Organic Reactions in the Gas Phase: Part I. The Thermal Rearrangement of 3,3-Dimethylcyclopropene. Part II. Interaction of Remote Functional Groups in the Ion Chemistry of Bifunctional Ethers

Citation

Morton, Thomas Hellman (1973) Organic Reactions in the Gas Phase: Part I. The Thermal Rearrangement of 3,3-Dimethylcyclopropene. Part II. Interaction of Remote Functional Groups in the Ion Chemistry of Bifunctional Ethers. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0b6f-h333. https://resolver.caltech.edu/CaltechTHESIS:01312018-114130193

Abstract

PART I: The Thermal Rearrangement of 3, 3-Dimethylcyclopropene

The thermal rearrangement of 3, 3-dimethylcyclopropene was investigated by entering the energy surface for the reaction by two routes: thermal isomerization of the cyclopropene and pyrolysis of a diazo compound precursor, 3-methyl-1-diazo-2-butene. The products from both reactions are identical; however the proportions vary greatly. Greater than 95% of the product from the diazo compound is the cyclopropene, and the remainder of the product is isoprene and isopropylacetylene in a 5:2 ratio, with trace gem-dimethyl­allene. The products from isomerization of the cyclopropene are isopropylacetylene, isoprene, and gem-dimethylallene in a ratio of 500:50:1. From these data it is concluded that two intermediates exist for the isomerization, gem-dimethylvinylcarbene, (CH₃)₂C=CH CH, and a 90° rotamer, designated as a diradical, (CH₃)₂ĊCH=ĊH. Relative rates of interconversion and cyclization and an energy surface are determined and the results are compared with Huckel and CNDO/2 calculations on vinylcarbene.

PART II. Interaction of Remote Functional Groups in the Ion Chemistry of Bifunctional Ethers

An Ion Cyclotron Resonance examination of bifunctional ethers of the form CH₃O(CH₂)_nOR, where n = 1 - 6 and R = H, CH₃, or C₂H₅, reveals a large number of mass spectral processes and ion-molecule reactions in which the interaction of remote functional groups plays a prominent role. Chainlength effects are particularly pronounced: 6-member cyclic intermediates are inf erred in rarrangements of odd­ electron species, while larger cycles appear pref erred in rearrange­ments of many even electron species.

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