Carboxylic acid with carbon dioxide

Exercise 26-7 1,3-Benzenediol (resorcinol) can be converted to a carboxylic acid with carbon dioxide and alkali. Would you expect 1,3-benzenediol to react more, or less, readily than benzenol Why Which is the most likely point of monosubstitution Explain. 

Methyl-1,2,5-oxadiazoles are lithiated on the methyl group by -butyllithium yielding the corresponding carboxylic acid with carbon dioxide ... 

In the case of sodium tris-(/>-nitrophenyl)-methide the carboxylation reaction with carbon dioxide to give the acid fails to take place, although less stable carbanions are readily carbonated.410... 

Many carboxylic acids lose carbon dioxide on either direct or sensitized irradiation, and in some cases (4.10 the evidence points to the operation of an initial electron-transfer mechanism rather than primary a-deavage. Cleavage occurs readily with acyl halides, and this can [ead to overall decarbonylation (4.11). Aldehydes also cleave readily, since the (0=)C—H bond is more prone to homolysis than the (0= C-C bond. This offers a convenient method for replacing the aldehydic hydrogen by deuterium in aromatic aldehydes (4.12. and a similar initial reaction step accounts for the production of chain-Iengtheped amides when formamide is irradiated in the presence of a terminal alkene (4.13). 

Reactions with Chloroformates, Carboxylic Acid Chlorides, Carbon Dioxide, Chlorotrimethylsilane and Nitrile Oxides... 

H0-C-(CH2)3CH3 oxidation of a terminal alkyne with warm, basic KMn04 cleaves the carbon-carbon bond, producing the carboxylic acid and carbon dioxide O O... 

That compound X has a peak near 3200 cm indicates that it has a terminal triple bond. The peak near 2100 cm Ms also associated with that triple bond. These facts surest that compound X is 1-hexyne, something that is confirmed by the results of its oxidation to a five-carbon carboxylic acid and carbon dioxide. 

Sodium bicarbonate. An unknown that is soluble in dilute NaOH solution should also be tested for its solubility in 0.6 M NaHC03. If it is soluble, the tentative conclusion is that a carboxylic acid group is present, owing to the formation of the water-soluble sodium salt (Eq. 25.5a) phenols are normally not deproto-nated in this medium (Eq. 25.5b). Dissolution should be accompanied by effervescence resulting from decomposition of the carbonic acid, H2CO3, formed from reaction of bicarbonate with the carboxylic acid, to carbon dioxide and water (Eq. 25.5a). 

Scheme 12.93. A representation of the conversion of 7,8-diaminononanoate (7,8-diaminopeiargonic acid) to the bisamide dethiobiotin (an imidazolidone) by carboxyl-ation with carbon dioxide (CO2) in the presence of ATP magnesium (Mg+ ) and dethiobiotin synthase (EC 6.3.3.3). X-ray of a mixed carbonic phosphate anhydride has lent support to this picture (PDB la82) (after Kack, H Gibson K. I Lindqvist, Y Schneider, G. Proc. Natl. Acad. Sci. tZXA., 1998,95,5495). With biotin synthase (EC 2.8.1.6), biotin results. EC numbers and some graphic materials provided in this scheme have been taken from appropriate links in a URL starting with http //www.chem.qmul.ac.uk/iubmb/enzyme/.

An alkyne with molecular formula C4H6 was treated with ozone followed by water to produce a carboxylic acid and carbon dioxide. Draw the expected product when the alkyne is treated with aqueous acid in the presence of mercuric sulfate. 

Treatment of Silver Salts with Halogens. Silver salts of carboxylic acids lose carbon dioxide when treated with chlorine or bromine, and alkyl halides are produced in good yield. Although this reaction... 

Carboxylic acids eliminate carbon dioxide when heated with soda lime or electrolyzed to produce paraffins (Kolbe reaction). The former is a more useful method in the laboratory. 

H2O Ozonolysis When treated with these reagents, an alkyne undergoes oxidative cleavage of the C C bond. Internal alkynes are converted into two carboxylic acids, while terminal alkynes are converted into a carboxylic acid and carbon dioxide. 

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). 

