Craig W. Jones

The introduction of SCF3 into aromatic substrates using CuSCF3 and alumina-supported CuSCF3

Abstract Trifluoromethylthiocopper(I) has been readily prepared from the silver analogue, using a metathetical reaction with copper(I) bromide. Homogeneous CuSCF 3 and the supported reagent CuSCF 3 -alumina have been compared in their reactivity towards aryl iodides, in order to form trifluoromethylaryl sulphides in good yields.

The effect of charcoal on the trifluoromethylation of aryl chlorides using Burton's reagent

Abstract The reactivity of the trifluoromethylating system copper-dibromodifluoromethane-N, N-dimethylacetamide towards aryl chlorides can be enhanced by the addition of charcoal.

The stabilisation and characterisation by infrared spectroscopy of the different bonding modes of copper(I) thiocyanate adsorbed on high surface area solids

Abstract High surface area solids such as alumina, silica or charcoal, have been used to stabilise the various bonding modes of copper(I) thiocyanate. Infrared spectroscopy was used to characterise the different species, for example on alumina sulfur bonded, nitrogen bonded and bridged thiocyanate species were observed. The effect of the high surface area solid was in some cases dramatic and the bonding modes stabilised were found to be dependent upon the concentration of the impregnating solution, relative to the amount of high surface area solid present. The most striking differences were between charcoal and the other two solids, in the former case high loadings of copper(I) thiocyanate resulted in stabilisation of a bridged species, whereas only low loadings of copper(I) thiocyanate on alumina or silica resulted in stabilisation of a bridged thiocyanate species. Both nitrogen and sulfur bonded thiocyanate species were evident on all the supports. The N-bonded species were generated in dimethyl sulfoxide solvent before impregnation onto the solids, whereas the S-bonded species were generated in either N -methyl pyrollidone or aqueous KSCN prior to impregnation. The effect of the high surface area solid manifests itself in the reaction chemistry of copper(I) thiocyanate with 1-iodo-2-nitrobenzene (an ipso substitution reaction) by altering the proportion of aryl isothiocyanate to aryl thiocyanate to aryl nitrile products.

Reverse halogenation using supported copper(I) iodide

Alumina and charcoal supported copper(I) iodide reagents can be used to convert bromo- and chloro-benzenes into iodobenzenes with no back attack by bromide or chloride.

Solvent-dependent proton transfer in a strongly hydrogen bonded fluoride complex

The nature of the hydrogen bonded complex formed between tetramethylammonium fluoride and 4-cyanophenol in solution is dependent on the solvent although, unusually, dissociation of the complex in dipolar aprotic solvent favours the fluoride rather than the proton transfer species.

Aromatic thiocyanation using supported copper(I) thiocyanate

Charcoal supported copper(I) thiocyanate can be used to convert bromo- and iodo-benzenes into phenyl thiocyanates with no contamination from phenyl isothiocyanates.

Tetramethylammonium fluoride: a versatile fluoride ion source

Abstract The excellent solubility of quaternary ammonium fluorides makes them attractive alternatives to traditional fluoride ion sources such as potassium fluoride. Unfortunately the high hydroscopicity and low thermal stability of most of these reagents severely restricts their synthetic value. In the light of the work of Christe on the preparation of anhydrous tetramethylammonium fluoride (TMAF) we have carried out research into the use of this reagent. TMAF forms stable hydrogen bonded complexes with a variety of protic molecules, including 4-cyanophenol. The TMAF 4CNue5f8C 6 H 4 OH complex shows a number of interesting properties and in particular the tendency to decompose into the parent molecules rather than the proton transfer products as is normally the case with strongly H-bonded complexes. This observation in particular led us to believe that TMAF can be prepared and used as a soluble and reasonable stable fluoride ion source. 1 The use of anhydrous TMAF as a variety of nucleophilic fluorine transfer reactions will be reported. Very high reactivity towards chloroaromatics and nitroaromatics has been observed. The results from n.m.r. studies will also be reported so as to help explain the unusual solvation behaviour of this reagent which can be attributed to complex equilibria of the type: An understanding of this association behaviour can help to predict the best conditions for using this reagent in organofluorination reactions.

Selective incorporation of F,CF3 and CF3S groups into aromatic substrates

Abstract The use of modern inorganic reagent such as Bu 4 NF, PH 4 PHF 2 , CuCF 3 and alumina-CuSCF 3 enables the preparation of a wide range of aromatic molecules containing F,CF 3 and CF 3 S groups [1-3]. Fluorodenitration and fluorodechlorination can be used for the selective fluorination of aromatic substrates. The susceptibility of the nitro groups to exchange by fluorine is influenced by both steric and electronic factors and the relative rates of fluorodenitration and fluorodechlorination can be influenced by the reaction conditions. Burtons reagent can be used to selectively replace aromatic chlorines ortho to chelating groups by CF 3 . The novel reagent alumina-CuSCF 3 is a convenient and easily prepared source of SCF 3 for aromatic substitution. Some of the subsequent reaction chemistry of molecules containing F,CF 3 and CF 3 and CF 3 S groups will be described.