Pyromellitic anhydride

Hydroxyl number and molecular weight are normally determined by end-group analysis, by titration with acetic, phthaUc, or pyromellitic anhydride (264). Eor lower molecular weights (higher hydroxyl numbers), E- and C-nmr methods have been developed (265). Molecular weight deterrninations based on coUigative properties, eg, vapor-phase osmometry, or on molecular size, eg, size exclusion chromatography, are less useful because they do not measure the hydroxyl content. 

In analogy to the original preparation of Malachite Green lactone, pyromellitic anhydride has also been reacted with N, Ar-di me thy laniline in a zinc chloride melt to yield mixtures of the bisphthalides 29 and 30.109 However, far superior yields were obtained if reaction was carried out in two steps, as described in Scheme 12. The initial condensation was carried out... 

Reaction of pyromellitic anhydride with 1,1-bisdimethylaminophenyl-ethylene has been shown110 to yield a mixture of the bisphthalides 31 and 32 which are infrared-absorbing color formers on clay. 

Finally, 1-ethyl-2-methyl indole was reacted111 with pyromellitic anhydride to give a mixture of keto acids, as in Scheme 12, which was then treated with diphenylamines to yield bisphthalides such as 33 and 34. These color formers produce orange images on development, as also do those in which the indole residue is replaced by a 4-dialkylaminophenyl group. 

The following preparation of a polyimide from a diimidazolide and pyromellitic anhydride took advantage of the fact that imidazole is an excellent blocking agent for isocyanates 11551... 

If considerable amounts of pyromellitic anhydride separate in the neck of the retort, it is advisable to rinse it into a... 

These are produced by polycondensation of pyromellitic anhydride and p,p -diamino diphenyl ether. The reaction, is carried out in stages. To start with, the reaction is carried out in suitable solvents, like DMF, at around 50°C, when a polyaddition reaction occurs with the formation of polyamic acid as under ... 

Hi-Blen pyromellitic anhydride and 4,4-diaminodiphenyl ether ABS polymers Japanese Geon... 

Aromatic polyimides are synthesized by the reactions of dianhydrides with diamines, for example, the polymerization of pyromellitic anhydride with p-phenylenediamine to form poly(pyromeUitimido-l,4-phenylene) (XLV) [de Abajo, 1988, 1999 Hergenrother, 1987 Johnston et al., 1987 Maier, 2001]. Solubility considerations sometimes result in using the half acid-half ester of the dianhydride instead of the dianhydride. 

A reactor was charged with 1,10-diaminodecane (20 mmol) dissolved in 170 ml of /V, /V - d i m e t h I fo rm amide containing pyromellitic anhydride (20 mmol) and the mixture stirred at ambient temperature for 60 hours. It was then precipitated in 4 liters of acetone/hydrochloric acid, 1 4, respectively, and collected. The solid was washed with aqueous hydrochloric acid solution and acetone and then heated and dried in vacuum at 60°C for 36 hours and 7.65 g of product isolated as a white powder. 

First referred to in a publication in 1983, this latter monomer, has been involved in much research first, American Aerospace prepared composites [93-96] e.g. Fusaro et al. prepared polyimides with pyromellitic anhydride (Tg = 390 C) ... 

A typical formulation for a metal-to-metal adhesive-sealant that is cured with a combination of phthalic anhydride and pyromellitic anhydride is shown in Table 12.6. Table 15.9 shows the high-temperature properties of another epoxy formulation cured with pyromellitic dianhydride. Epoxy formulations cured with pyromellitic dianhydride (PMDA) show good short-term thermal stability in the temperature range of 150 to 230°C. 

Other recent work shows that the lectin Con A, cross-linked with glutaral-dehyde, binds to DEAE-cellulose, irreversibly. The bound lectin possesses adequate biological activity with respect to binding to glycoprotein enzymes (35). Trypsin modified by pyromellitic anhydride binds much better to DEAE-cellulose as compared to native enzyme (M. N. Gupta, unpublished results). 

Perylene and tetracene both undergo photo-induced electron-transfer reactions with pyromellitic anhydride (Levin, 1976). If a mixture of perylene and tetracene is used, and the light absorbed by the perylene, the perylene radical cation will be formed which because of the relative oxidation potentials will react with tetracene to give the tetracene radical ion. Thus the photogenerated perylene radical cation has undergone a redox reaction with tetracene. In effect, the perylene has acted as a sensitiser for the production of the tetracene radical cation. This type of sensitisation has been used to effect a number of reactions. 

When studying systems in which the photochromes are directly bound to the polymers, first mention should be made of the report of Agolini and Gay on the photo- and thermocontractile behavior of azoaromatic polyimides (XV) obtained by condensation of 4,4 -diaminoazobenzene with pyromellitic anhydride and dehydration of the resulting polyamine acid ... 

Controlled potential electrolyses of phthalic and pyromellitic anhydrides at the potential of the first wave gave highly colored, oxygen-sensitive solutions, which later were shown to give well-resolved esr spectra of the corresponding radical ions [55]. Phthalic anhydride has been reduced to phthalide on a preparative scale [109], but the reaction conditions employed (ethanol-water-ammonium carbonate) indicate that monoethyl phthalate must have been the actual substrate. An interesting reduction of 3,6-diphenylphthalic anhydride in the presence of trimethylsilyl chloride gives two types of dimeric species [110] ... 

Poly(imides) contain the group -C(0)-NH-C(0)- in their structure. Many poly(imides) with practical applications have a more complicated formula and contain oxygen atoms and aromatic rings in the backbone [1]. One example is poly(pyromellitic dianhydride-a/f-4,4 -oxydianiline) or PMDA-ODA, CAS 25038-81-7, which is obtained from pyromellitic anhydride and oxybis(benzenamine) by water elimination as follows ... 

The work of Hayashi et al. (2 ), however, has indicated that an ion pairs component can be introduced by adding strong electrons acceptors such as pyromellitic anhydride. 

Whang and Wu [3] have described the liquid crystalline state of polyimide precursors and shown that certain polyamic acids derived from pyromellitic anhydride exhibit lyotropic behaviour. Liquid crystal phases have also been observed by Wenzel et al. [4] in polyimides derived from pyromellitic anhydride and 2,5-di-n-alkoxy-1,4-phenyl ene diisocyanate. Dezern [5] has disclosed a synthesis for linear polyamide-imides derived from benzophenone dianhydride but the occurrence or otherwise of mesophases is not mentioned. 

PEIs were synthesised from pyromellitic anhydride and CO-aminoacids, condensed first to form a di-acid (13) and subsequently reacted with a range of mes-ogen forming diols, e.g. 4,4 -biphenyldiol, 2,6-dihydroxynaphthalene, methyl-, chloro- and phenylhydroquinone. None of the polymers were found to contain a liquid crystal phase [27]. 

A series of wholly aromatic poly(etherimide)s were synthesised [80,81], one of which was found to contain a smectic A phase in the melt. Its structure is given in Chap. 8 (number 160) and consists of pyromellitic anhydride co-reacted with a five ringed diamine containing a central meta- unit linked via an isopropylene unit to two para- linked ether diphenylamine units. If the central ring is made para-oriented, then an LC phase is not observed. 

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