Aluminium oxyfluoride

Fluorodecarboxylation of arylchloroformates in the vapour phase to give fluoro-benzene and its analogues can be achieved in high yield using anhydrous HF.199 Reaction occurs quickly at 300—400 °C using chromium and aluminium oxyfluoride. The effects of micelles on the decarboxylation of /i-aminosalicylic acid (224) have been examined.200... 

At the anode the electrode reactions involve the aluminium oxyfluoride complex ion ... 

The catalytic fluorodecarboxylation of arylchloroformate to fluorobenzene and analogues has been achieved with high yield in an anhydrous hydrogen fluoride vapor phase flow reactor. This methodology can be successfully applied to various derivates, the main limitation being the stability of substituents under the reaction conditions. The best catalysts are chromium and aluminium oxyfluoride. The reaction proceeds between 300 and 400°C and occurs in a short space of time. The catalytic activity decreases by coking but can be fully recovered by an oxydative treatment at high temperature. An ionic mechanism is proposed. 

Figure 3.10 Oxidative conversion of CjHs (X) and yields (Y) of CsHe, CO and CO2 over VOx containing aluminium oxyfluorides with different V content (Reprinted with permission from [28] Copyright (2005) Royal Society of Chemistry.)...

Figure 3.14 X-band ESR spectra of VOx doped on aluminium fluoride (VAIF 15) and on aluminium oxyfluoride (VOx/AIFyOJ (Reprinted with permission from [29] Copyright (2008) Elsevier Ltd.)...

Antimony trifluoride [7783-56-4] M 178.8, m 292 . Crystd from MeOH to remove oxide and oxyfluoride, then sublimed under vacuum in an aluminium cup on to a water-cooled copper condenser [Woolf J Chem Soc 279 1955]. 

Oxides, oxyfluorides and fluorides of trivalent metals among which aluminium, chromium and iron, are generally used as catalysts, also supported or in mixture with other metals, usually bivalent metals [8]. In particular chromium oxide and fluorinated chromium oxide have found industrial applications [9] but the study relative to the catalytic mechanism and to the catal34ic nature of the species involved is still under way. 

Antimony trifluoride [7783-56-4] M 178,8, m 292", b 376", dj 4.379. It crystallises from MeOH to remove oxide and oxyfluoride, then it is sublimed under vacuum in an aluminium cup on to a water-cooled copper condenser. Its solubility is 443g/100g in H2O at 20 and 562g/100g in H2O at 30 with partial hydrolysis. [Woolf J Chem Soc 279 7955, Kwasnik in Handbook of Preparative Inorganic Chem (Ed. Brauer) Academic Press Vol I p 199 7965]. 

Without catalyst, we do not obtain at this temperature any fluorinated derivatives (Table 2, entry 1). Several catalysts (Table 1) are suitable for the fluorodecarboxylation of phenylchloroformate to fluorobenzene such as oxyfluoride (Al, entry 2 Cr, entry 4 Zr, entry 5 Ti, entry 10) or fluorides (Al, entry 3 La, entry 6 Ce entry 7 Mg entry 9). The best activity and selectivity is observed using as catalyst aluminium fluoride or oxyfluoride (entries 2 and 3). 

The fluorodecarboxylation of arylfluoroformates in the vapor phase, under anhydrous hydrogen fluoride has been successfully realised by using catalysts such as aluminium fluoride or aluminium or chromium oxyfluoride. This transformation is quite versatile, the main limitation being the stability of substrates or products under the reaction conditions. The catalyst used, deactivates rapidly by coking but can be reactivated by a simple oxidative treatment. This new access to fluorinated aromatics derivatives appears to be an attractive industrial alternative to the diazotisation of anilines. 

A number of such systems were found experimentally in the reactions of ceramic materials with ionic melts, for example, quarts with molten alkali [39], alumina with molten borax [40], ceramic oxides (AI2O3, Si02, Zr02, porcelain) with fluoride melts [41], germanium with oxyfluoride melts [24], and aluminium with cryolite-alumina melts [42,43]. ... 

The molten cryolite-based electrolyte (see above) is dissociated into Na cations and AIF ", A1F4, F and various oxyfluoride anions, like Al204F4 . For aluminium electrolysis there are two possible cell reactions ... 

Grande T, Rutlin J. Viscosity of oxyfluoride melts relevant to the deterioration of refractory linings in aluminium reduction cells. Light Met. 1999 138 431-436. 

The V MAS NMR spectra (Figure 3.13) and ESR spectra (Figure 3.14) of the VOx-doped aluminium fluoride and oxyfluoride systems revealed that vanadium exists there predominandy in oxidation state +IV and to a small part -fV, although no signs of V2O5-Uke species have been detected. 

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