Dissociation constants for certain cyclic oxyacids of phosphorus and values of ?? for cyclic fragments

Synthesis and hydrolytic stability of cyclic phosphatidic acids: implications for synthetic- and proto-cell studies

“…This increase in p K a with chain length of cPA is consistent with what is known for p K a of fatty acids with increase in chain lengths, 29 and seems to be reflective of the increase in p K a value of cyclic phosphates in an increasing non-polar environment. 28 If this interpretation is correct, then the increasing p K a would result in a protonated neutral cyclic phosphoric acid species at pH 4, to a greater extent for 1c and 1f (when compared 1a and 1b ). And, therefore, 1c and 1f would be more prone to nucleophilic attack by water leading to hydrolysis at pH 4.…”

“…This increase in pK a with chain length of cPA is consistent with what is known for pK a of fatty acids with increase in chain lengths, 29 and seems to be reflective of the increase in pK a value of cyclic phosphates in an increasing nonpolar environment. 28 If this interpretation is correct, then the Fig. 2 Isolation of medium and long chain cPAs by manipulating the critical aggregate concentration (CAC) during workup.…”

“…S133 versus S154, ESI †), suggesting that an aggregation-type behaviour may not be the only reason for this unexpected diverging hydrolytic behaviour at pH 4 versus pH 9. It may also be related to the pK a of the cyclic phosphate moiety (E2), 28 and the modulation of the negative charge of the cyclic phosphate moiety (by protonation with change in pH), which could enable a hydrolytic attack on the cyclic phosphate and the neighbouring carboxylate-ester moiety. The apparent pK a of the cyclic phosphate moiety in myristic 1c and oleate 1f lies closer to 4, while for hexanoate 1a and decanoate 1b it is closer to 2 (Table S3, ESI †).…”