Abstract
The hydrolysis of amino acid esters is catalysed by the palladium(II) complex [Pd(Pic)]2+ (Pic = 2-picolylamine). The reaction has been studied by the pH-stat technique. The overall PdII chelate-promoted hydrolysis of the ethyl esters of glycine and alanine may be accounted by inter-and intramolecular mechanisms depicted in Eqns (1) and (2) respectively.
The kinetic data for histidine and methionine methyl esters are fitted assuming that hydrolysis proceeds solely by the intermolecular mechanism [Eqn (1)]. The rate enhancement compared with the free ester is discussed in terms of the structure of the complex. Activation parameters associated with the hydrolysis have been determined and discussed.
References
1.
Chakraborty H.
, and
Rahman M.L.
(1993 ) Trans. Met. Chem , 18 , 545 –347 .
2.
Nolan K.B.
,
Ryan L.P.
, and
Gonzalez E.B.
(1994 ) Inorg. Chim. Acta , 215 , 55 –60 .
3.
Hopgood D.
, and
Angelici R.J.
(1968 ) J. Am. Chem. Soc. , 90 , 2508 –2518 .
4.
Sigel H.
(1976 ) In:
Hay R.W.
, and
Morris P.J.
(eds), Metal ions in biological systems , pp. 173 –218 . Marcel Dekker , New York .
5.
Walker J.K.
, and
Nakon R.
(1981 ) Inorg. Chim. Acta , 55 , 135 –140 .
6.
Shoukry M.M.
,
Khairy E.M.
, and
Khalil R.G.
(1997 ) Trans. Met. Chem. , 22 , 465 –470 .
7.
Mohamed M.M.A.
, and
Shoukry M.M.
(2002 ) Polyhedron , 21 , 167 –173 .
8.
Shoukry M.M.
,
Khairy E.M.
, and
Saeed A.
(1989 ) Trans. Met. Chem. , 14 , 347 –350 .
9.
Shehata M.R.
,
Shoukry M.M.
,
Nasr F.M.H.
, and
van Eldik R.
(2008 ) J. Chem. Soc. Dalton Trans. , 779 –786 .
10.
Shehata M.R.
,
Shoukry M.M.
,
Abdel-Shakour F.H.
, and
van Eldik R.
(2009 ) Eur. J. Inorg. Chem. , 3912 .
11.
Rau T.
,
Shoukry M.
, and
van Eldik R.
(1997 ) Inorg. Chem. , 36 , 454 .
12.
Shoukry M.M.
,
Khairy E.M.
, and
El-sherif A.A.
(2002 ) Trans. Met. Chem. , 27 , 656 –664 .
13.
Shoukry M.M.
,
Khairy E.M.
, and
Saeed A.
(1988 ) Trans. Met. Chem. , 13 , 146 –149 .
14.
Leach B.E.
, and
Angelici R.J.
(1969 ) J. Am. Chem. Soc. , 8 , 907 –913 .
15.
Bates R.G.
(1975 ) Determination of pH theory and practice , 2nd edn, Wiley Interscience , New York .
16.OLIS KINFIT , Olis Inc ,
Bogart G. A.
17.
Robinson R.A.
, and
Stokes R.H.
(1979 ) Electrolyte solutions , 2nd edn, Butter-worths , London .
18.
Davies C.D.
(1936 ) J. Chem. Soc. , 2093 .
19.
Hay R.W.
, and
Yau-Quan C.
(1995 ) Polyhedron , 14 , 869 –872 .
20.
Hay R.W.
, and
Basak A.K.
(1982 ) J. Chem. Soc. Dalton Trans. , 1819 –1823 .
21.
Alexander M.D.
, and
Busch D.H.
(1966 ) J. Am. Chem. Soc. , 88 , 1130 –1138 .
22.
Buckingham D.A.
,
Harrowfield J.M.
, and
Sargeson A.M.
(1974 ) J. Am. Chem. Soc. , 96 , 1726 –1729 .
23.
Edwards J.O.
,
Monacelli F.
, and
Ortaggi G.
(1974 ) Inorg. Chim. Acta , 11 , 47 –104 .
24.
Hay R.W.
, and
Morris P.J.
(1976 ) In: Metal ions in biological systems ,
Sigel H.
(ed.), Marcel Dekker , New York , 5 , 173 –218 .
25.
Hay R.W.
, and
Baneijee P.
(1981 ) J. Chem. Soc., Dalton Trans. , 362 –365 .
26.
Hay R.W.
, and
Porter L.J.
(1969 ) J. Chem., Soc., A , 127 –133 .
27.
Hay R.W.
, and
Morris P.J.
(1971 ) J. Chem. Soc. A , 1524 –1533 .
28.
Hay R.W.
, and
Morris P.J.
(1973 ) J. Chem. Soc., Dalton Trans. , 56 –61 .
29.
Hay R.W.
, and
Banerjee P.
(1980 ) Inorg. Chim. Acta , 44 , L205 –L207 .
30.
Hay R.W.
, and
Porter L.J.
(1967 ) J. Chem., Soc., B , 1261 –1264 .