Studies of viscosities of dilute solutions of alkylamines in non-electrolyte solvents. V. Alkylamines in toluene and benzene at 303.

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1 Indian Jurnal f Chemistry Vl. 48A, Nvember 9, pp Studies f viscsities f dilute slutins f alkylamines in nn-electrlyte slvents. V. Alkylamines in tluene and benzene at 33.5 K S L Oswal a, * & S P Ijardar b a Bichemistry Divisin, R&D Span Diagnstic Limited, 73-B, New Industrial Estate, Udhna, Surat 394, India swalsl@yah.c.uk b Department f Chemistry, S V Natinal Institute f Technlgy, Surat 395 7, India Received 7 July 9; revised and accepted 9 Octber 9 Viscsities f dilute slutins f n-prpylamine, n-butylamine, di-n-prpylamine, di-n-butylamine, tri-n-prpylamine and tri-n-butylamine in tluene, and f tri-n-butylamine in benzene, have been measured at 33.5 K. The values f viscsity deviatins are negative fr all the amine slutins and their magnitude increases with the increase in cncentratin f alkylamine. The specific viscsities and excess Gibbs energy f activatin f viscus flw, based n Eyring's thery f abslute reactin rates, are f varying magnitude and sign depending upn the viscsities and type and nature f slute and slvent mlecules. The specific viscsities have been analyzed in terms f Herskvits and Kelly equatin and Nakagawa equatin. The change in Gibbs activatin energy and the heat f slutin per mle f slute (alkylamine) at infinite dilutin in cyclhexane, benzene and tluene slutins have been calculated in terms f the transitin state thery. Keywrds: Slutin chemistry, Thermdynamics, Alkylamines, Hydrcarbns, Transitin state treatment, Viscsities The thermdynamic and transprt prperties f dilute slutins prvide infrmatin abut slute-slute and slute-slvent interactins and can be used fr the develpment f mlecular mdels fr describing the thermdynamic behaviur f slutins. Systematic investigatins f thermdynamic and transprt prperties f slutins invlving imprtant rganic bases, viz., primary, secndary and tertiary alkylamines in plar and nn-plar slvents are being carried ut in ur labratries -9. In an earlier paper, vlumetric prperties f dilute slutins f seven alkylamines in tluene (C 6 H 5 CH 3 ) at 33.5 K have been reprted. As the viscsity behaviur in dilute slutin is als very sensitive t predict slute-slute and slute-slvent interactins,,, herein, viscsity behaviur f dilute slutins f n-prpylamine (C 3 H 7 NH ), n-butylamine (C 4 H 9 NH ), di-n-prpylamine ((C 3 H 7 ) NH), di-n-butylamine ((C 4 H 9 ) NH), tri-n-prpylamine ((C 3 H 7 ) 3 N) and tri-n-butylamine ((C 4 H 9 ) 3 N)) in tluene (C 6 H 5 CH 3 ) and tri-n-butylamine in benzene (C 6 H 6 ) at 33.5 K has been reprted. This study is expected t reveal sme mre interesting facts cncerning the nature and different extent f interactins in amines. The results have als been analyzed in terms f Herskvits and Kelly equatin and Nakagawa equatin 3. The change in the activatin energy per mle f slute n replacing ne mle f slvent by ne mle f slute in infinite dilute slutin and heat f slutin fr alkylamine in cyclhexane, benzene, and tluene slutins have been determined as per transitin state treatment. Materials and Methds The viscsities (η) were measured with a mdified calibrated suspended level Ubbelhde viscmeter. The viscmeter was designed s as t reduce surface tensin effects t negligible values. The apparatus was submerged in a thermstatic bath at 33.5 K with a reslutin f ±.5 K and allwed t attain thermal equilibrium. The viscmeter has been calibrated s as t determine the tw cnstants, C and B, in the equatin η/ρ = Ct -B/t, btained by measuring the flw time t with pure water, benzene, tluene, cyclhexane and p-xylene 4. The flw time f a definite vlume f liquid thrugh the capillary was measured with an accurate stpwatch with a precisin f ±. s. Fur t five sets f readings fr the flw times were taken fr each pure liquid r liquid mixture and the arithmetic mean was taken fr the calculatins. The densities (ρ) required t cnvert kinematic viscsities int dynamic viscsities (η) were taken frm previus papers 3,.

