Richard D. Chambers

Fluorine in organic chemistry

General discussion of organic fluorine chemistry Preparation of highly fluorinated compounds Partial or selective fluorination The influence of fluorine of fluorocarbon groups on some reaction centres Nucleophilic displacement of halogen from fluorocarbon systems Elimination reactions Polyfluoroalkanes, polyfluoroalkenes, and derivatives Functional compounds containing oxygen, sulphur, or nitrogen and their derivatives Polyfluoroaromatic compounds Organometallic reagents References Index

Direct fluorination of 1,3-dicarbonyl compounds☆☆☆

Abstract In acid media, 1,3-diketones and 1,3-ketoesters can be fluorinated in high yield and often with high conversion mainly to the corresponding 2-fluoro- compounds. Diesters such as diethyl malonate do not react with fluorine under the same reaction conditions. The mechanism of these reactions has been investigated and while the identity of the electrophilic fluorinating species is uncertain, we believe that the essential features of the reaction pathway are understood.

Polyfluoroaryl organometallic compounds. XVII: 2,4,6-Tris(trifluoromethyl)phenyllithium, a sterically crowded system

Abstract A lithium derivative ( 3 ) is generated from 1,3,5-tris(trifluoromethyl)benzene ( 2 ) and is shown to be remarkably thermally stable. It is shown that 2 is less acidic than pentafluorobenzene, in competition for butyllithium. A preliminary survey of reactivity shows that 2,4,6-tris(trifluoromethyl)phenyllithium ( 3 ) undergoes a variety of transformations including the formation of mercury and copper derivatives, in spite of crowding in the system.

Microreactors for elemental fluorine

A microreactor has been designed for use with elemental fluorine, both for selective fluorination and for perfluorination of organic compounds.

Fluorine in enzyme chemistry part 2 The preparation of difluoromethylenephosphonate analogues of glycolytic phosphates. Approaching an isosteric and isoelectronic phosphate mimic

Abstract The preparation of difluoromethylenephosphonate analogues of the glycolytic intermediates, glycerol-3-phosphate and 3-phosphoglycerate are described. Attempts to prepare the corresponding analogue of dihydroxyacetone phosphate failed due the facile elimination of hydrogen fluoride from the target molecule. Finally the synthesis of a difluoromethylenephosphonate possessing inhibitory activity against RNA transcriptase from the influenza virus is described.

Polyhalogenated heterocyclic compounds. Macrocycles from perfluoro-4-isopropylpyridinePart 50. For part 49 see ref. 1.

Perfluoro-4-isopropylpyridine was used as a building block for the two-step synthesis of a variety of macrocyclic systems bearing pyridine sub-units which were characterised by X-ray crystallography. Electrospray mass spectrometry revealed that complexation of either cations and, unusually, anions is possible depending on the structure of the macrocycle.

Free radical chemistry. Part 5. [1] A new approach to the synthesis of perfluorinated ethers

Abstract Fluorinations of the free-radical adducts of fluorinated alkenes, to ethers, over cobalt trifluoride are described and perfluorinated ethers are obtained at temperatures in excess of 400°C. The effect of structure on the formation of perfluoroethers is outlined.

Synthesis of fluorinated telomers. Part 4. Telomerization of vinylidene fluoride with commercially available α,ω-diiodoperfluoroalkanes

Abstract The synthesis of a new fluorinated αω-diiodo telomer I[(TFE)(VDF),]I (A), where TFE and VDF represent tetrafluoroethylene and vinylidene fluoride respectively, has been carried out by telomerization of VDF with αω-diiodoperfluoroalkanes. The thermal telomerization of VDF with 1,2-diiodoperfluoroethane IC2 F4I led to good yields of the monoadduct IC2F4CH2CF2I and of the diadduct which was composed of an almost equimolar ratio of ICF2CH2C2F4CH2CF2I and IC2F4(CH2CF2)2I, together with a small amount of IC2F4CH2CF2CF2CH2I and a triadduct containing I (VDF) C2F4(VDF)2I and IC2F4(VDF)3. This procedure has been applied successfully to αω-diiodo-n-perfluorobutane and α,ω-diiodo-n-perfluorohexane. The reactivity of VDF relative to the fluorinated α,ω-diiodo telogens has been studied from which it is shown that the environment of the terminal group of the telogen is a major factor affecting the reactivity.

Microreactors for oxidations using fluorine

Abstract Continuous flow gas–liquid thin film microreactors have been effectively used for the oxidation of alcohols and Baeyer–Villiger oxidation of ketones using elemental fluorine.

Mechanisms for reactions of halogenated compounds. Part 4.[1] activating influences of ring-nitrogen and trifluoromethyl in nucleophilic aromatic substitution

Abstract Rate constants have been measured for the reactions of ammonia with various fluorinated pyridines and diazines in aqueous dioxan at 25°. From the results the activating effects of ring-nitrogen (relative to CH) and of trifluoromethyl (relative to -H) have been determined. Ring-nitrogen activates the system at points ortho -, meta - and para - to the point of substitution, in the ratios ortho - 6.2 × 104, meta - 8.5 × 102, and para - 2.3 × 105. Similarly a trifluoromethyl substituent is activating by a factor of 2.4 × 103 ortho - and 4.5 × 103 para - to the point of substitution.