The reaction of ethylene with tetraborane: The preparation, structure and properties of dimethylenetetraborane

Harrison, Ben C.; Solomon, Irvine J.; Hites, Ralph D.; Klein, Morton J.

doi:10.1016/0022-1902(60)80258-8

Cited by 24 publications

(6 citation statements)

References 11 publications

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“…The other possible isomer, 2-Me 3 Si-1,2-C 2 B 3 H 6 , was not present in the fractions collected. [39][40][41] The mechanisms were corroborated by theoretical computations on the proposed reaction pathways. 42 Minor basket products were also present in which a second ethene molecule appears to have been hydroborated by B 4 H 10 to form an alkyl group, RCHCH 2 R, since the basket compound formed initially does not give such products with ethenes.…”

Section: Quenched Gas-phase Reactions Of B 4 H 10 With Other Alkynesmentioning

confidence: 56%

Quenched gas-phase reactions of tetraborane(10), B₄H₁₀, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

2008

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Section: Quenched Gas-phase Reactions Of B 4 H 10 With Other Alkynesmentioning

confidence: 56%

Quenched gas-phase reactions of tetraborane(10), B₄H₁₀, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

2008

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“…Two reactions and , both first order in B 4 H 10 , have been claimed to be the rate-limiting step in the initial stages of pyrolysis. − normalB 4 normalH 10 → normalB 4 normalH 8 + normalH 2 normalB 4 normalH 10 → normalB 3 normalH 7 + BH 3 Reaction was proposed as the rate-determining step from several experimental observations. First, the reaction between B 4 H 10 and ethylene yielded B 4 H 8 (C 2 H 4 ), while the reaction between deuterated ethylene and B 4 H 10 yielded B 4 H 8 (C 2 D 4 ). , Next, B 4 H 8 D 2 was captured as the product of the reaction between B 4 H 8 CO and D 2 . Also, mass-spectrometric analysis supported B 4 H 8 but not BH 3 or B 3 H 7 as a reactive intermediate. ,, Later publications by Greenwood and co-workers − were consistent with the proposal of reaction as the rate-limiting step.…”

Section: Introductionmentioning

confidence: 56%

Evaluating the Role of Triborane(7) As Catalyst in the Pyrolysis of Tetraborane(10)

Sun

McKee

2013

J. Phys. Chem. A

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The initial steps in the B4H10 pyrolysis mechanism have been elucidated. The mechanism can be divided into three stages: initial formation of B4H8, production of volatile boranes with B3H7 acting as a catalyst, and formation of nonvolatile products. The first step is B4H10 decomposition to either B4H8/H2 or B3H7/BH3 where the free energy barrier for the first pathway is 5.6 kcal/mol higher (G4, 333 K) than the second pathway when transition state theory (TST) is used. When variation transition state theory (VTST) is used for formation of B3H7/BH3, the two pathways become very similar in free energy with the B4H8/H2 pathway becoming favored at G4 by 1.0 kcal/mol at 333 K (33.1 versus 34.1 kcal/mol). The experimental activation energy for B4H10 pyrolysis is about 10 kcal/mol lower than the calculated barrier for B4H10 → B4H8 + H2, which indicates that this reaction is not the rate-determining step. We suggest that the rate-determining step is B4H10 + B3H7 → B4H8 + H2 + B3H7 where B3H7 acts as a catalyst. The role of reactive boron hydrides such as B3H7 and B4H8 as catalysts in the build-up of larger boron hydrides may be more common than that previously considered.

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“…This would seem to arise from the introduction of disymmetry and to the introduction of an increased reduced mass a t the outer end of the bridge system. ,4 similar alteration occurs in the dimethylene tetraborane spectrum, where the shift is to 2130 cm-l, and the intensity loss by the original band is much greater (20). In general the alteration of 5-60 cm-l in B4H10 frequencies upon methylation is somewhat greater than that found for B5Hll.…”

Section: Table Vmentioning

confidence: 61%

“…41kyl pentaborane-9 and alkyldecaborane derivatives have been synthesized by methods not involving other alkylboron compounds as reagents (17,18,19). Since the less stable hydrides, tetraborane, B4H10, and dihydropentaborane or pentaborane-11, B5Hll, could scarcely be alkylated by such drastic nleans, though diineth] leiletetraborane is made in the hot-cold reactor (20) The results obtained illustrate that these alkylation reactions, like those of the diboranes, proceed in conforlllance with the analogies suggested by the exchange processes. EXPERIMENTAL The vacuum litle operations used were those developed by Stock (21) and by Schlesinger and his coworkers, and described by Sanderson (22).…”

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confidence: 99%

Observations on Alkylboranes

Lutz¹,

Ritter²

1963

Can. J. Chem.

