Polymer, heterocyclic

Heterocoagulation Heterocyclic Heterocyclic amines Heterocyclic azo dyes Heterocyclic compounds Heterocyclic dyes Heterocyclic polymers Heterocyclic thiophenes Heteroepitaxy Heterogeneous catalysis Heterogemte Heteroglycan Heterojunction... 

Hochleistungsschwebstoffilter) hepatotoxic hepatotoxisch, leberschadigend hermaphroditic contact e/ecfr Zwitterkontakt hermetic(al) heimetisch heterochain polymer Heteroketten-Polymer heterocyclic... 

Just after the first conductive LB film based on molecular conductors was reported, the studies extended to those based on conductive polymers. Heterocyclic polymers, i.e. polypyrroles and polythiophenes are mainly used as film-forming materials due to their stability compared with aliphatic conductive polymers like polyacetylenes. The other stable polymers, for example, polyanilines, poly(p-phenylenevi-nylene)s, etc. are also the subjects of LB studies. A... 

Polymers are subdivided into principle classes by the composition of their repeating chain segment acyclic carbon polymers, carbocyclic polymers, acyclic heteroatom polymers, heterocyclic polymers, and copolymers. All entries are placed in the most senior class their structure commands (109,110) and appear in only one class. The subclasses and their entries are organized in alphabetical order. 

Chapters V-X deal respectively with Heterocyclic and Alicyclic Compounds Miscellaneous Reactions Organic Reagents in Inorganic and Organic Chemistry Dyestuffs, Indicators and Related Compounds Some Physiologically-Active Compounds and Synthetic Polymers. Many of these preparations are of course intended for advanced students, but a mere perusal of the experimental details of selected preparations by those whose time for experimental work is limited may assist to impress them on the memory. Attention is particularly directed to the chapter... 

Polyheterocycles. Heterocychc monomers such as pyrrole and thiophene form hiUy conjugated polymers (4) with the potential for doped conductivity when polymerization occurs in the 2, 5 positions as shown in equation 6. The heterocycle monomers can be polymerized by an oxidative coupling mechanism, which can be initiated by either chemical or electrochemical means. Similar methods have been used to synthesize poly(p-phenylenes). 

Electrochemical polymeriza tion of heterocycles is useful in the preparation of conducting composite materials. One technique employed involves the electro-polymerization of pyrrole into a swollen polymer previously deposited on the electrode surface (148—153). This method allows variation of the physical properties of the material by control of the amount of conducting polymer incorporated into the matrix film. If the matrix polymer is an ionomer such as Nation (154—158) it contributes the dopant ion for the oxidized conducting polymer and acts as an effective medium for ion transport during electrochemical switching of the material. 

Polymers with a backbone of five-membered heterocyclic rings have been developed in the new area of thermally stable materials during the last 10 years (B-80MI40408). The simple polypyrazole (741) is prepared by condensation of polydiethynylbenzene with hydrazine in pyridine with yields of 60-97%. 

Ubichromenol synthesis, 3, 752 Ugi reaction, 5, 830 Uliginosin B, bromo-molecular dimensions, 3, 621 Ullman and Fetvadjian synthesis quinolines, 2, 477 Ullman synthesis acridines, 2, 470-benzacridines, 2, 470 Ultraviolet light absorbers in polymers, 1, 397-398 Ultraviolet spectroscopy heterocyclic compounds reviews, 1, 78... 

The special topics discussed are (i) the biological aspects of heterocyclic compounds, i.e. their biosynthesis, toxicity, metabolism, role in biochemical pathways, and their uses as pharmaceuticals, agrochemicals and veterinary products (ii) the use of heterocyclic compounds in polymers, dyestuffs and pigments, photographic chemicals, semiconductors and additives of various kinds and (iii) the use of heterocyclic compounds as intermediates in the synthesis of non-heterocyclic compounds. 

Being irregular in structure the polymer is amorphous and gives products of high clarity. In spite of the presence of the heterocyclic ring the deflection temperature under load is as low as that of the poly(butylene terephthalates) and is also slightly softer. Some typical properties are given in Table 25.9. 

A considerable number of non-cross-linked aromatic and heterocyclic polymers has been produced. These include polyaromatic ketones, aromatic and heterocyclic polyanhydrides, polythiazoles, polypyrazoles, polytriazoles, poly-quinoxalines, polyketoquinolines, polybenzimidazoles, polyhydantoins, and polyimides. Of these the last two have achieved some technical significance, and have already been considered in Chapters 21 and 18 respectively. The most important polyimides are obtained by reacting pyromellitic dianhydride with an aromatic diamine to give a product of general structure (Figure 29.17). 

Transformations of heterocycles with participation of functionalized polymers including heterocyclic fragments 97S1217. 

Asymmetric Sharpless dihydroxylation of olefins using catalysts supported by polymers with heterocyclic fragments 98EJ021. 

Electroluminiscent conjugated polymers with heterocyclic fragments 98AG(E)402. 

Polymer-supported synthesis of natural macrocyclic lactones and other 0-heterocycles 99AG(E)1903. 

---