My PhD dissertation - Institut Fresnel

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20 organic molecules have been determined [113 - 116] , those of many of the simplest, namely the linear and cyclic alkanes, remain to be established. This specific lack of information accounts for the very weak acidity of such compounds which hardly generate the corresponding carbanion in the gas phase [ ] 117 and thus do not afford any thermodynamic ° data evaluation. The exact acidity of methane ∆H CH ) [i.e. proton affinity, PA(CH4)] acid ( 4 was calculated by means of a Born-Haber thermodynamic cycle (Figure 1) and using the relationship PA(CH4) = D°(H3C-H) + IP(H · ) - EA(CH3 · ), involving the homolytic bond-dissociation energy of methane D°(H3C-H) [118] , the ionization potential of hydrogen IP(H · ) [119] , and the electronic affinity of the methyl radical EA(CH3 · ) [120] . D ° (H 3C-H) PA (CH 4) H3CH CH3 + H CH 3 + H CH3 + IP (H ) Figure 1. Born-Haber cycle for the determination of PA(CH4). - EA (CH 3 ) Unfortunately, some of these thermodynamical values are unavailable for other alkanes, which made the determination of their acidity impossible by this way. As a consequence, C.H. DePuy, R. Damrauer et al. [108] devised a kinetic method for studying extremely weak acids such as alkanes. By treatment of alkyltrimethylsilanes with hydroxide ions in a flowing afterglow-selected ion flow tube (FA-SIFT), they could produce a mixture of alkyldimethylsiloxide ions by loss of methane and trimethylsiloxide ions by loss of alkane. Going by the linear correlation between the ratios of siloxide ions formed and the pKa's of the expelled alkanes reported by C. Eaborn et al. [121] , C.H. DePuy, R. Damrauer et al. [108] determined the relative basicities of methyl and various alkyl anions. Furthermore, a calibration of this method by making use of the known acidity of methane and benzene, allowed the deduction of the exact gas phase acidity of a series of alkanes. In parallel to endeavors in establishing a "gas phase acidity scale" of various hydrocarbons, several research groups investigated the behavior of various carbanions in solution. H
3.2 Alkyl Carbanions Stabilities in Solution hydrocarbons 21 A few pioneering studies first carried out acidity measurements of [109, , ] 122 123 such as indene, or phenylfluorene where the carbanions enjoyed conjugative stabilization. The equilibrium studied were the exchange reactions of the type: where M was sodium or potassium. Because of the non-polar media and of probable covalent character in the RM bonds, it was not possible to derive Ka's which could be compared quantitatively to those of stronger acids in aqueous media. Furthermore, none of the techniques thus far described have been generally applicable to the less acidic hydrogens found in simple hydrocarbons. In order to evaluate the relative stabilities of carbanions derived from weakly acid hydrocarbons, D.E. Applequist and D.F. O'Brien [110] later studied equilibria by permutational halogen/metal interconversion between cyclic (cyclobutyl, cyclopentyl) or linear alkanes (ethyl, propyl, isobutyl, neopentyl). To determine equilibrium constants the metalated substrates were added to halogenated ones and samples regularly withdrawn were treated with water to replace lithium by hydrogen. Intending to avoid possible complications due to the Wurtz coupling, and the dehydrohalogenation side reactions, R.E. Dessy et al. RH + R'M RM + R'H [111] rather studied metal-metal exchange reactions between organomagnesium and organomercuric species, relying on the fact that the most stable carbanions would prefer to be paired to the most electropositive element. Although meritorious, these earlier endeavors suffered a major problem. As the authors admitted [110] , an ambiguity remained whether the results obtained were indeed reflecting relative stabilities of carbanions in a quantitative way or whether they were partially influenced by aggregation of the metallic species [47] . In conclusion, none of the equilibrium techniques devised to sort carbanionic stabilities [110, 111, , ] 124 125 could afford accurate data concerning simple alkyl groups, devoid of any other factors' influence.
