Singh, H. S.

Singh, L. N.

Singh, R. N.

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R. N. SINGH, L. N. SINGH & H. S. SINGHDepartmentof Chemistry,University of Allahabad,AllahabadReceived24 Marck 1976;accepted1 July 1976Kineticsof Ag(I)-ioncatalysedoxidationof isoamylalcoholbyperoxydisulphatehasbeenstudiedinaqueousmedium.Thereactionshowsfirstorderkineticswithrespecttoperoxydisulphate~and.zero.orderwithrespectto isoamylalcohol. Theeffectof varying[Ag+]onthereactionrate indicatesthe directproportionalityon[Ag+]even at differenttemperatures.A probablemechanismhasbeensuggested.1·\00·94INDIAN J. CHEM., VOL 15A, JANUARY 1977Kinetics of Ag(I) CatalysedOxidationofIsoamylAlcohol by PeroxydisulphateTABLE 2 - EFFECT OF VARYING [ISOAMYL ALCOHOL] ON THEREACTION RATE2·525'214'5020·715·74026·855-8121·042·025·804'6621-144'30526·775-8120·961·526'105,3420·762'87026'265·8120·451·026'265·8120·450,527·106·0721·031-43527·035·8121·22[S.O~lX 102Mka X 103 min-1kd X 103 min-Ik X 103 min-1TABLE 1- EFFECT OF VARYING [SaO:-J ON THEREACTION RATETHE kineticsof oxidationof isoamylalcoholhasbeen studied by a numberof workersusingoxidantssuchas potassiumpermanganate1,potas-sium dichromate2, cobalt bromide3, nitric acid',tert-butylchromate5andchromicacid6• Thepresentnotedealswith theresultsof kineticsof silver(I)-ioncatalysedoxidationof isoamylalcoholby peroxy-disulphatein aqueousmedium.All the chemicals(Analaror GR) wereprocuredfrom eitherBDH or E. Merck.The progressof reactionwasfollowedby estimat-ing unreactedK2S20S iodometrically7at variousintervalsof time in pyrex glassbottle, coatedonthe outsidewith black Japan and wrappedwithblackcloth.The resultsgiven in Table 1 indicatethe firstorder kinetics with respectto peroxydisulphate.Theoverallfirstordervelocityconstant(k••), velocityconstant(kd) for the decompositionof the peroxy-disulphateand first ordervelocityconstant(k) fortheoxidationof isoamylalcoholat different[peroxy-disulphate]are also given in Table 1. The orderof reactionwith respecto isoamylalcoholhasbeenfound to be zero (Table2). A perusalof Fig. 1clearlydemonstratesthedirectproportionalityof thereactionrateon[Ag+]evenat differentemperatures.{[Isoamyl alcohol]=2,87x 10a-M; [Ag+]=I'Ox10-8M;temp.=55°}(Isoamyl alcohol)X 10'Mka X 103 min-1kJ,X 10smin-1k X 10smin-I11·0 0·470·672110·51'391 430810·063 5969·51-829672 32·03 05884902 471651056ig. 2 - Plot of log (-d[MJ/dt) versuslog [catalystJ09 1·3LOGC catalyst J+ 4.dualincreasein the ratewasobservedup to acom ositionof 33'3%water (maximumrate)afterwhi h the rate droppeddowngradually(Table2).Chan lengthsof the PMMA samplesincreasedwithan i creasein the monomerconcentrationand de-cre d with the catalyst concentration,in thema er expectedfrom the rateequation.G atefulacknowledgementis madeto the CSIR,Ne Delhi, for the award of a senior researchfell ship to oneof us (Q.A.).Refeences1. R NEHART, R. E., SMITH, H. P., WITT, H. S. & ROMEYN,H. (Jr), J. Am. chem.Soc., 83 (1961),4864.2. C NALE, A., HEWITT, W., SHRYNE, T. & YOUNGMAN, E.,ChemyInd., No. 24 (1962),1054.3. A DERSON, T., JENNER, E. L. & LINDSEY, R. V. (Jr),J. Am. chem.Soc.,87 (1965),5638.4. BXENDALE, J. H., BYWATER, S. & EVANS, M. G., J.Polym. Sci., 1 (1946),236.5. B RGER, R. S. & YOUNGMAN, E. A" J. Polym. Sci., 2(1964),357.6. R. EHART, R. E., SMITH, H. P., WITT, H. S. & ROMEYN,H. (Jr), J. Am. chem.Soc., 84 (1962),4145.TAB!j.li: 2 - EFFECT OF VARYING WATER CONTENT OF THEREAtTION MEDIUM ON THE RATE OF RhS+-CATALYSEDPOLYMERIZATION OF MMA{[MOr_.omer]-2 ml (1,253molelitre '1) ; timeof reaction=1hr;[Catlyst]-1'5 ml of lxl0-a mole litre-I; solution (lxl0-Smole litre-I); temp.-60o; total vol=15 ml}W ter Ethanol -d[MJ/dt log -d[MJ/ ChainI ml X 10' dt+6 length(moles nlitre-I see-I)40'Ilj'[AgJx IdMFig. 1- Effect of varying [Ag+] on the reaction rate atdifferent temperaturesOn the basis of resultsthe rate law may berepresentedby Eq. (1)- d[S;?tJ =k,[S20~-J[Ag+] ...