Akhare, V P

Burghate, D K

Deogaonkar, V S

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NOTEIndian J.Phys. «9A (3), 381-386 (1995)I J P  Ajin mtemational |oumalDielectric behaviour and charge transfer complexation in ternary liquid mixturesD  K Burghate, V P Akharc and V S DeogaonkarP G  Department, of Physics, Shri Shivaji Science College. Amrayati 444 603, India \R ece ived  6  O ctober ]994, accep ted  9  M arch 1995Abstract : Dielectric constant measurements for four ternary mixtures, (i) n-hutylanune + pentanoic acid + benzene, (n) n-butylarvune + cupuc acid + benzene, (in) f butylnnune + pentumm acid + benzene and (iv>/ -butylamine + capric acid ■+ benzene have been made ad 30, 3S 40 and 45°C, The excess dielectric constants ol the various ternary mixtures (dihcrcnce between experimental and ideal mole fraction mixture law values) have been attributed lo the lormatum ol charge transfer complexes between the fatty acids and the amines. The decrease in die values of excess dielectric constants, with rise ol temperature, has Ixicn explained’5on the basis ol disruption of molecular alignments by thermal energyK eyw ords : Dielectric constant, viscosity, refractive index P A C S  No. : 77.22 -dD ipole  m om ent studies had been undertaken by Sabesan and Vardharajan 11] to study (he association  co m p lexes o f  benzaldehyde + phenol in carbomeirachloride. Mishra et nl 12 1 studied the charge transfer com plexes in binary and ternary system s. They aitribuied ihc positive values o f  interaction dielectric constant to the formation o f  som e new polar species in the solution. Nath and D a s |3 ] have reported the dielectric behaviour ol binary and ternary system s containing w eakly  interacting com ponents at 30°C\ The behaviour o f donor and acceptor m olecules in liquid mixtures is therefore, expected to give an idea about the nature o f  interaction betw een the constituents o f  the mixtures. The dielectric constant measurem ents have therefore, been  em p loyed  in  this investigations to study the ternary liquid m ixtures consisting o f  tile four system s and the effect o f  temperature on the extent o f  interactions,69A(3)-u® 1995IACS382 D KBurghate, VPAkhare and V SDeogaonkarT he sy stem s studied  in the presen t in vestig a tio n  are (i) n-b uty lam in e +  pentan o ic  acid  +  b en zen e, ( ii)  n -b uty lam in c  + capric acid  + b en zen e , ( iii)  r-butylam ine +  pentan o ic  acid  +  b enzene and (iv ) r-butylam ine +  capric acid +  benzene.SYSTEru f  N-BUfYL Art. + P.ACID -f Ben )HOLAft RAT TO A/0□ 3 0  D.CEL 0 3 5  D.C 0 4 0  D.C X45 D.CFigure 1. Excess dielectric constants of System 1.T he liquids supp lied  by M E R C K -schuchards, C h em ischc Fabriek H olland, w ere used w ithout further purification. The capacitance m easurem ents w ere m ade 1 K Hz usin g  an TCR - Q -m etcr supp lied  by A plab A u tocom p ul L C R -Q -m eter m odel 4 0 1 0 . T he temperature can he kept co n sta n t to ±  0 .1 ° . T h e  a ccu racy  in d ie  m easu rem en t o f  d ie lec tr ic  co n sta n t was ascerta ined  by com paring the experim ental values o f  d ielectric constant o f  f iv e  pure liquids w ith  their literature 14,5,61 v a lu es, at the tem perature o f  m easurem ent. T he m easurem ents w ere m ade at 30, 35, 4 0  and 45°C .T he va lu es o f  e x c e ss  d ie lectric  constants o f  the four system s at 30°C , 35°C , 4 0 °C  and 4 5 °C are p lotted  in F igures 1, 2, 3 and 4  respectively  a long  w ith the m olar ratio o f  am ine and acid .D ielectric  behaviour and charge transfer cpm plexation e tc  T he values o f  ex cess  dielectric constants have been calculated using the relation4 f l,2.3 = ei,2,3 -  £ 1* 1  -  £2X2 -  eyx vFigure 2. E x c e s s  dielectric tonsianis of System IIw h c ie  e , .  