ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The kinetics of the base catalysed racemization of [Co(EN3A)H2O]Abbreviations: EN3A3-=(-OOCCH2)2N(CH2)2NHCH2COO-; ME3A3-=(-OOCCH2)2N(CH2)2 N(CH3)CH2COO-; EDDA2-=-OOCCH2NH(CH2)2NHCH2COO-; EDTA4-=(-OOCCH2)2N(CH2)2N(CH2COO-)2;TNTA4-=(-OOCCH2)2N(CH2)3N(CH3COO-)2; HETA3-=(-OOCCH2)2N(CH2)2N(CH2COO-)CH2CH2OH; en=H2N(CH2)2NH2; Meen=H2N(CH2)2NHCH3; sar-=-OOCCH2NHCH3. were studied polarimetrically in aqueous buffer solution. The reaction rate is first order in OH- and in complex, in weakly acidic medium. Activation parameters are ΔH≠=22 kcal · mol-1, ΔS≠=26 cal · K-1. The results are discussed in terms of an SN1CB mechanism involving exchange of the ligand water molecule.The N-methylated analogue [Co(ME3A)H2O] does not racemize in the pH-range investigated. Loss of optical activity occurs at a rate which is about 1,000 times slower than the racemization of [Co(EN3A)H2O](60°) and coincides with the decomposition of the complex.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19770600725
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