Aluminate tetrachloro

The Li-SOCl2 battery consists of a lithium-metal foil anode, a porous carbon cathode, a porous non-woven glass or polymeric separator between them, and an electrolyte containing thionyl chloride and a soluble salt, usually lithium tetrachloro-aluminate. Thionyl chloride serves as both the cathode active material and the elec-... 

The benzene complexes have silver bound rf to two benzene rings in the perchlorate but only to one in the tetrachloro aluminate (Figure 4.31), while in the COT complex, each silver is bound to two double bonds in one molecule. 

Treatment of lead(n) chloride with aluminum trichloride and o-xylene furnishes bis(o-xylene)lead(ll) bis(tetrachloro-aluminate) 41. According to the results of an X-ray structure determination, 41 consists of a monomeric complex with two arene ligands in a distorted 77-mode of coordination and two bidentate AICI4- ions at the central Pbz+ ion. The interaction of the lead center with the tetrachloroaluminate ligands is presumably highly ionic, suggesting that 41 is a triad of arene-stabilized ions, rather than a molecule.7... 

As noted in the earlier section Basics of Electrophilic Substitution Reactions, the loss of the hydrogen ion (H ) requires the presence of a strong base. The chloride ion (CL) is a base, but it isn t strong enough to accomplish this task. However, as shown in the mechanism, the tetrachloro-aluminate ion (A1C1 ) is a sufficiently strong base. This process also regenerates the catalyst so that it s available to continue the process. 

Dimethyllthiophene forms a stable 2,5-dimethylthiophenium tetrachloro-aluminate salt on reaction with HCI-AICI3 thus, a novel reduction system of HSiEts HCI-AICI3 was developed [131] for the complete reduction of substituted thiophenes to thiophanes. For 2,5-dimethylthiophene and 2-ethylthiophene, the completely hydrogenated tetrahydrothiophenes were obtained in 76 and 80% yields, respectively (Table 5). 2,5-Diphenylthiophene, which was a challenge for... 

AICI3 reacts with the chloride salt of the alkali metals and forms the corresponding alkali metal tetrachloro aluminate complexes (ref.26). The aluminium atoms of these complexes exhibit a chemical shift of ca. 100 ppm (refs.29,33) with respect to aqueous sodium aluminate. HCl and AICI3 are formed during dealumination of HY zeolites (ref.28). 

Table 2 shows that the degree of dealumination depends mainly on Tr2 It seems very difficult to remove the last framework aluminium atoms from NaY and consequently it has been suggested that the dealumination of NaY with SiCl4 is a product-inhibited reaction (refs.27,45,51). According to this hypothesis, the precipitation of sodium tetrachloro aluminate complexes inside the zeolite pores terminates the progression of the dealumination reaction since it prevents SiCl4 from further diffusing into the zeolite cavities. The decomposition temperature of NaAlCl4 in zeolite Y is estimated to occur at ca. 780 K (ref.27). The use of LiY zeolites offers the advantage that the LiAlCl4 complexes volatize and/or decompose already at a temperature of 733 K (ref.45). Complete dealumination of LiY can be achieved (Table 2, No.33) under conditions where 3 A1 /UC remain in NaY (Table 2, No.29). A zeolite Y product with virtually no aluminium atoms left in the framework was obtained from NaY at 833...

The thermostability in inert atmosphere of NaY is much reduced after the treatment with SiCl4 (ref.27). Structural collapse starts already at a temperature of 770 K (ref.27). This degradation of the framework was interpreted as a reaction of the zeolite framework with AICI3 coming from partially dissociated tetrachloro aluminate complexes (ref.27). The resonance at 100 ppm in NaY samples disappears during post-treatments at 823 K and 923 K (ref. 28) but the amount of aluminium that desorbs from the zeolite bed at these temperatures is always low (ref.28). White fumes typical of AICI3 vapor are not observed at the outlet of the dealumination reactor (ref.29). 

Heating of SiCl4-treated NaY samples in inert atmosphere causes the formation of mesopores (ref.28). This mesopore formation is probably due to a more gentle attack of the framework by AICI3 and/or tetrachloro aluminate complexes and can be considered to be an onset to amorphisation. It can be concluded that thermal elimination of the dislodged aluminium does not seem to be a successful approach with NaY. 

The higher volatility and the lower stability of lithium compared to sodium tetrachloro-aluminium complexes is reflected in the formation of mesopores and amorphisation (ref.28). The mesopore volume in LiY zeolites is systematically higher than in NaY zeolites, post-treated at the same temperature (Fig.6). Post-treatment temperatures of 823 K can be applied to LiY without important damage to the zeolite lattice when a Tp of 423 K is used (ref.28). LiY zeolites reacted with SiCl4 at 523 K and 623 K become partially amorphous during a posttreatment at 823 K, while NaY retains a better crystallinity (ref.28). The decomposition of tetrachloro aluminate complexes in inert atmosphere is harmful to the microporosity and crystallinity of LiY zeolites. The mesopore volume of HY zeolites is situated between that of NaY and LiY zeolites treated at the same temperatures (Fig.6). No further data are actually available on the thermostability of SiCl4-treated HY zeolites. 

Decomposition of tetrachloro-aluminium complexes in the presence of SiC1i. The final temperature of the SiCl4 treatment used in dealumination method B sometimes exceeds the decomposition temperature of the chloro aluminate complexes (Table 2). In such instances, AICI3 vapors are observed at the outlet of the dealumination reactor. A thick white fume of AICI3 was observed when LiY was treated at a Tr2 value of 733 K (ref.45). The zeolite retained full crystallinity. Within the detection limits of the 29 MASNMR technique, the substitution of silicon for aluminium was complete, but even after washing a substantial amount of extra-framework aluminium remained in the sample (Table 2, No.33). 

The reaction of SiCl4 with LiY, NaY and HY zeolites at temperatures below 423 K leads to the formation of framework-bound SiC13 species and LiCI, NaY and HC1, respectively. The SiCls species exhibit a 29 MASNMR resonance at ca. -45 ppm. The MASNMR spectra of the zeolite samples at this stage of the reaction show the presence of aluminium in distorted tetrahedral environments. Upon heating of the zeolites to temperatures exceeding 423 K, the Si atoms of the SiCl3 species are inserted in the framework, while the A1 atoms are released as AICI3. The latter is transformed into alkali metal tetrachloro-aluminate complexes in presence of alkali metal chloride salts. 

Thermal elimination of dislodged aluminium in NaY zeolites results in the formation of mesopores and, in the most severe conditions, in amorphisation. The higher volatility of lithium compared to sodium tetrachloro-aluminium complexes is reflected in more extensive mesopore formation in LiY compared to NaY samples. The desorption of AICI3 is facilitated and the detrimental effect of AICI3 neutralised when the tetrachloro-aluminate complexes are decomposed in the presence of SiCl4. However, an important fraction of the dislodged aluminium always remains in the sample. 

---