| http://www.w3.org/ns/prov#value | - Preferably, the condensation is conducted at a temperature within the range of about 70 and about C. Moreover, the condensation can be suitably carried out in the presence of an inert organic solvent, for example, a hydrocarbon, such as benzene, hexane and the like, or an ether such as ether, tetrahydrofuran or dioxane, or dimethylformamide or hexamethylphosphoramide.
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