Cyclic poly imides

Tsai Pai-Feng, Wu Chyong-Fen, Hsiao Yu-Che, and Shau Min-Da. Properties of novel poly-imides containing bismaleimide and cyclic phosphine oxide. J. Polym. Res. 16 no 6... 

The preparation of imides from reaction of isocyanates with anhydrides dates back to the early days of organic chemistry [96]. With the advent of polyimide chemistry in the early 1960s, this chemistry was soon explored for the synthesis of polyimides. However, in contrast to the preparation of polyimides via thejr poly(amic acid) intermediate, the reaction of aromatic dianhydrides with aromatic diisocyanates is much less understood. The reaction of aromatic dianhydrides with aliphatic or aromatic diisocyanates is believed to form a cyclic seven-membered intermediate which then splits out C02 to form the polyimide [97], see Scheme 27. The addition of water, which has been reported to accelerate the anydride/isocyanate reaction, can result in several transformations of either the anhydride or the isocyanate reagent, see Scheme 28... 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

Acrylamide polymers in aqueous solution undergo thermal hydrolysis and cyclic imide formation. Acrylate, acrylamide and cyclic imide functional groups were detected when a poly(acrylamide) is heated at 150°C in water. The formation of intramolecular imide has been reported in literature. Moradi-Araghi, Hsieh and Westerman reported the formation of cyclic imide in acid, neutral and slightly basic media at 90° C.7 In acidic media, imide formation is favored. In neutral and basic media, both hydrolysis to acrylate and imide formation do occur, but hydrolysis is the dominant reaction. We speculate the high conversion of amine to amide is the result of transamidation, amidation and the nucleophilic addition of the amine to the glutarimide intermediate (Reaction 1). 

Some other inorganic polymers may be mentioned [8,10] polyoxothiazenes 18 (prepared by thermal condensation of sulfon imidates, R0(0)S(R)=NH) highly conducting polythiazyl (poly(sulfur nitride)) 19 (prepared from S2CI2 and NH3 via a cyclic alternating nitride tetramer (SN)4) polycarboranes and polycarbosilanes (e.g. (-CB oH oC-Si(CH3)2-0-) ) containing a /w-carborane moiety. 

If there is only a small number of reactive groups per macromolecule, the environment of these groups is not changed as the reaction proceeds. The macromolecular chain simply acts as a diluent. Of course, neighboring group effects can also play a role, especially if five- and six-membered cyclic transition states can be formed. An example of this is the partial imidization of poly(methacrylamide) at temperatures above 65°C ... 

In 2001, Meng and Wudl et al. reported the synthesis of poly(benzo[c]thiophene-A -2"-ethylhexyl-4,5-dicarbodiimide) P3.13 (Chart 1.45), which had a broad absorption band with a maximum at 832 nm and an onset absorption at 1000 nm corresponding to a bandgap of Eg = 1.24 eV [324]. Cyclic voltammograms of P3.13 exhibited an oxidation potential of 0.88 V and a reduction potential of -1.10 V vs SCE, showing p-and n-dopable properties of P3.13. Compared with the parent polymer PITN, both oxidation and reduction are shifted to positive potentials due to the electron-withdrawing effect of the imide group. 

Miller et al. used various ohgoimides in conjunction with several generations of poly(benzylether) dendrons to synthesize molecular dumbells", the largest of which extended 9.6 nm in length. The electrochemistry of the imide reduction was studied using cyclic voltammetry at scan rates up to 100 Vs , and it was found that the dendrimer did not... 

Hamciuc Corneliu, Vlad-Bubulac Tachita, Petreus Oana, and Lisa Gabriela. Synthesis and characterization of new aromatic polyesters and poly(ester-imide)s containing phosphorous cyclic bulky groups. Polym. Bull. 60 no. 5 (2008) 657-664. 

Trimellitic anhydride (TMA) is an important raw material for high temperature resistant polymers such as polyesterimide, poly-amideimide etc. The cyclic anhydride group in the TMA molecule offers a reaction site for imide formation and the carboxyl group for synthesis of ester or amide linkages. The polycondensation of TMA with glycol and/or diamine results in the formation of semiladder structures in the polymer, which is responsible for high temperature resistance. 

A further reaction shown by poly(acrylic acid) and poly(methacrylic acid) is with ammonia to form cyclic imides. Polymethacrylimide is prepared commercially by heating a copolymer of methacrylic acid and methacrylonitrile with an ammonia-producing compound (e.g. urea or ammonium hydrogen carbonate) at about 200°C ... 

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