Dicarboxylic acid, reaction with

Some of the typical conditions of polycondensations used for aliphatic and aromatic monomers are not suitable for furan derivatives, e.g., the melt polycondensation of 2,5-furan dicarboxylic acid chloride with 2,5-b/s(hydroxymethyl) furan at about 80 °C only yields a black insoluble product5. The hydrochloric acid liberated in the reaction is clearly responsible for the charring of the furanic diol which like its simpler homologue furfuryl alcohol, resinifies rapidly in acidic media (see below). 

Heating pyridine-2,3-dicarboxylic acid anhydride with l-ethyl-2-methylindole has been claimed to yield solely the pyridine-2-carboxylic acid, albeit in low yield. This then clearly reacts with Af,A/-diethyl-3-toluidine in acetic anhydride to give the 7-azaphthalide. This is surprising in view of a later report70 in which a one-pot process has been described. Heating pyridine-2,3-dicarboxylic anhydride, prepared in situ, with the indole and subsequent reaction with 3-/V,/V-diethylamino-phenetol under identical conditions to those used in Scheme 8 (but without intermediate isolations) produced a 20 1 mixture of the 4- and 7-azaisomers 16 and 17. It appears that in the previous report the major intermediate isomer, the pyridine-3-carboxylic acid, has not been isolated. 

Another novel synthesis of phenazines was introduced by Vagg and co-workers <00JHC151>. The key step was the reaction of dicarboxylic acid 230 with various 1,2-diamines to give 231, 232, and 233. Each was a potential polydentate ligand capable of interacting with DNA via their extended phenanthroline or phenazine components. 

Later, polythioesters were prepared by the polycondensation of dicarboxylic acid diesters with a dithiol [43] (Fig. 12). Initially, various lipases were screened in the polycondensation between diethyl adipate and hexane-1,6-dithiol at 120 °C in the presence of molecular sieves. The use of 70wt% immobilized CALB as catalyst proved to be efficient in these polycondensation reactions with dicarboxylic acid... 

Recently, treatment of the esters or amides of l-methylpyridinium-3,5-dicarboxylic acid salts with an alkanethiol and TEA in methylene chloride was found to give a mixture of dihydropyridines (Scheme 77) (80CC1147). These yellow adducts are particularly useful as thiolate transfer agents. Excellent yields of thioesters, for example (133), are formed by the reaction of the adducts with activated acid derivatives. 

The reaction of a pyridazine, 5 dicarboxylic acid derivative with hydrazine remains a favored approach for the preparation of pyridazino[4,5-4 pyridazines <2000TL2863, 2002JCCS217>, and di- /t-butyl hydrazodicarboxylate has been used as a hydrazine substitute in the presence of perhydro derivatives, as illustrated in Equation (6) <1993JPC13408>. 

Cyclic tetrafluoro ethers are also the main or sole products of the sulfur tctrafluoridc fluorination of phthalic and pyromellitic acids, or their anhydrides, possessing two bulky ortho substituents (e.g., CF3. N02, Br. Cl or even Me). These substituents create steric crowding which pushes two neighboring carboxylic acid groups towards each other and forces cyclization acid anhydrides and difluoro lactones are the intermediates and they may be isolated from reactions carried out under sufficiently mild conditions. Thus, reaction of 3,6-bis(trifluoromcthyl)bcn-zcnc-1,2-dicarboxylic acid (4) with sulfur tctrafluoridc at ambient temperature results in dehydration to give exclusively the corresponding cyclic anhydride 5 at 60"C a mixture of the anhydride 5, 3,6-bis(trifluoromethyl)phthaloyI difluoride (6) and 3,3-difluoro-4,7-bis(trifluoro-methyl)isobenzofuran-l(3//)-one (7) is obtained, but at 200"C the final product, 1,1,3,3-tct-rafluoro-4,7-bis(trifluoromethyl)-l,3-dihydroisobenzofuran (8), is formed as the sole product.137... 

