A-Dicarboxylic acid halides

Cationic condensation products, namely, the reaction products of a dicarboxylic acid or an ester or acid halide thereof and an aminoalkylamine, that are quatemized are recommended for breaking cmde oil emulsions from fireflooding [365],... 

This is a general method of preparing enamines from a secondary aliphatic amine and cyclohexanone or cyclopentanone. Acylation of such enamines is the first step in a general procedure for increasing the chain length of a carboxylic acid by 5 or 6 carbon atoms and of a dicarboxylic acid by 10 or 12 carbon atoms.6 Alkylation of enamines of cyclohexanones by alkyl halides 7 or electrophilic olefins,8 followed by hydrolysis, is a good route to a-monoalkyl cyclohexanones. 

Wittig-Smiles reaction.l The reaction of a triarylmethylphosphonium halide and a base with an a-keto dicarboxylic acid halide imide such as 1 results in a Wittig reaction followed by a Smiles rearrangement to provide a pyrrolidine dione... 

The benzoic acid derivative 457 is formed by the carbonylation of iodoben-zene in aqueous DMF (1 1) without using a phosphine ligand at room temperature and 1 atm[311]. As optimum conditions for the technical synthesis of the anthranilic acid derivative 458, it has been found that A-acetyl protection, which has a chelating effect, is important[312]. Phase-transfer catalysis is combined with the Pd-catalyzed carbonylation of halides[3l3]. Carbonylation of 1,1-dibromoalkenes in the presence of a phase-transfer catalyst gives the gem-inal dicarboxylic acid 459. Use of a polar solvent is important[314]. Interestingly, addition of trimethylsilyl chloride (2 equiv.) increased yield of the lactone 460 remarkabiy[3l5]. Formate esters as a CO source and NaOR are used for the carbonylation of aryl iodides under a nitrogen atmosphere without using CO[316]. Chlorobenzene coordinated by Cr(CO)j is carbonylated with ethyl formate[3l7]. 

The scope of this reaction is similar to that of 10-21. Though anhydrides are somewhat less reactive than acyl halides, they are often used to prepare carboxylic esters. Acids, Lewis acids, and bases are often used as catalysts—most often, pyridine. Catalysis by pyridine is of the nucleophilic type (see 10-9). 4-(A,A-Dimethylamino)pyridine is a better catalyst than pyridine and can be used in cases where pyridine fails. " Nonbasic catalysts are cobalt(II) chloride " and TaCls—Si02. " Formic anhydride is not a stable compound but esters of formic acid can be prepared by treating alcohols " or phenols " with acetic-formic anhydride. Cyclic anhydrides give monoesterified dicarboxylic acids, for example,... 

Racemic fra .s-A--benzyl-2.5-bis-(ethoxycarbonyl)pyrrolidine has been resolved via its dicarboxylic acid, followed by subsequent transformation to offer (2R,5R)-21 or (25,5S -21. The absolute configuration of the alkylated carboxylic acids indicates that the approach of alkyl halides is directed to one of the diastereotopic faces of the enolate thus formed. In the following case, the approached face is the 57-face of the (Z)-enolate. By employing the chiral auxiliary (2R,5R)-21 or its enantiomer (25.55)-21. the (/ )- or (S)-form of carboxylic acids can be obtained with considerably high enantioselectivity (Table 2-4). 

Heating dicarboxylic acids, HOOC(CH,) COOH n = 2 or 3), forms cyclic anhydrides by intramolecular dehydration [Problem 16.22(a), (6)]. Anhydrides resemble acid halides in their reactions. Because acetic anhydride reacts less violently, it is often used in place of acetyl chloride. Acid anhydrides can also be used to acylate aromatic rings in electrophilic substitutions. 

Due to reduction or lack of hydrogen bonding, carbonyl carbon nuclei of amides [313-315], anhydrides [316], esters [310-312], and halides [317] display smaller shift values relative to the parent acids (Tables 4.34 and 4.35). Methyl esterification shieldings are about — 6+1 ppm for mono- and — 1.5 + 1 ppm for diesters, reflecting weaker hydrogen bonding in dicarboxylic acids [316] Taking the methoxy carbon as a /i effect... 

There are two principal synthetic routes to dicarboxylate complexes. One of these uses an aqueous solution of the alkali metal dicarboxylate and the corresponding metal halide,93 while the other depends upon the dicarboxylic acid reduction of higher oxidation state metals. This reductive property of oxalic acid results in its ready dissolution of iron oxides and hence a cleaning utility in nuclear power plants.94 Mention must also be made of the successful ligand exchange synthesis of molybdenum dicarboxylates, Mo(dicarboxylate)2 H2 O, from the corresponding acetate complex. Unfortunately the polymeric, amorphous and insoluble nature of these complexes has restricted the study of these systems, which may well provide examples of multiple M—M bonding in dicarboxylate coordination chemistry.95... 

Monocationic acyl ions are readily prepared as persistent species in solutions of low nucleophile strength.68 These acyl ions have been thoroughly characterized by IR and NMR spectroscopy, and several acyl ion salts have been characterized by X-ray crystallography. The monocationic acyl ions are often prepared in situ from carboxylic acids, esters, or anhydrides, by the action of a strong Brpnsted acid, or the ions can be prepared from ionization of an appropriate acid halide with a strong Lewis acid. Both methods have been used to prepare acyl-centered dications, some of which can be considered distonic superelectrophiles. As described previously, dicarboxylic acids cleave to the bis-acyl ions in superacid (FSChH-SbFs) provided that the acyl cations are separated by at least three methylene units (eq 54).55 The first bis-acyl dications were reported by Olah and Comisarow, being prepared by the reactions of dicarboxylic acid fluorides with superacidic SbFs (eq 72).69... 

Cubane- 1,2-dicarboxylic acid 12 (see Fig. 2.19), a precursor for 1,2-dihalocubanes was prepared from commercially available cubane-1,4-dicarboxylic acid in 65% yield. The other acids 14a and 14c were similarly prepared from the cubane-l,4-dicarboxylic acid 14b according to the literature procedures. 1H NMR spectra of the compound 13a showed a broad singlet at 4.41 for the clibyl protons, whereas compound 13b showed two multiplets. Conversion of bridgehead carboxylic acids to the corresponding halides using Pb(OAc)4 and iodine in refluxing benzene under illumination is reported. This is considered to be an alternative to Barton s method, because of its simplicity and ease of preparation, but it involves toxic lead compounds. 

Silver salts of carboxylic acids react with bromine or chlorine in an inert solvent to give carbon dioxide, a silver halide, and the halide containing one less carbon atom than the acid. The method has been reviewed. " Both low- and high-molecular-weight aliphatic bromides have been prepared. "t i i The degradation of silver salts of aromatic acids is complicated by nuclear halogenation." The procedure is valuable as a step in the synthesis of oi-bromo esters (C, to C,) from dicarboxylic acids. ... 

An acid—base reaction forms a nucleophilic anion that can react with an unhindered alkyl halide— that is, CH3X or RCH2X—in an 5 2 reaction to form a substitution product. This alkylated imide is then hydrolyzed with aqueous base to give a 1° amine and a dicarboxylate. This reaction is similar to the hydrolysis of amides to afford carboxylate anions and amines, as discussed in Section 22.13. The overall result of this two-step sequence is nucleophilic substitution of X by NH2, so the Gabriel synthesis can be used to prepare 1° amines only. 

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