2,3-Pyridine dicarboxylic anhydride

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. 

Polythieno[3,4-f)]pyridine (Fig. 27b) has also been prepared by reaction of 2,3-pyridine dicarboxylic anhydride. Conductivities after doping were on the order of 10 S cm [614]. 

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. 

Pyrazine-2,3-dicarboxylic anhydride gave no products of the reaction of the corresponding heteroaryne with pyridine however, it gave a small but definite amount of phenylpyrazine with benzene, suggesting the formation of pyrazyne. This anhydride is readily converted by ring opening and rearrangement to succinonitrile (Brown et al., 1966). 

Synthesis of the Thiono Isostere of Imazethapyr. The thiono isostere of imazethapyr was prepared in the same fashion from 5-ethyl-pyridine-2,3-dicarboxylic anhydride 13. The resulting mixture of regioisomers 14 and 15 was treated with aqueous sodium hydroxide to afford acid 16 after acidification and fractional crystallization. 

Sulfonation was carried out by heating the asphalt with sulfur trioxide-trimethyl amine complex or sulfur trioxide-pyridine complex at temperatures near 135°C. Sulfamic acid treatment was also included in this series. Many other reagents were evaluated such as methyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, 2-dimethyl-aminoethyl methacrylate, 2-vinylpyridine, 4-vinylpyridine, tetrahydro-phthalic anhydride, norbomene dicarboxylic anhydride, and phthalic anhydride. 

Dicarboxylic anhydrides. Duckworth prepared acid anhydrides in about 90% yield by reaction of 1 mole of trifluoroacetic anhydride with 1 mole of a dicarboxylic acid in ether. Treatment of the mono-mixed anhydride with 1 mole of pyridine then led to the anhydride and pyridinium trifluoroacetate, which was precipitated by addition of petroleum ether. Alternatively, the mixed anhydride can be cyclized by heat treatment in vacuum at about 70°. This latter method was used by Moore and Kelly to prepare the anhydride (3) of tetra-hydrofurane-cw-2,5-dicarboxylic acid (1) in >90% yield. 

Trifluoroacetic anhydride pyridine Dicarboxylic acid anhydrides from dicarboxylic acids... 

Mixed cellulose esters containing the dicarboxylate moiety, eg, cellulose acetate phthalate, have commercially useful properties such as alkaline solubility and excellent film-forming characteristics. These esters can be prepared by the reaction of hydrolyzed cellulose acetate with a dicarboxylic anhydride in a pyridine or, preferably, an acetic acid solvent with sodium acetate catalyst. Cellulose acetate phthalate [9004-38-0] for pharmaceutical and photographic uses is produced commercially via the acetic acid-sodium acetate method. 

Derivatives of some pyridine-dicarboxylic acids are of interest and value. Quinolinic acid anhydride gives, with ammonia, 2-aminocarbonylnicotinic acidi , which in the Hofinann reaction yields 2-aminonicotinic acid. Similarly, cinchomeronic anhydride gives 4-aminocarbonylnicotinic acid and thence 4-aminonicotinic acid . Use of quinolinic imide in the Hofinann reaction produces mainly 3-aminopicolinic acid and cinchomeronic imide gives 3-amino-isonicotinic acid whilst diamides of... 

The parent polythieno[3,4-Z ]pyrazine (19, R = H) has recently been prepared by reaction of 2,3-pyrazine-dicarboxylic anhydride (92) with P4S10 (Scheme 8) as a black powder whose dedoped conductivity was 10 -10 S/cm. Doping with NO BF4, I2. or FeCU gave conductivities of (5-7) x 10 S/cm [22]. A similar reaction using 2,3-pyridinedicarboxylic anhydride (93) produced polythieno[3,4-/>]pyridine (94), whose dedoped conductivity was 10 S/cm and whose conductivities after doping with NO BF4 . I2. and FeCIi were 2 X 10 3 X 10 , and6 x 10 S/cm, respectively [22]. No band gap data were presented for either polymer. 

Guesten, H. Heinrich, G. Ache, H.J. (Inst. Radiochem., Kemforschungszent. Karlsruhe, 7500 Karlsruhe, Fed. Rep. Ger.). J. Photochem. 1985, 28 (3), 309-14 (Eng.). The use of photoacoustic spectroscopy in the study of the absorption spectra and thermal kinetics of photochromic reactions in the cryst. and adsorbed states was demonstrated in the following photochem. reactions E-a-(2,5-dimethyl-3-furylethylidene) (isopropylidene) succinic anhydride into 7,7 -dihydro-2,4,7,7 -pentamethylbenzo[b]furan-5,6-dicarboxylic anhydride, 2-(2 -dinitrobenzyl)pyridine into its blue tautomeric form, bis-(2-o-chlorophenyl-4,5-p-methoxyphenyl)diimidazolyl-l,l into its stable free imi-dazolyl radical and rrans-l,2-bis[quinolinyl-(2)]ethylidene dioxalate into its violene radical cation. By using the dnal illumination technique the absorption spectra and thermal lifetimes of short-lived photochromic species can be recorded by means of photoacoustic spectroscopy. 

Sulfur compounds have also been widely studied as activating agents for polyesterification reactions. p-Toluenesulfonyl chloride (tosyl chloride) reacts with DMF in pyridine to form a Vilsmeir adduct which easily reacts with carboxylic acids at 100-120° C, giving highly reactive mixed carboxylic-sulfonic anhydrides.312 The reaction is efficient both for aromatic dicarboxylic acid-bisphenol312 and hydroxybenzoic acid314 polyesterifications (Scheme 2.31). The formation of phenyl tosylates as significant side products of this reaction has been reported.315... 

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,... 