(1)wherek, is thespecificrateconstantandcomesoutto be kj[Ag+] litres mole-lmin-l.The results obtained might be explainedonproposingthe mechanismgivenin Scheme1.k1S20~-+AgT_~Ag2++S04-+S0i- ...(2)k2SO.-+Ag+-~Ag2++S0i- ...(3)ks .RCH20H+Ag2+--+RCHOH+Ag++H+ ...(4). k,RCHOH +S20~--~RCHO+SO:-+S04-+H+...(5). k"RCHOH+SOr~ RCHO+HSO( ...(6)where(CHS)2CHCH2=RScheme1This mechanismclearlyexplainsthe first orderkineticswith respectto peroxydisulphateand Ag+both. The variousstepsproposedare quite justi-fied becausein the Ag+-catalysedoxidations,Ag2+anda numberof freeradicalsasintermediateshavebeenreportedby severalworkers8-14•The rate of disappearanceof peroxydisulphatemay be given as,d[S20t]=kl[S20~-][Ag+]+k4[RCHOH] [S202-J ... (7)Consideringthesteadystateconditions,thevalueof [RCHOH] comesout to be _C (J2kl k2 k~ k2 ) [A +] (8)[R HOH] = klkS + 4k~- 2kr, - g ..,Apparently Eq. (8) shows quite complicatedfeaturebut the closeexaminationclearly revealsthat the wholefactorconsistsof variousconstantsalongwith the [Ag+]andhenceit canbesimplifiedas follows:[RCHOH] =constant[Ag+] ...(9)References1. TRONov, B. V., LUKANIN, A. A. & PAVLVINOW, I. 1.J. Russ. pkys. ckem.Soc., 59 (1927),1173.2. KIRKHGAF, G. A., KORZINA, O. I. & ASTROVA, R. YA.,Ckem.Abstr., 28 (1934),3713.3. NEZNANOV, A. G. & LEVANEVSKU, O. E., Ckem.Abstr.,79 (1973),4895z.4. KNOERR, FRITZ & GUNZENHAUSER, WERNER, ClIem.Abstr., 78 (1973),158947j.5. SUGA, T., KIHARA, K. & MATSUURA, T., Bull. chem.Soc.Japan, 38 (1965),893.6. ANANTKRISHNAN, S. V. & VARADARA]AN, S., Indian J.Ckem.,10 (1972),66.7. KOLTHOFF, 1. M. & CARR, E. M., Analyt. Ckem., 25(1953),298.8. SRIVASTAVA, S. P. & GHOSH, S., Proc. natn. Acad. Sci.,22 (1953),91.9. BAWN, C. R. H. & MARGERISON, D., Trans. FaradaySoc., 51 (1955),525.10. EVANS, M. G. & BAXENDALE, J. H., Trans. FaradaySoc., 42 (1940),195.11. HIGGINSON, W. C. & MARSHALL, J. W., J. ckem.Soc.,(1957),447.12. MENGHANI, G. D. & BAKORE, G. V., Bull. chem.Soc.Japan, 41 (1968),2574.13. MENGHANI, C. D. & BAKORE, G. V., Indian J. Chem.,7 (1969),786..14. HABER, F. & WEISS, J., Proc. R. Soc.,A-147 (1934),332.Studieson HeteropolyNiobotun~state(VI)LAPITSKU andcoworkerslreporteda numberofheteropolyniobatecomplexesof severaltramj-tional metalions and alsoof Ce(III). Later Daleet al.2 examinedsomeof thesecomplexesand ingeneralfound that the Russian work was notreproducible.In this notewereportthe resultsofG. C. BHATTACHARYA & SALIL KUMAR RoyDepartmentof PostgraduateStudies& Researchin ChemistryRanchi University, Ranchi 8Received6 September1975;accepted16 January 1976Thenatureandconditionsofformationofheteropolyniobotungstate(VI)havebeenestablishedwiththehelpofpH andthermometrictitrations.Basedonchemicalandphysicalstudies,thecompoundhasbeenformulatedas KijNaij[WNb120aslllHsO.The molecular weiAht(2380)for thecompound,eterminedfromtheunitcelldimensions,tallies with the formulaweight. Thepressure-compositionisothermalstudiedin thesolidphaseat 35° and 45° indicatedKijNaij[WNbllOaa16H•Oto bethemoststableform.NotESOn substitutingthe valueof [ReHOH] in Eq. 1we getdeS02-] -.LL =kl[S20~-][AgTJ+k4.constant.[Ag+]=k,[S20~-][Ag+] •..(10)wherek,=(kl+k4' constant).The aboveequationclearlyexplainsthe experi-mental results obtained at different conditions.The oxidationproduct,isopentanalwas estimatedfrom the reactionmixture and confirmedby itscharacteristicNMR spectrum.Authorsare gratefulto (late)Dr B. N. Prasad,Departmentof Chemistry,BanarasHindu Univer-sity, for constantguidanceand cooperationincompletionof the work.0'5Vsoamyl alcohol] =2-87><I02.M[SaO~] '"to x I02.Mo1545+1

Kinetics of Ag(I) Catalysed Oxidation of Isoamyl Alcohol by Peroxydisulphate

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Kinetics of Ag(I) Catalysed Oxidation of Isoamyl Alcohol by Peroxydisulphate

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