Nitronic acids acid strength

In summary, reactions of nitronates with acid anhydrides or acyl chlorides give the O-acylated products, and reactions with acyl imidazoles, phenyl esters, acyl nitriles, and enol-lactones gives the C-acylated products, (see Eq. 5.13).25 The C/O selectivity of nitronate acylation by RCOX is qualitatively correlated with strength (pKJ of the acid HX conjugated to the leaving group X .25... 

Acidification of these nitronic acid salts may lead to a variety of products depending upon the nature and strength of the acid employed. Weak acids, such as acetic or carbonic acids, simply regenerate the nitro-paraffin. Warm, concentrated mineral acids hydrolyze the salts of primary aci-nitroparaffins to produce fatty acids and salts of hydroxyl-amine. This is in reality a reaction of the nitronic acids and occurs when the primary nitroparaffins themselves are warmed with concentrated mineral acid.17... 

Two model reactions have been investigated with different bases ethyl nitroacetate with allyl alcohol ( in water example) and ethyl nitroacetate with styrene ( on water example). In both cases the results do not depend on the kind of base however, there is evidence that bases considerably weaker than nitronate have little, if any, catalytic effect on the reaction [72]. Thus, when the dipolarophile is an unsaturated carboxylic acid, the catalytic effect of an added base (sodium hydroxide or DABCO) depends on its acid strength, as... 

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