e 2 , f ,  and X It X 2, X} denote  the d ie lectric  constants and m ole  fractions  respectively , o f  the pure com ponents, f , is the dielectric constant o f  the sam ple mixture.T he data show n, exp lic itly  brings out the follow ing observations.1 ■ T he e x ce ss  dielectric constant A£ \ 23 is + ve  in case o f  all the sam ple m ixtures studied and at all the temperatures.2. T he e x c e ss  d ie lectric  constant fo llo w s a particular trend, first it increases, b ecom es m axim um  and then decreases again.3 . H ie  m axim a o f  Aex 2 i3 decreases with increase o f  temperaumr.m , t VC VaIUes o f  can be a,tributcd t0 '"crease m the alignm ent o f  the  ules o f  the constituent liquids. The m axim um  o f  4 e ,  iW v.v, m olar ratio can p o ssib ly  bedue to the com plex formation between the am ines and the acids. The tone  pair o f  electron an  the nitrogen o f  the am ine group is alw ays in  a readiness to pu ll the protonic charge. T his  attraction betw een the protonic charge and the - v e  charge on the N  atom , m ay lead to  a  com plex formation betw een the a d d  and the am ine, the com plexation  being o f  the charge  transfer type at the particular m olar ratio, corresponding to peak o f  ^ 1 ,2 ,3 . Further ev id en ce  to the form ation o f such charge transfer com plexes in the present case , fo llo w s from  the observations o f  Lindem ann and Zundcl 171 from 1R absorption spectra. A ccording to them  proton uansler w as observed in anhydrous system when the carboxylic acid was m ore a d d ic  than the nitrogen base by a pka difference o f  4. In our case, the pka difference betw een the acid and amine is greater than 5.384 DKBurghate, VPAkhareandV SDeogaonkarFigure 3. Excess dielectric constants of System IIIfurther, as liie ^ 1 2 , 3  values lor each sam ple mixture arc found to decrease with rise o f  temperature, it fo llo w s  that the increase in the thermal energy disturbs the process o f  m olecular alignment, thereby resulting in the fall o f  1,2,3 over the entire com posiUdoxange.D ielectric behaviour and charge transfer complexation etc 385It can therefore, be  concluded that the d ielectric constant m easurem ents can predict the form ation o f  charge transfer com plexes in ternary m ixtures.Figure 4. Excess dielectric constants of System IV.A cknow ledgm entThe authors are very m uch thankful to the Principal Dr. V R Gburde, Shri Shivaji Scien ce  C o lleg e , A m ravati, for the encouragem ent. O ne o f  the authors (V S D ) is thankful to U niversity  Grants C om m ission  for financial assistance.References11] R Sabesan and R Vardharaian Indian J Phys. 55B 353 (1981)(2] Rujaru Mishra, Arnar Singh, J P Shukla and M C Saxena Indian J Phys. 58B I (1984)(3) lagan Nath and S S Das Indian J PureAppl. Phys. 19 343 (1981)14] G W C  Kaye and T H Daby Tables of Physical and Chemical Constant (New York : Longman Green) p 92 (1959)15) J A Dean Hand Book of Organic Chemistry (New York : McGraw Hill) 4 86 (1987)[6] R C Weast CRC Handbook o f Chemistry and Physics (Roton, Florida : CRC Press) E-50 (1986-87)[7] R Lindemann and G T Zundcl Ghent. Soc. Faradey 2 68  979 (1972)

Dielectric Behaviour and Charge Transfer Complexation in Ternary Liquid Mixtures

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Dielectric Behaviour and Charge Transfer Complexation in Ternary Liquid Mixtures

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