2 5 INDIAN J CHEM, SEC A, NOVEMBER 9 All the slutins were prepared by mixing knwn masses f pure liquids in air tight, narrw-muth grund stppered bttles taking due precautins t minimize the evapratin lsses. Eight t nine slutins up t. ml fractin f each alkylamine in different slvents were prepared. The pssible errr in the mle fractin, x and mlality, m is estimated t be less than ± -4. The errr in viscsity was less than -3 mpa s. n-prpylamine (Merck, Schuchardt), n-butylamine (Fluka AG), di-n-prpylamine (Fluka AG), di-n-butylamine (Fluka AG), tri-n-prpylamine (Fluka AG) and tri-n-butylamine (SRL, Bmbay), f purity better than 99 ml % were refluxed ver Na metal and distilled twice fractinally befre use. Tluene (Galax AR) and benzene (Merck, GR) f purity better then 99.5 ml % were used after further purificatin and drying by standard prcedures 4. Tluene and benzene were shaken repeatedly with cncentrated sulphuric acid until free frm thiphene, washed first with aqueus sdium carbnate and then with water, dried ver P O 5 and fractinally distilled. Immediately befre use, the samples were dried ver a mlecular sieve (.4 nm, Fluka) and fractinally distilled twice. The purity f all the liquid samples was checked by gas-liquid chrmatgraphy and by cmparing measured nrmal biling pints. The measured values f densities were cmpared with literature values in Table. Theretical Herskvits and Kelly equatin In general fr interpreting viscsity data, many investigatrs, have emplyed the fllwing relatinships (Eq. ), Table Densities and viscsities f pure cmpnents at 33.5 K Cmp. Density (g cm -3 ) Viscsity (mpa s) Expt. Lit. Expt. Lit. C 3 H 7 NH a f C 4 H 9 NH b e.7849 c.456 b (C 3 H 7 ) NH d g (C 4 H 9 ) NH d h.758 e.7593 g (C 3 H 7 ) 3 N a h (C 4 H 9 ) 3 N b h C 6 H 5 CH f f C 6 H f f a Ref. 5; b Ref. 6; c Ref. 7; d Ref. 8; e Ref. 9; f Ref. 4; g Ref. ; h Ref. η η = + Bm + Dm () where η η is the relative viscsity, B is a cefficient related t the size and shape f slute mlecule and t slvatin effects, whereas the cefficient D includes slute-slute interactins and thse slute-slvent interactins which arise with higher cncentratins and are nt accunted fr by the Bm term. Herskvits and Kelly substituted mlality in terms f vlume factin, φ, as m = 3 φ / M vρ in Eq. (), and btained the Eq. (), η η = + 3 B/( M vρ ) φ + ( 6 ) D/( M vρ ) φ () where v is partial specific vlume, M mlar mass f slute and ρ density f neat slvent. The cefficients B and D f equatin can be evaluated frm the intercept and slpe f ( η η -)/m versus m plts. Nakagawa equatin Matsubayashi and Nakahara extended the cnfrmal slutin (ECS) thery t the dynamic prblem thrugh the first-rder perturbatin thery fr the binary regular mixtures. Accrding t the ECS thery, a dynamic prperty η fr binary regular slutin is given by Eq. (3), x ( x ) ( x ) x int η = η + η + η (3) where η and η are viscsities f slute and slvent cmpnents, η int is the interactin term fr regular slutin and x is the mle fractin f slute. Fr nn-electrlyte slutins f higher cncentratins, Jnes-Dle equatin is rewritten as (Eq. 4), η η = + B JD c + D JD c (4) where c is the cncentratins (mlarity) in ml dm -3, B JD and D JD are Jnes-Dle cefficients. The value f cefficient B JD can be evaluated frm the intercept f ( η η -)/c versus c plts. Matsubayashi and Nakahara theretically shwn that Jnes-Dle cefficient B JD fr nn-electrlyte regular slutins is given by Eq. (5). B JD = M ( η / η ) ηint / η ) + ρ (5)

