1,2,4,5-Benzenetetracarboxylic dianhydride

Benzenetetracarboxylic dianhydride (pyromellitic dianhydride) is a typical bifunctional acid anhydride, and it is a useful raw material for preparing many useful chemicals. Polyimides and polyimidazopyrrolons prepared from this dianhydride have excellent heat and chemical resistance, as well as excellent mechanical and electrical properties. Pyromellitic dianhydride is produced by the oxidation of 1,2,4,5-tetraalkylbenzenes such as 1,2,4,5-tetramethylbenzene (commonly known as durene) and 4,6-diisopro-pyl-l,3-dimethylbenzene. Durene, in particular, is a fundamental raw material for the production of the dianhydride 1-8). 

Photolysis of 1,2,3,4- and 1,2,4,5-benzenetetracarboxylic dianhydride with different wavelengths invariably results in formation of hexatriyne 125. Attempts to isolate 1,2,5,6- and 2,3,6,7-tetradehydronaphthalenes (naphthdiynes) by photolysis of the corresponding naphthalenetetracarboxylic dianhydrides yield only acetylenic compounds, which suggests that naphthdiynes are formed, but rapidly decompose under photochemical conditions. 

Should we wish to allow for related multi-ring species (> three rings), there are also enthalpy of formation data for carbazole (XLIX), dibenzofuran (L) and dibenzothi-ophene (LI), some benzo and dibenzotetraazapentalenes (also called benzoannelated triazolotriazoles) (e.g., LH, LIII, both drawn without formal charges) [81] and their nitro derivatives [82], for 4-methyl-4//-a/a- (LIV) and 4-oxa-indene (LV) [83] (also called /V-methyl-azalene or 1-pyrindene, and oxalene, respectively), or more properly the 2,3 5,6-dibenzo derivatives thereof, and for 1,2,4,5-benzenetetracarboxylic dianhydride (LVI) [84], However, in the name of brevity we have decided not to discuss these benzoannelated species in this chapter. Instead, these await future analysis. 

N,N -Dimethylacetamide (DMAc) (Aldrich, HPLC grade) was used without further purification. Acetic anhydride (BDH) was pre-dried over anhydrous sodium acetate. Pyridine (Aldrich, anhydrous) was distilled from KOH prior to use. Poly(maleic anhydride-co-octadec-l-eneXl l) (Polysciences), as a polymeric stabilizer, was used as supplied. Paraffin oil (A.J. Beveridge Ltd., liquid paraffin 5LT) was used as a suspending medium. Pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride) (Aldrich) was recrystallized from butan-2-one before use. p-Phenylenediamine (Aldrich) and 2,6-diaminopyridine (Aldrich) were recrystallized from ethanol. 3,5-Diaminobenzoic acid (Aldrich) and 2,5-diaminobenzene sulfonic acid (Aldrich) were recrystallized from water and heated at HOT) under vacuum to remove water. 3,5-Diamino-l,2,4-triazole (Aldrich) and tris(2-aminoethyl)amine (Tokyo Kasei) were without further purification. 

Benzene-1,2,4,5-tetracarboxylic dianhydride 1,2,4,5-Benzenetetracarboxylic dianhydride 1,2,4,5-Benzenetetracarboxylic 1,2 4,5 dianhydride. See Pyromellitic dianhydride... 

Synonyms Benzene-1,2,4,5-tetracarbo) lic dianhydride 1,2,4,5-Benzenetetracarboxylic dianhydride 1.2.4.5-Benzenetetracarboxylic 1,2 4,5 dianhydride 1 H,3H-Benzo(1,2-c 4,5-cO difuran-1,3,5,7-tetrone PMDA Pyromellitic acid anhydride Pyromellitic anhydride Classification Aromatic anhydride Empirical QoHjOs Frmnida CsH2(C20,)2... 

Neither polyimides derived from 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) nor from biphenyl tetracarboxylic anhydride with aliphatic spacers have yielded a liquid crystalline phase. The need for an extraring to obtain meso-genic properties was evident. Inoue et al. reported the existence of mesophase in a series of polyimides synthesized from the nylon-salt-type terphenyl tetracarboxylic anhydride with aliphatic diamines (Structure 4) [53-55]. 

