Cyclic acid anhydrides phthalic anhydride

Cyclic acid anhydrides such as maleic, dodecylsuccinic, hexahydrophthalic, phthalic, phyromellitic, etc. are widely employed as curing agents for epoxy resins. They form esters with epoxy resins. These resins have better thermal stability and good electrical insulation and chemical resistance expect to alkalis. 

Potassium carboxylate groups introduced onto the surface of carbon fibers initiated anionic polymerization of epoxides (e.g., styrene oxide, epichlorohydrin, and glycidyl phenyl ethers) and cyclic acid anhydrides (e.g., maleic anhydride, succinic anhydride, and phthalic anhydride) in the presence of 18-crown-6 [41]. 

Oxirane/cyclic acid anhydride alternating copolymers of controlled molecular weight with a narrow molecular weight distribution were found by Aida et al. [188,189] to be formed under mild conditions when copolymerising ethylene oxide and phthalic anhydride in the presence of the (tpp)AlCl-quater-nary phosphonium salt catalyst system. The copolymerisation carried out with (tpp)AlCl alone proceeded very slowly, and the product was not polyethylene terephthalate) but contained ether linkages in considerable amount. The development of the living character and the tendency towards alternation of the copolymerisation when using the aluminium porphyrin catalyst, coupled with a quaternary salt, have been postulated [188,189] to be due to the formation of... 

Half of an anhydride s acid units are lost as leaving groups. If the acid is expensive, we would not use the anhydride as an activated form to make a derivative. The acid chloride is a more efficient alternative, using chloride as the leaving group. Anhydrides are used primarily when the necessary anhydride is cheap and readily available. Acetic anhydride, phthalic anhydride, succinic anhydride, and maleic anhydride are the ones we use most often. Diacids commonly form cyclic anhydrides, especially if a five- or six-membered ring results. 

A cyclic acid anhydride will react with AlCl3 to open the ring. Using phthalic anhydride as in the problem, the... 

The reaction of a cyclic acid anhydride with an alcohol produces a molecule with both an ester and carboxylic acid functionality. The mechanism for the reaction of phthalic anhydride with methanol is ... 

Synthesis of Cyclic Carboxylic Acid Anhydrides Succinic Anhydride and Phthalic Anhydride... 

Cyclic acid anhydrides are widely employed as curing agents for epoxy resins. Both mono- and dianhydrides are used. Examples of anhydrides which find application are maleic anhydride (MA) (XIX), dodecenylsuccinic anhydride (DDSA) (XX), hexahydrophthalic anhydride (HPA) (XXI), phthalic anhydride (PA) (30(11), pyromellitic dianhydride MDA) (XXIII), nadic methyl anhydride (NMA) (a mixture of maleic anhydride adducts of methylcyclopentadienes cf.. Section 10.2.2.3) (XXIV) and chlorendic (HET) anhydride (XXV see also Section 102.2.3). 

Finally, the catalytic activity of DMCs in esterification reactions can be readily combined with their catalytic activity in epoxide ring-opening polymerizations, as was reported by Suh et al. [35]. This study showed that the copolymerization of propylene oxide with cyclic acid anhydrides such as succinic, maleic, or phthalic anhydride, catalyzed by a Zn-Co-DMC, afforded polyester polyols characterized by a moderate molecular weight and narrow polydispersity index. 

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

After acyl halides, acid anhydrides are the most reactive carboxylic acid derivatives. Three of them, acetic anhydride, phthalic anhydride, and maleic anhydride, are industrial chemicals and are encountered far- more often than others. Phthalic anhydride and maleic anhydride have their- anhydride function incorporated into a ring and are refened to as cyclic anhydrides. 

Commodities are large-volume, low-price, homogeneous, and standardized chemicals produced in dedicated plants and used for a large variety of applications. Prices are cyclic and fully transparent. Petrochemicals, basic chemicals, heavy organic and inorganic chemicals (large-volume) monomers, commodity fibers, and plastics are all part of commodities. Typical examples of single products are ethylene, propylene, caprolactame, methanol, BTX (benzene, toluene, xylenes), phthalic anhydride, poly (vinyl chloride) soda, and sulfuric acid. 

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... 

Diastereofacial selectivity in the a-allylation of cyclic a-acyloxy amides 259 derived from succinic or phthalic anhydride can be controlled by the Lewis acid. Thus, while TiCLt gives 260, allylation promoted by SnCLt affords 261393. No rationalization has been offered. 

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). 

With acid anhydrides, the exothermic reaction yields similar products, subject to the limitation on n. For higher anhydride ratios, condensed acylates form. If n = 3, the result is (R 0Ti(00CR)2)20 if n = 4, then ((RC00)3Ti)20 forms. Phthalic anhydride does not give a cyclic product ... 

Indium-mediated allylation of cyclic and acyclic acid anhydrides gives w-diallyl esters.203,204 Examples are shown in Scheme 48 the allylation of succinic anhydride or phthalic anhydride with allyl bromide in DMF in the presence of indium metal results in the formation of diallylbutenolides or diallylphthalides. In contrast, monoallylated hydroxy esters are formed exclusively with y-substituted allylic halides. 

Cyclic anhydrides are also obtained from maleic acid, o-phthalic acid and 2,3-seco-5a-cholestane-2,3-dioic acid." ... 

Cyclic anhydrides of dibasic acids react with ammonia and certain amines to give cyclic imides, such as phthalimide (97%) and a-ethyl-glutarimide (85%). Aqueous ammonia, ammonium carbonate, and dry ammonia gas have been used. 2-Aminopyridine and phthalic anhydride react at 180° to yield N-(2 pyridyl)-phthalimide (76%). t-Butylphthali-mide is made by the action of phthalic anhydride on /-butylurea at 200-240°. The use of alkylureas in this reaction is general. ... 

Voltammetric data for ester reductions are available for several aromatic esters [51-54], and in particular cyclic voltammetry shows clearly that in the absence of proton donors reversible formation of anion radical occurs [51]. In dimethylfonnamide (DMF) solution the peak potential for reduction of methyl benzoate is —2.29 V (versus SCE) for comparison dimethyl terephthalate reduces at —1.68 V and phthalic anhydride at —1.25 V [4]. Half-wave potentials for reduction of aromatic carboxylate esters in an unbuffered solution of pH 7.2 are linearly correlated with cr values [51] electron-withdrawing substituents in the ring or alkoxy group shift Ei/o toward less negative potentials. Generally, esters seem to be more easily reducible than the parent carboxylic acids. Anion radicals of methyl, ethyl, and isopropyl benzoate have been detected by electron paramagnetic resonance (epr) spectroscopy upon cathodic reduction of these esters in acetonitrile-tetrapro-pylammonium perchlorate [52]. The anion radicals of several anhydrides, including phthalic anhydride, have similarly been studied [55]. 

Like other anhydrides, cyclic anhydrides react wfth ammonia to yield amides in this case the product contains both --CONH2 and —COOH groups. If this acid-amide is heated, a molecule of water is lost, a ring forms, and a product is obtained in which two acyl groups have become attached to nitrogen compounds of this sort are called imides. Phthalic anhydride gives phthalamic acid and phthalimide ... 

The last reaction illustrates how useful it can be to convert an acid first into its anhydride and then into its chloride. Most carboxylic anhydrides are relatively stable to inorganic acid chlorides cyclic anhydrides are even formed preferentially if a dicarboxylic acid such as maleic, tartaric, or phthalic acid is treated with an inorganic acid chloride such as SOCl2 under the usual conditions 1092 however, phthalic anhydride is converted by PC15 at higher temperatures into phthaloyl dichloride (A). 

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