3 OSWAL & IJARDAR: VISCOSITIES OF DILUTE ALKYLAMINES + TOLUENE/BENZENE SOLUTIONS 53 Fr an ideal slutin, namely, reduces t Eq. (6), B JD,id = M ( η / η ) ρ η int =, Eq. (5) (6) where B JD,id is the cntributin f ideal mixture fr the B JD cefficient, which is based n the difference between the viscsity f slute and f slvent. If η is larger than η, the B JD,id cefficient is psitive and vice versa. This finding implies that the B JD cefficient is nt characteristic fr slute-slvent interactin. The interactin parameter B JD,int = B JD B JD,id, is related t Eq. (7), B JD,int M η = = Kηint (7) int ρη 3 where K= M /( ρη ) = V / η is the cnstant, which is independent f the slutin cmpsitin. Gibbs energy f activatin as per transitin state thery The applicatin f transitin state thery 3 t viscsity behavir has been utstandingly successful fr viscsities f electrlyte slutins 4. Here, it is applied t a slutin when bth slute and slvents are nn-electrlyte liquids. The quantity,#,# ( µ µ ), the change in the activatin energy per mle f slute n replacing ne mle f slvent by ne mle f slute in infinite dilute slutin emplying the transitin state thery is given by Eq. (8), B JD,#,# V V V µ µ = + RT which can be rearranged t Eq. (9), 3 (8),#,# RT 3 µ µ = { BJD ( V V )} (9) V where and,# RT ln ( V µ = η / hn) (),#,# 3 RT [ B JD ( V V )] / V µ µ = () Here, V and V are partial mlar vlumes f slvent and slute at infinite dilutin. Eqs (9)-() enable the,# calculatin f µ frm Jnes-Dle cefficient B JD. Heat f slutin as per transitin state thery A semi-empirical equatin is described by Alexander and My 5 t estimate the heat f slutin * ( H H ) f the liquid slute frm the B JD -cefficient. They derived the relatinship Eq. (), η B JD H H =.45RT ln η V + V where η and η are the viscsities and () V and V are mlar vlumes f the pure slute and slvent, respectively. Equatin () has been examined fr number f slutins 5.including alkanls in benzene and idine in cyclhexane, benzene, tluene, tetrachlrmethane, chlrfrm, methanl and ethanl. Results and Discussin The experimental viscsities ( η ) f dilute slutins f C 3 H 7 NH, C 4 H 9 NH, (C 3 H 7 ) NH, (C 4 H 9 ) NH, (C 3 H 7 ) 3 N, and (C 4 H 9 ) 3 N in tluene and f (C 4 H 9 ) 3 N in benzene at 33.5 K are presented in Table. The experimental η are expressed by Eq. (3). η = m i- Aix (3) i= The cefficients A i btained frm a least-squares fit with equal weights assigned t each pint, are listed in Table 3 tgether with the standard deviatin, σ. The specific viscsity f slutin is related as in Eq. (4). sp r η = η = η / η (4) Since bth cmpnents used in the slutin frmatin are liquids, and each has dynamic viscsity. It wuld be apprpriate t take int accunt viscsity f bth the cmpnents in calculating viscsity deviatins frm a linear dependence n mle fractin. The viscsity deviatins ( η ) have been evaluated by Eq. (5). η η ( xη ( x ) η ) = + (5) On the basis f the thery f abslute reactin rates 3, the excess Gibbs energy f activatin, G *E, f viscus flw has been calculated frm Eq. (6), G *E /RT = ln ( ηv / η V ) x ln ( ηv / η V ) (6)

