ORGLIST: summary of amines+ phosphates

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From: Kamil Wojciechowski (kamilwoj$##$chemix.ch.pw.edu.pl)
Date: Fri Sep 17 1999 - 03:59:28 EDT


Here's my original message and below are the answers:

Hello,
My name's Kamil, and I'm new here.
Does anybody know what may happen after mixing of
o-phenylenodiamine
with NaH2PO4 in water ? If so, please help me.

Tnak you in advance,
Kamil Wojciechowski,
PhD student, Department of Analytical Chemistry, PW, Warsaw,
Poland


1)
<ocad$##$mahendra.iacs.res.in>
Calcutta, 14 September 1999
o-phenylenediamine is a strong base. I surmise that it will
abstract one
proton from monosodiumdihydrogen phosphate. NaHPO4 anion will
remain with
it as a counter ion.

2)
zabicky$##$bgumail.bgu.ac.il (Jacob Zabicky)

Hello Kamil,
You'll get a nice buffer, but remember that o-phenylenediamine
is toxic,
and the solution will probably darken with time by
autooxidation.

3)
and finally my conclusion:
That must be in fact autooxidation, what causes yellowing of the
solution, but after repeating the experiment replacing NaH2PO4 by clear
water and NaNO3 sol., I came to the conclusion that phosphates faster
the process, maybe due to partial protonation of diamine

Thank you very much

Kamil Wojciechowski



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