Polycondensation of diols with dicarboxylic acids or reesterification of dicarboxylic acid esters with diols are the main methods of preparing polyesters. Because of the reversibility of this classical polyester formation, high reaction temperatures, long polycondensation times and low pressures are required to remove low molecular weight reaction products in order to shift the equilibrium to the direction of polyester formation and to obtain sufficiently high molecular weights. 

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... 

A typical member (la) of this group of chiral C2-symmetrical ligands is prepared by reaction of pyridine-2,6-dicarboxylic acid chloride with L-valinol (60% yield). 

Pyrazino[2,3- / pyridazine-5,8-dione 420 can be prepared from pyrazine-2,3-dicarboxylic acid anhydride 419 (Scheme 218). Likewise, the reaction of a pyridazine-4,5-dicarboxylic acid derivative with hydrazine is the most convenient approach to pyridazino[4,5-d]pyridazines <2000TL2863, CHEC-III(10.19.2.1.3)984> a related synthesis of pyridazino[4,5- /]pyridazin-l(2//)-ones 422 from ethyl 5-acylpyridazine-4-carboxylates 421 is shown in Scheme 219 <1979M365>. 

A total synthesis of ( )-royleanone from 5,7,8-trimethoxy-l-tetralone (123) has been described.129 The tetralone was converted into the tricyclic ketone (124), which was in turn converted into 11,12,14-trimethoxypodocarpatriene (125). Demethyla-tion and oxidation afforded the quinone (126 R = H) which was alkylated to give royleanone (126 R = Pr ). Synthetic studies in the resin acid series have led130 to the preparation of the dicarboxylic acid (127) with a cis a/b ring junction. The preparation of some tetracyclic ketones as intermediates for gibberellin synthesis has been described.131 132 The key reaction involves photolysis of a diazoketone (128) to afford the tetracyclic system (129). In a synthesis of phyllocladene from abietic acid... 

Dicarboxylic acids react with carbodiimides depending on their structure. From oxalic acid and carbodiimides the corresponding urea, carbon monoxide and carbon dioxide are obtained. This reaction was used by Zetzsche and Friedrich as a quantitative analytical method for the determination of carbodiimides. The carbodiimide content of polymer supported carbodiimides is also determined with oxalic acid." ... 

However, cyclization to give 511 was observed in the reaction of 3,6,9-trioxaundecanoic dicarboxylic acid 510 with DCC. 510 was reacted with an aminomethylstyrene resin, which was also utilized in the solid phase synthesis of oligopeptides using diisopropyl-carbodiimide/HOBt and carboxyl protected amino acids." ... 

A carbonyl function in the a-position relative to the cyclopropane ring renders the adjacent endocyclic bond susceptible to cleavage by nucleophiles. The reactivity can be greatly increased when the polarity of the carbonyl group is enhanced by the addition of electrophiles such as protons or Lewis acids. This is exemplified by the reaction of cyclopropane dicarboxylic acid (2a) with sulfuric acid which leads to (2-hydroxyethyl)malonic acid (3a) if water is present. In a similar fashion, 2-phenylcyclopropane-l, 1-dicarboxylate (2b) gives dimethyl (2-methoxy-2-phenylethyl)malonate (3b) when treated with sulfuric acid in methanol. ... 

A few examples of functional group interconversions of cycloproparenes are known which occur without modification of the molecular skeleton. Mild reaction conditions or the use of protecting groups (silylation) are necessary for these reactions. Dimethyl 1,2,3,4-tetraphenyl-benzocyclopropene-l,l-dicarboxylate (1) was hydrolyzed to the dicarboxylic acid 2 with potassium hydroxide in methanol reesterification of 2 was possible with diazomethane. i... 

The reaction of dicarboxylic acid dichlorides with aryl cyanides in the presence of antimony(V) chloride gives his(1,3,5-oxadiazinium) salts 9a-l whose colors range from yellow to brown.67 The stability of the salts increases with the distance of the heterocyclic rings from each other. 

Ester Exchange. The most practical methods for the preparation of high molecular weight polyesters involve ester exchange reactions. The simplest exchange method involves a catalyzed alcoholysis reaction between a diol and a dicarboxylic acid ester with elimination of the alcohol ... 

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