Uses of Carboxylic Acids

Carboxylic acids are used as intermediates in the preparation of esters, amides, acid anhydrides, and acid chlorides. Esters are formed from carboxylic acids and alcohols when the mixture is heated in the presence of a mineral acid 

Physical properties acid acid acid acid 

Solubility solvent in water (g/IOO g) Complete Complete Complete Complete 

Source data compiled from product literature of Hoechst Celanese Chemical. 

Acetic acid is both a reactant and solvent in the manufacture of cellulose acetate, polyester fibers, and plastics. Other products that utilize acetic acid as a reactant include vinyl acetate, ester solvents, dyes, metallic salts, pharmaceuticals, and pesticides. Formic acid is used in textile dyeing and finishing, leather tanning and treatment, pharmaceuticals, and the synthesis of the versatile methyl formate solvent. n-Butanoic acid is used in the preparation of cellulose acetate butyrates used for lacquers and molding plastic compositions. The acid is also used for the production of useful coating ester solvents, plasticizers, and pharmaceuticals. 

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Guo et al. [70,71,73] recently attempted to hydrogenate NBR in emulsion form using Ru-PCy complexes. However, successful hydrogenation can only be obtained when the emulsion is dissolved in a ketone solvent (2-butanone). A variety of Ru-phosphine complexes have been studied. Crosslinking of the polymer could not be avoided during the reaction. The use of carboxylic acids or first row transition metal salts as additives minimized the gel formation. The reactions under these conditions require a very high catalyst concentration for a desirable rate of hydrogenation. 

FIGURE 15.3 PLC separation of carboxylic acids from soluble organic matter with the use of carboxylic acids esterification based on experimental data given in Reference 36, Reference 67 to Reference 69, and Reference 102 to Reference 104. 

Although related reactions have also been done under low pressures/ very low rates of product formation are observed (8/10/11). We have found/ however, that a ruthenium carbonyl catalyst is quite active for converting H2/CO to methanol under moderate pressures (below 340 atm). More significantly, we also discovered that an ethylene glycol product could be obtained from this catalyst by use of carboxylic acid promoters or solvents (12) This remarkable and intriguing promoter effect deserved, we felt, further mechanistic investigation... 

Carboxilic acid flotation of malachite has been commercially used for over 70 years. This collector is prepared by heating a mixture of hydrolysed palm oil (or oleic acid) and fuel oil in a 3 1 ratio. This mixture is manly used for recovery of malachite from siliceous ores. The use of carboxylic acid for malachite flotation from carbonaceous ores resulted in both reduced concentrate grade and recovery. 

Some of the most remarkable achievements include microencapsulation in polystyrenes such as entrapped 0s04 for olefin hydroxylation (exploiting the interaction between n-electrons of benzene rings of the polystyrenes used as polymer backbones and the vacant orbitals of the catalysts) 5 polyurea-entrapped palladium (PdEnCat)6 for a multiplicity of C C forming reactions and the use of carboxylic acid-functionalized polymer (FibreCat).7 In general, however, metal leaching cannot be avoided. The PdEnCat catalyst, for instance, leaches some 4% of palladium per catalytic reaction run. 

In addition to the methods previously described in this chapter, there are numerous other ways to make aldehydes and ketones, depending on the stcirting materials. These include using alkynes, doing a Friedel-Crtifts acylation of an acid chloride and an aromatic compound, using organic nitriles, and the use of carboxylic acid. We examine each of these in the following sections. 

Aliphatic carboxylic adds are an important and widely used class of commercial chemicals. The commertial uses of carboxylic acids include synthetic intermediates, lubricants, catalysts, and preservatives, to name just a few. Some carboxylic adds cause liver (hepato) toxicity, most notably valproic add (2-propylpentanoic add) (12), and 2-ethylhexanoic add, (13). Although relatively few carboxylic adds cause liver toxicity, when it does occur it can be severe [49]. 

In Chapter 2 the DSC technique is discussed in terms of instruments, experimental methods, and ways of analysing the kinetic data. Chapter 3 provides a brief summary of epoxy resin curing reactions. Results of studies on the application of DSC to the cure of epoxy resins are reviewed and discussed in Chapter 4. These results are concerned with the use of carboxylic acid anhydrides, primary and secondary amines, dicyanodiamide, and imidazoles as curing agents. 

The use of carboxylic acids for the removal of iron(III) from solutions of the rare-earth metals has been reported,38 but has not been described in detail. The stoichiometries of the extracted complexes of iron(III) have not been clearly established. The n-decanoic acid complex has been variously described as (FeA3)3 and Fe3A9 x(OH) (HA) 51 or [Fe(OH)A2]2 and [Fe(OH)2A-HA]2,57 the H-octanoic acid complex as (FeA3-H20)3,58 the naphthenic acid complex as FeA3,47 and that of Versatic 10 acid as [FeA3(HA)J>, or [Fe(OH)A2]3.59... 