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Some synthesis and exchange reactions of diborarle and its allcyl derivatives and of the higher boron hydrides were reviewed as baclrground for new work.In pursuit of an idea prorripted by knowledge of the deuterium and BI0 exchanges found for the reactive and unstable higher boron hydrides and BeH11, mono-and di-methyldih y d r~~e n t a b o r a n e arid methyltetraborane ha\-e been prepared by direct reaction between the parent higher hydrides and 1,2-dimethyldiborane or monomethyldiborane. The identity and the reactions of each product have been delineated by gas chromatographic separation, gas density, and mass, infrared, and 1l.m.r. spectrotnetry. The H' n.ni.r. spectrum of dihydro~e n t a b o r a n e has been reinterpreted and used to decide that monomethyldihydrope~ltaborane is probably a B 111 derivative which displays stereolsomerism.T o confine the topic within proportioils suitable for a symposium this paper concerns mostly alkylation reactions in which carbon atoms are transferred fronl sites in one boron coillpound to sites in another, thus excluding allnost conlpletely the extensive material on hq droborntion.As a preliminary, coilsider some facts about the boron hydrides. They occur in two types, the open pqramidal and the closed pqrainidal structures, with the commonest members, diborane, tetraborane-10, pentaborane-11, as examples of the first class and pentaborane-9 and decaborane-14 of the second. The former are the labile, reactive hydrides, the latter the ones of lesser reactivity. Exchange and interconversion reactions show the labile hydrides to maintain effective steady-state concentrations of reactive f r a g m e n t s~ the more stable ones do not (1, 2).Diboraile is convertible to the other hydrides by pyrolysis (3) and by interactions such as that with tetraborane (4):Three boron and deuterium exchanges-exemplify models for alkylation reactions: (a) self-exchange of diborane, (b) diborane exchange with pentaborane-9, and (c) diborane exchange with pentaborane-11. The first is 3/2 order involving successively dissociation of diborane and a borane-diborane displacement reaction with E* = 22 kcal. Deuterium exchanges three times faster than boron. Similarly, the second is 1/2 order in diborane (dissociation) and first order with respect to pentaborane-9, but without boron exchange, E+ = 27 kcal. Since the third, pentaborane-11 -diborane exchange, is 1/2 order with respect to the higher hydride and first order in diborane the dissociation is that of pentaborane-11 and the displacement is borane-diborane. With these varying patterns 'Presented at the Synzposium on Organometallic Compounds, Vancouver, British Columbia, September 4-6, 1962, sponsored

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The reaction of ethylene with tetraborane: The preparation, structure and properties of dimethylenetetraborane

Cited by 24 publications

References 11 publications

Quenched gas-phase reactions of tetraborane(10), B₄H₁₀, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

Quenched gas-phase reactions of tetraborane(10), B₄H₁₀, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

Evaluating the Role of Triborane(7) As Catalyst in the Pyrolysis of Tetraborane(10)

Observations on Alkylboranes

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The reaction of ethylene with tetraborane: The preparation, structure and properties of dimethylenetetraborane

Cited by 24 publications

References 11 publications

Quenched gas-phase reactions of tetraborane(10), B4H10, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

Quenched gas-phase reactions of tetraborane(10), B4H10, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

Evaluating the Role of Triborane(7) As Catalyst in the Pyrolysis of Tetraborane(10)

Observations on Alkylboranes

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Product

Resources

About

Quenched gas-phase reactions of tetraborane(10), B₄H₁₀, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

Quenched gas-phase reactions of tetraborane(10), B₄H₁₀, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes