Dicarboxylic anhydrides

Aqueous ring-opening metathesis polymerization (ROMP) was first described in 1989 (90) and it has been appHed to maleic anhydride (91). Furan [110-00-9] reacts in a Diels-Alder reaction with maleic anhydride to give exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3—dicarboxylate anhydride [6118-51 -0] (24). The condensed product is treated with a soluble mthenium(Ill) [7440-18-8] catalyst in water to give upon acidification the polymer (25). Several apphcations for this new copolymer have been suggested (91). 

Thiophene-2,3-dicarboxylic anhydrides flash vacuum thermolysis, 4, 750 reactions, 4, 72... 

Chlorendic anhydride (l,4,5,6,7,7,-hexachloro-5-norbornene-2,3-dicarboxylic anhydride) [115-27-5] M 370.9, m 234-236 . 235-237 , 238 . Steam distn or recrystn from H2O yields the diacid. The purified diacid yields the anhydride with AC2O. [Prill 7 A/w Chem Soc 69 62 1947.]... 

Methylnorbornene-2,3-dicarboxylic anhydride (5-methylnorborn-5-ene-2-endo-3-endo-di-carboxylic anhydride) [25134-21-8] M 178.2, m 88.5-89 . Purified by thin layer chromatography on AI2O3 (previously boiled in EtOAc) and eluted with hexane- C6Hg (1 2) then recrystd from CgH -hexane. The free acid has m 118.5-119.5 . [Miranov et al. Tetrahedron 19 1939 1963.]... 

Didehydropyrazine is believed to be an intermediate in the pyrolysis of pyrazine-2,3-dicarboxylic anhydride. According to DFT calculations, this molecule has a triplet ground state with a singlet state about 10 kcal/mol higher in... 

Cyclic 1,3-diacetoxy-l,3-dienes can be generated in situ from cyclic 1,3-diketones under the influence of isopropenyl acetate. The dienes then undergo Diels-Alder reactions with maleic anhydride giving as products 1-acetoxybicycloalkane dicarboxylic anhydride derivatives (10). The procedure is also successful with cyclic 1,2- and 1,4-diketones as well as cyclic a,j3-unsaturated ketones. The products, after hydrolysis to... 

Condensation of Biphenyl-2,2 -dicarboxylic Anhydride with Hydrazines... 

Hydrazine or its substituted derivatives react with biphenyl-2,2 -dicarboxylic anhydride (1) to provide 1,2-diazocinedione derivatives 2.13 1S... 

A. 3-Methylenecycldbutane-l,2-dicarboxylic anhydride. A 2-1. stainless steel autoclave equipped with stirrer, pressure gauge, and thermocouple is charged with 500 g. (5.1 moles) of maleic anhydride, 645 ml. of benzene, and 0.25 g. of hydroquinone. The autoclave is closed, cooled to — 70° with stirring, and evacuated to a pressure of about 20 mm. Allene (100 g., 2.5 moles) (Note 1)... 

The crude anhydride is carefully fractionated through a 13-mm. x 1.2-m. Nester still at a pressure of 25 mm. (Note 4) and a reflux ratio of at least 10 1. After a fore-run of maleic anhydride, b.p. 50-100°/25 mm., and a small intermediate fraction, there is obtained 75-90 g. (22-26%) of 3-methylenecyclobutane-l,2-dicar-boxylic anhydride b.p. 155-159°/25 mm. 1.4935-1.4952 (Note 5). This material is of sufficient purity for most uses, but it contains approximately 2-5% of propargylsuccinic anhydride. Redistillation through the Nester still gives 65-80 g. (19-23%) of 3-methylenecyclobutane-l,2-dicarboxylic anhydride b.p. 155°/25 mm. 1.4946-1.4955. 

B. Dimethyl 3-methylenecyclobutane-l,2-dicarboxylate. One liter of methanol is added cautiously with occasional shaking to 276 g. (2.00 moles) of 3-methylenecyclobutane-l,2-dicarboxylic anhydride ( d 1.4946-1.4955 Note 6) and 5 g. of />-toluenesulfonic acid in a 2-1. three-necked flask fitted with a thermometer, a condenser, and a dropping funnel. Refluxing starts after about two-thirds of the methanol has been added. The remainder is added at a rate that maintains vigorous boiling. The solution is refluxed for 30-40 hours with the pot temperature increasing... 

Since 3-methylenecyclobutane-l,2-dicarboxylic anhydride is easily converted to 3-methyl-2-cydobutene-l,2-dicarboxylic acid, it is an intermediate to a variety of cyclobutenes. The dimethyl ester of 3-methylenecyclobutane-l,2-dicarboxylic acid is also a versatile compound on pyrolysis it gives the substituted allene, methyl butadienoate, and on treatment with amines it gives a cyclobutene, dimethyl 3-methyl-2-cyclobutene-l,2-di-carboxylate. ... 