4 54 INDIAN J CHEM, SEC A, NOVEMBER 9 Table Viscsities fr alkylamine slutins in tluene r benzene at 33.5 K m x η m x η (ml kg - ) (mpa s) (ml kg - ) (mpa s) C 3 H 7 NH in C 6 H 5 CH 3 C 4 H 9 NH in C 6 H 5 CH (C 3 H 7 ) NH in C 6 H 5 CH 3 (C 4 H 9 ) NH in C 6 H 5 CH (C 3 H 7 ) 3 N in C 6 H 5 CH 3 (C 4 H 9 ) 3 N in C 6 H 5 CH (C 4 H 9 ) 3 N in C 6 H

5 OSWAL & IJARDAR: VISCOSITIES OF DILUTE ALKYLAMINES + TOLUENE/BENZENE SOLUTIONS 55 where η and V are the viscsity and mlar vlume f the slutin. The η values decrease with the increase in mlality f C 3 H 7 NH, C 4 H 9 NH, (C 3 H 7 ) NH and (C 3 H 7 ) 3 N in tluene, and increase fr (C 4 H 9 ) NH and (C 4 H 9 ) 3 N in tluene and (C 4 H 9 ) 3 N in benzene (Table ). The dependence f ( η η ) / η n m is shwn in Fig.. The slid lines drawn thrugh the data pints f the specific viscsity plts f Fig. have been made n the basis f B and D parameters (Table 4) f the Eq. (), cmputed by the least squares methd. The values f ( η η ) / η are negative fr C 3 H 7 NH, C 4 H 9 NH, (C 3 H 7 ) NH and (C 3 H 7 ) 3 N slutins and psitive fr (C 4 H 9 ) NH and (C 4 H 9 ) 3 N slutins. The slpes f these curves depend n the size and shape f slute mlecule and als t slvatin effects. The magnitude and sign f ( η η ) / η are based n the difference between the viscsities f slute and slvent, apart frm the mlecular interactins. The dependence f η and G *E n x, shwn in Figs. and 3, is almst linear. The values f η are negative fr all alkylamines in tluene and in benzene and their magnitude increases with the increase in cncentratin f amine. The G *E values are negative fr C 3 H 7 NH, C 4 H 9 NH, (C 3 H 7 ) NH and (C 3 H 7 ) 3 N, almst zer fr (C 4 H 9 ) NH, and small psitive fr (C 4 H 9 ) 3 N slutins in tluene. The G *E values are large psitive fr (C 4 H 9 ) 3 N slutins in benzene. The relative values f η and G *E have been analyzed in terms f slute-slute and slute-slvent interactins. The verall behaviur f η and G *E can be envisaged as a result f ppsite effects: (i) disruptin f π-π (slvent-slvent) interactins, (ii) breakdwn f diplar and/r H-bnding self assciatin in amines Table 3 Cefficients A i f Eq. (3) alng with standard deviatin (σ) fr viscsity f amine slutins Slute A A A 3 σ (mpa s) In tluene C 3 H 7 NH C 4 H 9 NH (C 3 H 7 ) NH (C 4 H 9 ) NH (C 3 H 7 ) 3 N (C 4 H 9 ) 3 N In benzene (C 4 H 9 ) 3 N Fig. Dependence f specific viscsities n mlality at 33.5 K. [, C 3 H 7 NH ( );, C 4 H 9 NH ( ); 3, (C 3 H 7 ) NH ( ); 4, (C 4 H 9 ) NH ( ); 5, (C 3 H 7 ) 3 N ( ); 6, (C 4 H 9 ) 3 N ( ) in tluene; 7, (C 4 H 9 ) 3 N ( ) in benzene]. Table 4 The values f B and D cefficients and standard deviatins (σ) estimated frm Eq. () and the 6 values f partial specific vlume ( v ), viscsity increment (ν) and D / ( M vρ) System B D σ v ν a 6 (kg ml - ) (kg ml - ) D (cm 3 g - ) (M vρ) In tluene C 3 H 7 NH C 4 H 9 NH (C 3 H 7 ) NH (C 4 H 9 ) NH (C 3 H 7 ) 3 N (C 4 H 9 ) 3 N In benzene (C 4 H 9 ) 3 N a ν = B / M v ρ

