Formation of Carboxylic Acids

REACTIONS OF ALDEHYDES AND KETONES Formation of Carboxylic Acids 

Aldehydes can be oxidized to carboxylic acids using oxidizing agents such as potassium permanganate or potassium dichromate. 

Aldehydes selectively react in a solution of silver-ammonia complex called Tollen s reagent. A sample reaction is given below. 

---

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]. 

The tri/luorovinyloxy group is cleaved by potassium persulfate [37J The pnmanly formed dihydroxy compound undergoes spontaneous hydrolysis with the formation of carboxylic acid (equation 29)... 

Many procedures for the formation of carboxylic acid amides are known in the literature. The most widely practiced method employs carboxylic acid chlorides as the electrophiles which react with the amine in the presence of an acid scavenger. Despite its wide scope, this protocol suffers from several drawbacks. Most notable are the limited stability of many acid chlorides and the need for hazardous reagents for their preparation (thionyl chloride, oxalyl chloride, phosgene etc.) which release corrosive and volatile by-products. Moreover, almost any other functional group in either reaction partner needs to be protected to ensure chemoselective amide formation.2 The procedure outlined above presents a convenient and catalytic alternative to this standard protocol. 

An important problem encountered with polymer electrodes is that of overoxidation. It occurs after reversible charging of the electrode at high oxidation potentials and leads to polymer degeneration. The results of thorough studies show that such degenerative mechanisms are promoted by the nucleophilicity of the solvent. Especially the activity of water leads to the formation of quinone-type compounds, to the cleavage of C—C bonds, the liberation of CO2, and the formation of carboxylic acids Hence, there is a clear tendency to avoid both nucleophile solvents... 

The phosphinic isocyanates (116) and isothiocyanates (117) react with oxygen, nitrogen, and phosphorus nucleophiles by attack at carbon rather than phosphorus. Phenyl phosphonodichloridate has been recommended as a useful reagent for the activation (presumably by mixed anhydride formation) of carboxylic acids for conversion to amides and hydrazides. ... 

C[bicarbonate] and mass spectrometry were used to demonstrate the formation of carboxylic acids during the sulfidogenic mineralization of naphthalene and phenanthrene (Zhang and Young 1997). 

There are two pathways for the degradation of nitriles (a) direct formation of carboxylic acids by the activity of a nitrilase, for example, in Bacillus sp. strain OxB-1 and P. syringae B728a (b) hydration to amides followed by hydrolysis, for example, in P. chlororaphis (Oinuma et al. 2003). The monomer acrylonitrile occurs in wastewater from the production of polyacrylonitrile (PAN), and is hydrolyzed by bacteria to acrylate by the combined activity of a nitrilase (hydratase) and an amidase. Acrylate is then degraded by hydration to either lactate or P-hydroxypropionate. The nitrilase or amidase is also capable of hydrolyzing the nitrile group in a number of other nitriles (Robertson et al. 2004) including PAN (Tauber et al. 2000). 

After identifying the optimal etherification conditions, our attention turned to isolation of 18 in diastereomerically pure form. Diastereomers 18 and 19 were not crystalline, but, fortunately, the corresponding carboxylic acid 71 was crystalline. Saponification of the crude etherification reaction mixture of 18 and 19 with NaOH in MeOH resulted in the quantitative formation of carboxylic acids 71 and 72 (17 1) (Scheme 7.22). Since the etherification reaction only proceeded to 75-80% conversion, there still remained starting alcohol 10. Unfortunately, all attempts to fractionally crystallize the desired diastereomer 71 from the crude mixture proved unfruitful. It was reasoned that crystallization and purification of 71 would be possible via an appropriate salt. A screen of a variety of amines was then undertaken. During the screening process it was discovered that when NEt3 was added... 

Apart from the isomeric relation between 7 and 1, the appearence of the ternary associate now showing coordinatoclathrate properties gives a reasonable motive for putting up these compounds for discussion here. The dimer formation of carboxylic acids known from the related inclusions of 1 and 26 does not occur here. Instead, one observes a well-balanced system of H-bonds between groups of different acid/base properties. It is left to future studies to find other acid/base combinations which give a comparable situation. Actually, such H-bonded systems remind one of the multiple non-bonded interactions at the active centers of enzymes. 

The highest surface activity of fraction A3 extracted from shale oil needs to be explored in detail in order to understand this very unique phenomena. The benchmark experiments performed by Lee et al. (22) in studies of dissociation phenomena of Stuart oil shale in an alkaline environment proved the formation of carboxylic acids as it was verified from GC results. In another study by Lee et al. (23), it was shown that the hydroxyl ions from an alkaline solution could decompose the silicate and aluminasilicate structures in oil shale samples, provided that ultrasonic radiation and electrolytic current were simultaneously applied. 

In the Grignard reagent, the alkyl radical acts like a carbanion as shown by its reactions with C02 leading to the formation of carboxylic acids... 

The strategy pursued to elucidate the metabolism of AG was to postulate a mechanism based on the known degradation pathway of the structurally related surfactant LAS. This exclusively proceeds via co-oxidation of the alkyl chain, resulting in the formation of carboxylic acids, which are then further broken down through (3-oxidations as described previously. The corresponding pathway relevant to AG is shown in Fig. 5.1.17. From the putative carboxylic acids that are theoretically possible, only the C4-glucamide acid could be detected (Fig. 5.1.18) [38] 3... 

