Carbon dioxide carboxylic acids prepared with

Oxidative decarboxylation. Dianions of carboxylic acids (prepared with LDA) react with O2 in ether at -78° to form a-hydroperoxy acids. These need not be isolated when DMF dimethyl acetal or an acid is added at room temperature, carbon dioxide is lost with formation of a carbonyl compound. 

The methyl ester has also been obtained by esterification of cyclopentanecarboxylic acid.8 The acid, in turn, has been prepared by the Favorskii rearrangement,6 7 9-11 by the reaction of cyclopentyl Grignard reagent with carbon dioxide,12 by the carbonylation of cyclopentyl alcohol with nickel carbonyl13 or with formic acid in the presence of sulfuric acid,14 and by the hydrogenation of cyclopentene-1-carboxylic acid prepared from ethyl cyclopentanone-2-carboxylate 15 or from cyclopentanone cyanohydrin.16... 

Carboxylic acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthalic acid [88-99-3], react with aryl isocyanates to yield the corresponding N-aryl phthalimides (73). Reactions with carboxylic acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature applications where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). 

Silver salts of carboxylic acids react with bromine or chlorine in an inert solvent to give carbon dioxide, a silver halide, and the halide containing one less carbon atom than the acid. The method has been reviewed. " Both low- and high-molecular-weight aliphatic bromides have been prepared. "t i i The degradation of silver salts of aromatic acids is complicated by nuclear halogenation." The procedure is valuable as a step in the synthesis of oi-bromo esters (C, to C,) from dicarboxylic acids. ... 

Direct introduction of the carboxyl group into an aromatic ring is accomplished with urea hydrochloride, phosgene, oxalyl chloride, or carbon dioxide. Carboxylation of benzene is effected in 15-58% yields by treating with liquid phosgene and aluminum chloride. No catalyst is required in the conversion of dimethylaniline and phosgene to p-dimethyl-aminobenzoic acid (50%). 9-Anthroic acid (67%) is prepared from anthracene by heating to 240° with oxalyl chloride and nitrobenzene. ... 

Carboxylic acids could be prepared from compounds containing an active hydrogen atom with dry carbon dioxide in the presence of 2-12 mol equiv. of DBU at ambient temperature in dimethylformamide or dimethyl sulfoxide, or without solvent (74CL427 77JAP(K)202). The yields of the carboxylic acids increased with the pressure of carbon dioxide (77JAP(K)202). 

In the Hunsdiecker reaction, the silver salt of a carboxylic acid, prepared by treating the acid with silver oxide, is treated with a halogen. Bromine is the usual reagent, but iodine may also be used. Carbon dioxide is evolved and the corresponding alkyl halide is obtained, usually in fair to good yield. 

As can be seen from these examples, a great number of exceptional carboxylic acids can be prepared starting from CO2 with the aid of nickel complexes, but up to the present only stoichiometrically. However, if phenyl isocyanate is used which has a structure very analogous to carbon dioxide, a catalytic reaction with ethene occurs in the presence of nickel(0) complexes [17]. When a mixture of phenyl isocyanate, nickelbis(cyclooctadiene) and triphenylphosphine is initially treated with ethene under pressure (3 bar) at -50°C and then heated for 2 d at 60 C, acrylanilide is obtained after protonation in about 180 % yield with respect to nickel(0). This corresponds to 1,8 catalytic cycles (Figure 7). 

The Grignard reaction is used synthetically to prepare secondary alcohols from aldehydes and tertiary alcohols from ketones. The Grignard reagent will react with esters twice to give tertiary alcohols. Synthetically, it also can be allowed to react with carbon dioxide to give carboxylic acids and with oxygen to give hydroperoxides ... 

The triethylamine salt of a carboxylic acid, prepared by the reaction of triethylamine and a carboxylic acid 1372, undergoes reaction with one-sixth of an equivalent of triphosgene to give an equimolar mixture of the carboxylate and the predicted intermediate acyl chloroformate 1373 [1042]. Nucleophilic displacement of the chloroformate function by the carboxylate affords the desired anhydride 1374, with concomitant formation of triethylammonium chloride as a precipitate and carbon dioxide gas. The reaction reaches completion in minutes. The solvents of choice have been THF or ethyl acetate, and no evidence for the formation of diacyl carbonates as potential by-products of the reaction has been found. The reaction has been used to prepare the anhydrides from both electron-rich and electron-deficient carboxylic acids (see below) [1042]. 

