Estimation of ionisation constants

The value of linear free-energy relationships in estimating pA values is beyond question the method is especially useful in mechanistic studies where it is often 

The p/ST of the hydrate of formaldehyde is a useful example this species is clearly unstable in water and simple titration techniques do not allow a measurement to be made. An indirect method [107] yields a value of 13.7. Reference to Table 27 indicates that the of RCHjOH is governed by the equation p T = 15.9 — 1.42a allowing for the change in a from H to OH and a statistical factor (0.3) as there are two hydroxyls leads to p. T = 14.4 — 1.42a. Substitution of ajj gives p T = 13.29 in good agreement with experimental findings. 

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