N-silylated imines 509 react with the Li salts of tosylmethylisonitriles to give 4,5-disubstituted imidazoles in moderate yields [93]. Acetylation of N-trimethylsilyl imines 509 with acetyl chloride and triethylamine affords 72-80% of the aza-dienes 510 these undergo readily Diels-Alder reactions, e.g. with maleic anhydride at 24 °C to give 511 [94] or with dimethyl acetylenedicarboxylate to give dimethyl pyridine-3,4-dicarboxylates [94] (Scheme 5.29). 

Another approach to improve the color formation properties of Malachite Green lactone has been the introduction of nitrogen atoms into the phthalide ring. Thus, condensation of pyridine-2,3-dicarboxylic acid anhydride with dimethylaniline in the presence of zinc chloride has been shown54 to yield a mixture of the 4- and 7-azaphthalides 11 and 12. 

Stepwise addition of the aniline moieties in analogy to Scheme 7 (Route A) allows the preparation of asymmetrically substituted derivatives.55,56 The use of pyridine-3,4-dicarboxylic acid anhydride similarly results in the formation of mixtures of 5- and 6-azaphthalides.57 Quinoline-2,3-dicarbo-xylic anhydride has also been converted into the corresponding azaphthal-ides in a similar manner.58 Pyrazine-2,3-dicarboxylic acid anhydride yields... 

PLLA-fr-PCL) multiblock copolymers were prepared from the coupling reaction between the bischloroformates of carboxylated PLLA with diol-terminated PCL in the presence of pyridine [140]. LLA was polymerized with SnOCt2 and 1,6-hexanediol followed by the reaction with succinic anhydride to provide the dicarboxylated PLLA. The carboxyl end groups were subsequently transformed to acid chloride groups by the reaction with thionyl chloride (Scheme 65). As expected, the molecular weight distributions were broad for all samples (1.84 < Mw/Mn < 3.17). 

Figure 14.7. Chemical structures of some chelators and enhancers used in time-resolved fluoroimmunoas-says 1, isothiocyanatophenyl-EDTA 2, Ari-p-(isothiocyanatobenzyl)-diethylenetriaminetetraaceticacid 3, diethylenetriaminepentaacetic anhydride (DTPA) 4, Tb3+-DTPA-/t-aminosalicylic acid S, Eu3+-pyridine-bisfmethylaminodiacetic acid) 6, benzoyltrifluoroacetone (BTA, a /i-diketone) 7, trifluoroacetylacetone (a/jt-diketone) 8,4,7-bis(chlorosulfonylphenyl)-l,10-phenanthroline-2,9-dicarboxylic acid (BCPDA).

Reaction of 1,2 -dicarboxylic acids has been used for the formation of a number of strained alkenes and also applied to the Diels-Alder addition products from maleic anhydride (Table 9.5). Both cis- and tr s-diacids take part in the process. Aqueous pyridine containing, triethylamine as a strong base, is considered the best solvent and higher yields are obtained at temperatures of around 80 "C [130]. Use of a divided cell avoids a possibility of electrocatalytic hydrogenation of the product at the cathode. The addition of /a/-butylhydroquinone as a radical scavenger prevents polymerization of the product [127], An alternative chemical decarboxylation process is available which uses lead tetraacetate [131] but problems can arise because of reaction between the alkene and lead tetraacetate. 

Amino-,3-amino-9-methyl-, and 3-amino-9-(2-cyanoethyl)carba-zoles and significantly 3-nitro-, 3-formyl-9-(2-cyanoethyl)-, - and 3-formyl-9-alkylcarbazoles reportedly undergo a double acylation with phthalic anhydride giving the quinones 176. Pyridine-2,3-dicarboxylic acid anhydride brought about the 3-monoaroylation of 9-ethylcarbazole attack at both of the pyridine carbonyl groups was observed. 

Proof for the existence of benzene isomers in irradiated benzene has been obtained in several ways. These will not be discussed in detail, but they may be classified broadly as physical and chemical. Nuclear magnetic resonance has been used by Wilzbach and Kaplan to identify benzvalene.39 Prismane has also been identified by NMR and by vapor-phase chromatography. The Dewar form has been synthesized in several steps which start with ris-1,2-dihydrophthalic anhydride. Photochemically this compound yields bicyclo(2,2,0)hexa-5-ene-2,3-dicarboxylic aqid anhydride. This was followed by catalytic reduction and oxidative decarboxylation to give the Dewar form of benzene.39 The method of synthesis alone provides some basis for structure assignment but several other bits of supporting evidence were also adduced. Dewar benzene has a half-life of about 48 hr at room temperature in pyridine solution and its stability decreases rapidly as the temperature is raised. 

Abbreviations arene, i/6-benzene or substituted benzene derivative bipy, 2,2 -bipyridyl Bu, Bu", Bu, iso-, n-, or rerf-butyl COD, 1,5-cyclo-octadiene Cp, /5-C5H5 DAD, dimethyl-acetylene dicarboxylate dam, 1,2-bis(diphenylarsino)methane DBA, dibenzylideneacetone DMF, A. A -dimethylformamide dpe, l,2-bis(diphenylphosphino)ethane dpen, os-l,2-bis(di-phenylphosphino)ethylene dpm, 1,2-bis(diphenylphosphino)methane ESR, electron spin resonance F6-acac, hexafluoroacetylacetone FN, fumaronitrile MA, maleic anhydride Me, methyl MLCT, metal ligand charge transfer phen, 1,10-phenanthroline Pr , Pr", iso- or n-propyl py, pyridine RT, room temperature TCNE, tetracyanoethylene tetraphos, (Ph2PCH2CH2)jP THF, tctrahydrofuran Xylyl, 2,6-Me2C6H3. 

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