Blokhra, R. L.

Parmar, M. L.

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NOTES.---- 1Viscositiesof Solutionsof CadmiumHalidesin AqueousAcetoneR. L. BLOKHRA & M. L. PARMARDepartment of Chemistry, Himachal Pradesh UniversitySimla 171001Received17 September1976; accepted16 February 1977Viscositiesandrelativeviscositiesof CdX2 (X =Cl,Br, I) in aq.acetone(80%, w/w)weremeasuredas afunctionof salt concentrationat 30°. The datahavebeenanalysedin terms of the Jones-Doleequation(11/110 = l+AVC+BC) and the results discussedinterms of the effectsof salts on the structureofthe solvent.CdCl2 and CdBr2 are suggestedto bestructurebreakerswhileCdI. is structurepromotor.MI?CEDbinaryaqueousolventsystemsbehave1•2In an unexpectedmanneras comparedwiththebehaviourofmixednon-aqueoussystems.Theseobservationshavegivenanewimpetusto a detailedstudyof the structureof aqueousolutions. Whileion-solventinteractionshavebeenstudiedin detailin aqueousolutions,sucheffectshavereceivedmuchless attention in mixed binary aqueoussolventsystems. In thepresentnote,resultsof ourstudieson viscositiesof cadmiumhalidesin aq. acetone(80% wjw) at 30° are being reported.For preparingthe aqueoussolutionsof acetone,triply distilled water (specificconductance,...,,10-6ohm-Iem-I)wasused. Acetone(BDH) of AR gradewas purifiedfurtherby refluxingsuccessivelywithsmall portions of potassiumpermanganateuntilthe violet colourpersisted. It was then distilled,driedoveranhydrouscalciumsulphateanddistilledagain. Densityand viscosityof the acetoneusedfor thepresentstudywere0·78521g mP and0·0032poiserespectivelyat 25°andthesevaluesagreewellwith the literaturevalues3.AR gradesalts,afterdryingoverP205, wereusedfor the presentstudyand the solutionsweremadeby weight under dry conditions. Conversionbe-tweenmolarconcentrationand molalitywas doneusingthe relation4 :m=1j(P(M-M2(1000)whereM representsthe molarity,m the molality,P the densityof the saltsolutionandM2 the mole-cularweightof the salt used. The densityof thesolutionneededfor viscositywas determinedwiththe help of a doublecapillarypycnometer5.Forabsoluteviscosities,the viscometerwas calibratedwith water and pure tolueneof known viscosityusingEq. (1) (ref.6):V (kinematicviscosity)="fJ(P=at-bIt ...(1)where"fJis the dynamicviscosity,P is the densityof the liquid, t is the effluxtimein seconds,and aand b are the characteristicconstantsof tbeviscometer.The viscositywas determinedat 30°±0·01°with thehelpof a capillarytypeviscometer,the detailsandworkingof whicharereportedelse-where7• The errorin the flow-timewas ±0·05sec.The viscositydatareportedherehavean accuracyof ±0·001 (cp).TABLE 1 - VISCOSITY, DENSITY ANDRELATIVE VISCOSITY OF AQUEOUS ACETONE(80%, W/W) SOLUTIONS F CADMI M HALIDES AT 30°Cone. x103Density (P)Viscosity (1))1)/1)0(g mole litre-I)(g mP)( p)CADMIUM CHLORIDE37·490'97301- 362·261446,06406355·57· 51· 51· 7768,78' 69- 08391-1480 54112· 20·98 29, 7818CADMIUM BROMIDE36·98· 2·0 41 1·6359 3' 057 421170, 5 68 707 0900 29CADMIUM IODIDE31-4170 96 2894- 991'29 91 0 723' 31Valuesof viscosity,densityandrelativeviscosityof the d.ifferentaq. acetonesolutionsof cadmiumhalidesat 30° are given in Table 1.From Table 1 it is clear that the viscosityin-creaSeswith the increaseof concentrationof thesalt. The variationof viscositywith concentrationcanberepresentedby Jones-Dole equatioI"8(Eq. 2)"fJ("fJo=I+AO+BC ...(2)where"fJand'fJoarethe viscositiesof thesaltsolutionand solvent (aqueousacetone)respectively.Bisanadjustableparameter,eitherpositiveornegative,that accountsfor ion-solventinteraction. Valueof B wasdeterminedfrom the slopeof the linearplot of (rd'fJo-1)(VC versusVC. The valuesofB for CdCI2,CdBr2 andCdI2 are-3,13,-0,46and2·63respectivelyand the valuesof the parameterA for CdCI2,CdBr2 and CdI2 are1,52,1·04and 0·27respectively.SincecoefficientB of the Jones-Doleequationis a characteristicof ion-solventinter-action,thenegativevaluesofB for CdCl2andCdBr2suggestthatthesesaltsbehaveasstructurebreakers,whilethe positivevalUESofB for CdI2 indicatethatit actsas structurepromoter.Oneof the authors(M.L.P.) is gratefulto CSIR,NewDellti,for the awardof a post-dcctoralfellow-ship.References1. PRASAD, B. N., SINGH, N. P. & SINGH, M. M., Indian J.Chem.,14A (1976),322.2. PRASAD, B. N. & AGRAWAL, M. M., Indian J. Chem.,14A (1976),343.3. TIMMERMAN, J., Physico-chemicalconstantsof pure organicliquids (Elsevier, New York), 1950.4. SHOEMAKER, D. P. & GARLAND, C. W., Experimentsinphysical chemistry (McGra,w-Hill, New York), 1967,130.557INDIAN J. CHEM., VOL. 15A, JUNE 1977TIME (minIFig. 2- Polymerizationof n-butylvinyletherin n-hexanecatalysedby stannouschlorideat [monomer]=1'56Mand13° andvarious[catalyst]{Curve1, [SnCI2]=2·2x 102M;curve 2, 3'5xl0-2M; curve 3, 5'5x 10-2M; curve 4,6,6 x 10-2M}140 i100 120806040zoIiia:Ul>Zou282216Z Q<J)crUl>Z0~ B4Data regardingthe dependenceof the numberaveragedegreeof polymerization(DP) of thepolymerson monomerconcentrationare showninTable1. Theresultsmayberepresentedby Eq. (1),DP =K2[M] ... (1)whichindicatesabsenceofchaintransferto monomer.TIME trnill)Fig. 1- Polymerizationof n-butylvinyl etherin n-hexanecatalysedby stannouschlorideat [SnCI2]=2'2X 10-2M and13°;andvarious[monomer]{Curve1, [monomer]=1'56M;curve2, [monomer]=2'34M; curve3, [monomer]=3·00M;curve4, [monomerJ=3-65M}StannousChlorideCatalysedPolymerizationof n-ButylVinyl EtherA. K. MUKHERJEEDepartmentof TextileTechnologyIidian Instituteof Technology,NewDelhi110029eceived29July 1976;accepted24January 1977US NG several reagentslike boron trifluoridee herate1,boron trifluoride2, stannicchloride3,ferric chloride4,etc., n-butyl vinyl etherhas beenpoly erized. In thepresentstudy,thepolymeriza-tion f n-hutylvinyl etherhasbeencarriedout inn-he ane solutionusing stannouschlorideas theinitia.or and the kinetics of the homogeneouspoly erizationsystemhavebeenstudied.Th monomer,solventand otherchemicalsusedwere of analyticalgrade and they were furtherpurifi d anddriedusingstandardprocedures.Thesolvet andrequisiteamountof initiatorwereplacedin a small standardjoint flask and the monomerwas njectedby a hypodermicsyringethrougharubb I' seal. A dry box wasusedfor handlingthemateials in orderto protectthe reactionsystemfrom moisture. After a definite time period ofpoly erization,in a thermostaticbath at 13°, thepoly er wasprecipitatedby the additionof excessammniacalmethanol. It was centrifuged,washedand dried in vacuo at 50° to constantweight.Num er averagemolecularweightwas determinedby d pressionin freezingpoint methodin benzene.Th percentconversionversustimeplots for thesyste (Figs. 1 and 2) are reproducibleand passthro h origin indicating the adequacyof thepurifi ationof reagentsandabsenceof anyinductionperio. The lack of dependenceof degreeof poly-meri'tion on increasingconversionper cent andon I'sannouschloridel conformto a normalcationicpoly erizationsystem.Fi s. 1 and 2 representhe dependenceof therate of polymerization(Rp) on [monomer]and[stanouschloride]respectivelyat 13°. The corres-pondng log Rp versus [M] and log Rp versuslog nC12] plots show the orderof the reactionwith respectto [monomer]to be about 1·5 andthat with respectto [stannouschloride] to beabou one.Th kineticsofcationicpolymerizationofthesystemn-but I vinylether-stannouschloride-n-hexaneat 13°have eenstudied.The initialrateof polymerizationis fou dtobedirectlyporportionalto[monomer]3/2and[stanouschloride].The averagedegreeofpolymeri-zatio of thepolymervarieswith themonomercon·centrtionaccordingto therelationDP=K2[M] andisindepndentof [stannouschloride].The polymerissaturtedasevidencedbybrominationandIR spectralstudis.5. WEiSSBERGER, A., Techniquesof organicchemistry,Vol. I, 20·0art I (John Wiley, New York), 1965.6. COlETTE' M., Ann. chim. Phys., 21 (1890),433.7. BL KHRA, R. L. & PARMAR, M. L., Aust. J. Chern.,27( 974),1407.8 Jo ES, G. & DOLE, lVI.,J. Am. chem.Soc.,51 (1929),2050.558li;j1.111.1111

Viscosities of Solutions of Cadmium Halides in Aqueous Acetone

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Viscosities of Solutions of Cadmium Halides in Aqueous Acetone

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