ISOHYPOPHOSPHATE - KINETICS OF HYDROLYSIS AND POTENTIOMETRIC AND NUCLEAR MAGNETIC RESONANCE STUDIES ON ACIDITY AND COMPLEXING
ISOHYPOPHOSPHATE - KINETICS OF HYDROLYSIS AND POTENTIOMETRIC AND NUCLEAR MAGNETIC RESONANCE STUDIES ON ACIDITY AND COMPLEXING
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DOI：
10.1021/ic50052a016
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发表时间：
1967-01-01
影响因子：
4.6
通讯作者：
MESMER, RE
中科院分区：
文献类型：
--
作者：
CARROLL, RL;MESMER, RE
研究了在0.5M氯化钠溶液中，在25.0、40.0和60.0的强酸、强碱和几种缓冲混合物中，异次磷酸盐的水解动力学。该反应被所有的Brunnsted酸和亲核试剂催化。详细的速率定律是根据异次磷酸盐的质子化形式进行水解而写成的。对于酸催化，每种质子化形式的水解比任何质子化程度较低的形式都要快。添加金属离子对碱催化水解率也有一定的促进作用。H_(30+)、醋酸、乙醇酸和水对H_2O_2~(2-)阴离子的催化活化热分别为26.1、18.3、19.0和24.9千卡/摩尔。测定了Li+、Na~(2+)、K~(2+)、Mg~(2+)、Ca~(2+)在四甲基氯化铵中1：1络合物的pK值和形成常数，并与焦亚磷酸盐和焦磷酸盐的络合性能进行了比较。核磁共振研究表明，酸性最弱的氢原子与PO4基团的联系最强。此外，还给出了两个强酸性质子的去质子化顺序的证据。对P(III)和P(V)原子在不同金属离子浓度下的~(31)P核磁共振化学位移的分析表明，阴离子可能是双齿配体。
The kinetics of the hydrolysis of isohypophosphate was studied in strong acid, strong base, and several buffered mixtures at 25.0, 40.0, and 60.0 in 0.5 M sodium chloride. The reaction is catalyzed by all Br0nsted acids and by nucleophiles. The detailed rate law is written in terms of the protonated forms of isohypophosphate undergoing hydrolysis. For acid catalysis each protonated form hydrolyzes faster than any of the less protonated forms. An enhancing effect of added metal ion on the rate of base-catalyzed hydrolysis was also observed. The heats of activation for the catalysis of the H2P2O62-anion by H30+, acetic acid, glycolic acid, andwater are 26.1, 18.3, 19.0, and 24.9 kcal/mole, respectively. The pK values and formation constants for 1: 1 complexes of Li+, Na" 1", K+, Mg2+, and Ca2+ were determined at 25.0 in tetramethylammonium chloride and compared with the complexing properties of pyrophosphite and pyrophosphate. Nuclear magnetic resonance studies indicate that the least acidic hydrogen atom is most strongly associated with the PO4 group. Also, evidence for the order of deprotonation of the two strongly acidic protons is given. Analysis of the 31P nmr chemical shifts for the P (III) and P (V) atoms at various metal ion concentrations suggests that the anion probably acts as a bidentate ligand.