Date of Award

2-1-1989

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Abstract

The degradation of C-O and C-C bonds have been examined using model compounds that are similar in structure to those found in coal and other natural products.Part 1. The purpose of the C-O study was to determine how general the cleavage of arylalkyl and diaryl ethers in terms of aryl structure when using a solution of alkali metal dissolved in a highly solvating solvent. The cleavage of the ether bond was attempted using a reductive medium of sodium metal dissolved in a solution of hexamethylphosphoric triamide and tetrahydrofuran. The conditions to maximize ether cleavage and minimize the formation of undesirable side products were determined by varying the concentration of reagents, temperature, and reaction time. 2-Phenoxynaphthalene (1) and 1-methoxypyrene (2) were the compounds examined. The optimum conditions demonstrated complete disappearance of 1 and 2, mass recoveries were above 84%, and the formation of reduced dimers in less than 10 mole % yield.Part 2. The cleavage of the benzyl carbon from an aryl ring was examined using the principles of organometallic arene chemistry. In an effort to promote nucleophilic substitution on an arene ring the nucleophiles cited as being the best for nucleophilic addition were tested. In all cases nucleophilic addition was not observed for fully alkylated benzenoid rings complexed to Cr(CO)$\sb3$ or Fe(II)Cp. However, a benzylic proton was abstracted in an acid-base fashion.The possibility of cleaving a C-C bond by a (3+2) cycloaddition and subsequent cycloreversion reactions was examined by treating a variety of dipolarphiles with deprotonated (($\eta\sp6$-arene)FeCp) $\sp{+}$ complexes (arene = hexamethylbenzene or tetralin) Azides and ozone were found to add quantitatively to the metal-arene complexes. Upon decomplexation of the ring, moderated yields of benzyl substituted products were isolated (i.e., $\alpha$-substitution = ArCO$\sb2$H, ArC(O)R, ArCH(OH)R, ArCH(NHCOOEt)R, ArCH(NHSO$\sb2$Ph)R, ArCH(NHSO$\sb2$CF$\sb3$)R). The mechanism of this reaction is yet unknown but is postulated to occur by direct nucleophilic addition of the complex anion to the most electropositive atom of the dipolarphile.Chemical and electrochemical oxidation techniques were applied to the deprotonated (($\eta\sp6$-arene)FeCp) $\sp{+}$ complexes. Only minor yields of benzylic oxidation products were observed.

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