Carboxylic acid salts, alkylation

This method is based on the generation of the tetraalkylammonium salt of pyrrolidorle, which acts as a base. The method is compatible with a large variety of carboxylic acids and alkylating agents. The method is effective for the preparation of macrolides. 

Alternatively, esterification of carboxylic acid can be carried out in aqueous media by reacting carboxylic acid salts with alkyl halides through nucleophilic substitutions (Eq. 9.10).20 The reaction rate of alkyl halides with alkali metal salts of carboxylic acids to give esters increases with the increasing concentration of catalyst, halide, and solvent polarity and is reduced by water. Various thymyl ethers and esters can be synthesized by the reactions of thymol with alkyl halides and acid chlorides, respectively, in aqueous medium under microwave irradiation (Eq. 9.11).21 Such an esterification reaction of poly(methacrylic acid) can be performed readily with alkyl halides using DBU in aqueous solutions, although the rate of the reaction decreases with increasing water content.22... 

Selection of appropriate hydroxamic esters and carboxylic acid salts has enabled synthesis of a wide range of A-acyloxy-Af-alkoxyamides in which and can be alkyl or aryl but, to date, only aUcoxyl or arylalkoxyl groups have been present at R". ... 

Alkylation of Carboxylic Acid Salts Acyloxy-de-halogenation... 

Alcoholysis of trihalides 0-6 Hydrolysis of ortho esters 0-20 Alcoholysis of acyl halides 0-21 Alcoholysis of anhydrides 0-22 Esterification of carboxylic acids 0-23 Transesterification 0-24 Alkylation of carboxylic acid salts 0-25 Cleavage of ethers with anhydrides 0-26 Alkylation of carboxylic acids with diazo compounds... 

The O-alkylation of carboxylates is a useful alternative to the acid-catalyzed esterification of carboxylic acids with alcohols. Carboxylates are weak, hard nucleophiles which are alkylated quickly by carbocations and by highly reactive, carbocation-like electrophiles (e.g. trityl or some benzhydryl halides). Suitable procedures include treatment of carboxylic acids with alcohols under the conditions of the Mitsunobu reaction [122], or with diazoalkanes. With soft electrophiles, such as alkyl iodides, alkylation of carboxylic acid salts proceeds more slowly, but in polar aprotic solvents, such as DMF, or with non-coordinating cations acceptable rates can still be achieved. Alkylating agents with a high tendency to O-alkylate carboxylates include a-halo ketones [42], dimethyl sulfate [100,123], and benzyl halides (Scheme 6.31). 

C. Attack by OCOR at an Alkyl Carbon 10-17 Alkylation of Carboxylic Acid Salts Acyloxy-de-halogenation... 

Active catalysts for butadiene polymerization are obtained from aluminium alkyl halides and soluble Co and Co salts and complexes. The structure of the organic grouping attached to the cobalt is not important, but compounds most widely employed are acetylacetonates and carboxylic acid salts such as the octoate and naphthenate. The activity of the catalyst and structure of the polymer are affected by the groupings in the complex. Catalysts from aluminium trialkyls and cobalt salts other than halides are relatively unstable and give syndiotactic 1,2-polybutadiene. If halogens are present, e.g., from CoClj or CoBrj,... 

The quadrupolar 2H spin-lattice relaxation of specifically deuterated surfactants, such as the methyl deuterated n-alkyl phosphocholine surfactants, also shows a concentration dependence. The CMC of dodecyl phosphocholine was determined by exploiting the difference in the 2H spin-lattice relaxation times of the monomers versus the micellar state.68 Quadrupole splittings of 14N were also used to characterize the micellization process of short-chain perfluoro-carboxylic acid salts.69... 

Halodecarboxylation. Kochi1 has found that halide salts in the presence of lead tetraacetate convert carboxylic acids into alkyl halides in good yield. The method is particularly convenient for preparation of alkyl chlorides. Unlike the classical Huns-diecker reaction, the new method is applicable to secondary and tertiary acids as well... 

