Esterification aliphatic acids

Table 7-12. Kinetics of Acid-Catalyzed Esterification of Aliphatic Acids...

It is known from the literature [12] that aliphatic acids are less reactive towards 2-hydroxyalkylamide groups than aromatic ones. Since the final network formation with the polyesteramides involves predominantly aliphatic acid groups, this could explain (in part) why the gel times found were longer than the commercial 2-hydroxyalkylamide crosslinkers, which react directly by esterification alone with the aromatic acid end groups of the polyester. 

The introduction ol a nitrile group on an aliphatic acid has a pronounced inhibiting effect on the rate of esterification. 

Sequential Methylation Technique. A sequential methylation-extraction technique has been devised primarily to separate phenolics from aromatic and aliphatic acids. The procedure, outlined below, allows quantitative conversion of phenolic hydroxyls to methyl ethers in one step and esterification of carboxyl groups in another. 

Aromatic esters may be prepared by direct esterification methods similar to those already described for aliphatic esters (Section 5.12.3, p. 695). A large range of examples of simple alkyl esters of aromatic carboxylic acids is included in Expt 6.163. Corresponding esterification of a simple aliphatic acid (e.g. acetic acid) with benzyl alcohol is illustrated in Expt 5.142. 

The direct esterification of undec-lO-enoic acid with phenylalkanols using DCC and 4-(N,N-dimethylamino)pyridine affords the corresponding esters in quantitative yields. Esterification of the secondary alcohol 655 with long chain aliphatic acids in the presence of DCC and DMAP affords the dioxane esters 656 in yields of 80-93 %. ... 

Most aliphatic acid.s enter the process easily, but more vigorous reaction conditions are necessary for aryl carboxylic acids or for sterically hindered alkanoic acids. Increased pressure can help counteract such problems, e.g. 2,2-dimethylpropanoic acid heated at 112°C in ethanol with o-phenylenediamine dihydrochloride for 24 h at 8kbar pressure gives a 48% yield of 2-l-butylbenzimidazolc 76. Care has to be taken, though, that the ethanol concentration is not too high, as esterification of the carboxylic acid becomes a competing reaction DMSO appears to be a suitable alternative... 

This mechanism (A = acid catalyzed, AC = acyl transfer, 1 = unimolecular) is observed in the esterification of 2,4,6-trisubstituted benzoic acids with R groups of moderate -i-M effect e.g. methyl). The Aac2 mechanism is blocked by the steric interference of the ortho substituents. Therefore, the acylium cation (17) is generated with anhydrous sulfuric acid and then treated with the alcohol (equation 2). R groups with strong -i-M effects, like methoxy, are not tolerable, as the aromatic nucleus undergoes sulfo-nation under the conditions. A variation of the AacI mechanism for aliphatic acids is achieved by using... 

Gu YL, Shi F, Deng YQ (2004) Esterification of aliphatic acids with olefin promoted by Brpnsted acidic ionic liquids. J Mol Catal A Chem 212 71-75... 

Extraction of free fatty acids from naturally occurring glycerides removal of HCl from chlorinated organic compounds recovery of aliphatic acids HE and HCl from aqueous solutions nitration of phenol solvent extraction in mineral processing interfacial polycondensation and esterification manufacture of organo-phosphate pesticides. 

Other important metabolites of O-glucuronidation are acylglucuronides. They are formed by esterification of carboxylic acids with glucuronic acid. Many therapeutic agents such as arylacetic acids (diclofenac, diflunisal), aliphatic acids (valproic acid) and arylpropionic acids (ketoprofen, naproxen) are metabolized as acylglucuronides (Fig. 31.37). 

Acyloxy-4,6-dimethoxy-[l,3,5]-triazines 301, obtained by reaction between carboxylic acids and CDMT 137, have been used as acylating agents for the synthesis of esters from primary, secondary, and tertiary alcohols (Scheme 59). Because of the mild acylation conditions, the method could be applied to esterification of labile alcohols with aromatic and aliphatic acids in good yields <1999S593>. 

Nevertheless there remains several possible routes to the formation of ethyl esters from CO/H2 (see Scheme A). The direct production of ethanol (path c) can be discounted in our systems since both methanol and ethanol are generated in significant concentrations at high propionic acid conversions (see Table VI, expt. 2 and 8). Path (d) appears less likely in view of the relatively slow rates of I-free, ruthenium-catalyzed, methanol homologation (55), relative to esterification. Path (a), also eq. 24, and (b), however, could represent parallel reaction paths where at high acid levels (and therefore low acid conversions) the ester route (a) might be expected to predominate (we see little or no evidence for methanol under those conditions). Preliminary results with stronger aliphatic acid coreactants, such as trifluoroacetic acid, are also in accord with these conclusions. 

The silica gel may adsorb the esters of the short-chain fatty acids. For the esterification of those acids, a chloroform solution of the Cj—C aliphatic acids (50/rl) is treated with an equal volume of a freshly prepared 1% solution of 2,2,2-trichloroethanol in chloroform, together with 150 /A of heptafluorobutyric anhydride (HFBA) in a closed tube at room temperature for 30 minutes. Excess trichloroethanol is removed by reaction with 50 1 of a 25% solution of palmitic acid in chloroform, added subsequently and left to react at room temperature for 15 minutes. (The trichloroethyl palmitate p>eak comes off the GC column long after the shorter-chain fatty acid ester peaks). Further purification is achieved by shaking with 100 /il of chloroform and 100 1 of 0.1 M HCl the aqueous layer is discarded, and the organic layer is washed with 100 fi of 0.1 M NaOH and evaporated to dryness. The residue is dissolved in 100 fil of diethyl ether for analysis by GC with electron capture detection [46]. 

Diazoalkanes 2.8 Selective alkylation of acidic functions in the presence of aliphatic hydroxyls esterification The reaction should be alkyl homogeneous (see Note, procedure 2.8) de-O-acetylation... 

Melt polycondensation is the most used procedure for the preparation of polyesters such as PBSu or PESu from butylene or ethylene diols and dicar-boxyllc acids. Poly(propylene alkylanedicarboxylate) polyesters can be also prepared by the two-stage melt polycondensation method (esterification and polycondensation) using proper amounts of aliphatic acids and 1,3-PD in a glass batch reactor using a procedure described in detail in Ref. [9]. The esterification reaction progress is monitored by measuring the amount of water produced as a by-product and removed by distillation. Other reaction conditions are included in Scheme 4.4. 

The chemistry and technological principles of methacrylic acid esterification with aliphatic alcohols is fairly well known. However, the reports dealing with the kinetics studies of esterification of methacrylic acid with n-propanol and isopropanol have not been found. 

C. cylindracea AOT Brij Esterification of aliphatic alcohols by fatty acids Enantioselective synthesis of ibuprofen esters Transesterification of triglycerides by fatty acids Esterification of DL-menthol [113-117]... 

XRD samples 638 f alignment defects, displays 756 alignment materials, displays 732 aliphatic chains 125,395 alkanes, solvents 883 alkanoic acids, esterification alkanols, esterification 106 alkenes, solvents 883 alkenyl, terminal substituents alkyl functionalization, arenes alkyl groups... 

Chlorosulfonic acid, as well as catalysing the a-halogenation of aliphatic acids, also functions as an acidic dehydration catalyst which can be valuable in the esterification of carboxylic acids. 

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