6 56 INDIAN J CHEM, SEC A, NOVEMBER 9 Fig. Dependence f viscsity deviatins n mle fractin at 33.5 K. [, C 3 H 7 NH ( );, C 4 H 9 NH ( ); 3, (C 3 H 7 ) NH ( ); 4, (C 4 H 9 ) NH ( ); 5, (C 3 H 7 ) 3 N ( ); 6, (C 4 H 9 ) 3 N ( ) in tluene; 7, (C 4 H 9 ) 3 N ( ) in benzene]. (slute-slute interactin), (iii) alkylamine-armatic hydrcarbn (n-π) interactin (slute-slvent interactin), and, (iv) alkylamine-tluene diplediple interactin. The diple mments 4 f alkylamines are in the range D and.3 D fr tluene. The primary and secndary amines are als self-assciated thrugh H-bnding. The disruptin f assciated structure (effects (i) and (ii)) reduces the chesive frces between the mlecules, thereby increasing the mbility. On the ther hand, diple-diple and n-π interactins between unlike cmpnents (effects (iii) and (iv)) increases the chesive frces, and as a result mbility is reduced. Frm the large psitive equimlar excess E enthalpy, H m, (65 J ml - fr tluene + cyclhexane, 84 J ml - fr benzene + cyclhexane, 55 J ml - fr tluene + heptane, 97 J ml - fr benzene + heptane at 98.5 K) 6,7, it is clear that the π-π interactin in armatic hydrcarbns is quite strng; and the strength f interactin is strnger in benzene as cmpared t that in tluene. The present study is cncerned with the dilute amine slutins, where the π-π interactin will nt be significant, and the cntributin will be cmparatively small and can be ignred. In rder t arrive at certain meaningful cnclusins abut the slute-slute and slute-slvent interactins f amine slutins in tluene r benzene, it will be interesting t cmpare present viscsity behaviur with that btained fr amine slutins in cyclhexane. The values f η and G *E fr amine slutins in tluene and cyclhexane are negative, but are less negative in tluene slutins as cmpared t the cyclhexane slutins. The reductin in the negative values f η and G *E fr the studied Fig. 3 Dependence f excess Gibbs energy f activatin f viscus flw n mle fractin at 33.5 K. [, C 3 H 7 NH ( );, C 4 H 9 NH ( ); 3, (C 3 H 7 ) NH ( ); 4, (C 4 H 9 ) NH ( ); 5, (C 3 H 7 ) 3 N ( ); 6, (C 4 H 9 ) 3 N ( ) in tluene; 7, (C 4 H 9 ) 3 N ( ) in benzene]. amines in tluene as cmpared t cyclhexane slutins may be attributed t the additinal enhanced diple-diple and n-π interactins between unlike cmpnents. In the case f amine slutins in cyclhexane, the lcal rder in amine mlecules due t self-assciatin r diple structure is disrupted by the additin f cyclhexane mlecules,8. Hwever, the verall negative values f η and G *E fr the tluene slutins, definitely suggest that the dispersive interactin due t the disruptin f π-π interactin, the breaking f diplar rder in amine as well as in tluene and the disruptin f H-bnding in primary and secndary amine mlecules dminate ver the enhanced diple-diple and n-π interactins between the unlike cmpnents. The smaller psitive values f excess mlar enthalpy and vlumes 7-9 fr primary, secndary and tertiary amines in benzene r tluene as cmpared t that in cyclhexane r n- hexane r n-heptane als crrbrate the abve interpretatin. In the case f tri-n-butylamine, the psitive values f G *E are due large size difference between the amine and tluene r benzene 9,9. The values f η and G *E fr amine slutins in tluene are slightly different than thse bserved in benzene slutins. The small difference in viscmetric behaviur between benzene and tluene is a result f substitutin f methyl grup in benzene. It has been bserved that alkylamines interact less strngly with armatic hydrcarbn mlecules cntaining an electrn dnating grup 8,3. The methyl grup in tluene is an electrn-dnating grup, resulting in weaker interactin with amine as cmpared t the interactin in benzene.

