Formal anhydride

Studies of the chemical reactivity of N2O3 are complicated by its extensive dissociation into NO and NO2 which are themselves reactive species. With water N2O3 acts as the formal anhydride of nitrous acid and in alkaline solution it is converted essentially quantitatively to nitrite ... 

HOF reacts with HF to reverse the equilibrium used in its preparation. It does not dehydrate to its formal anhydride OF2 but in the presence of H2O it reacts with F2 to form this species. 

Carbon monoxide, CO, is produced when carbon or organic compounds burn in a limited supply of air, as happens in cigarettes and badly tuned automobile engines. It is produced commercially as synthesis gas by the re-forming reaction (Section 14.3). Carbon monoxide is the formal anhydride of formic acid, HCOOH, and the gas can be produced in the laboratory by the dehydration of formic acid with hot, concentrated sulfuric acid ... 

Give the formula for the formal anhydride of each acid ... 

Give the formula for the acid corresponding to each of the following formal anhydrides (a) N2Os (b) P4O 0 (c) Se03. 

Cyclotriboroxanes (RBO)3 (also known as boroxines) are formally anhydrides of the corresponding boronic acids RB(OH)2 only mild heating is required to convert these dibasic acids into a wide range of cyclic trimeric anhydrides [eqn (9.18)]. This dehydration process can be adapted for the synthesis of B3O3 rings with different aryl groups on the boron atoms by using two or more arylboronic acids in the appropriate stoichiometric ratio. 

Many oxides of nonmetals form acidic solutions in water and hence are called acid anhydrides. The familiar laboratory acids HN03 and H2S04, for instance, are derived from acidic binary oxides. Even oxides that do not react with water can be regarded as the formal anhydrides of acids. A formal anhydride of an acid is the molecule obtained by striking out the elements of water (H, H, and O) from the molecular formula of the acid. Carbon monoxide, for instance, is the formal anhydride of formic acid, HCOOH, although CO does not react with cold water to form the acid. 

Examples The acids HNO3 and H2SO4 are derived from the oxides N2O5 and SO3, respectively. Oxides that do not react with water are called formal anhydrides of acids. The formal anhydride is obtained by removing the elements of water (H, H, and O) from the molecular... 

CO is the formal anhydride of formic acid and is produced in the laboratory by dehydration of formic acid with hot, concentrated sulfuric acid ... 

Methylene(oxo)phosphoranes are formally anhydrides of phosphinic acids a recent review 14) has summarized the existing knowledge on methods of generation of the species and their reactivity. Two cases (14 and 15) are known of compounds with sufficient stability to allow isolation, but as in the case of other metaanhydride substances, they are usually far too reactive to allow observation or isolation. 

N2O5 Dinitrogen pentoxide Cor" White ionic solid at room temperature [N02]" [N03] at the formal anhydride of HNO3 N2O5-I-H2O 2HNO3... 

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