Aliphatic fluorides

4 Aliphatic Fluorides Aliphatic fluorides give the weakest molecular ion peak of the aliphatic halides. Fluorine is monoisotopic, and its detection in polyfluoro compounds depends on suspiciously small isotopic peaks relative to the molecular ion, on the in- 

The molecular ion peak of heteroaromatics and alkylated heteroaromatics is intense. Cleavage of the bond /3 to the ring, as in alkylbenzenes, is the general rule in pyridine, the position of substitution determines the ease of cleavage of the /3-bond (see below). 

Localizing the charge of the molecular ion on the heteroatom, rather than in the ring 7r structure, provides a satisfactory rationale for the observed mode of cleavage. The present treatment follows that used by Djerassi (Budzikiewicz et al., 1967). 

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Gilman, H. (1944). Organic Chemistry. Vol. 1, Aliphatic Fluorides, by A. L. Henne. John Wiley and Sons. 

The C—bond strength renders the aliphatic fluorides much less reactive than the corresponding chlorides in S l or Sn2 reactions (from 10 to 10 ). In fluoroalkenes, the C—bond is also strong the more fluorine atoms there are, the stronger the n double bond is. In general, the reactivity of these double bonds decreases with electrophiles while it increases with nucleophiles. 

Under acidic reaction conditions, however, aliphatic fluoride can be readily displaced (Scheme 4.13), especially in alkyl monofluorides. This is probably because of the strong hydrogen bonds formed by fluoride [75], As illustrated by the second example in Scheme 4.13, for some substrates the fluorides will be even more reactive than the corresponding chlorides or bromides [76]. The first two reactions sketched in Scheme 4.13 can be driven to completion by use of higher temperatures or longer reaction times, to give almost quantitative yields of alkyl iodides. 

Adcock, W. and Abeywickrema, A.N., Concerning the origin of substituent-induced fluorine-19 chemical shifts in aliphatic fluorides carbon-13 and fluorine-19 nuclear magnetic resonance study of l-fluoro-4-phenylbicyclo[2,2,2]octanes substituted in the arene ring, J. Org. Chem., 47, 2945, 1982. 

The oxidation of primary alkyl halides to carboxylic acids is accomplished on incubation of long-chain aliphatic fluorides, chlorides, bromides, and iodides with the yeast Torulopsis gropengiesseri [1086,1087] (equation 200). The biooxidation starts at the terminal methyl groups and gives w-halogenoalkanoic acids, which are ultimately converted to a,oj-dicarboxylic... 

Aliphatic fluorides from other halides and sulfonates. 345-346... 

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