Anhydrides, cyclic

Although some dibasic acids, e.g, succinic acid and phthalic acid, readily lose water on heating with the formation of cyclic anhydrides, most monobasic... 

Open-chain carbon skeletons (including cyclic acetals, lactones, lactams, cyclic anhydrides, etc.)... 

Some of these compounds are used as potential intermediates for the preparation of 4,7-dioxo-4,5,6,7-tetrahydrothiazolo[4,5d]pyridazines (78). The diesters (77) are hydrolyzed under appropriate conditions to free acids (79), whose monopotassium salts (80) yield the cyclic anhydrides (81) under the influence of thionylchloride. Pyrolysis of 79, Rj = a-thienyl, results in its decarboxylation to 82. 

After acyl halides acid anhydrides are the most reactive carboxylic acid derivatives Three of them acetic anhydride phthahc anhydride and maleic anhydride are mdus trial chemicals and are encountered far more often than others Phthahc anhydride and maleic anhydride have their anhydride function incorporated into a nng and are referred to as cyclic anhydrides... 

Cyclic anhydrides m which the ring is five or six membered are sometimes pre pared by heating the corresponding dicarboxyhc acids m an inert solvent... 

Hydrolysis (Section 20 6) Acid anhydrides react with water to yield two carboxylic acid func tions Cyclic anhydrides yield di carboxylic acids... 

Excluding enantiomers there are three isomeric cyclopropanedicarboxyhc acids Two of them A and B are constitutional isomers of each other and each forms a cyclic anhydnde on being heated The third diacid C does not form a cyclic anhydride C is a constitutional isomer of A and a stereoisomer of B Identify A B and C Construct molecular models of the cyclic anhy dndes formed on heating A and B Why doesn t C form a cyclic anhydride" ... 

Acid Anhydrides. Symmetrical anhydrides of monocarboxylic acids, when unsubstituted, are named by replacing the word acid by anhydride. Anhydrides of substituted monocarboxylic acids, if symmetrically substituted, are named by prefixing bis- to the name of the acid and replacing the word acid by anhydride. Mixed anhydrides are named by giving in alphabetical order the first part of the names of the two acids followed by the word anhydride, e.g., acetic propionic anhydride or acetic propanoic anhydride. Cyclic anhydrides of polycarboxylic acids, although possessing a... 

Aryl and a,/3-unsaturated 1830-1780 intense in acyclic anhydrides, and the lower-frequency band is more intense in cyclic anhydrides. 

Cyclic anhydrides in which the ring is five- or six-rnembered are sometimes prepared by heating the conesponding dicarboxylic acids in an inert solvent ... 

Boronic acids readily dehydrate at moderate temperatures (or over P4O10 at room temperature) to give trimeric cyclic anhydrides known as trialkyl(aryl)boroxines ... 

Kost et al. studied the interaction of indole magnesium iodide with a number of cyclic anhydrides of dibasic organic acids.In addition to 254 the following. 3-indolyloxo acids were prepared in this manner -(3-indolyl)-8-oxovaleric acid (274), y-(3-indolyl)-y-oxocrotoiiic acid... 

With a mixed anhydride two different arylketones may be formed. Reaction of a cyclic anhydride of a dicarboxylic acid, e.g. succinic anhydride, leads to formation of an arylketo acid. ... 

Epoxy resins have a wide range of molecular weights (=1,000-10,000). Those with higher molecular weights, termed phenoxy, are hydrolyzed to transparent resins that do not have the epoxide groups. These could he used in molding purposes, or crosslinked hy diisocyanates or hy cyclic anhydrides. 

Symmetrical anhydrides of unsubslituted monocarboxylic acids and cyclic anhydrides of dicarboxylic acids are named by replacing the word acid with anhydride. 

What product would you expect from reaction of 1 equivalent of methanol with a cyclic anhydride, such as phthalic anhydride 0,2-benzenedicarboxylic anhydride) What is the fate of the second "half" of the anhydride ... 

Lustoh, J. and Vass, F. Anionic Copolymerization of Cyclic Ethers with Cyclic Anhydrides. Vol. 56, pp. 91 —133. 

Polyesters have been obtained in organic medium by polyesterification of hydroxy acids,328,329 hydroxy esters,330 stoichiometric mixtures of diols and diacids,331-333 diols and diesters,334-339 and diols and cyclic anhydrides.340 Lipases have also been reported to catalyze ester-ester interchanges in solution or in die bulk at moderate temperature.341 Since lipases obviously catalyze the reverse reaction (i.e., hydrolysis or alcoholysis of polyester), lipase-catalyzed polyesterifications can be regarded as equilibrium polycondensations taking place in mild conditions (Scheme 2.35). 

Complete characterization of arylboronic acids is often difficult because they are readily transformed into stable cyclic anhydrides called boroxines5 and other polymeric species. Arylboronic acids are also known to be hygroscopic. Thus, arylboronic acids are often prepared and used directly as a mixture of different entities. Commercial arylboronic acids will very often contain varying amount of anhydrides. 

Carbon dioxide 53 55). If excess C02 and polar solvents are used the carboxylation is quantitative and free of side reactions. In nonpolar solvents association phenomena favor ketone formation 55). An alternate way to get re-carboxylic polymers is to react the living sites with a cyclic anhydride 561. 

Azido formyl-2-quinoxalinecarboxylic acid (34) underwent a Curtius reacrtion to afford the cyclic anhydride of 3-carboxyamino-2-quinoxalinecarboxylic acid, 4//-[l,3]oxazino[4,5-fc]quinoxaline-2,4(17/)-dione (35) (for details, see original). ... 

Figure 6.2 Separation of products by (a) cyclic anhydrides as acyl donors and (b) fluorous phase technique.

Despite its widespread application [31,32], the kinetic resolution has two major drawbacks (i) the maximum theoretical yield is 50% owing to the consumption of only one enantiomer, (ii) the separation of the product and the remaining starting material may be laborious. The separation is usually carried out by chromatography, which is inefficient on a large scale, and several alternative methods have been developed (Figure 6.2). For example, when a cyclic anhydride is the acyl donor in an esterification reaction, the water-soluble monoester monoacid is separable by extraction with an aqueous alkaline solution [33,34]. Also, fiuorous phase separation techniques have been combined with enzymatic kinetic resolutions [35]. To overcome the 50% yield limitation, one of the enantiomers may, in some cases, be racemized and resubmitted to the resolution procedure. 

Enantioselective alcoholysis of racemic, prochiral, or meso cyclic anhydrides can be catalyzed by hydrolases, yielding the corresponding monoesters (Eigure 6.25). In most cases, the enantioselectivity was moderate ]75-77]. Organometallic catalysts or organocatalysts such as cinchona alkaloids are often more efficient than enzymes for the stereoselective ring opening of cyclic anhydrides. 

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,... 

Malonic acid and its derivatives, which would give four-membered cyclic anhydrides, do not give this reaction when heated but undergo decarboxylation (12-38) instead. 

Friedel-Crafts acylation can be carried out with cyclic anhydrides, in which case the product contains a carboxyl group in the side chain. When succinic... 

Reduction of Cyclic Anhydrides to Lactones and Acid Derivatives to Alcohols... 

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