7 OSWAL & IJARDAR: VISCOSITIES OF DILUTE ALKYLAMINES + TOLUENE/BENZENE SOLUTIONS 57 It is an accepted prcedure t estimate the strength E f interactin frm excess mlar enthalpy, H m, r partial mlar enthalpies. The n-π interactin fr C 3 H 7 NH, C 4 H 9 NH, and (C H 5 ) 3 N with tluene and benzene was estimated by subtracting the sum f partial mlar excess enthalpy f amine in cyclhexane r methylcyclhexane and armatic hydrcarbn in n-heptane frm the partial mlar excess enthalpy f amine in armatic hydrcarbn 3. The partial mlar excess enthalpies btained frm the excess mlar enthalpy data f crrespnding mixtures 6,7 shw that the interactin energy fr crrespnding alkylaminebenzene is smewhat mre negative than that fr alkylamine-tluene, indicating that the amine-tluene specific interactins are cmparatively weaker than the amine-benzene interactins. Thus, in general, the predicted extent f specific interactins frm the viscsity data f amine slutins in bth the armatic hydrcarbns is in agreement with the calrimetry results. On Herskvits and Kelly equatin The values f cefficients B and D, viscsity 3 increment ν = B / ( M v ρ ) and the values f 6 D / ( M vρ) f Herskvits and Kelly (Eq. ) are presented in Table 4. The partial specific vlume v at infinite dilutin f amines been taken frm earlier wrk 3,. The values f B-cefficient fr the present alkylamine slutins range frm -.55 t.43 kg ml -. The values f viscsity increment ν= 3 B / ( M vρ ) are negative fr C 3 H 7 NH, C 4 H 9 NH, and (C 3 H 7 ) NH slutins and psitive fr (C 4 H 9 ) NH and (C 4 H 9 ) 3 N slutins. A cmparisn f B values in different slvents shws that the values f B fr the crrespnding amine slutins in tluene are less negative than that fund in cyclhexane and mre negative in benzene slutins. They generally, increase frm primary t secndary t tertiary. On the basis f Einstein mdel f sphere in a cntinuum 3 the viscsity increment ν shuld be equal t.5. The values f viscsity increment in the present case are nt nly very different frm.5 but als have negative values. The deviatin f B cefficient and related viscsity increments may be attributed t the nature f slvent in terms f structure frming and structure breaking and the deviatin f slute particle frm sphericity. The lwer and negative values f ν have als been reprted fr a series f nn-electrlytes in plar and nn-plar slvents,,,. On Nakagawa equatin The B JD, B JD,id and B JD,int cefficients were estimated frm the ηint values using Eqs (5)-(7). The values f B JD cefficient range frm -.7 t.44 dm 3 ml - fr alkylamines in tluene and.53 dm 3 ml - fr tri-n-butylamine in benzene. Since, the B JD cefficient als cntains the cntributins t the difference f viscsities fr slute and slvent cmpnents (Eq. 6) and therefre, it is inapprpriate t discuss the slute-slvent interactin in terms f B JD. The slute-slvent interactins can be cnsidered by the term B JD,int defined by Eq. (7). The values f B JD,int are negative (frm -.3 t -.9 dm 3 ml - ) fr the present amine slutins in tluene r benzene, but are less negative as cmpared