Doctoral Dissertations

Date of Award

12-1983

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

James L. Adcock

Committee Members

Lily H. Grossman, Mark L. Robin

Abstract

The fluorination of compounds with survivable functionality permits the preparation of fluorinated compounds with preselected sites for further reactions. Perfluoroacyl fluorides and perfluoroalkyl chlorides have been successfully synthesized by the aerosol direct fluorination method in good yields and high purity.

Aerosol direct fluorination of the acid chloride analogs produced F-pivaloyl fluoride, F-butyryl fluoride, F-isobutyryl fluoride and chloro-F-acetyl fluoride. Aerosol fluorination of cyclopropyl carbonyl chloride gave F-isobutyryl fluoride and F-butyryl fluoride. Aerosol fluorination of the primary alkyl chloride analogs produced F-neopentyl chloride, F-propyl chloride, F-butyl chloride, F-isobutyl chloride, F-isoamyl chloride, and 1-chloro- F-2-methylbutane. The aerosol fluorination of tert-butyl chloride gave complete 1,2-chloride rearrangement to produce F-isobutyl chloride. A similar chloride shift was observed upon fluorination of 1,2-dichloro-2-methylpropane to give l,3-dichloro- F-2-methylpropane. These 1,2-chloride shifts occurred by rearrangement of primary radicals formed upon initial fluorination giving more stable tertiary radicals. In the aerosol fluorination of the secondary chlorides, isopropyl chloride, 2-chlorobutane, and 3-chloropentane, the production of analogous isomeric mixtures of primary and secondary F-alkyl chlorides gave evidence of a partial 1,2-chloride shift. This partial chloride rearrangement for secondary chlorides is similar to the tertiary chlorides but does not occur completely due to the smaller difference in stabilities of primary and secondary radicals.

In the aerosol fluorination of secondary gem dichlorides, the observed 1,2-chloride shift results in the formation of chlorine-stabilized, tertiary-like radicals. 2,2-Dichloropropane gave l,2-dichloro-F-propane and 1,3-dichloro-F-propane. 1,1-Dichlorocyclopentane gave a mixture of cis/trans-l,2-dichloro-F-cyclopentane and cis/trans-l,3-dichloro-F-cyclopentane. The primary gem dichloride, 1.1-dichloropropane, upon fluorination gave 1,l-dichloro-F-propane and 1.2-dichloro-F-propane. This partial 1,2-chloride shift would form a chlorine-stabilized, secondary-like radical. In the aerosol fluorination of 1,1-dichloroneopentane, a 1,2-chloride shift is blocked and only 1,1-dichloro-F-neopentane is produced. 1,1,1-Trichloroethane gave 1,1,2-trichloro-F-ethane via a 1,2-chloride shift.

Aerosol fluorination of neopentyl bromide produced Bj-isopentane and bromine. Data are presented which support carbocation rearrangements. The carbocations are presumed to arise from disproportionation of neopentyl bromine fluorides, (CH3)3-C-CH2BrFx.

The gas phase photolysis of mixtures of mono hydryl perfluorinated compounds, obtained from the fluorination of the analogous hydrocarbons, and one of the interhalogen compounds, BrCl or BrF, provided a simple route to F-alkyl bromides in good yields.

FNeopentyl lithium was produced by reaction of F-neopentyl chloride with alkyl lithium.FNeopentyl lithium reacted with cyclohexene to give 7-fluoro-7-(nonafluoro-tert-butyl)-norcarane, with iodine to give F-neopentyl iodide, and with excess n-butyl lithium to give cis/trans-1,1,1-trifluoro-2,2-bis-(trifluoromethyl)-3-heptene.

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