Kiefer, Edgar Francis (1961) Synthesis and solvolytic reactivities of unsaturated cyclobutyl bromides. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-04112006-152145
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In order to study the effect of unsaturation electrons at the 3-position of a cyclobutyl carbonium ion, 3-methylenecyclo-butyl bromide and 1-methyl-l-bromocyclobut-2-ene have been synthesized and their rates of solvolysis in aqueous ethanol determined and correlated with the solvolytic rates of a series of analogous bromides.
The synthesis of 3-methylenecyclobutanol, the precursor of 3-methylenecyclobutyl bromide, was accomplished by two independent schemes, both utilizing the cycloaddition reaction of allene and an activated olefin. Allene and vinyl benzoate afforded small yields of 3-methylenecyclobutyl benzoate, which liberated the alcohol on reduction. 3-Methylenecyclobutanecarbonitrile, obtained in good yield from allene and acrylonitrile by a published procedure, was converted to 3-methylenecyclobutylamine by hydrolysis followed by Curtius degradation. 3-Methylenecyclobutanol was obtained from the amine by nitrous acid deamination. 3-Methyl-3-bromocyclobutene was synthesized by dehydrobromination of 3-methyl-enecyclobutyl bromide, followed by low-temperature addition of one mole of hydrogen bromide.
The rate of solvolysis of 3-methylenecyclobutyl bromide in aqueous ethanol was found to be appreciably slower than the value predicted from simple molecular orbital theory by assigning a small resonance integral between the 1- and 3-positions in the carbonium ion intermediate. It is concluded that "homoallylic resonance" is hindered in this system because the planar structure requires inefficient [...]-type overlap of the p-orbitals at the 1- and 3-positions, instead of the [...]-type orbital overlap which contributes to the startling rate enhancement observed elsewhere in the solvolysis of anti-7-norbornenyl derivatives, for example. Cross-ring interaction is considered to be of some importance in the methylcyclobutenyl carbonium ion, although the solvolysis rate data in this case permit a wide range of interpretation.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Chemistry and Chemical Engineering|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 January 1961|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||12 Apr 2006|
|Last Modified:||26 Dec 2012 02:37|
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