t that in the cyclhexane, supprting the ccurrence f specific interactins due t enhance diple-diple r diple induced diple interactins in unlike cmpnents, in additin t the usual dispersin interactins. The interpretatin based n the relative magnitude f B JD,int derived frm the ECS thery is thus cnsistent with the partial mlar vlume and the heat f slutin,33,34. Gibbs energy f activatin Using the transitin state thery f viscus flw,,#,#,# the values f µ µ and µ fr amine slutins in cyclhexane, benzene, and tluene were calculated using Eqs. (8) - () and the results are summarized in Table 5. The required data fr the amine slutins in cyclhexane and benzene were taken frm earlier wrk,3,. We have als included data f Klfutar et al. fr tri-n-alkylamine (trihexyl, trictyl, tridecyl and triddecyl amines) in benzene slutins fr cmptutatin. The value f B JD increases as the mlar vlume f slute mlecule V increases (Table 5) and is als qualitatively predicted by the classical thery f Einstein 3. It is interesting t bserve that the first term f Eq (8), ( V V ) /, influences B JD inversely, since it decreases as V increases. It is unifrmly negative fr the present amine slutins except fr first and/r secnd member f the series. In fact, the secnd term swamped the results. Like B JD,,# increases with the increase in mlar vlume r µ

8 58 INDIAN J CHEM, SEC A, NOVEMBER 9 mlar mass f slute (Table 5), especially fr the tri-n-alkylamine-benzene series. It is at least partly,#,#,# explained by the fact that ( µ µ ) r µ in Eq. (9) r () is prprtinal t V at cnstant V and T. The influence f different slvents can be seen by,# cmparing µ. Eq. (9) predicts that increasing the mlar vlume f the slvent, decreases the µ.,#,# The µ fr the crrespnding amine is smaller in cyclhexane than that in benzene, since mlar,#,# Table 5 The activatin energies ( µ µ ), µ,# * and heat f slutin ( ( H H ) ) in infinite dilute slutin f Slute * alkylamines in cyclhexane, benzene, and tluene calculated frm B JD -cefficient and cmparisn f ( H H ) Slvent with experimental results V η B JD * H H ( ),#,# µ µ µ,# (cm 3 ml - ) (mpa s) (dm 3 ml - ) (kj ml - ) (kj ml - ) ( kj ml - ) Calc. Expt. a Alkylamine slutins in cyclhexane b V = 9.4 cm 3 ml -,#, η =.88 mpa s, µ = 3.64 kj ml - C 3 H 7 NH c-c 6 H C 4 H 9 NH c-c 6 H (C 3 H 7 ) NH c-c 6 H (C 4 H 9 ) NH c-c 6 H (C H 5 ) 3 N c-c 6 H (C 3 H 7 ) 3 N c-c 6 H (C 4 H 9 ) 3 N c-c 6 H Alkylamine slutins in benzene b V = 9. cm 3 ml -,#, η =.563 mpa s, µ =. kj ml - C 3 H 7 NH C 6 H C 4 H 9 NH C 6 H (C 3 H 7 ) NH C 6 H (C 4 H 9 ) NH C 6 H (C H 5 ) 3 N C 6 H (C 3 H 7 ) 3 N C 6 H (C 4 H 9 ) 3 N C 6 H (C 6 H 3 ) 3 N C 6 H (C 8 H 7 ) 3 N C 6 H (C H ) 3 N C 6 H (C H 5 ) 3 N C 6 H Alkylamine slutins in tluene V = 7.5 cm 3 ml -,#, η =.59 mpa s, µ =.45 kj ml - C 3 H 7 NH C 6 H 5 CH C 4 H 9 NH C 6 H 5 CH (C 3 H 7 ) NH C 6 H 5 CH (C 4 H 9 ) NH C 6 H 5 CH (C H 5 ) 3 N C 6 H 5 CH (C 3 H 7 ) 3 N C 6 H 5 CH (C 4 H 9 ) 3 N C 6 H 5 CH a * H H ( ) determined using E Hm data frm Refs. 7,8; b B JD -cefficient taken frm Refs.,3,.