Page 1: Various Facets of Organophosphorus
Page 5: III Remerciements Je tiens à remer
Page 9: 3.3.6 Relevance of the Data Assesse
Page 13: VII Literature References 115 Compo
Page 17: IX Version Abrégée Les composés
Page 21 and 22: 1 Introduction 1 The present thesis
Page 23 and 24: 3 research groups in the field are
Page 25 and 26: 5 However, this mechanism suffers f
Page 27: 7 At first, a double bromine/lithiu
Page 30 and 31: 10 Although the most frequently emp
Page 32 and 33: 12 The preparation of the latter ph
Page 34 and 35: protected to its dioxolane derivati
Page 36 and 37: N (S)-14 1) NBS, THF, - 75 °C 2) -
Page 39: 3 Alkaline Decomposition of Phospho
Page 43 and 44: 3.3.1 Mechanistic Discussion on the
Page 45 and 46: 25 The assumption reported by these
Page 47 and 48: 27 However, in the eventuality of a
Page 49 and 50: 29 To prepare tertiary phosphines b
Page 51 and 52: 31 Table 4. Mixed tertiary alkylpho
Page 53 and 54: 33 were comparable to those obtaine
Page 55 and 56: 35 led to the formation of di-tert-
Page 57 and 58: 37 depending on the alkyl substitue
Page 59 and 60: 39 4 A Novel Access to Atropisomeri
Page 61 and 62: 41 Since the homocoupling of the ha
Page 63 and 64: 43 Few other attempts to selectivel
Page 65 and 66: 45 The second phenol ether 36 was f
Page 67 and 68: 47 The enantiomeric purity was chec
Page 69 and 70: 49 A second purpose of this derivat
Page 71 and 72: 51 substrates considered. In conseq
Page 73 and 74: 53 Single-crystal X-ray analysis of
Page 75 and 76: 55 To convert atropisomer Ia into I
Page 77 and 78: 57 This finally allows one to use t
Page 79 and 80: the steric bulk and charge delocali
Page 81 and 82: 61 To check the reproducibility of
Page 83: 63 Figure 9. Full lineshape analysi
Page 86 and 87: 66 suitably substituted dilithiobip
Page 89: Experimental Part
Page 92 and 93:
70 deuterochloroform (CDCl3) unless
Page 94 and 95:
72 1 H NMR: δ = 7.32 (dddd, J = 9,
Page 96 and 97:
1 H NMR: δ = 6.96 (s, 3 H), 6.94 (
Page 98 and 99:
76 C21H21O9P (448.36) calcd. C 56.2
Page 100 and 101:
78 C12H12BrN (250.13) calcd. C 57.6
Page 102 and 103:
80 C13H13NO2 (215.25) calcd. C 72.5
Page 104 and 105:
82 3.1.1 Dialkyl-N,N-diethylaminoph
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84 apparatus. The solution was adde
Page 108 and 109:
86 Di-tert-butylisopropylphosphine
Page 110 and 111:
88 13 C NMR: δ = 32.9 (d, J = 12 H
Page 112 and 113:
90 13 C NMR: δ = 41.5 (d, J = 61 H
Page 114 and 115:
31 P NMR: δ = 53.4 ppm. 92 C16H31O
Page 116 and 117:
94 13 C NMR: δ = 40.8 (d, J = 3 Hz
Page 118 and 119:
96 31 P NMR settings: It is known t
Page 120 and 121:
98 Theoretical ratio: (96.1:3.9) Ex
Page 123 and 124:
101 4 The Preparation and Racemate
Page 125 and 126:
103 extraction protocol with ethyl
Page 127 and 128:
105 extracted with ethyl acetate (2
Page 129 and 130:
107 (+)-(M)-Dimethyl-6,6’-dibromo
Page 131 and 132:
109 (+)-(M)-2,2’-Dibromo-6,6’-b
Page 133 and 134:
111 1 H NMR: δ = 7.2 (m, 20 H), 7.
Page 135 and 136:
113 2,2’-Dilithio-6,6’-bis(meth
Page 137:
References
Page 140 and 141:
116 Conference Proceedings, Naples,
Page 142 and 143:
118 [ 70] J. Drowart, C.E. Myers, R
Page 144 and 145:
120 [117] S.T. Graul, R.R. Squires,
Page 146 and 147:
122 [170] B.H. Lipshutz, F. Kayser,
Page 148:
124 [212] M. Schlosser, in Organome
Page 152:
O P 27i: p. 30, 80 C 9H 21OP P 26b:
Page 156:
P P P O 2: p. 11, 59 3 P O O O 11:
Page 160:
Nom Maurin Prénom Michaël 129 Cur
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My PhD dissertation - Institut Fresnel

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