STUDIES OF THE OPTICAL PURITY OF ALPHA-PHENYLNEOPENTYL CHLORIDE.
Item
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Title
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STUDIES OF THE OPTICAL PURITY OF ALPHA-PHENYLNEOPENTYL CHLORIDE.
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Identifier
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AAI8508688
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identifier
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8508688
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Creator
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BRIGHT, DANIELLE ANGRAND.
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Contributor
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H. E. Zieger
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Date
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1985
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic
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Abstract
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Several different approaches toward the determination of the specific rotation of optically pure (alpha)-phenylenopentyl chloride, 5, were studied. In the first of these procedures, S(,N)i decomposition of optically pure (alpha)-phenylneopentyl chlorocarbonate gave samples of chiral 5 whose specific rotations were twice as high ( (alpha) (,D)('24) = -79(DEGREES)) as literature values.;Application of the trialkylphosphine-carbon tetrachloride reaction to (R)-(+)-(alpha)-phenylneopentyl alcohol produced (S)-(-)-(alpha)-phenylneopentyl chloride whose specific rotation is (-)-112(DEGREES). This is the highest rotation ever observed for this chloride. Thus, a greater degree of inversion stereospecificity was found in the R(,3)P/CCl(,4) reaction than retention stereospecificity in the thermal rearrangement of the chlorocarbonate.;As a synthetic precursor to chiral (alpha)-phenylneopentyl chloride, racemic 1-chloro-(2,2-dimethylpropyl)-o-aminobenzene hydrochloride, V, was synthesized by a six-step sequence from anthranilic acid. It was converted to racemic 5 by diazotization-H(,3)PO(,2) treatment successfully demonstrating the removal of the aryl amino group without loss of the benzylic chlorine.;The attempted resolution of the ortho substituted anilinium chloride, V, by means of anion exchange with (R)-(+)-d-10-camphorsulfonate was partially successful in that a sample of (R)-(+)-(alpha)-phenylneopentyl chloride of specific rotation +81(DEGREES) (t = 25(DEGREES)C) was obtained after diazotization-H(,3)PO(,2) removal of the amino group of the less soluble camphor sulfonate anilinium salt.;A second effort to resolve V involved transformation of the amino group into an isocyanate function followed by reaction with optically pure (-) menthol to form levorotatory diastereoisomeric l-menthyl carbamates. Fractional crystallization permitted separation of these isomers but all attempts to cleave them in acidic media frustrated resolution by yielding 4-t-butyl-3,1-benzoxazine-2-one.;The primary motivation for this work emerged from a mechanistic investigation of benzylic carbanion coupling processes. Reaction of diphenylmethyllithium with chiral (alpha)-phenylneopentyl chloride of rotation -106.5(DEGREES) at 25(DEGREES)C gave (R)-(-)-3,3-dimethyl-1,1,2-triphenylbutane of rotation -113(DEGREES). The significance of this result is that coupling occurred with a minimum of 60% inversion of configuration. It also suggests that a polar nucleophilic displacement process is the predominant reaction pathway for the carbanion coupling process.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
