Cyclization thermo

A series of glycol bis(aUyl phthalates) and bis(aUyl succinates) and their properties are reported in reference 88. In homopolymerizations, cyclization increases in the order diaUyl aliphatic carboxylates < glycol bis(allyl succinates) < glycol bis(allyl phthalates). Copolymerizations with small amounts of DAP can give thermo set moldings of improved impact (89). 

Ganter has developed three different approaches to tricyclo[5.2.1.0 ]decane (403), yet another of the nineteen isomeric hydrocarbons of adamantaneland As seen in Scheme XXXIII, the routes involve intramolecular cyclization of keto tosylate 399 followed by Wolff-Kishner reduction of the resulting ketone, thermo-cyclization of 400 and subsequent dechlorination, hydrogenation, and photocycli-zation of aldehydes 401. Majerski s approach involved hypoiodite cleavage of alcohol 402... 

Photochemical cyclization occurs by a conrotatory mechanism, while thermal cyclization occurs by a disrotatory one. In the symmetrical fulgide / 7 -ArF2, the phenyl substituents of both benzylidene groups participate in the reaction with equal probability. In unsymmetrical benzylidene(diphenylmethylene)-succinic anhydride, -ArFl, only one phenyl substituent of the diphenylmethylene moiety participates both in thermo- and in photochemical reactions. The selectivity of such a transformation is not determined by a rule of orbital symmetry preservation, so it was suggested that it may be related to the specific spatial structure ofArFl.81... 

Polyetherlmldes Thermoplastic cyclized polymers of aromatic diether dianhydrides and aromatic diamine. Has good chemical, creep, and heat resistance, and dielectric properties. Processed by extrusion, thermo forming, and compression, injection, and blowmolding. Used in auto parts, jet engines, surgical instruments, industrial apparatus, food packaging, cookware, and computer disks. Also called PEI. 

No volatiles can be detected by mass spectrometry [215, 216] or by thermo gravimetric analyses during the cross-linking reaction. The thermo oxidative stability of the resultant polymers is at least equivalent to polyphenylquioxalines not terminated by acetylene. The cross-linking reaction was shown on a model compound to be an intramolecular cyclization [215-217] ... 

The degradation of polyacrylonitrile deuteriated in the alpha position has been followed by Fourier transform i.r. spectroscopy. The results are consistent with imine-enamine tautomerism followed by oxidation to give pyridone structures. A variety of thermo-analytical techniques has been employed to study thermal and thermo-oxidative reactions and it is concluded from these that a carboxylate moiety is responsible for initiating cyclization in an oxidizing atmosphere. The role of oxygen is said to be three-fold, creation of the carboxylate initiator sites, dehydrogenation, and crosslinking. 

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