Carboxylic acid formation

The net effect of Fischer esterification is substitution of an -OH group by —OR. Aii steps are reversible, and the reaction can be driven in either direction by choice of reaction conditions. Ester formation is favored when a large excess of alcohol is used as solvent, but carboxylic acid formation is favored when a large excess of water is present. 

Addition of two oxygen atoms and two-electron oxidation (carboxylic acid formation)... 

Exceptionally, in Escherichia coli acireductone dioxygenase (enediol dioxygenase) carries out two enzymatic activities that are responsible for the salvage of methionine, but are encoded by the same gene. Whereas one enzyme is dependent on Fe and produces the ketoacid and formate (Figure 3.34a), the other that is nickel-dependent produces the carboxylic acid, formate, and CO (Figure 3.34b) (Dai et al. 1999). 

Strong acid-catalyzed tertiary carboxylic acid formation from alcohols or olefins and CO. 

J2.2.14 Carboxylic Acid Formation. Reimer-Tiemann Reaction... 

Dehydrogenation of an aldehyde hydrate leads to carboxylic acid formation. 

Montevecchi PC, Manetto A, Navachhia ML, Chatgilialoglu C (2004) Thermal decomposition of the tert-butyl perester of thymidine-5 -carboxylic acid. Formation and fate of the pseudo-C4 radical. Tetrahedron 60 4303-4308... 

Similar results are obtained with 2-adamantanol which rearranges to 1 -ada-mantanol (> 98 %) at 28°C in sulfuric acid. An equilibrium mixture containing small amounts of 2-adamantanol is rapidly achieved fromeither direction67 6 K This isomerization is one of the mechanistic bases for the preparation of ada-mantanone by the reaction of adamantane with sulfuric acid at 77°C (see Section V.A.l) 57> 67> 691. The Koch-Haaf carboxylation of 2-adamantanol similarly results in predominant 1-adamantyl carboxylic acid formation unless highly dilute reaction conditions are employed 57> 7°). 

The hydrolysis of nitriles, which are organic molecules containing a cyano group, leads to carboxylic acid formation. These hydrolysis reactions can take place in either acidic or basic solutions. 

In the presence of alkyl halides and base, alkyltetracarbonylcobalt complexes are formed with Co2(CO)8 these species [RCo(CO)4] carbonylate a wide range of aryl halides or heterocyclic halides to various products, which depend upon the specific conditions. In the presence of alcohols, carboxylic esters are formed. Under phase transfer conditions and with iodomethane, mixtures of methyl ketone and carboxylic acid formation are realized (equation 207). In the presence of sodium sulfide or NaBH4 in water-Ca(OH)2 (equation 208) good amounts of double carbonylation are realized under very mild conditions412-414. 

For example, the functional group represented by FG might be an amine, and the functional group represented by FG might be a carboxylic acid. Formation of an amide bond between the amine of one monomer and the carboxylic acid of the other results in the formation of a dimer. Continuation of this process results in polymer formation. Let s examine some specific examples to better understand how this process works. 

The primary processes in PET probably involve scission of the 0(=( 0 backbone link, a Norrish Type I cleavage (reaction II, Table l) and an Intramolecular H-abstraction, a Norrish Type II process (reaction III, Table l) ( ). Carboxylic acid formation in... 

Carboxylic acid formation [quantum yield 8xl0 m elnst ( )] is a much more efficient process than CO elimination or Photo Fries rearrangement observed during vacuum irradiation (Table l). Carboxylic acid formation in PmPiPA films and fibers has been observed by IR spectroscopy (at 1T20 cm ) and by potentiometrlc titrations on dissolved samples ( ). 

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