Two aminophosphonic acid dimethylesters 1 and 3 bearing COOH functions attached to W-VIS absorbing groups were hydrolysed by aqueous NaOH to yield the corresponding monomethylesters 2 and 4. The rates of hydrolysis were monitored by UV-VIS methods. The type of reaction observed is of pseudo first order with rate constants k(1)[1 mol(-1)s(-1)] of 1.92.10(-6) (1, 25 degrees C), 4.96.10(-5) (1, 50 degrees C) and 4.63.10(-5) (3, 50 degrees C). Hydrolysis is sufficiently slow to enable the practically undisturbed determination of dissociation constants for 1-(4-carboxyphenyl)-1-(N-t. butyl)-aminomethylphosphonic acid dimethylester (1) and 1-(4-benzoic-acid)-1-(N-4-phenyl-azo-phenylene)-aminomethylphosphonic acid dimethyl ester (3).
Monitoring the rate of hydrolysis of aminophosphonic acid esters by UV-VIS- and NMR-spectroscopy
FAILLA, Salvatore;
1999-01-01
Abstract
Two aminophosphonic acid dimethylesters 1 and 3 bearing COOH functions attached to W-VIS absorbing groups were hydrolysed by aqueous NaOH to yield the corresponding monomethylesters 2 and 4. The rates of hydrolysis were monitored by UV-VIS methods. The type of reaction observed is of pseudo first order with rate constants k(1)[1 mol(-1)s(-1)] of 1.92.10(-6) (1, 25 degrees C), 4.96.10(-5) (1, 50 degrees C) and 4.63.10(-5) (3, 50 degrees C). Hydrolysis is sufficiently slow to enable the practically undisturbed determination of dissociation constants for 1-(4-carboxyphenyl)-1-(N-t. butyl)-aminomethylphosphonic acid dimethylester (1) and 1-(4-benzoic-acid)-1-(N-4-phenyl-azo-phenylene)-aminomethylphosphonic acid dimethyl ester (3).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