We ve seen how Grignard reagents add to the carbonyl group of aldehydes ketones and esters Grignard reagents react m much the same way with carbon dioxide to yield mag nesium salts of carboxylic acids Acidification converts these magnesium salts to the desired carboxylic acids... 

Section 19 11 Carboxylic acids can be prepared by the reaction of Gngnard reagents with carbon dioxide... 

Section 24 10 The Kolbe-Schmitt synthesis of salicylic acid is a vital step m the preparation of aspirin Phenols as their sodium salts undergo highly regioselective ortho carboxylation on treatment with carbon dioxide at elevated temperature and pressure... 

Resorcinol carboxylation with carbon dioxide leads to a mixture of 2,4-dihydroxyben2oic acid [89-86-1] (26) and 2,6-dihydroxyben2oic acid [303-07-1] (27) (116). The condensation of resorcinol with chloroform under basic conditions, in the presence of cyclodextrins, leads exclusively to 2,4-dihydroxyben2aldehyde [95-01-2] (28) (117). Finally, the synthesis of l,3-bis(2-hydroxyethoxy)ben2ene [102-40-9] (29) has been described with ethylene glycol carbonate in basic medium (118), in the presence of phosphines (119). Ethylene oxide, instead of ethyl glycol carbonate, can also be used (120). 

Alkylphenols undergo a carboxylation reaction known as the Kolbe Schmidt reaction. In the following example, the phenolate anion of /)-nonylphenol (15) reacts with carbon dioxide under pressure. Neutralization generates a sahcyhc acid (16) (10). 

Ca.rhoxyla.tlon, This is the process of iatroduciag a carboxyUc acid group iato a phenol or naphthol by reaction with carbon dioxide under appropriate conditions of heat and pressure. Important examples are the carboxylation of phenol and 2-naphthol to give sahcyhc acid and 2-hydroxy-3-naphthoic acid, respectively. 

Carboxylation (Section 19.11) In the preparation of a carboxylic acid, the reaction of a carbanion with carbon dioxide. Typically, the carbanion source is a Grignard reagent. 

The first report on the carboxylation of an a-sulfinyl anion showed that the lithium salt of (S)-(methylsulfmylmethyl)benzene treated with carbon dioxide afforded (/ ,SS)-2-(mcthyl-sulfinyDphenylacetic acid, which was isolated in 30% yield after crystallization of the crude product64. 

Phosphorus ylids react with carbon dioxide to give the isolable salts (48), which can be hydrolyzed to the carboxylic acids (49) (thus achieving the conversion RR CHX RR CHCOOH) or (if neither R nor R is hydrogen) dimerized to... 

Vitamin K is the cofactor for the carboxylation of glutamate residues in the post-synthetic modification of proteins to form the unusual amino acid y-carboxygluta-mate (Gla), which chelates the calcium ion. Initially, vitamin K hydroquinone is oxidized to the epoxide (Figure 45-8), which activates a glutamate residue in the protein substrate to a carbanion, that reacts non-enzymically with carbon dioxide to form y-carboxyglut-amate. Vitamin K epoxide is reduced to the quinone by a warfarin-sensitive reductase, and the quinone is reduced to the active hydroquinone by either the same warfarin-sensitive reductase or a warfarin-insensitive... 

The reaction of a carboxylic acid with N,Af -carbonyldiimidazolellH33 (abbreviated as CDI), forming an imidazolide as the first step followed by alcoholysis or phenolysis of the imidazolide (second step), constitutes a synthesis of esters that differs from most other methods by virtue of its particularly mild reaction conditions.t41,[5] It may be conducted in two separate steps with isolation of the carboxylic acid imidazolide, but more frequently the synthesis is carried out as a one-pot reaction without isolation of the intermediate. Equimolar amounts of carboxylic acid, alcohol, and CDI are allowed to react in anhydrous tetrahydrofuran, benzene, trichloromethane, dichloromethane, dimethylformamide, or nitromethane to give the ester in high yield. The solvents should be anhydrous because of the moisture sensitivity of CDI (see Chapter 2). Even such unusual solvent as supercritical carbon dioxide at a pressure of 3000 psi and a temperature of 36-68 °C has been used for esterification with azolides.[6]... 

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