Reactivity and mechanism of hydrolysis of phosphonamides

Journal Article · Wed Apr 08 04:00:00 EST 1981 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00397a024· OSTI ID:6455570

Rahil, J; Haake, P

The rates of hydrolysis of three phosphonamides, N,N-dimethylphenylphosphonamide (XII), N-(phenylphosphonyl)pyrrolidine (XIII), and N-(phenylphosphonyl)morpholine (XIV), have been investigated. There is first-order dependence on acidity in the pH range 4 to 7 with a pH independent region at low pHs, consistent with saturation due to complete formation of the neutral amide. The specific rate constant (k/sub 2/) and the acidity constant (K/sub a/) were obtained from the dependence of psudo-first-order rate constants on (H/sup +/); k/sub 2/ is 1.27 x 10/sup -2/s/sup -1/ and 1.42 x 10/sup -3/s/sup -1/ and pK/sub a/ is 4.8 and 5.3 for XII and XIII, respectively. The small value of the acidity constants is consistent with predominant N-protonation. The activation parameters for XII are ..delta..H/sup +/ = 11.1 kcal/mol, ..delta..G/sup +/ = 20.35 kcal/mol, and ..delta..S/sup +/ = -31 eu. Solvent and salt effects on the rate of hydrolysis of XII are insignificant. The solvent isotope effect, k/sub 2/(H/sub 2/O)/k/sub 2/(D/sub 2/O), is 1.2 and K/sub a/(H/sub 2/O)/K/sub a/(D/sub 2/O) is 3.2. Fluoride ion catalyzed the rate of reaction of XII. The Broensted ..beta.. value is about -1, implying rate-determining breakage of the P-N bond. The results appear to be most consistent with an S/sub n/2(P) mechanism. The reactivity of phosphorus amides is discussed in terms of their structure.

• Research Organization: Wesleyan Univ., Middletown, CT
• OSTI ID: 6455570
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:7; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400300* -- Organic Chemistry-- (-1987)
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AMIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
DEUTERIUM
EXPERIMENTAL DATA
HYDROGEN ISOTOPES
HYDROLYSIS
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
LYSIS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
REACTION KINETICS
SOLVOLYSIS
STABLE ISOTOPES