The effect of electron, positive ion, and hydrogen atom scavengers on the yields of atomic and molecular hydrogen in the radiolysis of liquid cyclohexane

Asmus, K.‐D.; Warman, John M.; Schüler, Robert H.

doi:10.1021/j100697a005

Cited by 44 publications

(2 citation statements)

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“…Since the four electron scavengers studied here neither react with hydrogen atoms nor undergo energy transfer other than electron capture,2'3•17 one can safely assume that some of the hydrogen has ionic precursors. In 2,2,4-trimethylpentane such a decrease of the hydrogen yield with increasing electron scavenger concentration (SF6 and N20) has been already observed by Iida, et alfi As previously shown,3 the hydrogen production by ionic processes can be represented by the following scheme RH+ + e-->e(H, H2) (1) e~-f-S -> -s- RH+ + S--> e'(H, H2) (3) where e and e' are efficiencies for production of hydrogen from reactions 1 and 3 because the hydrogen atoms produced finally give hydrogen by abstracting a hydrogen atom from the solvent. In the case of cyclohexane, it has been shown that the efficiency of hydrogen production from reaction 3, i.e., e', is zero or nearly so.3 Since hydrogen production from 2,2,4-trimethylpentane is a much less efficient process than from cyclohexane ((7(H2) = 2.44 and 5.67, respectively), it should be expected that e' would be equal to zero in 2,2,4-trimethylpentane.…”

Section: Resultsmentioning

confidence: 57%

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Radiolysis of liquid 2,2,4-trimethylpentane. Effect of charge scavengers on product formation

Bansal¹,

Rzad²

1972

J. Phys. Chem.

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Section: Resultsmentioning

confidence: 57%

“…One can extend to 2,2,4-trimethylpentane the kinetic model recently proposed for cyclohexane. 3 In this model, for a given ethylene concentration, the electron scavenger concentration dependence of the yield of ethyl radicals (measured as ethyl iodide) is given by…”

Section: Resultsmentioning

confidence: 99%

Radiolysis of liquid 2,2,4-trimethylpentane. Effect of charge scavengers on product formation

Bansal¹,

Rzad²

1972

J. Phys. Chem.

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Radiation chemistry of the carbon–halogen bond

Bühler

1973

PATAI'S Chemistry of Functional Groups

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Über den einfluß von fängern auf die hochfeldpolymerisation von α‐methylstyrol

Wablat¹,

Schmidt²,

Schnabel³

1974

Makromol. Chem.

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ZUSAMMENFASSUNG:Die durch Feldemission (FE) in flussigem a-Methylstyrol ausgeloste Polymerisation wird durch Kationenfanger (N(C2Hs)3, HzO, Cyclopropan) inhibiert. Die Elektronenfanger SF6, N20, COz und O2 inhibieren ebenfalls, wobei die Inhibitorwirksamkeit in der genannten Reihenfolge abnimmt. Dieses Verhalten wird darauf zuruckgefuhrt, daI3 von der Hochfeldelektrode emittierte Elektronen Monomermolekeln ionisieren; dabei gebildete Radikalkationen starten die kationische Polymerisation. Durch Kationenfanger wird daher die Wachstumsreaktion inhibiert, wahrend Elektronenfanger die Startreaktion inhibieren.Bei der durch Feldionisation (FI) gestarteten Polymerisation sind Elektronenfanger wirkungslos; Kationenfanger inhibieren dagegen.Aufgrund der Abhangigkeit der spezifischen Polymerausbeute von der N(C2Hs)3-Konzentration wurde abgeschatzt, daR im Falle der FE nur 1 bis 10% der emittierten Elektronen polymerisationsauslosend wirken. Im Falle der FI starten bis zu 100% der an der Hochfeldelektrode erzeugten Ladungstrager ki~ietische Ketten.Bei allen Versuchen wurde Oligomeres (Polymerisationsgrad 3 bis 4) durch eine Kettenreaktion gebildet. Die spezifische Oligomerausbeute nahm bei der FE-initiierten Polymerisation mit steigender SF6-Konzentration bemerkenswert zu. SUMMARY:Cation scavengers (N(CzHs),, H 2 0 , cyclopropane) inhibit the polymerization of liquid r-methylstyrene initiated by field emission (FE). Electron scavengers also inhibit the polymerization with efficiencies declining in the series SFs > NzO > COZ > 0 2 . It is assumed that electrons emitted by the high field electrode ionize monomer molecules. Radical cations formed thereby initiate the cationic polymerization. Thus cation scavengers inhibit the growth of kinetic chains, whereas electron scavengers inhibit the initiation reaction.The polymerization initiated by field ionization (FI) is not affected by electron scavengers. However, cation scavengers inhibit this polymerization.Based on the dependence of the specific polymer yield on the N(C2H5)3-concentration it was estimated that in the case of FE only 1 to 10% of the emitted electrons initiate polymerization. In the case of FI up to 100% of the ions generated at the high field electrode start kinetic chains.During all experiments oligomer (degree of polymerization 3 to 4) was formed in a chain reaction. The specific oligomer yield increased with increasing SF6-concentration significantly when the reaction was initiated by FE.

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The effect of electron, positive ion, and hydrogen atom scavengers on the yields of atomic and molecular hydrogen in the radiolysis of liquid cyclohexane

Cited by 44 publications

References 8 publications

Radiolysis of liquid 2,2,4-trimethylpentane. Effect of charge scavengers on product formation

Radiolysis of liquid 2,2,4-trimethylpentane. Effect of charge scavengers on product formation

Radiation chemistry of the carbon–halogen bond

Über den einfluß von fängern auf die hochfeldpolymerisation von α‐methylstyrol

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