9 OSWAL & IJARDAR: VISCOSITIES OF DILUTE ALKYLAMINES + TOLUENE/BENZENE SOLUTIONS 59 vlumes f cyclhexane are abut % larger than that f benzene. The mlar vlumes f cyclhexane and tluene are nt much different and therefre the values f,# µ in these slvents are clse t each ther. The slightly larger values in tluene may be attributed t n-π interactin in tluene. Heat f slutin The calculated values f heat f slutins H H f amines in cyclhexane, benzene and tluene, frm Eq. () are reprted in Table 5 and cmpared with the experimental results 6,7. It is bserved that always crrect sign f heat f slutin H H was predicted fr amine slutins in cyclhexane, benzene and tluene, expect fr di-n-butylamine in benzene. Hwever, the quantitative agreement, generally, is nt very encuraging except fr few slutins. This may be because the values f B JD fr nn-electrlyte liquid slutins, nt nly depend upn mlecular interactins but als n the viscsities f slute as well as slvent in additin t their mlar vlumes. Cnclusins In the present studies the viscsities, specific viscsities and viscsity deviatins f dilute slutins f n-prpylamine, n-butylamine, di-n-prpylamine, di-n-butylamine, tri-n-prpylamine, and tri-n-butylamine in tluene, and tri-n-butylamine in benzene have been determined. The viscsity increment, ν, and Jnes-Dle B JD -cefficient are negative fr slutins f C 3 H 7 NH, C 4 H 9 NH, (C 3 H 7 ) NH and (C 3 H 7 ) 3 N and psitive fr (C 4 H 9 ) NH and (C 4 H 9 ) 3 N. The interactin term, B JD,int, is less negative fr all amine slutins in tluene as cmpared t slutins in cyclhexane, supprting the presence f specific interactins between unlike mlecules. The change in activatin energy and the heat f slutin per mle f amine at infinite dilutin in cyclhexane, benzene, and tluene have been calculated frm the transitin state treatment f viscsity. References Oswal S L, Desai J S & Ijardar S P, Thermchim Acta, 43 (4) 9. Oswal S L, Desai J S, Ijardar S P & Malek N I, Thermchim Acta, 47(5) 5. 3 Oswal S L, Desai J S & Ijardar S P, Thermchim Acta, 449 (6) Oswal S L, Desai J S, Ijardar S P & Jain D M, J Ml Liq, 44 (9) 8. 5 Oswal S L & Ijardar S P, J Ml Liq, 44 (9) 5. 6 Oswal S L & Ijardar S P, J Sl Chem, 38 (9) 3. 7 Oswal S L & Ijardar S P, Thermchim Acta, 49 (9). 8 Oswal S L, Prc 3 rd Natl Cnf Thermdyn Chem Bil Sys, Nagpur, 8, p Oswal S L & Ijardar S P, Thermchim Acta, (9), di:.6/j.tca Oswal S L & Ijardar, Indian J Chem, 48A (9) 93. Herskvits T T & Kelly T M, J Phys Chem, 77 (973) 38. Klfutar C, Paljk S & Kremser D, J Inrg Nucl Chem, 37 (975) Nakagawa T, J Ml Liqs, 63 (995) Riddick J A, Bunger WB & Sakan T K, Organic Slvents: Physical Prperties and Methds f Purificatin, (Wiley Interscience, New Yrk) Timmermans J, Physic Chemical Cnstant f Pure Organic Cmpunds, Vl., (Elsevier, Amsterdam) Pal A, Gaba R & Sharma S, J Chem Eng Data, 53(8) Kinart C M, Kinart W J, Checinska-Majak D & Cwiklinska A, J Ml Liq, 9 (4) 9. 8 Ratkvics F & Dmnks L, Acta Chim Acad Sci Hung, 89(976) Oswal S L & Patel A T, Int J Thermphys, (99) 8. Oswal S L, Oswal P, Gardas R L, Patel S G & Shinde R.G, Fluid Phase Equilib, 6 (4) 33. Klfutar C, Paljk S & Malnersic R, J Chem Sc Faraday Trans, I 78 (98) Matsubayashi N & Nakahara M, J Chem Phys, 94 (99) Glasstne S, Laidler K & Eyring H, The Thery f Rate Prcesses, (McGraw-Hill, New Yrk ), Feakins D, Freemantle J D & Lawerence K G, J Chem Sc Faraday Trans, 7 (974) Alexander D M & My D C, Aust J Chem, 34 (98) Christiansen J J, Hanks R W & Izatt R M, Handbk f Heats f Mixing, (Wiley Interscience, New Yrk) Heats f Mixing (Excess Enthalpy) in Binary and Ternary Systems, edited by K N Marsh (TRC Data Series) Letcher T M, J Chem Thermdyn, 4 (97) Jambn C & Delmas G, Can J Chem, 55 (977) Kkknen P, J Chem Thermdyn, 8 (986) Letcher T M, Gvender P U & Dmanska U, J Chem Eng Data, 44 (999) Einstein A., Ann Phys, 34 (9) Sephensan W. K & Fuchs R, Can J Chem, 63 (985) Fernandez J, Garriga R, Velasc I & Otın S, Fluid Phase Equilib, 5 (998) 43.