The reaction of furan with 2,5-dihydrothiophene-3,4-dicarboxylic anhydride is remarkable (Scheme 6.19). Furan is a poor diene and requires high pressure to affect cycloadditions [39]. On the other hand, high temperatures are forbidden because cycloaddition products derived from furan undergo cycloreversion under these conditions. In 5.0m LP-DE, the Diels-Alder reaction of furan with 2,5-dihydrothiophene-3,4-dicarboxylic anhydride proceeds at room temperature and atmospheric pressure in 9.5 h with 70 % yield and with the same diastereos-electivity found when the reaction is carried out under high pressure [40]. 

Cycloaddition of bicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic anhydride 81 with cyclopentadiene was also studied by Bartlett et al., who found exclusive top addition, the top-endo/top-exo ratio being 3 2 [147]. The endolexo ratio is significantly different from that of 80 (60-70 1). The observed top selectivity in norbornadiene (80) and norbomene (81) derivatives is consistent with the inherent top reactivity of norbomanone 25 and norbomene 57. Orbital unsymmetrization of the dienophile... 

The rate of polymer erosion in the presence of incorporated anhydride and release of an incorporated drug depends on the pK of the diacid formed by hydrolysis of the anhydride and its concentration in the matrix (20). This dependence is shown in Fig. 7 for 2,3-pyridine dicarboxylic anhydride and for phthaUc anhydride. In this study, methylene blue was used as a marker. The methylene blue release rate depends both on the pK and on the concentration of diacid hydrolysis product in the matrix. However, at anhydride concentrations greater than 2 wt%, the erosion rate reaches a limiting value and further increases in anhydride concentration have no effect on the rate of polymer hydrolysis. Presumably at that point Vj, the rate of water intrusion into the matrix, becomes rate limiting. 

Heating pyridine-2,3-dicarboxylic acid anhydride with l-ethyl-2-methylindole has been claimed to yield solely the pyridine-2-carboxylic acid, albeit in low yield. This then clearly reacts with Af,A/-diethyl-3-toluidine in acetic anhydride to give the 7-azaphthalide. This is surprising in view of a later report70 in which a one-pot process has been described. Heating pyridine-2,3-dicarboxylic anhydride, prepared in situ, with the indole and subsequent reaction with 3-/V,/V-diethylamino-phenetol under identical conditions to those used in Scheme 8 (but without intermediate isolations) produced a 20 1 mixture of the 4- and 7-azaisomers 16 and 17. It appears that in the previous report the major intermediate isomer, the pyridine-3-carboxylic acid, has not been isolated. 

Cyclohexene-1,2-dicarboxylic ANHYDRIDE, cis-, 30, 93 Cyclohexene oxide, 32, 39, 40 Cyclohexene sulfide, 32, 39... 

Methylene cyclopropene (5), the simplest triafulvene, is predicted to be of very low stability. From different MO calculations5 it has been estimated to possess only minor resonance stabilization ranging to 1 j3. Its high index of free valency4 at the exocyclic carbon atom causes an extreme tendency to polymerize, a process favored additionally by release of strain. Thus it is not surprising that only one attempt to prepare this elusive C4H4-hydrocarbon can be found in the literature. Photolysis and flash vacuum pyrolysis of cis-l-methylene-cyclopropene-2,3-dicarboxylic anhydride (58), however, did not yield methylene cyclopropene, but only vinyl acetylene as its (formal) product of isomerization in addition to small amounts of acetylene and methyl acetylene65 ... 

The addition of maleic anhydride to dibenzo calicene 49 7293 proceeds according to the same (2 + 2) or (4 + 2) mode discussed for the addition of ADD, giving rise to the dihydro triphenylene dicarboxylic anhydride 505, which is capable of addition of a second molecule of the dienophile 506). 

Benzeneazobenzene, a312 Benzenecarbonitrile, b51 Benzenecarbonyl chloride, b66 Benzenecarboxyaldehyde, b3 Benzenecarboxylic acid, b44 Benzene-1,2-dicarboxylic acid, pi68 Benzene-1,2-dicarboxylic anhydride, pi69... 

The efficiency and limitations of 3-oxabicyclo[3.2.0]hept-6-ene-2,4-dione 386 (cyclobut-3-ene-l,2-dicarboxylic anhydride) as an acetylene equivalent in 1,3-dipolar cycloadditions has been reported. It reacted readily with a variety of reagents, including nitrile oxides. In all cases, the sterically favored anti-isomers... 

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