Dicarboxylic acid anhydrides cyclic

Hydrolysis (Section 19.5) Acid anhydrides react with water to yield two carboxylic acids. Cyclic anhydrides yield dicarboxylic acids. 

A simplified synthesis relies on the potential to protect difunctional compounds as cyclic derivatives. For example, 1,2-diols are masked as cyclic acetals (Section 24-8), hydroxy acids as lactones (Section 19-9), amino acids as lactams (Section 19-10), and dicarboxylic acids as anhydrides (Section 19-8). The last two possibilities merit consideration as applied to Asp. However, direct lactam formation can be quickly ruled out because of the complications of ring strain (although /3-lactams have been used in the preparation of aspartame). This problem is absent with respect to dehydration to the five-membered ring anhydride. Because anhydrides are activated carboxylic acid derivatives (Section 20-3), the Asp anhydride can be coupled directly with Phe-OCHa without the help of added DCC. Nucleophilic attack of the amino end of Phe-OCHs occurs preferentially at the desired position, albeit not completely so 19% of the product derives from peptide-bond formation at the /3-carboxy group of Asp. 

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

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. ... 

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

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,... 

Polymers with hetero-atoms in the chain are suitable for chemical recycling of waste materials. In addition to depolymerisation (nylon 6) and solvolysis (nylon 6,6, PETP, PU) the degradation of aliphatic polyamides with dicarboxylic acids, diamines and cyclic anhydrides, especially trimellitic anhydride, becomes more and more important. The utilisation of the obtained fragments is described. 

So far, various dicarboxylic acid derivatives, dicarboxylic acids, their activated and non-activated esters, cyclic acid anhydrides, and polyanhydrides have been polymerized with glycols through lipase catalysis to give polyesters. 

In common with many other ort o-dicarboxylic acids, indolizine-l,2-dicarboxylic acid, when treated with trifluoro-acetic anhydride, gives the cyclic anhydride <2000H(53)2123> (Equation 31). 

Various combinations of dicarboxylic acid derivatives and glycols enzymatically afforded polyesters under mild reaction conditions. Dicarboxylic acids as well as derivatives, activated and non-activated esters, cyclic acid anhydride, and polyanhydrides, were found to be useful as monomer for the enzymatic synthesis of polyesters. 

Pyrrole is one of the most prominent heterocycles, having been known for more than 150 years, and it is the structural skeleton of several natural products, synthetic pharmaceuticals, and electrically conducting materials. A simple access to the pyrrole ring system involves the conversion of cyclic anhydrides into five-membered imides. Mortoni and coworkers have described the conversion of 2-methylquinoline-3,4-dicarboxylic acid anhydride to a quinoline-3,4-dicarboximide library by treatment of the anhydride with a diverse set of primary amines under microwave conditions (Scheme 6.180) [341]. The authors studied a range of different conditions, including dry media protocols (see Section 4.1) whereby the starting materials were adsorbed onto an inorganic support and then irradiated with microwaves. For the transforma-... 

The unlikely molecule in Figure 20—1 is a cyclic anhydride known by several names 2-butene-1,4-dicarboxylic acid anhydride cis-butene-dioic acid anhydride maleic anhydride (MA) and when youVe been in the business a long time, maleic. ... 

Maleic anhydride is a cyclic anhydride with one double bond in the ring and two double-bonded oxygens hanging off the ring. The resulting reactivity leads to maleics use in making polymers, unsaturated polyesters, alkyd resins, plasticizers, and dicarboxylic acids. 

The above-mentioned concept of the synthesis of carboxylic acid functional hyperbranched polyesteramides is not limited to cyclic anhydrides as building blocks. It can be carried out with diisopropanolamine and any dicarboxylic acid as well. The same ratios as written above and calculated in Scheme 1 have been applied in the synthesis of carboxylic acid functional hyperbranched polyesteramides starting from adipic acid and diisopropanolamine. The first one (ratio 2.3 1) gelates as expected, the second one (ratio adipic acid diisopropanolamine 3.2 1) affords the expected product. Again, with GPC the amount of free adipic acid detected is in good agreement with theory (Fig. 17). 

The replacement of ring C by a cyclic anhydride ring could be looked upon either as elimination of ring C or replacement of the ring by a heterocyclic anhydride ring. In any case, Fields et al. showed that quinolizinium 2,3-dicarboxylic acid anhydride (37) underwent cycloaddition reactions with either cyclopentadiene or styrene to alFord the expected products (e.g., 38). The 2,3-dimethylquinolizinium ion did not undergo cycloaddition even with the more reactive ketene diethylacetal. 

