IJSRD - International Journal for Scientific Research & Development Vol. 3, Issue 11, 2016 ISSN (online):

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1 IJSRD - International Journal for Scientific Research & Development Vol. 3, Issue 11, 2016 ISS (online): Induced Electron Transfer Reaction of obalt (III) omplexes of α ydroxy Acids by 2, 2 -Bipyridinium omo hromate (BPB) in the Presence of.vijayakumar 1 K. Subramani 2 1,2 Department of hemistry 1,2 Islamiah ollege, Vaniyambadi (T..) India Abstract The kinetics mechanistic studied of BPB with obalt (III) bound and unbound complexes of α-hydroxy acid in micellar medium at 323 K in 50% acetic acid 50 % water. In this reaction the rate of oxidation shows pseudo first order kinetics each in obalt (III)] and BPB. It rules out the synchronous - bond fission and electron transfer to obalt (III) centre. With increasing micelles concentration an increase in the rate is observed. xidation of obalt (III) complexes increases with increase in temperature. The kinetic and stoichiometric results have been accounted by a suitable mechanism. Key words: α ydroxy Acids, 2,2 Bipyridinium omochromate, Sodium Lauryl Sulphate, etyl Trimethyl Ammonium omide, TRIT-X100 cleavage accompanied by an induced electron transfer to the o (III) in the complex and one electron transfer to the oxidant. The contest between the two mechanisms became interesting and produced definite results when mild oxidizing agents like BPB were kinetically followed. The structure of BPB is given below + - Fig. 1: Structure of BPB II. EXPERIMETAL 2,2 -Bipyridine (A.R. Qualigens, India),, chromium trioxide from (SD Fine chemicals. India 95%) Preparation of BPB to I. ITRDUTI ml of 6 M hydrobromic acid (0.11mole) is added 10.0g. (0.11mole) of chromium trioxide rapidly while stirring. After hromium (VI) reagents have been widely used in organic dissolution of the chromium trioxide is complete, 15.6 g. chemistry for the oxidation of primary and secondary alcohols to (0.1mole) of 2, 2 -bipyridine is added in portions while stirring carbonyl compounds. Pyridine chromium trioxide complexes vigorously. A yellow slurry results which is stirred for 1 hour at and pyridinium bromo chromate have been especially useful room temperature. The slurry is then collected on a sintered reagents for the mild oxidation of primary alcohols to aldehydes. glass funnel and washed with two 15 ml portions of cold There are, however, some significant difficulties associated with distilled water. The resulting solid yellow filter cake is dried for the reagents. For instance, chromium containing by-products 3 hours in vacuum at room temperature.the resulting product is often contaminate the desired products, requiring time 2,2 -bipyridinium bromochromate, its purity was checked by an consuming purifications. A novel compound 2, 2 -bipyridinium iodometric method and is obtained in a typical yield of 26.8 g. chlorochromate, 2, 2 -bipyridinium bromo chromate has been which is 92% of the theoretical yield. Mandelic, lactic and discovered which is useful as an oxidizing agent. The compound glycolic acids from (SD Fine chemicals. India 95%) is especially useful as an oxidizing agent in reactions which l 4 (Merck, India 95%) was standardized using require relatively mild oxidizing conditions, such as the standard sodium carbonate (BD.AR) solution with methyl conversion of primary or secondary alcohols to carbonyl orange as an indicator. Acetic acid was purified by standard compounds. Evolution 60 thermo spectrophotometer has been method and the fraction distilling at was collected. The utilize to study the oxidation of α-hydroxyacids 1 such as cobalt (III) complexes of alpha-hydroxy acids were prepared as mandelic acid, lactic acid, glycolic acid and their obalt (III) their perchlorates using the method of Fau and Gould 4. The omplexes using Pyridinium dichromate as an oxidant in the surfactants used in the present work are sodium lauryl sulphate presence of surfactant. Surfactants are often used in the (als) and cetyl trimethylammonium bromide 5 (TAB).The formulations of pesticides and herbicides 2. They have also found surfactants are purified by adopting earlier procedure 6 Kinetic a wide range of applications because of their unique solution measurements of the oxidation of cobalt (III) complexes of α - properties such as detergency, solubilisation, and surface hydroxy acids and unbound ligands were carried out under wetting capabilities in diverse areas such as chemical as well as pseudo first order conditions in 50% acetic acid 50% water at 55 biochemical research 3. Surface active materials are major ± 2 o by following the concentration of BP at 365 nm with building blocks of many physical, chemical, anti-biological the help of an UV visible spectrophotometer. The total volume systems. They have been introduced into several commercial of reaction mixture in the spectrophotometric cell was kept as products such as antiseptic agents in cosmetics and as 2.5 ml in each kinetic run all the solutions for the experiments germicides 7, and have also found a wide range of applications in were maintained at the specified temperature in an electrically diverse areas such as mining, petroleum, and pharmaceutical operated thermo stated bath. Perchloric acid was used as the industries. A mechanism involving the - bond cleavage source of + ions and ionic strength was maintained by leading to the formation of aldehydes as the product was al 4.Stoichiometric studies for the oxidation of Penta proposed. The formation of keto acids by the - cleavage of ammine cobalt (III) complexes of alpha-hydroxy acids and the alpha-hydroxy acids was reported with many chromium (VI) unbound ligands by BPB were carried out with the oxidant in oxidant 3. In the case of complexes, the hydroxyl group of the excess. The [ + ] and ionic strength were maintained as such in bound ligand is free for oxidation with - cleavage leading to the corresponding rate measurements. After ten half-lives when the formation of keto complexes. Formation of aldehydes as a the reaction was nearing 80% completion the concentration of product is possible with decarboxylation and synchronous - r All rights reserved by 169

2 Induced Electron Transfer Reaction of obalt (III) omplexes of α ydroxy Acids by 2, 2 -Bipyridinium omo hromate (BPB) in the Presence of unreacted BPB was determined spectrophotometrically.the B. Rate Dependence of Bound o (III) of α ydroxy Acids difference in the concentration of the oxidant [BPB] was in Micellar Medium measured and then the stoichiometry was calculated from the The reaction proposes that BPB oxidizes centre of the ratio between reacted [oxidant] and [substrate]. The amount of cobalt (III) bound α - hydroxy acids at a rate comparable to cobalt (III) reduced was also calculated from the decrease in the that of the unbound ligand and there is 99 % reduction at the absorbance measured for the o (III) complex (Table 1).All cobalt(iii) centre The kinetic data for the oxidation of the kinetic measurements were carried out by the spectro pentaamminecobalt (III) complexes by BPB in presence of photometer. The spectrophotometer was kept at 365 nm the Perchloric acid catalyst and maintained temperature 55± monitoring changes the absorbance of the progress reaction is given in the Table 2.The behaviour of the nm was set for remaining r (VI) by monitoring changes of the complexes were similar to the free ligands and the reaction cobalt (III) complexes. The required α-hydroxy acid, l 4 and showed a total pseudo first order dependence on them and BPB were premixed in a reaction vessel, thermostated in an oil the reagent. The rates of oxidation of complexes were found bath, and BPB solution (thermally equilibrated) was then added prior to the absorbance measurements. A. Product Analysis o (II) was estimated after the completion of reaction, by diluting the reaction mixture 10-fold with concentrated l, allowing evolution of chlorine to cease, and then measuring the absorbance at 692 nm. The amount of o (II) estimated to nearly 40% of [o (II)] initial. After 48h, the product was extracted with ether and analysed iodoimetrically for the amount of aldehyde formed in the case of the [Mandelato] and [Lactato] obalt (III) complexes, the dimeric o (III) complex, and unbound mandaleic acid. The yield of aldehyde in all these cases is nearly 60% [o (III)] initial. After neutralization of the reaction mixture with sodium bicarbonate, the p of the aqueous layer was adjusted to about 6.5 and the aqueous layer was separated by filtration in the case of both free ligands and corresponding complexes. n evaporation of water under reduced pressure, the product separated and the percentage yield was calculated. Though the yield of mandelic acid was nearly quantitative, the estimation of mandaleic acid complex was less nearly quantitative. In both the cases the IR spectra of the product agreed with that of authentic samples of mandalic acid or the [mandelato] cobalt (III) complex. III. RESULT AD DISUSSI A. Rate Dependence of Free Ligand of α ydroxy Acids in Micellar Medium The rate of BPB oxidation of alpha-hydroxy acids had been followed under pseudo first order condition by keeping excess of the alpha-hydroxy acid concentration than the reagent summarized kinetic data for the oxidation of α-hydroxy acids and their o III complexes by BPB in presence of perchloric acid of anionic and cationic micells at 55±0.2.BPB induced electron transfer in pentaammine cobalt(iii) complexes of alphahydroxy acids seems to involve nearly synchronous - fission and reduction at cobalt(iii)centre. An explanation for the higher reactivity of lactic acid involving - cleavage was given based on the higher acidity of - proton. In the present investigation, the absence of such an observation leads to - cleavage. Finally product analysis confirmed the formation of aldehydes due to - cleavage and not formed keto acids. Stoichiometric analysis showed that the following overall reaction 6 5 () + 2r - bpy r - bpy + The rate equation for this reaction could be deduced as Rate = K [alpha-hydroxy acid] [BPB] to be higher than the corresponding free ligands showing that the oxidation was facilitated by complexation. Further the absence of keto complexes in the product and formation of aldehydes as the only organic product confirm the - cleavage. The reduction of o (III) to o (II) to an extent of 99% showed an induced electron transfer from the ligand to the metal due to decarboxylation and synchronous cleavage of the - bond in the complexes. BPB undergoes a one electron change and the overall reaction between BPB and the complexes could be written as: [ 6 5 () o III ] + 2r - bpy r V + o II + 2 The rate equation for this reaction could be deduced as Rate = K [o III omplex] [BPB] Table-1 shows the Stoichiometric Data of 2,2- bipyridinium bromo hromate oxidation of pentaammine cobalt (III) complexes of bound and unbound alpha hydroxy acids in presence als at maintained temperature 55±0.2 and alternatively changed micelles such as etyl Trimethyl ammonium omide (TAB) and TRIT-X100 respectively BPB [ompound] Initial 10 2 BPB Final 10 2 BPB [ompound] : [ BPB] mol dm : : : : : : : : : 0.70 o III Mandelato : : : 0.34 o III Lactato : : : 0.37 o III Glycolato : : 0.37 All rights reserved by 170

3 Induced Electron Transfer Reaction of obalt (III) omplexes of α ydroxy Acids by 2, 2 -Bipyridinium omo hromate (BPB) in the Presence of : 0.36 Table 1: Stoichiometric Data for BPB oxidation of o (III) bound and unbound α hydroxy acids in presence of Sodium Lauryl Sulphate (als) at 55 ± 0.2 º [l 4] = 1.00x10-1 mol dm -3 [als] = 1.00x10-2 mol dm -3 Temperature = 55 ± 0.2º. Effect varying of Temperature The reaction has been carried out at four different temperatures keeping [BPB] =10-3 mol dm -3 Mandellic Acid =1.00 x10-2 mol dm -3 (Table 2).Absorbance decrease the while reaction time of BPB with alpha hydroxy acid. The rate constants were calculated by the integrated rate equation. The graph of logarithm of absorbance versus time was linear and the rate [BPB] = 10-3 mol dm -3 constants calculated from the slope of the graph. Temperature [l 4] = 0.1 mol dm -3 increases rate also increased. Temperature = 55 ± 0.2 Time(s) log(absorbance) 10 4 k 1s -1 [Micelles] = 1.00x10-2 mol dm Table 2: Kinetic data on the effect of Temperature [BPB] = 10-3 mol dm -3 [l 4] = 0.1 mol dm -3 Temperature = 55 ± [( 3) 5o(III)-L] Mandellic Acid = 1.00 x10-2 mol dm -3 mol dm -3 [als] = 1.00x10-2 mol dm -3 Fig 1: First order dependence plot 10 2 [α-hydroxyacids] 10 4 k 1s -1 mol dm -3 als Triton TAB Table 3: Kinetic data for the oxidation of alpha-hydroxy acids free ligands by BPB 4+logk Fig 2: Dependence of rate on α-hydroxy acid with TAB 10 4 k 1s -1 als Triton TAB Table 4: Kinetic data for the oxidation of o III complexes of alpha-hydroxy acids and bound ligands by BPB [BPB] = 2.00x10-1 mol dm -3 [l 4] = 0.1mol dm -3 Temperature = 55 ± 0.2 [Micelles] = 1.00 x10-2 mol dm -3 2+log[alpha-ydroxy acids] All rights reserved by 171

4 Induced Electron Transfer Reaction of obalt (III) omplexes of α ydroxy Acids by 2, 2 -Bipyridinium omo hromate (BPB) in the Presence of 4+logk Fig 3: Dependence of rate on [o (III)] with TAB D. Mechanism The reaction was show that pseudo first order dependence on the BP with o III AKWLEDGEMET α-ydroxy acids and alpha-ydroxy acids. It involve two steps. Mechanism proposes that BPB oxidizes We express sincere thanks to Department of hemistry, centre of the cobalt (III) bound alpha - hydroxy acids at a rate Islamiah ollege Vaniyambadi and VME society for comparable to that of the unbound ligand and there is 100 % providing the necessary facilities for the successful reduction at the cobalt (III) centre, forms a chromate ester with completion of this research work. cobalt (III) Mandelato complex which can decompose in a slow step, proceeds through - bond fission leading to the formation REFEREES of cobalt (II), carbonyl compounds and carbon dioxide as [1] Anbuselvan,., and Sankaran, K.R., (1998) xidation products. The kinetic results and absence of keto acids as a ommunications, 21, product leads to a mechanism involving one electron transfer to [2] Scramm, L. LStasiuk., E.., and Marangoni Annu, D. r (VI) with - cleavage and decarboxylation Scheme 1.In the G., (2003) Rep. Prog. hem. Sect., 3, 99. oxidation of the complexes a mechanism involving one electron [3] M. J. Rosen (2004) Surfactants and Interfacial transfer to r (VI) and an induced electron transfer to o (III) by Phenomenon, 3rd Edn.Wiley, ew Jersey, 25,569. the decarboxylation and synchronous cleavage of - was [4] Fan, R. F, and Gould, E. S., (1974), Inorg. hem.,13, proposed ) Scheme: 1 [5] Long J., Auborn J J., and Eyring, F M J.,(1973) olloid, Interface Sci., 41, P r + [6] Yasunaga J., Takeda, K., and arada S, J., (1973) + olloid, Interface, Sci., 4, P 457. [7] K.Rajalakshmi,K.,Ramachandramoorthy,T.,Srinivasan, S., (2012) Reactivity of phenol towards Benzyl triethyl r + ammonium hloro chromate xidation in the presence 2) Scheme: 2 r + Glycolato & TAB Mandelato & TAB Lactato & TAB III o r+ - bpy + + Slow o III - 2 r bpy + r + - bpy + 2+log[o III ] 100% - bpy + + slow Fast 2 o II r V 2 r+ VI 100% - bpy + r V IV. LUSI The kinetics and oxidation cobalt (III) of α-ydroxy acids viz, glycolic acid, mandelic acid, lactic acid by 2,2 - bipyridinium bromo chromate in surfactant medium have been using a novel chromium (VI) oxidant. In this reaction - cleavage occurs leading reduction at o III centre. In this reaction - cleavage occurs leading reduction at o III centre. The rate of the increase the observed presence surfactant als, TAB and TRIT. Among the surfactant which TAB enhances the rate much more than the TRIT, als. Temperature increases the rate of the reaction increases with micelles TAB higher than the TRIT, als. of 1,10- Phenanthroline as catalyst Der hemica Sinica, 3(2),336. [8] Sabita Patel, R., and Mishra, B.K., (2007) hromium (VI) oxidants having quatemary ammonium ions studies on Synthetic applications and oxidation kinetics, Tetrahedran, 63, [9] Tadros,T.F.,(2005) Applied Surfactants,1st Edn.Wiley V, Germany, 48, 589. [10] Anandratchagan, K., MD.awaz, K. B.,and Subramani, K., (2011) Induced electron transfer Reaction in pentaamine cobalt (III) complexes of α-ydroxy acids by quinolinium dichromate in acetic acid (70%) medium: kinetic study, Acta hem Pharm. Indica, 1(1), [11] Ramkumar,B.,SanthoshKumar,V., and Rukmangathan, M.,(2013) Kinetics and Mechanism of benzyl alcohol and substituted Benzyl alcohols with 1- bromobenzimidazole in aqueous acetic acid medium, International Journal of Research in Physical hemistry, 3(4), [12] Sekar.K.G., and Manikandan, G., (2013) xidation of S- Phenylmercapto acetic acid by quinoxalinium Dichromate Pelagia Research Library, Der hemica Sinica, 4(1), All rights reserved by 172

5 Induced Electron Transfer Reaction of obalt (III) omplexes of α ydroxy Acids by 2, 2 -Bipyridinium omo hromate (BPB) in the Presence of [13] Palaniappan, A..,Vaideki, S., Srinivasan S., and Raju,., (2012), Kinetics and mechanism of the xidative leavage Ketones by icotinium Dichromate- atalysed by 1, 10- Phenonthroline, Journal of hemical and Pharmaceutical Research,4(1), [14] Sekar, K. G., and Periyasamy, S. K. (2012) xidation of Distyryl ketone by Quinaldinium Fluorochromate: A Kinetic and mechanistic Study Journal of hemical and Pharmaceutical Research, 4(4), [15] Vellaisamy, M., and Sharmila, M., (2013) Kinetics of xidation of α, β-unsaturated alcohols by Pyridinium bromo chromate, Journal of hemical and Pharmaceutical Research, 5(4), [16] Shanthi Vyas, R., and Pradeep Sharma, K., (2002) Proc. Kinetics and mechanism of the oxidation of rganic sulphides by 2,2,-Bipyridinium hloromate, Indian Acad.Sci (hem.sci.), o.2, [17] RajKumar, P., and Subramani, K., (2012) Kinetic Study on Induced Electron Transfer Reaction in Penta ammine cobalt (III) omplexes of α-ydroxy acids by Permonosulphuric acid in Micellar Medium Journal of hemical and Pharmaceutical Research, 4(7), [18] Udhayavani, S., and Subramani, K., (2012), xidation of Penta amine cobalt (III) complexes of alpha-amino Acid by manganese (IV) etropolyanion in the Presence of surfactants, J.urrent hem Pharm. Sc., 2(2), [19] Thaminum Ansari, A., (2009) Pyridinium chloro chromate Induced electron transfer in Pentaammine obalt (III) omplexes of alpha -hydroxy acids in micellar medium, International Journal of hemtech Research Vol.1, o.2, [20] Mann, F.G., and Saunders,.., (1960). Practical rganic hemistry, Longman Group, London,455. All rights reserved by 173