Carboxylic anhydrides, cyclic

Other examples of the photochemical a-cleavage of cyclic sulfoxides have been noted. Lawesson and coworkers22 have proposed that the mixed sulfenic-carboxylic anhydride (16) is formed on photolysis of 17, by a-cleavage followed by the loss of benzaldehyde. The... 

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,... 

In the first step of the synthesis of the hyperbranched polyesteramides, a cyclic carboxylic anhydride is reacted with diisopropanolamine, ideally forming a... 

Fig. 2. Reaction of cyclic carboxylic anhydride with diisopropanolamine...

Suitable cyclic carboxylic anhydrides for this process are for example cz5-l,2-cyclohexane-dicarboxylic anhydride (HHPA), cz5-l,2-cyclohex-4-ene-dicarbo-xylic anhydride (THPA), phthalic anhydride (PA), succinic anhydride (SA), 1-oct-2-ene-succinic anhydride (OSA), and glutaric anhydride (GA) - see Fig. 9. 

Fig. 9. Suitable cyclic carboxylic anhydrides for hyperbranched resin synthesis...

Solid cyclic carboxylic anhydrides react with gaseous ammonia to give amide ammonium salts with quantitative yield. This has been observed with the labile Diels-Alder adduct 259 [25] (Scheme 38). Aliphatic amine vapors are equally able to open anhydride rings to form the amide salts from where the free amide acids can be obtained in 100% yield. The reaction of 261 with ethylamine to give 262 is an example of a large-scale preparative application [11-12]. Conversely, solid pyromellitic bis-anhydride (263) and methylamine vapor react exother-mally (rise to 95 °C) and quantitatively to yield the tetraamide 264. Interest-... 

There are many electrophiles which not only terminate living polymer chains but also produce end-group substitution. For example, macromolecules with hydroxyl, carboxyl, thiol, or chlorine termini can be prepared by reacting living polymers with such compounds as epoxides, aldehydes, ketones, carbon dioxide, anhydrides, cyclic sulfides, disulfides, or chlorine (15-23). However, primary and secondary amino-substituted polymers are not available by terminations with 1° or 2° amines because living polymers react with such functionalities (1.). Yet, tert-amines can be introduced to chain ends by use of -N-N-di-methylamino-benzaldehyde as the terminating agent (24). 

Initially, water can cause the hydrolysis of the anhydride or the isocyanate, Scheme 28 (reaction 1 and 2), although the isocyanate hydrolysis has been reported to occur much more rapidly [99]. The hydrolyzed isocyanate (car-bamic acid) may then react further with another isocyanate to yield a urea derivative, see Scheme 28 (reaction 3). Either hydrolysis product, carbamic acid or diacid, can then react with isocyanate to form a mixed carbamic carboxylic anhydride, see Scheme 28 (reactions 4 and 5, respectively). The mixed anhydride is believed to represent the major reaction intermediate in addition to the seven-mem bered cyclic intermediate, which upon heating lose C02 to form the desired imide. The formation of the urea derivative, Scheme 28 (reaction 3), does not constitute a molecular weight limiting side-reaction, since it too has been reported to react with anhydride to form imide [100], These reactions, as a whole, would explain the reported reactivity of isocyanates with diesters of tetracarboxylic acids and with mixtures of anhydride as well as tetracarboxylic acid and tetracarboxylic acid diesters [101, 102]. In these cases, tertiary amines are also utilized to catalyze the reaction. Based on these reports, the overall reaction schematic of diisocyanates with tetracarboxylic acid derivatives can thus be illustrated in an idealized fashion as shown in Scheme 29. 

With aliphatic acids, even in the absence of pyridine, considerable chlorosulfonation occurs on irradiation 150 with short chain acids, e.g., propionic, isobutyric acids, the products isolated are the cyclic sulfo-carboxylic anhydrides (XLVI) in which the sulfo groups are in the 8-or 8- and y-positions. No products derived from substitution at a-posi-... 

In the presence of a cinchona alkaloid, certain cyclic carboxylic anhydrides with meso structures are converted to the chiral diacid monoesters in up to 76% ee (Scheme 10) 31). Quinine or cinchonidine and quinidine or cinchonine show opposite asymmetric induction. 

