Salts acid anhydride synthesis

Inositols, ie, hexaliydrobenzenehexols, are sugars that have received increasing study and are useful in the treatment of a wide variety of human disorders, including vascular disease, cancer, cirrhosis of the Hver, frostbite, and muscular dystrophy (269). Myoinositol esters prepared by reaction with lower fatty acid anhydrides are useful as Hver medicines and nonionic surfactants the aluminum and ammonium salts of inositol hexasulfate are useful anticancer agents (270). Tetraarjloxybenzoquinones are intermediates in the preparation of dioxazine dyes (266,271). The synthesis of hexakis(aryloxy)benzenes has also beenpubUshed (272). 

Flavone formation is believed to proceed through a similar mechanism as the synthesis of chromones, albeit aromatic acid anhydrides and their corresponding salts are used. The first step is benzoylation of 12 to give the ester 14. Enolization and o-alkylation then affords the enolbenzoate 15. Enolbenzoate 15 then undergoes an acyl transfer to yield... 

Acid anhydride-diol reaction, 65 Acid anhydride-epoxy reaction, 85 Acid binders, 155, 157 Acid catalysis, of PET, 548-549 Acid-catalyzed hydrolysis of nylon-6, 567-568 of nylon-6,6, 568 Acid chloride, poly(p-benzamide) synthesis from, 188-189 Acid chloride-alcohol reaction, 75-77 Acid chloride-alkali metal diphenol salt interfacial reactions, 77 Acid chloride polymerization, of polyamides, 155-157 Acid chloride-terminated polyesters, reaction with hydroxy-terminated polyethers, 89 Acid-etch tests, 245 Acid number, 94 Acidolysis, 74 of nylon-6,6, 568... 

The preferred catalysts are salts of inorganic and organic acids as well as tertiary amines. Phthalic anhydride, succinic anhydride and maleic anhydride are typical acid anhydrides, while ethylene oxide, propylene oxide, epichlorohydrin and phenyl glycidyl ether are typical epoxides. The synthesis of a ladder polymer was carried out by using bisanhydrides264. ... 

The synthesis consists of heating a mixture of the o-hydroxybenzaldehyde with the sodium salt and anhydride of a carboxylic acid, usually acetic acid. Generally, a temperature in the range 150-200 °C is required and a prolonged reaction time is often necessary. A 1 2 molar ratio of aldehyde to anhydride gives optimum yields of coumarin (Scheme 124). 

A common synthetic method is that of equation (9), where X = MeC02,168 PhS03,169 NO3170 or C104,171 and relies on the precipitation of silver chloride. A variation of this method is the synthesis of the ring complex (5), by the reaction (10).172 In other cases, the synthesis may involve mercury(II) salts or sodium salts (equations 11 and 12).173,174 Another useful synthetic method involves reaction of alkyl- or aryl-gold(I) complexes with carboxylic acids or acid anhydrides (equations 13-15).176,177... 

General Anhydride Synthesis Other anhydrides must be made by less specialized methods. The most general method for making anhydrides is the reaction of an acid chloride with a carboxylic acid or a carboxylate salt. 

An acyl transfer agent which can be used for the synthesis of acid anhydrides is obtained from the reaction of an acid chloride with 4-benzylpyridine (equation 24). In this way benzoic acid anhydride and cinnamic acid anhydride were obtained in 72% and 57% yields, respectively. As the intermediate, 1-acyl-4-benzylidene-l,4-dihydropyridines, can be isolated, Ais procedure should be well suited for the preparation of mixed anhydrides. Mixed aromatic and aliphatic anhydrides can be prepared with 2-ben-zoylthio-l-methylpyridinium chloride and salts of carboxylic acids. These reactions are carried out in aqueous solution. Iliey make use of the high reactivity of esters of thiocarboxylic esters towards nucleophiles. The mixed anhydrides of benzoic acid with 3-phenylpropanoic acid, phenoxyacetic acid, isobu-tyric acid, p-toluic acid and cinnamic acid were formed in 82, 79,61,91 and 66% yields, respectively. 

The use of imidazolides in organic synthesis has been propagated by Staab and coworkers." " Acid anhydrides can also be prepared with carbonyldiimidazolide. The reaction of a carboxylic acid with this reagent leads to acid anhydride if the transacylation equilibrium (equation 35) can be shifted to the side of the anhydride. This is possible either if the acid is used in twofold excess and forms an insoluble salt with the liberated imidazole or if trifluoro- or trichloro-acetylimidazolide is taken as the reagent. Symmetrical acid anhydrides can be obtained in a number of cases in good yield according to equation (36). 20... 

Pyridine is used in catalytic amounts and acylpyridinium salts are assumed to be the reactive acylating agents. The method can be applied to the synthesis of both symmetrical and unsymmetrical acid anhydrides. " These can also be obtained in many cases directly from the acid halide and the sodium carbox-ylate without using a solvent or a catalyst. Tiiis approach has been described for a number of mixed acid anhydrides. Thus acetic palmitic anhydride (70%), butyric myristic anhydride (81%) and caproic lauric anhydride (85%) were prepared by heating the components for 2 h at 90 °C. 75 These anhydrides were successfully employed for the N-acylation of amino sugars. 7 ... 

Rinderknecht and Ma, requiring a quantity of nicotinic acid anhydride, noted that the known methods suffer from the extreme sensitivity of nicotinic acid chloride, and employed with success a method analogous to the mixed anhydride method of peptide synthesis. Equimolar amounts of nicotinic acid and triethylamine were dissolved in chloroform to produce a solution of the salt (1), and the solution was... 

Mixed anhydride synthesis. A method widfely used for the synthesis of peptides provides a general method of acylation, illustrated by the benzoylation of diethyl malonate. Benzoic acid is converted into the triethylamine salt in toluene, and the solution is treated at 0 with ethyl chloroformate to form the mixed benzoic-carbonic anhydride, with precipitation of triethylamine hydrochloride. The second component, ethoxymagnesium malonic ester, is prepared from diethyl malonate in ethanol-ether... 

The Perkin reaction involves the condensation of a carboxylic acid anhydride and an aldehyde in the presence of a weak base, often the sodium or potassium salt of the acid or triethylamine, to give unsaturated carboxylic acids (equation 1). The first example of this reaction was described by Perkin in 1868 and involves a synthesis of coumarin by heating the sodium salt of salicylaldehyde with acetic anhydride (equation 2). The reaction is generally applicable only to aromatic aldehydes and is particularly useful for the preparation of substituted cinnamic acids, as illustrated by equation (3). ... 

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