Kinetics of the Reactions of Pentacyanocobaltate(II) with Organic Halides

Halpern, Jack; Maher, John P.

doi:10.1021/ja00951a018

Cited by 115 publications

(45 citation statements)

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“…These trajectories represent the minimum-energy approach only when the steric interaction is predominantly repulsive. This same generalization is also consistent with the observations summarized in entries [14][15][16][17][18][19], 20-25, and 26-31. However, as alkyl groups are added to the N and /3 carbons, the approaching base is pushed out of the x z plane.…”

Section: Resultssupporting

confidence: 91%

“…The angular trajectories reported in entries [14][15][16][17][18][19] and 20-25 are consistent with the qualitative description of the minimum-energy approach of large bases that has been proposed by Bartsch. The angular trajectories reported in entries [14][15][16][17][18][19] and 20-25 are consistent with the qualitative description of the minimum-energy approach of large bases that has been proposed by Bartsch.…”

Section: Resultssupporting

confidence: 76%

“…1974)~---I(14) "CRC Handbook of Chemistry and Physics", R. L. Weast, Ed., 56th ed., CRC Pres!,, Cleveland, OH, 1975, p F 211-3. (15) Listings of the computer programs either in Fortran I\' or ALP-Plus may be obtained upon request.…”

mentioning

confidence: 99%

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Influence of steric factors in the E2 reaction. Calculation of nonbonded interactions and minimum-energy trajectories for base approach in the E2 reaction of some simple alkyl halide systems

Tremelling¹,

Hopper²,

Mendelowitz³

1979

J. Org. Chem.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 76%

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Influence of steric factors in the E2 reaction. Calculation of nonbonded interactions and minimum-energy trajectories for base approach in the E2 reaction of some simple alkyl halide systems

Tremelling¹,

Hopper²,

Mendelowitz³

1979

J. Org. Chem.

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“…1 have been investigated most extensively for low-spin cobalt(II) complexes, in the first instance pentacyanocobaltate(II) (11,12) and, subsequently, for bis(dioximato-) and for Schiffsbase cobalt(Il) complexes (13-15). The characteristic reactions of pentacyanocobaltate(II) with methyl and benzyl haUdes are dep:l.cted by the scheme of eqs.…”

Section: Generation Of Free Radicals By Reactions Of Organic Halides mentioning

confidence: 99%

Free radical mechanisms in coordination chemistry

Halpern¹

1979

Pure and Applied Chemistry

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“…Solution reactions analogous to [2] are well known and always produce substantial amounts of alkane except in the presence of hydrogen atom scavengers (4,5). An alternative to reaction 2 would be the immediate capture of the alkyl radical by a second active surface site to yield a surface alkyl species, reaction 3…”

Section: Catalytic Reactionsmentioning

confidence: 99%

Chemistry of the Transition Metals. II. Reaction of Branched Alkyl Chlorides with Titanium

Summers¹,

Harrod²

1972

Can. J. Chem.

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Except for t-butyl chloride, the I-and 2-methyl substituted ethyl chlorides reacted at ambient temperatures with clean titanium surfaces to produce mixtures of the corresponding alkanes and alkenes; t-butyl chloride gave only isobutene. At elevated temperatures (80-150 "C depending on reactant) the branched alkyl chlorides underwent clean, catalytic dehydrochlorination on hydrochlorinated titanium films to give gaseous olefin and hydrogen chloride, in contrast to the previously observed dehydrohalogenation of n-alkyl halides, where metal was consumed continuously in a non-catalytic fashion.The kinetics of the dehydrochlorination were exceptionally simple and reproducible for a heterogeneous reaction and all reactions were first order in reactant. The reactivity order was t-butyl > i-propyl > neopentyl > i-butyl (ca. lo6 : 6: 3 : 1). Although a slight dependence of activation energy on reactant pressure was observed, all reactants gave a limiting activation energy of 15.5 & 0.5 kcal/mol and the large variation in activity is attributed to differences in the Arrhenius pre-exponential factor.It is proposed that the non-catalytic and catalytic dehydrohalogenation reactions proceed by different mechanisms, the former via a dissociative chemisorption of the carbon-halogen bond and the latter via a concerted, surface-assisted HCl elimination.Sauf pour le chlorure de t-butyle, les chlorures d'kthyle substitues en -1 et -2 par un mirthyle reagissent a la temperature ambiante sur les surfaces de titane propres pour conduire a des melanges d'alcanes et d'alctnes correspondants; le chlorure de t-butyle donne seulement l'isobutene.Aux temperatures tlevires (80-150 "C en fonction du reactant) les chlorures d'alkyles ramifies subissent une dehydrochloration catalysee et propre, sur des films de titane hydrochlore, en donnant des olbfines gazeuses et de I'HCI, a l'oppose de la dehydrohalogenation prircedemment observee pour les halogenures de n-alkyle, od le metal irtait consomme de f a~o n continue et non catalysee.Les cinetiques de la dehydrochloration sont exceptionnellement simples et reproductibles pour une reaction hkterogirne et toutes les reactions sont du premier ordre par rapport au reactant. L'ordre de reactivite est t-butyle > i-propyle > neopentyle > i-butyle (environ lo6 :6: 3: 1). Bien qu'on observe une legere influence de la pression du reactant sur I'energie d'activation, tous les reactants donne une tnergie d'activation limitbe a 15.5 f 0.5 kcal/mol et la grande variation dans l'activitk est attribuke aux differences du facteur preexponentie1 dlArrhenius.On propose que les reactions de dChydrohalog6nation non catalysees et catalystes proctdent selon des mircanismes differents, la premiere via une chimisorption dissociative de la liaison carbone-halogene et la seconde, via une elimination concertee d'HC1 assistee par la surface metallique.

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Kinetics of the Reactions of Pentacyanocobaltate(II) with Organic Halides

Cited by 115 publications

References 0 publications

Influence of steric factors in the E2 reaction. Calculation of nonbonded interactions and minimum-energy trajectories for base approach in the E2 reaction of some simple alkyl halide systems

Influence of steric factors in the E2 reaction. Calculation of nonbonded interactions and minimum-energy trajectories for base approach in the E2 reaction of some simple alkyl halide systems

Free radical mechanisms in coordination chemistry

Chemistry of the Transition Metals. II. Reaction of Branched Alkyl Chlorides with Titanium

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