The diacylation of isopropenyl acetate with anhydrides of dicarboxylic acids is applicable for the synthesis of several other cyclic jS-triketones in moderate yield. - It has been used for the synthesis of 2-acetylcyclohexane-l,3-dione (40% yield), 2-acetyl-4-methylcyclopentane-l,3-dione (10% yield), 2-acetyl-4,4-dimethylcyclopentane-l,3-dione (10% yield), 2-acetyl-5,5-dimethylcyclohexane-l,3-dione (10% yield), 2-acetylcyclo-heptane-l,3-dione (12% yield) and 2-acetylindane-l,3-dione (26% yield). Maleic anhydrides under more drastic conditions give acetylcyclopent-4-ene-l,3-diones in yields from 5% to 12%. The corresponding acylation of the enol acetate of 2-butanone with succinic anhydride has been used to prepare 2-methylcyclopentane-l,3-dione, an important intermediate in steroid synthesis. - ... 

Reductions of anhydrides of monocarboxylic acids to alcohols are very rare but can be accomplished by complex hydrides [55, 99]. More frequent are reductions of cyclic anhydrides of dicarboxylic acids, which give lactones. Such reductions were carried out by catalytic hydrogenation, by complex hydrides and by metals. 

Procedure for ASD of a cyclic meso-anhydride using quinidine ASD of bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid endo cis-anhydride [204]... 

Procedure for ASD of a cyclic meio-anhydride using (DHQD)jAQN as catalyst ASD of cis-cyclopentane-l,2-dicarboxylic acid anhydride [208-210]... 

A cyclic anhydride can be formed from a diccirboxylic acid by heating if the anhydride that forms has a five- or six-membered ring. If the dicarboxylic acid contains a ring, only a c/s isomer (not the trans isomer) reacts. Figure 12-19 illustrates this type of reaction. The black circles in the figure indicate that the crs-isomer is reacting to form a cis product. 

The chemical transformation must not affect the stereogenic centers. Suitable acyclic candidates are compounds with easily convertible functional groups, such as diols, diamines, amino alcohols, dicarboxylic acids and so on. A number of procedures known before 1973 have been compiled, including conversion of diols and amino alcohols into sulfites or 1,3-dioxolanes by thionyl chloride, or acetalization with ketones31,1"319, as well as the conversions of dinitriles into imides320, dicarboxylic acids into cyclic anhydrides or imides321, and hydroxy acids into oxazolidones 322. 

The known adduct (385) of furan and vinylene carbonate, previously used for the synthesis of some cyclitols,256,257 has been transformed into DL-ribose derivatives. After hydroxylation of 385 and subsequent formation of the isopropylidene derivative, the carbonate group was removed by treatment with barium hydroxide, and the resulting diol was cleaved by oxidation with permanganate. Dicarboxyl-ic acid 386 gave, upon treatment with acetic anhydride, cyclic anhydride 387. The reaction of 387 with azidotrimethylsilane produced... 

The chemistry of dicarboxylic acids depends on the value of n. See Problem 16.18 for decarboxylations of oxalic acid (n =0) and malonic acid (n = 1). When n = 2 or 3, the diacid forms cyclic anhydrides when heated. When n exceeds 3, acyclic anhydrides, often polymers, are formed. 

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. 

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... 

A very successful approach to the preparation of starch-based emulsion stabilizers has been the development of polysaccharide derivatives of substituted dicarboxylic acids by Caldwell and Wurzburg (4). The invention involves the treatment of starch with substituted cyclic dicarboxylic acid anhydrides having the following structural formula ... 

The acid esters of 1,2-dicarboxylic acids are conveniently prepared by heating the corresponding cyclic anhydride with one molar proportion of the alcohol (see the preparation of alkyl hydrogen phthalates from phthalic anhydride and their use in the resolution of racemic alcohols, Section 5.19). 

Dicarboxylic acids are readily converted into cyclic anhydrides when heated alone or in acetic anhydride. Heat 0.5 g of the acid in 2-3 ml of refluxing acetic anhydride for 30 minutes. Remove most of the excess reagent by distillation and crystallise the residual cyclic anhydride from chloroform or toluene. The melting points of aliphatic and aromatic anhydrides are to be found in Tables 10.23 and 10.24 respectively. For conversion of the anhydrides into anilic acids see Section 9.6.16, below. 

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