145161-47-3

Basic information

• Product Name: (α-hydroxy-α-methoxy-benzyl)-phosphonic acid dimethyl ester
• CAS NO: 145161-47-3
• Molecular Weight: 246.2
• Mol File: 145161-47-3.mol
• Article Data: 1

Chemical Properties

• CAS DataBase Reference: (α-hydroxy-α-methoxy-benzyl)-phosphonic acid dimethyl ester(CAS DataBase Reference)
• NIST Chemistry Reference: (α-hydroxy-α-methoxy-benzyl)-phosphonic acid dimethyl ester(145161-47-3)
• EPA Substance Registry System: (α-hydroxy-α-methoxy-benzyl)-phosphonic acid dimethyl ester(145161-47-3)

Safety Data

• Hazardous Substances Data: 145161-47-3(Hazardous Substances Data)

Upstream product

• 67-56-1 methanol 
• 18106-71-3 dimethyl benzoylphosphonate 

Downstream Products

• 67-56-1 methanol 
• 18106-71-3 dimethyl benzoylphosphonate 

Relevant articles and documents

Acylphosphonate hemiketals - Formation rate and equilibrium. The electron-withdrawing effect of dimethoxyphosphinyl group

Examination of alcoholic solutions of dimethyl acetylphosphonate (1) and dimethyl benzoylphosphonate (2) by 31P NMR spectroscopy reveals the presence of considerable amounts of hemiketals. Because of the great difference between the 31P chemical shifts of acylphosphonates (ca. 0 ppm) and their hemiketals (17-21 ppm), 31P NMR spectroscopy is a uniquely suitable method for studying the rates and equilibria of hemiketal formation of acylphosphonates with different alcohols. The equilibrium constants Kf, K′f (K′f = Kf[ROH]), pseudo-first-order rate constants k′f, the second order rate constants, kf for hemiketal formation from dimethyl acetylphosphonate with various alcohols, as well as the reverse reaction rate constants, kr to starting materials, were determined. The kinetic isotope effect of 2.8 for the forward reaction kf (EtOH addition) and the backward reaction kr indicates a general catalysis pathway. On the other hand, the calculated values of the enthalpies of activation ΔH? = 10.37 kcal mol-1 (forward), ΔH? = 13.66 kcal mol-1 (backward) and the entropies of activation, ΔS? = -17.25 cal mol-1 K-1 (forward), ΔS? = -9.82 cal mol-1 K-1 (backward) are not in accord with high molecularity of the reaction (1 cal = 4.184 J). Our analysis led to the conclusion that this is probably due to the fact that the transition state is mainly reactant-like with the development of only limited extent of bond formation. Various plausible reaction pathways for hemiketal formation are discussed. In addition, we have calculated the value of 2.65 σ* for the P(O)(OMe)2 group based on proton affinity obtained from heats of formation (ΔHf) of applying the MNDO techniques. The following linear correlation between pKa values and PA values of hemiketals of the form (Me)(R)C(OH)(OCH2X) was developed: pKa = PA - 356.58 + 9.18 [σ*(Me) + σ*(R) + 0.2σ*(X)].