As with fullerenes, carbon nanotubes are also hydrophobic and must be made soluble for suspension in aqueous media. Nanotubes are commonly functionalized to make them water soluble although they can also be non-covalently wrapped with polymers, polysaccharides, surfactants, and DNA to aid in solubilization (Casey et al., 2005 Kam et al., 2005 Sinani et al., 2005 Torti et al., 2007). Functionalization usually begins by formation of carboxylic acid groups on the exterior of the nanotubes by oxidative treatments such as sonication in acids, followed by secondary chemical reactions to attach functional molecules to the carboxyl groups. For example, polyethylene glycol has been attached to SWNT to aid in solubility (Zhao et al., 2005). DNA has also been added onto SWNT for efficient delivery into cells (Kam et al., 2005). 

Favorskii rearrangement org chem A reaction In which a-halogenated ketones undergo rearrangement in the presence of bases, with loss of the halogen and formation of carboxylic acids or their derivatives with the same number of carbon atoms. fa vor-ske, re-3 ran -m3nt)... 

Matsumura and Bousch (1966) isolated carboxy lest erase (s) enzymes from the soil fungus Trichoderma viride und a bacterium Pseudomonas sp., obtained from Ohio soil samples, that were capable of degrading malathion. Compounds identified included diethyl maleate, desmethyl malathion, carboxylesterase products, other hydrolysis products, and unidentified metabolites. The authors found that these microbial populations did not have the capability to oxidize malathion due to the absence of malaoxon. However, the major degradative pathway appeared to be desmethylation and the formation of carboxylic acid derivatives. 

Sulfuric acid can form ester derivatives with alcohols, though since it is a dibasic acid (pAla — 3, 2) it can form both mono- and di-esters. Thus, acid-catalysed reaction of methanol with sulfuric acid gives initially methyl hydrogen sulfate, and with a second mole of alcohol the diester dimethyl sulfate. Though not shown here, the mechanism will be analogous to the acid-catalysed formation of carboxylic acid esters (see Section 7.9). 

Formation of carboxylic acids by reduction in dimethylformamide of the carbon-halogen bond in die presence of carbon dioxide and using sacrificial anodes. 

Formation of carboxylic acid from alkyl halide using the hydrolysis of a nitrile. 

HNO3 leading to the formation of carboxyl acids, nitric acid ester, and nitro and nitroso compounds. Rate parameters for chemical degradation under different conditions have been investigated [106,107], The reaction of -dodecane with HNO3 is quite slow. 

The formation of carboxylic acids in these reactions may be a significant source of organic acids in air. Reaction (48a) appears to occur by at least two mechanisms. Thus, the addition of isotopically labeled H2lxO leads to the formation of carboxylic acid, some of which contains the 18 O label and some of which does not (Hatakeyama et al., 1981), suggesting mechanisms such as the following ... 

The insertion of carbon monoxide into azolylpalladium complexes proceeds readily and in most cases leads to the formation of carboxylic acid derivatives or ketones. In a modified version of the carbonylation 3-bromothiophene was reacted with carbon monoxide in the presence of sodium formate. This reagents converts the intermediate acylpalladium formate complex, through the release of carbon dioxide into the acylpalladium hydride (c.f 7.47.), which in turn releases thiophene carboxaldehyde as the sole product (6.62.),92 If sodium formate was replaced... 

Alkenes and Alkynes. A series of metal carbonyl cations, such as [Au(CO)n]+,287,288 [c-Pd( i-CO)2]2+,289 [Rh(CO)4]+,290 and [(Pt(CO)3)2]2+,291 was found to induce the formation of carboxylic acids from alkenes and CO in the presence of H2SO4 under mild conditions. A novel water-soluble Pd catalyst292 and Pd complexes of calixarene-based phosphine ligands293 showed high activity in the regioselective carboxylation of vinyl arenes to yield 2-arylpropionic acids or... 

Formation of carboxylic acids from ethylene, isobutylene, and 1-octene was observed by in situ 13C solid-state MAS NMR over H-ZSM-5 zeolite at 23-100°C.298 A systematic study with various Pd complexes revealed that styrene is transformed into 2-phenylpropionic acid as the major product when monophosphine ligands were applied, whereas 3-phenylpropionic acid was obtained in the presence of diphosphines 299... 

The most often-reported metallic systems used in the formation of carboxylic acids are most certainly those systems that involve a zero-valent nickel species as the active intermediate. Ochiai et al. reported on a bimetallic catalytic system which allowed the synthesis of various saturated carboxylic acid in good yields, under very mild conditions [53] (0.1 MPa C02, 4—8 h reaction time, temperatures ranging from room temperature to 323 K). The catalytic system was based on the use of organozinc reagents as carbon nucleophiles, which could be selectively carboxy-lated in the presence of Ni(acac)2 as the main catalyst. 

Addition of halogen fluorosulfates XOS02F (X=C1, Br, I) to fluoroolefins is considered an electrophilic reaction [8]. However, the question of whether this process is concerted or the reaction proceeds via an independent carbocationic intermediate (Eqs. 2 and 3) is still open. Formation of carboxylic acid esters as byproducts in the reaction of HFP with C10S02F, which was carried out in trifluoroacetic or heptafluorobutyric acids as solvents, could not be a solid proof of conjugate addition, since formation of esters may be a result of addition of C10C(0)Rf to olefin. These materials are known to be formed in the reaction of ClOS02F with fluorinated carboxylic acids, even at low temperature [99]. 

Saito et al. [107] investigated ozonolysis of polystyrene in carbon tetrachloride. Their results indicated the formation of carboxylic acids and,... 

Oxidation of carbohydrate or Strecker aldehyde by S-MnOz to form carboxylic acid, or formation of carboxylic acid during Strecker degradation... 

Banerjee, A. and Falvey, D.E. (1998) Direct photolysis of phenacyl protecting groups studied by laser flash photolysis an excited state hydrogen atom abstraction pathway leads to formation of carboxylic acids and acetophenone. Journal of the... 

---