A number of carboxylic anhydrides have been converted into trifluoromethyl compounds by treatment with sulfur tetrafluoride, usually in the presence of hydrogen fluoride. As in the case of carboxylic esters, vigorous conditions are needed. Some examples have been presented in Houbcn-Weyl, Vol. 5/3, pp 92, 93. Depending on the reaction conditions, different compounds can be isolated. In some, cyclic di- or tetrafluorinated ethers predominate. 1.253.254 Upon reaction with sulfur tetrafluoride/hydrogen fluoride, pyromellitic dianhydride, as well as pyromellitic acid (benzcnc-l,2,4,5-tetracarboxylic acid), gives a mixture of 1,2,4,5-tet-rakis(trifluoromethyl)bcnzcne, 1,1,3,3-tetrafluoro-5,6-bis( trifluoromethyl)- ,3-dihydroisoben-zofuran, and the fully fluorinated tetrahydrobenzodifuran in an 85-88 10-13.5 1-2 ratio (see formation of compounds 13-15, vide supra)d ... 

Carboxylic anhydrides are similar to the halides, producing ketones by reaction with one equivalent of organometallic, but easily reacting with an excess of the reagent. Cyclic anhydrides produce lactones as final products with two equivalents of organometallic (equation 35). 

The reactivity of the cyclic sulfonic-carboxylic anhydride 12 toward ring opening with anilines to afford 53 has been examined in detail (Equation 4) <1995ZOR548>. 

Metallacyclic complexes were formed when cyclic carboxylic anhydrides were used as substrates to react with zero-valent group 9 and 10 metal complexes [71-74]. 

Nucleophilic ring opening of the cyclic sulfinic-carboxylic anhydride (11) is found to occur exclusively by attack at C=0 <86KFZ843, 88IZV1633>. 

As cyclic sulfonic-carboxylic anhydrides, the l,2-oxathiolan-5-one 2,2-dioxides (16) are conveniently prepared by dehydrative cyclization of the corresponding diacids, typically using thionyl chloride <40JA925>. The latter can be obtained by photochemical sulfonation of propionic acids with SO2CI2 <40JA2393>. The benzo derivative (12) is formed in 91% yield by reaction of (59) with ZnCl2 at 200°C <83USP4408058>. 

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). 

Carboxylic anhydrides and alkylcadmiums give ketones in 50-70% yield 359 this reaction is also smooth with Grignard reagents, especially at low temperatures (—70°).365 Oxo carboxylic acids are obtained when alkylcadmiums or alkylzincs are treated with cyclic acid anhydrides359,366,367 or when a monoester monochloride of a dicarboxylic acid reacts with an isoalkyl-magnesium bromide.368 (The oxo group can be reduced by Clemmensen s... 

A carbonyl group is a carbon double-bonded to an oxygen an acyl group is a carbonyl group attached to an alkyl or aryl group. Acyl halides, acid anhydrides, esters, and amides are called carboxylic acid derivatives because they differ from a carboxylic acid only in the nature of the group that has replaced the OH group of the carboxylic acid. Cyclic esters are called lactones cyclic amides are lactams. There are symmetrical anhydrides and mixed anhydrides. 

Enantioselective reductions. Lactones and hydroxylactams are obtained in chiral forms when meio-cyclic 1,2-carboxylic anhydrides and dicarboximides are treated with the complex at low temperature. 

CAS 552-30-7 EINECS/ELINCS 209-008-0 Synonyms Anhydrotrimellitic acid 1,2,4-Benzenetricarboxylic acid anhydride 1,2,4-Benzenetricarboxylic acid-1,2-anhydride 1,2,4-Benzenetti-carboxylic acid, cyclic 1,2-anhydride Benzene-1,2,4-tricarboxylic anhydride 4-Carboxyphthalic anhydride 1,3-Dihydro-1,3-dioxo-5-isobenzofurancarboxylic acid 1,3-Dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid 1,3-Dioxo-5-phthalanccarboxylic acid Diphenylmeth-ane-4,4 -diisocyanate trimellic anhydride TMA Trimellic acid anhydride Trimellic acid-1,2-anhydride Trimellitic acid cyclic-1,2-anhydride Empirical C9FI4OS Formula FIOCOCsFIsCOOCO... 

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

Trifluoroacetic anhydride Cyclic ketones from carboxylic acids... 

A-Heterocyclic carbenes (NHCs), used as organocatalysts, have received great interest due to their unique reactivity and selectivity observed in many different types of organic reactions (for selected recent reviews see [250-261]. More recently, NHC-mediated reactions have also been employed for polymer synthesis ([262-264] for selected reviews see [20, 265-267]), especially in the ROP of heterocyclic monomers, such as lactides [268-272], lactones [273-276], epoxides [277-279], cyclic carbonates [280], cyclic siloxanes [281, 282], and A-carboxyl-anhydrides [283, 284]. NHC-mediated step-growth polymerization has also been reported [285-287]. 

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