Pyridine-carboxylic acids have been prepared by the reaction of the 3-pyridyl Grignard reagent 36a and of 2- and 3-pyridyl lithium with carbon dioxide. Nicotinic acid isotopically labelled in the carboxyl group has been obtained in this way . The reaction is especially useful for preparing pyridine-acetic acids and has been applied to 2-2t t and 4-picolyl lithium i. Under conditions where phenyl lithium adds to the azomethine linkage of 4-picoline, 2-phenylpyridine-4-acetic acid i is produced. 2,6-Lutidine gave 6-methylpyridine-2-acetic acid, but the reaction failed with 2-methyl-6-phenoxypyridine . ... 

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... 

Manufacture. Several methods have been described for the preparation of -hydroxyben2oic acid. The commercial technique is similar to that of salicylic acid, ie, Kolbe-Schmitt carboxylation of phenol. The modification includes the use of potassium hydroxide in place of caustic (51). The dried potassium phenate is heated under pressure, 270 kPa (2.7 atm) or more, with dry carbon dioxide at 180—250°C. The potassium salt [16782-08-4] of Nhydroxyben2oic acid forms almost quantitatively and can be converted to free acid by using a mineral acid. 

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 synthesis of cinnoline was reported by von Richter in 1883. The diazonium chloride 5 which was obtained from o-aminophenylpropiolic acid (4), was heated in water at 70°C to provide the 4-hydroxycinnoline-3-carboxylic acid (6). When this acid 6 was heated above its melting point, carbon dioxide was liberated and 4-hydroxycinnoline (7) was obtained. Distillation of 4-hydroxycinnoline (7) with zinc dust furnished a small amount of oil, which was assumed to be cinnoline (8). The preparation of 4-hydroxycinnoline (7) was repeated by Busch and Klett, although in lower yield when compared to the original report. Busch and Rast later converted the 4-hydroxycinnoline (7) successfully to cinnoline (8) via the 4-chlorocinnoline (9). ... 

The Grignard reagents prepared from the activated magnesium appear to react normally with electrophiles. Thus reactions with proton donors, ketones, and carbon dioxide afford hydrocarbons, alcohols, and carboxylic acids, respectively. The reductive coupling of ketones to pinacols had also been accomplished with the activated magnesium. ... 

A V -Carbonyldiimidazole (CDI) is prepared in a convenient and safe procedure from phosgene and imidazole as a non-toxic crystalline compound (m.p. 116-118 °C).[5],[6] It reacts almost quantitatively at room temperature or by short and moderate heating with an equimolar quantity of a carboxylic acid in tetrahydrofuran, chloroform, or similar inert solvents within a few minutes to give the corresponding carboxylic acid imidazolide, which is formed under release of carbon dioxide, together with one equivalent of readily separable and recyclable imidazole.Thus, this reaction leads under very mild conditions to the activation of a carboxylic acid appropriate for transacylation onto a nucleophile with an alcohol to an ester, with an amino compound to an amide or peptide, etc. 

The hydroquinone process was developed by BASF [12]. Hydroquinone-2,5-di-carboxylic acid is prepared by a modified Kolbe-Schmidt synthesis from hydroquinone and carbon dioxide. Subsequent reaction with arylamine in an aqueous-methanolic suspension in the presence of an aqueous sodium chlorate solution and a vanadium salt affords the product in good yield ... 

Amination (11) and solution carbonation (8) reactions were carried out as described previously. For solid-state carbonations, a benzene solution of poly(styryl)lithium was freeze-dried on the vacuum line followed by introduction of high-purity, gaseous carbon dioxide (Air Products, 99.99% pure). Analysis and characterization of polymeric amines (11) and carboxylic acids (8) were performed as described previously. Benzoyl derivatives of the aminated polystyrenes were prepared in toluene/pyridine (2/1. v/v) mixtures with benzoyl chloride (Aldrich, 99%). 

Most 1,2,3-triazolecarboxylic acids lose carbon dioxide when heated above the melting point. These reactions are often useful for the preparation of simpler triazoles, for example, in the synthesis of 1-vinyl-triazoles by decarboxylation of the corresponding 4-carboxylic acids. 4,5-Dicarboxylic acids normally lose 2 moles of carbon dioxide on heating above the melting point this is so, for example, with the u-triazole and with the 1-benzyltriazole but l-phenyltriazole-4,5-dicarboxylic acid preferentially decarboxylates at the 5-position, giving the 4-carboxylic acid. 6-Methyl-l-phenyl-4-carboxylic acid is reported to be de-carboxylated slowly in boiling benzene. ... 

The classical preparation of alkyllithium compounds by reductive cleavage of alkyl phenyl sulfides with lithium naphthalene (stoichiometric version) was also carried out with the same electron carrier but under catalytic conditions (1-8%). When secondary alkyl phenyl sulfides 73 were allowed to react with lithium and a catalytic amount of naphthalene (8%) in THF at —40°C, secondary alkyllithium intermediates 74 were formed, which finally reacted successively with carbon dioxide and water, giving the expected carboxylic acids 75 (Scheme 30) °. 

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