We have made acyl, benzoyl and butyryl esters/amides of zein. These products were washed with ethyl acetate to remove unreacted acid chlorides or anhydrides. The NMR of these confirmed the acylation. When dianhydride, 1,2,4,5-benzenetetracarboxylic dianhydride (BTCD), was reacted in various levels, slightly crosslinked to highly crosslinked products were obtained. The highly crosslinked product gelled out of the DMF solution. However, the slightly crosslinked (10Jl) zein was still soluble in DMF and we could make bars out of them by compression molding. 

Benzenetetracarboxylic dianhydride derivatives undergo photolysis in a nitrogen matrix at 13 K to produce benzdiynes by a stepwise process which is dependent on the ring substituents <2002JA4512>. Upon irradiation at 308 nm, the dianhydrides are initially converted into cyclopropanone intermediate 85 by loss of carbon dioxide and subsequently decompose by loss of carbon monoxide to produce the benzyne (Scheme 5). 

A study of matrix isolated 1,2,3,4-benzenetetracarboxylic dianhydride has provided evidence for the formation of 1,3,5-hexatriyne. The possibility of the formation of CeH2 by photochemical extrusion of carbon dioxide and carbon monoxide was discussed. 

Attempts to observe unsubstituted 1,4- and 1,3-benzdiynes (126 and 127) by similar wavelength-selective photolyses of 1,2 4,5- and l,2 3,4-benzenetetracarboxylic dianhydrides were unsuccessful."" The corresponding cyclopropenone and benzyne photoproducts (c/. 120 and 121) were observed in the initial stage in each case, but only ring-opened final products, such as hexa-l,3,5-triyne,were detected thereafter. Comparable results were obtained in attempts to observe naphthdiynes such as 128." " Most recently, a second example of a 1,4-benzdiyne has been identified the 3,6-difluoro derivative, which like the 3,6-bis(trifluoromethyl) analogue 122, was converted into a hexatriyne on secondary photolysis." ... 

Moriyama, M., Sato, T., Uchimaru, T., and Yabe, A, Multi-step photolysis of benzenetetracarboxylic dianhydrides in low-temperature argon matrices exploration of reactive intermediates containing benzdiynes produced stepwise during photochemical reactions, Phys. Chem. Chem. Phys., 1, 2267, 1999. 

Sato, X, Arulmozhiraja, S., Niino, H., Sasaki, S., Matsuura, X, and Yabe, A., Benzdiynes (1,2,4,5-tetradehydrobenzenes) direct observation by wavelength-selective photolyses of benzenetetracarboxylic dianhydrides in low-temperature nitrogen matrices, /. Am. Chem. Soc., 124,4512, 2002. 

The polyamic acids were prepared in these laboratories using modifications of a standard preparation (7). Benzophenone tetracarboxylic acid dianhydride (BTDA), benzenetetracarboxylic acid dianhydride (pyromellitic dianhydride PMDA), oxydianiline (ODA), 1,4-phenylenediamine (PDA) and 1,3-phenylenediamine (MPDA) were all obtained from Aldrich Chemical Co. The S -biphenyl tetracarboxylic acid dianhydride (BPDA) was obtained from Ube Chemical Company. The polyamic acids were prepared in N-methylpyrrolidinone (BTDA-ODA, BTDA-MPDA and BTDA with a 1 1 molar ratio of MPDA and ODA) or dimethyl acetamide (BPDA-PDA and PMDA-ODA). 

Poly-(p- Aminophenylacetylene) - (2,5- Cyclohexa--dienedimalononitrile)) Complex (Poly-(p- Aminophenylacetylene) - Iodine) Complex jPoly-jp- Aminophenylacetylene) -(1,2,4,5- Benzenetetracarboxylic--1,2,4,5-dianhydride)) Complex Poly-(p- Aminophenylacetylene), Toluene Diisocyanate Crosslinked... 

Figure 8 Reaction of 1,2,4,5-benzenetetracarboxylic acid dianhydride (PMDA) 1 with 4,4 -oxybisbenzeneamine (ODA) 2 providing the intermediate high molecular weight polyamic acid 3, which is subsequently cyclodehydrated into aromatic polyimide 4.

Low molecular weight higher functional substituted macrocyclic metal complexes (M = Co, Ni, Cu, Zn) were converted with other bifunctional compounds to polymers. By the reaction of tetraaminophthalocyanine in the presence of another diamine with benzenetetracarboxylic acid dianhydride, at first in dimethylsulfoxide (DMSO) soluble amide-carbocylic acid copolymers were obtained and after film casting and... 

Explain how 1,2,4,5-benzenetetracarboxylic acid dianhydride could be used to make a thermosetting polyester. 

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