The Thermal Decomposition of Metal Alkyls in Hydrogen—ethylene Mixtures

Abstract

The reactivity of metal alkyls undergoing decomposition by heat offers many interesting problems of both scientific and practical interest. The production of a reactive fragment of decomposition among inert hydrocarbons might offer a means of bringing these compounds into a state of reactivity with the possible formation of more interesting products. A study of the reactivity of such fragments with hydrogen is of importance also as indicating the direction of chemical change in systems obtaining when hydrocarbons are subjected to processes of thermal degradation or "cracking." To these ends we have investigated the decomposition of several metal alkyls in the presence of various mixtures of hydrogen and ethylene.When a metal alkyl is decomposed by heat, leaving the free metal as a deposit, it seems an unavoidable assumption that the alkyl group must have existed, at least for a short space of time, as a free radical. If it can then be shown that any resulting reaction could not be attributed to the metal or to the temperature, the postulated mechanism of whatever reaction occurs must be such as to involve the alkyl radical. For this reason mercury diethyl and lead tetraethyl were chosen, since they decompose under temperature conditions which do not of themselves induce reaction of hydrogen and ethylene, and since the metals themselves do not exhibit any marked catalytic effect.

Unseeded growth of germanium nanowires by vapor-liquid-solid mechanism

“…However, as found before, alkyl radicals released during the decomposition of TEG form not only light gaseous products, but also heavy polymerized compounds that, in turn, catalyze further TEG decomposition. 15 This chain reactions supply droplets for NW formation ͓Fig. 2͑c͔͒.…”

“…When LBP solvents like hexane are used, additional droplets can form of the polymerized products of hydrocarbon cracking. 16 The rate of the polymerization is proportional to pressure, 15,16 which explains why NWs did not form in the experiments with pure TEG or TEG in hexane or toluene under a vacuum.…”

Tricoordinate Organochromium(III) Complexes Supported by a Bulky Silylamido Ligand Produce Ultra‐High‐Molecular Weight Polyethylene in the Absence of Activators

“…To test if shorter chain polymers form in the presence of chain‐transfer reagents, such as H 2 or ZnEt 2 , a toluene solution of 4 was exposed to ethylene (7 bar) in the presence of H 2 (1 or 20 bar) or ZnEt 2 (10, 50 and 100 equiv. with respect to 4 ).…”

A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications

“…Ge incorporates into the organic droplet, and when saturated, crystallises over a substrate, to initiate nanowire growth. Organic radicals released during the precursor decomposition might also polymerise and catalyse further precursor decomposition [ 227 ]. Barrett et al [ 172 ] presented their results with the commercially available Ge precursor DPG in HBP solvents.…”