HYDROLYSIS OF CR2O72- - NUCLEOPHILIC CATALYSIS BY TRIS AND RATE LAWS FOR THE FORMATION AND DECAY OF A (TRIS)CRO3 INTERMEDIATE

Authors
BRASCH NE BUCKINGHAM DA CLARK CR
Citation
Ne. Brasch et al., HYDROLYSIS OF CR2O72- - NUCLEOPHILIC CATALYSIS BY TRIS AND RATE LAWS FOR THE FORMATION AND DECAY OF A (TRIS)CRO3 INTERMEDIATE, Inorganic chemistry, 33(12), 1994, pp. 2683-2685
Citations number
13
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Inorganic chemistry → ACNP
ISSN journal
00201669
Volume
33
Issue
12
Year of publication
1994
Pages
2683 - 2685
Database
ISI
SICI code
0020-1669(1994)33:12<2683:HOC-NC>2.0.ZU;2-K
Abstract
Hydrolysis of Cr2O7-2 ion in the presence of TRIS buffer (H2NC(CH2OH)3 . pH 7.55-8.96) involves nucleophilic catalysis (k1 = 55 M-1 s-1, 25-d egrees-C, I = 1.0 M NaClO4) with the intermediate (TRIS)CrO3 species ( H3N+C(CH2OH)2CH2OCrO3-, pK(a)c = 8.00) decaying to free TRIS and CrO42 - via TRIS general base (k2 = 6.4 M-1 s-1) and specific OH- (k(OH) = 2 .2 x 10(4) M-1 s-1) catalyzed pathways. Rate constants for the catalyz ed hydrolysis of Cr2O72- by eight other species of basicity comparable (+/- 2 pK units) with TRIS (TRISH+, pK(a) = 8.12) vary by factors of up to 10(5).