Rates of Chloride Ion Exchange with Various Phosphonic Chlorides and Phosphorochloridates

Abstract

From measurements of the chloride-36 exchange rate with various RPOCU compounds and spectroscopic determination of the donor strength of various phosphoryl compounds, it has been possible to examine the electronic effects present in bimolecular displacement reactions on four-coordinate phosphorus. The exchange reaction with RPOCh compounds has been shown to follow secondorder kinetics in the solvent 1,2-dichloroethane at -30°.The effect of substituent is to decrease the rate in the order C6tf5 > CH3 > OCH3 ~Cl > OC,Hb. The effect of substituent on the donor strength of the phosphoryl oxygen gives rise to the order (CH^N ~C3H5 > CH% > OCH3 > OC3Hs, > Cl.The relative importance of inductive and conjugative effects for these substituents has been discussed. These studies aid in the interpretation of some previously published n.q.r. data. Interpreting the donor strength(1) (a)

The kinetics of the chlorine isotopic exchange between chloride ion at O,O‐diarylphosphorochloridates or O,O‐diarylphosphorochloridothionates

“…Such an assumption is based on the results of some comparative kinetic studies [l-81 and is also supported by the calculated charges [9] at the phosphorus atom and dipole moments [lo-131 of the P=O and P=S bonds. The second hypothesis, contrary to the first one, implies an increase of the positive charge at phosphorus as deduced from the results of spectroscopic [4,6,14,15] and potentiometric [16] studies.…”

“…30 an assumption is based on the results of some comparative kinetic studies [l-81 and is also supported by the calculated charges [9] at the phosphorus atom and dipole moments [lo-131 of the P=O and P=S bonds. The second hypothesis, contrary to the first one, implies an increase of the positive charge at phosphorus as deduced from the results of spectroscopic [4,6,14,15] and potentiometric [16] studies. In view of existing discrepancies we have undertaken the comparative kinetic studies of some 0,O-diarylphosphorochloridates (p -RC6H40)2POCl and their thio analogs ( p -RC&0)2PSC1, with the aim of determining quantitatively the effect of sulfur vs. oxygen replacement in the phosphoryl group on the reactivity of compounds investigated.…”