The degradation of carboxylic acids to alkyl halides using mercuric oxide and halogens involves the initial formation of the mercuric salt of the acid, followed by a normal Hunsdiecker reaction of the salt with halogen. The relative insensitivity of the reaction to water is a consequence of the solubility of the mercury salts in the solvent (CC14). There are two limitations tertiary acids are not degraded, and use of iodine as the halogen frequently leads to the ester RCOOR as the major product. The yields in the modified reaction are usually lower than those obtained with the silver salt method.2... 

The nomenclature of esters is similar to the nomenclature of the carboxylic acid salts. The alkyl group bonded to the oxygen atom is named first, then the -ic acid ending of the corresponding carboxylic acid is changed to -oate. 

Reductive alkylation of N-methylacridinium (87) occurs when it is irradiated with carboxylic acid salts. The reaction is thought to proceed by electron transfer from the carboxylate to the excited acrldinium ring followed by decarboxylation of RCOO coupling of the alkyl radical produced with the acridinyl radical then gives (88). A very similar sequence probably occurs in a reaction proposed as a synthetic procedure for decarboxylation of carboxylic acids.In this case an aza-aromatic compound such as acridine is irradiated with a carboxylic acid in benzene in the presence of tert-butyl thiol. The authors propose that a hydrogen bonded acridine-acid complex is excited and that adiabatic proton transfer is followed by electron transfer. This produces RCOO which decarboxylates, and reduction of the alkyl radical then ensues. The major fate of the acridine is coupling to (89) if the reaction is perfonned in the absence of oxygen. 

Esterification (4, 247). Shaw and Kunerth have reported further studies on the esterification of sodium salts of carboxylic acids with alkyl halides in HMPT at room temperature. The method is applicable to the preparation of ethyl esters of hindered acids for example, ethyl mesitoate can be obtained in 99% yield. In the esterification of acids that undergo ready decarboxylation, anhydrous potassium carbonate rather than NaOH is used as base (equation I). Diesters can be obtained by reaction of sodium salts of acids with dibromo-methane (equation II). Phenols are converted by this method into ethers in... 

PTC in liquid solid systems is often used for the synthesis and manufacturing of esters via the reaction of solid sodium or potassium salts of carboxylic acids with alkyl halides. Liquid-liquid systems are also applied for this purpose ... 

Nitro -NO, alkyl (-R) and acyl RCO-) groups can readily be added by electrophilic substitution and can then be converted to amino, carboxylic acid, and alkyl groups, respectively. Once the amino and carboxylic acid groups have been obtained, they can be further converted to a large range of other functional groups like secondary and tertiary amines, amides, diazonium salts, halides, nitriles, esters, phenols, alcohols, and ethers. 

The first word of the name of an ester is the name of the alkyl or aromatic group (R ) contributed by the alcohol. The second word is the carboxylic acid name, with the -ic acid ending changed to -ate. This is similar to the method used for naming carboxylic acid salts. Thus, an ester of acetic acid becomes an acetate, one of butyric acid becomes a butyrate, one of lactic acid becomes a lactate, and so on. 

The combination of alkali metal salts of carboxylic acids and alkyl halides seldom finds use in ester synthesis owing to low yields. The crucial 0-C bond formation is a hard-soft interaction. In contrast, the efficient reaction of acyl halides with alcohols consists of a hard-hard interaction. 

In addition, perfluoroalkyl carboxylic acids (PFCAs) and their derivatives have also been synthesized using the ECF process. Typically, an alkyl carbonyl fluoride (for example C7H15COF) is transformed into the corresponding perfluoroalkyl carbonyl fluoride (for example C7F15COF). The carbonyl fluoride is then reacted to yield esters, amides, or carboxylic acid salts which are have all been commercially produced and used as surfactants [4]. The most widely known is the ammonium salt of perfluorooctanoic acid (C7Fi5COOH-NH3), whose major historical use has been as a processing aid in the manufacture of fluoropolymers [29]. 

Anionic anti-static agents are usually alkali salts of alkyl sulphonic and sometimes phosphonic or carboxylic acids. Sodium alkyl sulphonates are recommended for styrenics. 

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