Catherine V.A. Duke

19F mas NMR and FTIR analysis of the adsorption of alkali metal fluorides onto alumina

Abstract NaF, KF, RbF and CsF have been adsorbed onto alumina and the resulting reagents have been analysed by IR and 19 F magic-angle spinning NMR spectroscopy. The results show that MF reacts with the alumina surface to form AlF 6 3− , and CO 3 2− is formed as a byproduct due to the adsorption and reaction of atmospheric CO 2 .

A comparison of the adsorption of KF and NH4F onto silica gel

Abstract Silica gel has been fluorinated with KF, Na2SiF6, NH4F and (NH4)2SiF6, and the resulting reagents have been analysed by 19F and 29Si magic angle spinning NMR and infrared spectroscopy. Fluorination with NH4F and (NH4)2SiF6 results in the formation of (SiO)3SiF groups at the surface, where F has replaced OH, whereas the anion SiF2−6 is formed when silica is fluorinated with KF.

The adsorption of Na2[Cu(CN)3] onto alumina: The existence of both crystalline and solvated forms on the surface

Abstract The sodium cuprous cyanide salt, Na 2 [Cu(CN) 3 ], has been adsorbed onto alumina, and the i.r. spectra, fast atom bombardment mass spectra and scanning electron micrographs of the reagent over a range of Na 2 [Cu(CN) 3 ] loadings have been obtained. These show that, at high loadings, Na 2 [Cu(CN) 3 ] is present on the surface in a crystalline form. At low loadings Na 2 [Cu(CN) 3 ] is dispersed over the alumina surface, with the i.r. spectrum corresponding to that of aqueous [Cu(CN) 3 ] −2 . There appears to be good correlation in the mass spectrum between the percentage intensity of the sodium ( m/z 23) peak relative to the sum of the Na + and Al + intensities, and the loading of Na 2 [Cu(CN) 3 ]. The scanning electron micrographs of the reagent at high loading clearly show crystalline material; at low loadings there is no difference in appearance between the reagent and uncoated alumina.

Direct observations of hydrogen bonded fluoride complexes by fast atom bombardment mass spectrometry

Abstract The direct observation of pre-formed hydrogen bonded fluoride complexes by mass spectrometry has been achieved for the first time by fast atom bombardment of the solid and liquid samples. For a series of substituted phenols hydrogen bonded to fluoride it has been found that the substituents affect the apparent stability of the complexes as measured by the relative intensities of the ion peaks.

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.

Evidence for the existence of Cu+ and Cu(CN)2– in supported copper cyanide reagents

I.r. analysis of supported CuCN reagents suggests that the active forms of these materials in nucleophilic cyanations contain the ions Cu+ and Cu(CN)2–; this is the first report of an active solid form of CuCN.

The adsorption of KCN, KOCN and KSCN onto silica gel: Chemisorption vs. physisorption

Abstract 29Si magic angle spinning NMR, and i.r. spectroscopy have been used to study the adsorption of KCN, KOCN and KSCN onto silica gel. KCN and KOCN chemisorb, forming Si-OCN groups at the silica surface, whereas KSCN is physisorbed. KCN-silica and KOCN-silica show a peak at −99 ppm in the 29Si NMR spectrum, and a broad band at 2300 cm−1 in the i.r. spectrum; these features are absent in the spectra of KSCN-silica.