SbCl5 ANTIMONY PENTACHLORIDE

SbCl5 ANTIMONY PENTACHLORIDE 73.6650 -4.3530E+03 -2.6389E+01 2.3832E-02 -9.0652E... 

Reaction of tetrasulphur tetranitride antimony pentachloride complex (S4N4.SbCl5) with a series of primary (3-enaminones and P-enamino esters 79 in toluene at 100 °C gave reasonable yields of 3,4-disubstituted 1,2,5-thiadiazoles 80. The formation of 80 was explained by the same mechanism as that proposed for the formation of 1,2,5-thiadiazoles from 3,5-disubstituted isoxazoles with S4N4.SbCl5 complex <00H159>. 

It has been suggested that the donor strength be defined relative to a reference acceptor, for which antimony pentachloride was arbitrarily selected which forms 1 1 adducts, D.SbCl5, with neutral donors. The negative A//D.SbCl5-value high dilution of 1,2-dichloroethane is considered to be a measure of the donor properties of D and is termed donicity or donor number", DN. 

A series of 3-acyl and 3-aroyl-4-substituted 1,2,5-thiadiazoles 82 have been synthesised by reaction of 3,S-disubstituted isoxazoles 81 with tetrasulfur tetranitride antimony pentachloride (S4N4.SbCl5) in toluene at 90 C to reflux temperature. Compounds 82 are produced regioselectively and a plausible mechanism for their formation discussed. Under the same conditions, 3,4-dialkyl and 5-alkyl(aryl)-isoxazoles furnished chloroketones of type 83 <98JCS(P1)2175>. 

The monoxide SgO forms the 0-bonded adduct SgO SbCl5 upon treatment with antimony pentachloride in CSy adduct formation results in pyramidal inversion at the three-coordinate sulfur atom. In contrast, the treatment of 850 with antimony pentachloride induces dimerisation to give the 2 1 adduct of SbCls with the cyclic dioxide SiyOy. The chair form of the two S O constituents of this dimerisation process are evident in the conformation of the 12-membered S12 ring in the adduct. 

Antimony pentachloride also unites with ammonia. Two products are formed by passing ammonia gas into cold antimony pentachloride, namely, triammino-antimony pentachloride, [Sb(NH3)3]Cl3, and tetranunino-antimony pentachloride, [Sb(NH3)1]Cl5.1 Triammino-antimony pentachloride is a red substance which decomposes on heating, with formation of a sublimate of composition 3NH4Cl.SbCl5. Tetram-mino-antimony pentachloride is a white volatile substance which decomposes into antimony ammonium chloride. NH4Cl.SbCls, on treatment with hydrochloric acid. 

Lewis acids such as A1C13, SbCl5, or PFS have been used successfully to generate a variety of radical cations. Antimony pentachloride was first used with hydrocarbons such as benzene or anthracene [22, 23]. Salts obtained from aromatic amines with this reagent were found to be paramagnetic [24] eventually, well resolved ESR spectra identified the formation of radical cations [25,26]. Although an electron transfer mechanism must be involved, the fate of the complementary radical anions and details of their decay are poorly understood. Once again, it appears doubtful that Lewis acids are suitable oxidants for the study of the sometimes delicate substrates discussed in this review. 

Fluorocarbons are made from chlorinated hydrocarbons by reacting them with anhydrous hydrogen fluoride, using an antimony pentachloride (SbCl5) catalyst. 

Depending on the substituents in (61) and on the concentration of the catalyst, however, other products may also subsequently be formed. In some cases, SbCl5-complexed primary intermediates of type (65) could even be isolated and characterized by NMR spectroscopy as well as by well-defined chemical reactions (81JA1789). Treatment of tetraphenyl-1,2,4-trioxolane (67) with antimony pentachloride or liquid sulfur dioxide, a mild Lewis acid, gave benzophenone and phenyl benzoate in a molar ratio of 1 1 (80JA288). The formation of the ester corresponds to that of the carboxylic acid from (61) via path A or path B. 

Arsenic pentachloride can be prepared at low temperature but decomposes above —50°C. Antimony pentachloride is made by reaction of Cl2 with SbCl3 and is stable up to 140°C. The solid (mp 4°C) contains Cl4Sb(/x-Cl)2SbCl4 dimers. The curious instability of AsC15 relative to PC15 and SbCl5 has been attributed to a stabilization of the 4s2 electron pair in all the elements immediately following the... 

Acute respiratory exposure of seven workers to 70-80 mgm" of antimony trichloride, SbCl3, resulted in irritation of the upper respiratory tract. Antimony pentachloride, SbCl5, caused severe pulmonary edema in three cases, two of them being lethal Completed inhalation studies have demonstrated that inhalation of antimony trioxide induces lung tumors in female rats. ... 

In the presence of antimony pentachloride PFCI2 and chlorine afford a salt [PFCl3][SbClfi], which is also formed more slowly from SbCl5 and PFCI2 directly. NMR and IR studies indicate the presence of the PFCls cation (278). 

Rose investigated the compounds of ammonia with titanium and stannic chlorides, and with chlorides of sulphur, selenium, phosphorus, arsenic, antimony, aluminium, and iron, as well as the compounds of ammonia with anhydrous halides, sulphates, and nitrates of several metals. He discovered antimony pentachloride by acting on antimony with excess of chlorine, and an interesting compound of it with sulphur chloride, obtained by the action of excess of chlorine on antimony trisulphide. He formulated this as SbCl5,3SCl4, but the pure compound, which can be obtained in crystals, is SbClg, SCI4. ... 

Sadeghi et al. (2011) reported silica-supported antimony pentachloride (SbCl5 Si02) as an efficient catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles. The reaction involved a one-pot, four-component reaction of aldehyde, amine, benzyl, and ammonium acetate under reflux conditions in ethanol with a catalytic amount of SbCl5"Si02 to afford the corresponding 1,2,4,5-tetrasubstituted imidazoles in improved yields (Scheme 6.15). The products can also be obtained... 

Both the DN and AN values are determined empirieally. The electron DN is taken as the molar enthalpy value for the reaction of die donor species with antimony pentachloride (SbCl5 ) as a reference acceptor in a 10 molar solution of 1,2-dichloroethane. The DN values range mainly from 0 to 60 keal/mol. The AN values are dimensionless numbers related to the capacity for sharing electron pairs from standard donating molecules. The numbers can be determined from P NMR ehem-ical shift measurements in triethylphosphine (Et3 PO) upon addition of the respee-tive acceptor. The normalized AN scale ranges from 0 for hexane to 100 for 1 1 components formed between SbCl5 and (Et3 PO). 

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