Open Access Open Access  Restricted Access Subscription or Fee Access

Kinetics and Mechanisms of the Reduction of Some Carbonyl Compounds with Sodium Dithionite in Aqueous Alkaline Medium

P. O. Ukoha, F. N. Okafor

Abstract


Kinetics of the reduction of some carbonyl compounds (acetophenone, benzophenone, benzaldehyde, and salicylaldehyde) with sodium dithionite was studied at 28± 0.5oC and basic concentration in the range of 0.01 to 0.05 mol dm-3 (NaHCO3). Under these conditions, the reaction rates were found to be first order with respect to sodium dithionite as plot of log kobs versus log [S2O42-] showed linearity to about 95% extent of reaction, however, the overall reaction rate was second order at constant [OH-]. Furthermore, order of reactions with respect to acetophenone, benzophenone, salicylaldehyde, and benzaldehyde was unity as the plot of log(A∞-At) versus time showed about 90% linearity. Reaction rates increased with ionic strength and addition of chloride ions of varying concentration. Michaelis–Menten plot of 1/kobs versus 1/[S2O42-] were linear and have small intercepts on y-axis. Increase in pH (from 1-13) also showed remarkable increase in the reaction rates. Kinetic investigations showed that an outer-sphere reaction mechanism was operational and plausible mechanisms have been proposed for these reactions. The rate laws for the reactions conform to the equations: Rate = {k3K1 + k2 [OH-]2} [S2O42-] [RCHO] where RCHO = benzaldehyde and salicylaldehyde Rate = {k3K1 + k2 [OH-]2} [S2O42-] [RCOR1] where RCOR1 = benzophenone and acetophenone Keywords: carbonyl compounds, dithionite ions, kinetics, mechanism, reduction

Full Text:

PDF

References


Burlamacchi L., Guarini G., Tiezzi E. Mechanism of decomposition of

sodium dithionite in aqueous solution, Trans Faraday Soc. 1969; 65: 496–502p.

Davies D.M., Lawther M.J. Kinetics and mechanism of electron transfer from dithionite to microsomal cytochrome B5 and to forms of the protein associated with charged and neutral vesicles, J Biochem. 2009; 253: 375–80p.

Mattews A.J., Brittain T. Some electron transfer reactions involving carbodi-imide-modified cytochrome C, J Biochem. 1987; 243: 379–84p.

Brunori M., Antonini G., Wilson M.T. Metal Ions in Biological Systems: Copper Proteins. Sigel H. (Ed.), New York and Basel: Marcel Dekker; 1981.

Vollhardt P.K.C., Schore N.E. Organic Chemistry: Structure and Function. 5th Edn., New York: W.H. Freeman And Company; 2007.

Burke S.D., Danheiser R.L. Handbook of Reagents for Organic Synthesis, Oxidizing and Reducing Agents. New York: Wiley-VCH; 1999.

Http://www.Google.Com/M = Reduction/Sodiumdithionite/Client.

Larock R.C. Comprehensive Organic Transformations: A Guide to Functional Group Preparations. 2nd Edn., New York: Wiley-VCH; 1999.

John D. Facts on File: Dictionary of Inorganic Chemistry. New York: Market House Books Ltd.; 2004.

Http://www.OrganicChemistry.Org/Chemicals/Reducatio n /Sodiumhydrosulfite.Shtm.

Benson D. Mechanism of Inorganic Reactions in Solutions. London: Mcgraw-Hill Pub. Com.; 1981.

Therien M.J., Bowler B.E., Gray H.B., et al. Electron transfer in inorganic, organic and biological systems, J A Chem. Soc. 1991; 191– 9p.

Morrison R.T., Boyd R.N. Organic Chemistry. 6th Edn., India: Pearson Education; 2004.

Holleman A.F., Wilberg E. Inorganic Chemistry. San Diego: Academic Press; 2001.

Finar I.L. Organic Chemistry. 6th Edn., Singapore: Pearson Education; 1988.

Felix A.C. Perspectives on Structure and Magnetism In Organic Chemistry. USA: Brooks/Cole Pub. Com.; 1998.

Mcmurry J. Organic Chemistry. 7th Edn., USA: Brooks/Cole Pub. Com.; 1998.

Ahluwalia V.K., Madhuri G. A Text Book of Organic Chemistry. India: Narosa Pub. House; 2000.

Vries G.J., Van Bergen T.J., Kellog M.R. Sodium dithionite as a reductant for aldehydes and ketones, J A Chem Soc. 1996; 856.

Jones D.G., Jones M.G., Wilson M.T., et al. Reactions of cytochrome c oxidase with sodium dithionite, J Biochem. 1983; 209: 175–82p.

Carol C., Sutin N. Reduction of ferricytochrome C. by dithionite ion: electron transfer by parallel adjacent and remote pathways, Proc Nat Acad Sci USA. 1973; 70(6): 1701–3p.

Ukoha P.O., Atiga S., Ujam T.O., et al. Kinetics and mechanism of electron transfer of an adipato bridged iron(III)-salen complex with dithionite ion in perchloric acid medium, Croat Chem Acta. 2015; 88(3): 259–66p.

Albert H., Robert G.J., Wayne K.W. Mechanism of substitution reactions of cobalt III cyanide complexes, J A Chem Soc. 1983; 2: 31–54p.

Iyun J.F., Ukoha P.O. Kinetics and mechanism of oxidation of 1,3dihydroxybenzene by trioxoiodate(V) ion in aqueous perchloric acid medium, Indian J Chem. 1999; 38(2): 180–2p.

Hamza S.A., Iyun J.F., Idris S.O. Kinetics and mechanism of toluidine blue reduction by dithionite ion in aqueous acidic medium, J Chem Pharm Res. 2012; 4(1): 6–13p.


Refbacks

  • There are currently no refbacks.