Die Blitzthermolyse organischer Verbindungen

Abstract

Die Blitzthermolyse ist eine spezielle Form der Gasphasenthermolyse, die sich besonders zur Erzeugung und Isolierung thermolabiler Reaktionsprodukte eignet. Nach der Erorterung der theoretischen Grundlagen und apparativen Aspekte wird die praparative Bedeutung der Blitzthermolyse fur die Synthese von Thioketenen, Allenen, Arinen, hochgespannten Ringsystemen, Chinodimethanen und anderen reaktiven Verbindungen an Beispielen demonstriert.

Hexakis (methylidene)‐cyclohexane (“[6]Radialene”). Chemical and spectral properties

“…Radialenes are a class of cyclic unsaturated hydrocarbons of composition C2nH2n possessing n ring atoms and n exocyclic double bonds which have attracted considerable interest in recent years both from the theoretical [ 11 and from the experimental [2] side. While the lower members of this series have been known for some time ( [3]radialene [3]; [4]radialene [4]) the formation of [6]radialene (1) h,as been claimed only recently [5]. This latter communication prompts us to report results of our own efforts in this field.…”

“…The gaseous products are either condensed on a cold finger (-78") at the exit of the pyrolysis tube or transferred through an electrically heated vacuum adapter into a receiver containing the appropriate solvent precooled to -78". From the rate of destillation (1 g in 15 miri), pressure (10 Pa)2) and dimension of the hot tube (25x 1 cm) a contact time of I) The synthetic usefulness of pyrolytic methods for the preparation of strained and reactive compounds has recently been reviewed [6]. Pertinent examples are the formation of benzocyclobutenones from o-methylaroylchlorides [7] and of benzocyclobutenes from o-methylarylmethylchlorides [8] upon flash pyrolysis.…”

Thermische Cyclisierung von α‐Alkinonen zu 2‐Cyclopentenonen

“…Andere, zum Beispiel radikalische Formulierungen, welche zu den gleichen Produkten fiihren, schliessen wir nicht aus. Reaktionen unter solchen Bedingungen werden in der Literatur [6] oft als Blitz-Thermolysen (flash thermolysis) bezeichnet.…”

Correlation between carbon–carbon bond length and the ease of retro Diels–Alder reaction

“…1 However, its reverse reaction i.e., retro Diels-Alder (rDA), has been relatively less explored owing to the high energy requirement to cross the activation barrier. 2 Despite existing problems, rDA reaction has evolved as a useful tool and remains to be a preferred method for the preparation of several reactive olefins or metastable molecular entities. 3 ,4 The rate of rDA reaction depends on several factors like the geometry of the adducts, hetero atoms, nature of substituents tagged with the adducts, catalysts used, etc.…”