrate, 63-65 Ceric sulfate. 65 Cesium fluoride, 346 trans-Chalcone oxide, 422 Chalcone phenylhydrazones, 257, 258 Chalcones, 406 Chloramine, 65-66, 69 Chloranil, 66-67, 113, 116, 401,454... 

A considerable amount of research has been concerned with the nature of the electrophiles that are involved in Friedel-Crafts acylation reactions. We will summarize the main points. Acyl halides and carboxylic acid anhydrides have been known, for many years, to form stable complexes with a variety of acid catalysts. A well-defined product is formed between acetyl fluoride and boron trifluoride at low temperatures. Analytical and conductivity data characterized the material as acetylium tetrafluoroborate, and this was further confirmed by IR measurements. In the system acetyl chloride-aluminum chloride the acetylium ion can be differentiated from the donor-acceptor complex involving the carbonyl group by means of their IR carbonyl stetching frequencies. A number of other acyl fluorides have been shown to form well-defined acylium salts by interaction with a number of metal fluorides. Acylium salts can also be prepared from acyl chlorides by means of metathetical reactions involving anhydrous salts such as silver hexafluoroantimonate. As well as characterization by means of IR spectroscopy, acylium salts have been studied in non-nucleophilic solvents by NMR spectroscopy. The NMR data for the ben-... 

In infrared spectra, the carbonyl group is usually indicated by a single strong and sharp absorption. However, in the case of carboxylic acid anhydrides, R—C—O—C—R, two peaks are observed even though the two carbonyl groups are chemically equivalent. 

Fallacious acetate I triphenylphosphine I sodium salt Carboxylic acid anhydrides from carboxylic acid salts and iodides Carbonylation under mild conditions... 

The process of substitution undertaken on carboxylic acids and the derivatives of carboxylic acids (anhydrides, acid halides, esters, amides, and nitriles) generally involves a series of replacement processes. Thus, individually, substitution may involve replacement of (a) the proton attached to oxygen of the -OH group (i.e., ionization of the acid) (b) the hydroxyl (-OH) portion of the carboxylic acid (or derivative) (e.g., esterification) (c) the carbonyl oxygen and the hydroxyl (-OH) (e.g., orthoester formation, vide infra) (d) the entire carboxylic acid functionality (e.g., the Hunsdiecker reaction, already discussed Scheme 9.101) and the decarboxylation of orotic acid (as orotidine monophosphate) to uracil (as uridine monophosphate)—catalyzed by the enzyme orotidine monophosphate decarboxylase (Scheme 9.115) or (e) the protons (if any) on the carbon to which the carboxylic acid functional group is attached (e.g., the Dieckman cycUzation, already discussed earlier, c Equation 9.91). Indeed, processes already discussed (i.e., reduction and oxidation) have also accomplished some of these ends. Some additional substitutions for the carboxylic acid group itself are presented in Table 9.6, while other substitutions for derivatives of carboxylic acids are shown in Tables 9.7-9.10 and discussed subsequently. 

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