Pentachlorides thionyl chloride complex

Although protactinium(V) chloro complexes can also be prepared using methyl cyanide as the solvent (32) (cf. PaBrg" and Pale ), the use of thionyl chloride has several advantages. Thus, it means that one can start with protactinium(V) hydroxide and not the pentachloride, thionyl chloride itself affords protection against atmospheric moisture and dry-atmosphere boxes are not necessary for the preparations, and, in addition, protactinium(V) concentrations up to 0.5 M have been obtained by dissolving the hydroxide in thionyl chloride (75). Such solutions are quite stable in contrast to the hydrolytic condensation reactions which occur in concentrated hydrochloric acid at Pa(V) concentrations as low as 10 M. 

The 1,4-diketone 1,2-dibenzoylethane 151 can be transformed in one step into 3,4-dibenzoyl-l,2,5-thiadiazole 152 when treated either with preformed trithiazyl trichloride in tetrachloromethane (Equation 29) <1997J(P1)2831> or with urethane, thionyl chloride, and pyridine in benzene (Katz reagent) <2002ARK90> (see also Section 5.09.9.2.l(iii)(b)). Similarly, treatment of 1,3-diketones 153 with tetrasulfur tetranitride antimony pentachloride complex in toluene at 100 °C < 1998J(P 1 )2175 >, or trithiazyl trichloride in boiling tetrachloromethane < 1997J(P 1)2831 >, affords 4-substituted-3-aroyl-l,2,5-thiadiazoles 154 (Equation 30). 

Thionyl chloride, as well as other inorganic acid chlorides, reacts with polyols to form mixed esters (see under Sulfate esters. Chapter III). In the presence of pyridine, partial chlorohydrin formation may occur (95), Selenium oxychloride forms a selenite ester upon reaction with mannitol (96), Phosphorus pentachloride yields unsaturated chlorohydrins of mannitol and galactitol which have the composition CeHeCU (97), Extremely interesting are the so-called complexes of alditols with various inorganic polybasic acids, their salts, or anhydrides in aqueous solutions. Complexes with boric, molybdic, tungstic, and other acids, as well as the oxides of antimony and arsenic, have been reported. It is believed that these complexes are true esters with one or more moles of alditol, a chelate type of structure being involved at some point. For the hexitols a compound with boric acid such as the following is postulated (98),... 

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