The detection of aromatic carboxylates via the formation of ternary complexes using lanthanide ion complexes of functionalised diaza-crown ethers 30 and 31 has been demonstrated [134]. Like the previous examples, these complexes contained vacant coordination sites but the use of carboxylic acid arms resulted in overall cationic 2+ or 1+ complexes. Furthermore, the formation of luminescent ternary complexes was possible with both Tb(III) and Eu(III). A number of antennae were tested including picolinate, phthalate benzoate and dibenzoylmethide. The formations of these ternary complexes were studied by both luminescence and mass spectroscopy. In the case of Eu-30 and Tb-30, the 1 1 ternary complexes were identified. When the Tb(III) and Eu(III) complexes of 30 were titrated with picolinic acid, luminescent enhancements of 250- and 170-fold, respectively, were recorded. The higher values obtained for Tb(III) was explained because there was a better match between the triplet energy of the antenna and a charge transfer deactivation pathway compared to the Eu(III) complex. 

Figure 30 Use of carboxylic acid groups in postesterification and amidation reactions. The precursor acid functionality is distributed aroimd the tubes and concentrated at the open ends. For clarity, one substitution with n multiples is illustrated...

In order to construct crystals of this required structure type, we applied some empirical rules of packing. We avoided the use of carboxylic acids or primary amides, since molecules containing these functional groups generally pack in centrosymmetric or Mfifi / -centrosymmetric structures. Instead, we selected ester moieties as X and Y, because in many crystals bearing these functional groups an attractive interaction between carbonyls and phenyls of adjacent molecules has been observed which would juxtapose the double bonds, in our case, at the correct distance and in the required geometry (Scheme 3). ° Non-equivalence between the two reactive sites was... 

The use of carboxylic acid esters as protective groups for alcohols is limited since they may undergo acyl substitution, hydrolysis or reduction. Reagents used for the preparation of esters in the presence of EtgN or pyridine are AcjO, AC2O-DMAP (note that DMAP increases the rate of acylation of alcohols with AcjO by a factor of 10" ), PhCOCl, (PhC0)20, and r-BuCOCl (pivaloyl chloride)." Deprotection of esters is usually done under basic conditions. ... 

Esterification of carboxylic acid results in a reverse polarity change and thus can be exploited in the design of aqueous base developable negative resists especially for 193 nm lithography. As mentioned earlier, 193 nm resists are predominantly based on the use of carboxylic acid as a polar group for good transparency. 

In this chapter, only special examples of stoichiometric acylation will be commented. For example, reactions showing extraordinary level of regiose-lectivity promoted by proximity or metal template effects are described. Moreover, examples of efficient use of carboxylic acids and esters as acylating agents under soft experimental conditions in combination with ecocompatible solvents are stressed as new and practicable synthetic methods. Studies on the highly efficient multistep s)mthesis of polyfunctional compounds via bis-acylation and alkylation-acylation processes are commented upon, and some mechanistic details are also shown. 

The mesoporous aluminosilicate AlMCM-41-type material, prepared from BEA zeolite seeds, can be utilized as catalyst in the acylation of anisole with acyl chloride with the aim of improving the transport of the reactants, especially for the relatively hindered molecules such as octanoyl chloride. The catalyst shows good activity, being para-octanoyl anisole obtained in 90% yield after 1 h. As commonly observed, the use of carboxylic acid as acylating agent results in a slower process (-20% yield after 26 h) due to its lower electrophilicity and the production of water that inhibits the active sites of the zeolite, as previously observed by Beers et al. ... 

The dependence of the plasmon band on the dielectric constant of the surrounding medium in metal nanocrystals had been used to detect binding events taking place at the ligand shell. Thus, Au nanocrystals could colorimetrically determine the successful hybridization of oligonucleotide strands bound to its surface [83, 86]. It has been proposed that colorimetric sensing of heavy metal ions could be obtained by the use of carboxylic acid terminated bifunctional... 

Hydrogen bonding has also offered a convenient and versatile approach to the design of bent-core mesomorphism. For example, the use of carboxylic acids and stilbazoles 9 and 10, which act as H-donor and H-acceptor, respectively, has afforded bent-shaped complexes. The SmCP phases (Fig. 5.3) represented by such... 

Anionic functional groups on the organic molecules circumvent the problems of a charged framework. Suslick and coworkers have explored the use of carboxylic acid-substituted porphyrins for building microporous porphyrinic... 

In the last few years our laboratory has developed a new group of polyurethanes based on the use of carboxylic acids as chain extenders (8-10), A carboxylic acid group, in the presence of a suitable catalyst, is capable of reacting with an isocyanate (77). An aliphatic isocyanate and an aliphatic carboxylic acid react to give an interm ate anhydride comj und, which dissociates at normal temperatures to yield carbon dioxide and a stable amide (72) ... 

In order to obtain effective non-covalent bonds, complementary functional groups are usually necessary. Strong hydrogen bonds, for example, can be generated by the use of carboxylic acid and pyridine moeities. Ionic bonds can be created by proton transfer from sulfonic acid to basic amine moieties, or by ion exchange involving sulfonate and ammonium groups. 

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