Chemistry of transition metals. I. Reactions of n-alkyl halides with titanium

Harrod, John F.; Summers, W. R.

doi:10.1021/ja00749a015

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…It is known that the reaction of alkyl chlorides with metallic titanium at ≤250 °C leads to the formation of a titanium hydride phase at the surface of the metal and the concomitant release of an alkene/alkane mixture . Although the distinctly different chemistry of silyl chlorides make a similar process unlikely, we investigated if gas evolves from titanium activated by Me 3 SiCl under thermal desorption conditions (→350 °C).…”

Section: Resultsmentioning

confidence: 99%

Chemical Impact on a Seemingly “Inert” Material: An Electron Microscopic Case Study of Titanium Activated by Chlorosilanes

Fürstner

Tesche

1998

Chem. Mater.

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Commercial titanium powder, after pretreatment with chlorosilanes, can be used as an "off-the-shelf" McMurry reagent for various types of carbonyl coupling reactions. Electron microscopic studies (SEM, TEM, HRTEM, and electron diffraction) of the activated titanium now reveal the morphological basis for the observed reactivity, which stems from a partial degradation of the passivating oxide layer on the surface as well as from a severe change of the inner structure of the particles. Therefore, altered surface and altered bulk properties cooperatively account for the chemical reactivity of titanium metal activated by purely chemical means. 29 Si NMR investigations fully support this view.

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Section: Resultsmentioning

confidence: 99%

Chemical Impact on a Seemingly “Inert” Material: An Electron Microscopic Case Study of Titanium Activated by Chlorosilanes

Fürstner

Tesche

1998

Chem. Mater.

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“…No hydrogen, or hydrogen chloride was detected and no loss of carbon to the film was observed. The rate laws for these reactions remained strictly half-order in reactant through complete reaction of a given dose and over many monolayer equivalents of reaction (1 ).…”

Section: Reactions At Elevated Temperaturesmentioning

confidence: 97%

“…( b ) The 2-Methyl Series The reactions of ethyl and propyl chlorides have previously been described (1 isobutyl chloride at 0 "C were isobutane and isobutene. Approximately one monolayer equivalent of isobutyl chloride reacted rapidly and completely, but the surface was completely deactivated towards further reaction.…”

Section: Reactions On Clean Surfaces At Ambientmentioning

confidence: 99%

“…titanium prepared by evaporation under ultraIn the first paper of this series we described the high vacuum (1 ). In all cases the reactions of normal alkyl halides with metallic observed was a non-catal~tic deh~drohalogena-tion in which the metal scavenged one halogen 'This work was done in partial fulfilment of the requirements for a Ph.D. thesis (W.R.S.).…”

Section: Introductionmentioning

confidence: 99%

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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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ChemInform Abstract: CHEMIE VON UEBERGANGSMETALLEN 1. MITT. RK. VON N‐ALKYLHALOGENIDEN MIT TITAN

Harrod¹,

Summers²

1971

Chemischer Informationsdienst. Organische Chemie

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Chemistry of transition metals. I. Reactions of n-alkyl halides with titanium

Cited by 8 publications

References 4 publications

Chemical Impact on a Seemingly “Inert” Material: An Electron Microscopic Case Study of Titanium Activated by Chlorosilanes

Chemical Impact on a Seemingly “Inert” Material: An Electron Microscopic Case Study of Titanium Activated by Chlorosilanes

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

ChemInform Abstract: CHEMIE VON UEBERGANGSMETALLEN 1. MITT. RK. VON N‐ALKYLHALOGENIDEN MIT TITAN

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