CHAPTER 11 • Hydrolysis Processes of Organotin(lV) Compounds in Sea Water
217
interest in the aqueous chemistry of organotin compounds considerably decreased.
Only in the nineties have the hydrolytic products and complex species formation
of dialkyltin(IV) cations, as well as structural investigations, been reconsidered
by some authors (Cunningham et al.I990; Cucinotta et al. 1992; Burger et al. 1993;
Natsume et al. 1994). By using the most recent developments in data fitting analysis,
definitive results on the hydrolysis products of dimethyltin cation in a wide range of
ionic strengths and in different ionic media have been reported by De Stefano et al.
(1996). Stability constants of hydrolysis products by different authors are reported in
Table 11.2.
On the basis of results obtained by De Stefano et al. (1996), a distribution diagram
of the hydrolytic species in a non-interacting medium (NaN0 3 ) has been drawn and
is shown in Fig. 11.2.
Table 11.2. Literature data for the hydrolysis constants of (CH3hSn 2 + at T= 25°C and 1= 0.1 and
3 moldm- 3
Medium
-log 13,,- -log 13 12 ' -log 13 13 ' -log 13 22 ' -log 13 23 ' Reference
KN0 3
b
3.12
8.43
19.45
5.05
9.75
Arena et al. (1989)
Nad
3.25
8.54
5.05
9.81
Tobias and Yasuda (1964)
NaN0 3
b
3.18
8.42
4.69
9.64
Natsume et al. (1994)
NaN0 3
b
3.06
8.36
19.36
5.16
9.44
De Stefano et al. (1996)
NaCl b
3.12
8.45
19.48
5.20
9.70
De Stefano et al. (1996)
NaCI0 4 '
3.54
8.98
4.60
9.76
Tobias and Yasuda (1964)
NaN0 3 '
3.52
9.07
20.10
5.10
10.20
De Stefano et al. (1996)
NaCI0 4
c
3.30
9.08
20.30
5.10
9.70
De Stefano et al. (1996)
a
.
2+
(p-q)
+
Log fJ pq refers to the reaction pM = Mp(OH)q + qH .
b 1=0.1 mol dm- 3
, 1=3.0moldm
-3
Fig. 11.2. Distribution diagram
of R2Sn2+ species vS'RH in
NaN03 (0.5 mol dm- ) at T=
25°C; [R = CH3] (De Stefano
100r-----------------~------~------~
et al.1996).
Species:
(1) [(CH 3 hSn]2+,
(2) [(CH3hSn(OH)]\
(3) [(CH3hSn(OHh]o,
(4) [(CH3hSn(OHhf,
(,5) [((CH3hSnhCOHh]2+,
(6) [((CH3hSnhCOHh]+
l
1: 50
VI
cr.""
4
6
8
10
12
pH