31P NMR studies of the kinetics of bisalkylation by isophosphoramide mustard: comparisons with phosphoramide mustard.
31P nuclear magnetic resonance spectroscopy was used to measure the pKa (4.28 +/- 0.2) of isophosphoramide mustard (IPM) at 20 degrees C and to study the kinetics and products of the decomposition of IPM at a solution pH value of ca. 7.4 and at temperatures between 20 and 47 degrees C in the presence of nucleophilic trapping agents. At 37 degrees C, the half-life for the first alkylation was ca. 77 min and ca. 171 min for the second alkylation; these data may be compared with those for phosphoramide mustard (Engle, T.W.; Zon, G.; Egan, W.J. Med. Chem. 1982, 25, 1347), wherein the half-lives for the first and second alkylations are approximately the same (18 min). The rate of fragmentation of aldoifosfamide to IPM and acrolein was also studied by NMR spectroscopy (pH 7.0; 37 degrees C; 0.07 M phosphate); under the noted conditions, the half-life of aldoifosfamide was found to be ca. 60 min.
Department of Chemistry, Catholic University of America, Washington, D.C. 20064.
J H
JH
Boal
M
M
Williamson
V L
VL
Boyd
S M
SM
Ludeman
W
W
Egan
D000477:Alkylating Agents; D000970:Antineoplastic Agents; D055598:Chemical Phenomena; D002621:Chemistry; D006207:Half-Life; D007069:Ifosfamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010752:Phosphoramide Mustards / Q000494:pharmacology*; D010761:Phosphorus Radioisotopes
D000477:Alkylating Agents; D000970:Antineoplastic Agents; D010752:Phosphoramide Mustards; D010761:Phosphorus Radioisotopes; C030090:phosphoramide mustard; C027061:isophosphamide mustard; D007069:Ifosfamide