Gas phase kinetics of pyrolysis of 1‐methyl‐1‐cyclopropene

Hopf, Henning; Wachholz, Gerhard; Walsh, Robin

doi:10.1002/cber.19851180914

Cited by 43 publications

(18 citation statements)

References 8 publications

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“…Thus we wanted to eliminate the possibilities of surface reactions and material loss, as well as obtain precise product distributions and Arrhenius parameters. Our first two studies were of 1-methyl- 28 and 1,2-dimethyl-cyclopropene. 29 Experiments were carried out at high enough pressures not to be in the fall-off region of unimolecular processes.…”

Section: Early Kinetic Studies With Alkyl Substituted Cyclopropenesmentioning

confidence: 99%

The cyclopropene pyrolysis story

Walsh

2005

Chem. Soc. Rev.

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Cyclopropene is the last of the small strained ring hydrocarbons to have its thermal decomposition subjected to intensive investigation. This critical review describes the nearly 40 year history of this investigation largely by gas kinetic methods with chromatographic analysis. These studies have revealed that cyclopropenes can decompose by a variety of mechanisms involving diradicals, vinylcarbenes and vinylidenes. Much detailed information has been obtained about the reactivity of these intermediates which has wider implications for thermal hydrocarbon pyrolysis. Theory has also played a important role. Cyclopropene itself has been shown to be an intermediate in the allene --> propyne rearrangement. The story itself illustrates how the evolution of mechanistic understanding has been anything but straightforward.

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Section: Early Kinetic Studies With Alkyl Substituted Cyclopropenesmentioning

confidence: 99%

The cyclopropene pyrolysis story

Walsh

2005

Chem. Soc. Rev.

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“…A 1,2-H-shift to dimethylallene is not possible for DMCP and so the absence of this product confirms our mechanistic preference for this pathway from MCP. 7 One other non-observed but possible CSH, isomer is methyl(methy1ene)cyclopropane. This would be formed oiu a 1,3-C-H insertion reaction of the carbene (2).…”

Section: Discussionmentioning

confidence: 99%

Gas-phase kinetics of pyrolysis of 1,2-dimethylcyclopropene

Hopf¹,

Wachholz²,

Walsh³

1986

J. Chem. Soc., Perkin Trans. 2

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The pyrolysis of 12-dimethylcyclopropene has been studied in the temperature range 260-300 "C. The sole product is isoprene and material recovery was complete to within 3.5%. The reaction obeyed firstorder kinetics and appeared to be homogeneous in a hexamethyldisilazane-conditioned Pyrex reactor, although surface catalysis could not be eliminated in a packed vessel. At 12 Torr (close to the highpressure limit) rate constants fitted the Arrhenius equation (i). This study provides further evidence for the log(k/s-') = (1 3.63 & 0.1 9) -(1 83.7 & 2.0 kJ mol-')/RTlnlO (0 deactivating effect of methyl substituents on cyclopropene isomeritation.

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“…Pentane, hexane, 1,3-cyclohexadiene, tert-butyl methyl ether, oxalyl chloride, methyl and ethyl chlorooxalate, lithium hydroxide monohydrate, sodium cyanide, activated manganese() oxide, 10 wt.-% Pd/C, dirhodium tetraacetate, methyltriphenylphosphonium bromide, potassium tert-butoxide, n-butyllithium solution in hexane, 2,6-ditert-butyl-4-methylphenol (BHT), dimethyl trans-cyclopropane-1,2-dicarboxylate (3d) and aliphatic urethane dimethacrylate (UDMA, Ivoclar Vivadent, from 2-hydroxyethyl methacrylate and 2,2,4-trimethylhexamethylenediisocyanate) were used as supplied without further purification. 1,1-Bis(ethoxycarbonyl)-2-vinylcyclopropane [17] (DECVCP), methylenecyclopropane [18] (2b), bicyclopro-pylidene [19] (2c), dimethyl bicyclo[3.1.0]hexane-6,6-dicarboxylate [20] (3f), diethyl 2-formylcyclopropane-1,1-dicarboxylate [7] (5e), potassium cyclopropyloxoacetate, [21] methyl and ethyl diazopyruvate, [22] 3,3-dimethylcyclobutyl bromide, [23] ethyl trans-(2-ethenylcyclopropyl)oxoacetate (7g) and ethyl trans-2-(2-ethenylcyclopropyl)-propenoate [13] (1g) were prepared as described previously. 2,2Ј-Azobisisobutyronitrile (AIBN) was purified by recrystallization from methanol.…”

Section: Radical Polymerizations Of 2-cyclopropylacrylates 1a؊nmentioning

confidence: 99%

Synthesis and Radical Polymerization of Various 2‐Cyclopropylacrylates

Meijere¹,

Bagutski²,

Zeuner³

et al. 2004

Eur J Org Chem

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Fourteen new alkyl 2-cyclopropylacrylates 1a−n with various substituents R 1 −R 5 were synthesized from readily available precursors by applying standard transformations such as cyanohydrin formation from an aldehyde, alcoholysis to an α-hydroxycarboxylic ester, oxidation and Wittig methylenation of an α-oxocarboxylic ester. Overall yields ranged from 33 to 54%. A new method for the hydrolysis of dimethyl cyclopropanedicarboxylates to the corresponding half-esters was developed. The α-oxocarboxylates 7g−n were prepared by dirhodium tetraacetate catalyzed cyclopropanation of alkenes 8g−n with methyl or ethyl diazopyruvate in 32−58% yield. The monomers 1a−n were characterized by 1 H, 13 C NMR spectroscopy, mass spectrometry and elemental analysis. The radical homopolymerizations of 1a−n were carried out with 2,2Ј-azabisisobutyronitrile (AIBN) as initiator in chloroben-

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Gas phase kinetics of pyrolysis of 1‐methyl‐1‐cyclopropene

Cited by 43 publications

References 8 publications

The cyclopropene pyrolysis story

The cyclopropene pyrolysis story

Gas-phase kinetics of pyrolysis of 1,2-dimethylcyclopropene

Synthesis and Radical Polymerization of Various 2‐Cyclopropylacrylates

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