Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 3(8), 63-67, August (2013) Res. J. Chem. Sci. International Science Congress Association 63 Effect of the Micellar Catalysed Hydrolysis of BIS -4-Chloro-3-Methyl Phenyl Phosphate EsterSingh A.P., Verma R.C. and Kushwaha R.S.Department of Chemistry, Janta College, Bakewar, Etawah, INDIA Department of Chemistry, Agra College, Agra, UP, INDIA Available online at: www.isca.in Received 22nd November 2012, revised 1st January 2013, accepted 25th January 2013Abstract The micellar catalysed reactions between hydroxide anions and bis-4-chloro-3-methyl phenyl phosphate ester (bis-4-CMPP) has been examined in buffered medium at pH 8 to10. The first order rate constant (K) for the reaction of OH with 4-CMPP go through maxima with increasing the concentration of cetyltrimethyl ammonium bromide(CTABr). Concentration of the surfactant can be analyzed in terms of Br ions in micellar pseudophases, which occur readily by aqueous CTABr and calculated second order rate constants. Keywords: Bis-4CMPP Introduction The rate enhancement of first order rate costant (K) of the reaction catalysed by the micelles is largely due to the increased concentration of the reactant in the micellar pseudo phase1-3. It is difficult to examine the partitioning of hydrophillic reactants between aqueous and micellar pseudophases instead of hydrophobic ions. The widely used approach is to assume that couterions comlete for ionic sites on the micellar surface and that the fraction ‘’ of these sites which are neutralized by approaches counter ions is approximately constant4,5. This approach has been applied to the rate and equilibrium constant of many reactions6-10. A reactive ion surfactant in which ionic reagent is the micellar counter ions11-14 can be used to eliminate the problem of inters ionic competition. Therefore, its concentration in the micellar pseudophase should be constant provided that ‘’ is constant. The first order rate constants (K) increases with increasing surfactant concentration to the maximum value at 1.6x10-3 mol dm-3 CTABr for 4-CMPP. This behavior has been observed for reactions involving hydroxide ions for nucleophillic addition by Br-15. Material and Methods Preparation Bis ester of 4-chloro-3-methylphenyl phosphate the residue left after removing mono- 4-chloro -3- methyl phenyl phosphate at b 120-140C was washed several times with boiling distilled water and 0.2 NaOH solution to remove 4-chloro- 3-methyl phenyl phosphate monoester, unreacted phosphorus oxy tri-chloride and the phenol and finally digested in hot water 0.5 NaOH solution. It was filtered and the filtrate acidified with dilute HCl using phenophthalene as an indicator. A white precipitate obtained was separated by filtration and made free from hydroxyl ions with repeated washings with boiling water. It was than dried at room temperature and recrystallised with absolute ethyl alcohol gave a white crystalline solid and it was identified to be Bis- 4-chloro -3-methyl phenyl phosphate as shown under: Cetyltrimethyl ammonium bromide was purified by given method 4-chloro -3-methyl phenyl phosphate were washed with anhydrous ether aceton until no amine is detected in the eluent recrystallised from methanol and then at least 4 times from methanol with addition of anhydrous ether. Amidol (1.4gm) was taken in conical flask covered with carbon paper, activated charcoal (2gm) and water (10ml) were added in to the conical flask and then it was shaken thoroughly for 15-20 min. The colourless amidol solution so obtained was filtered in to a solution containing 100ml solution of sodium meta bisulphate (20%). The reagent obtained was kept in a dark at low temperature (0C). This solution gradually decomposed and turned yellow after 6-8 days, than it was of no use and hence, discarded. Each time amidol was purified before use. Substrate in solution has the specific property of absorbing light of wave lenth characteristic of the particular substance. The basic principle of absorption is utilized in the measurement of various concentrations. The spectrophotometer instrument utilize a source of radiant energy , a means to isolate a band of radiant energy which is focused to on the solution and then measured with a detector. Kinetic study for the hydrolysis of all the mono-, di- and tri-ester was followed spectrophoto-metrically. This method involved the quantitative estimation of inorganic phosphates formed from the hydrolysis of phosphate esters. The inorganic phosphate react with the ammonium molybdate and forms a phosphate molybdate complex (NHPo.12MoO3, which is reduced to molybdnum blue, a soluble complex by addition of mixture of 2, 4-diamino phenyl hydrochloride (amidol,diamol or nerol). Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(8), 63-67, August (2013) Res. J. Chem. Sci. International Science Congress Association 64 Phosphate mono esters were prepared by standard methods16 purified by re crystalisation from absolute ethyl alcohol and examined by IR, CTABr used analytical grade, strength of borate buffer were prepared and purified by standard methods17. All kinetic runs were performed using doubly or triply distilled water. All reactions were carried out at 40±0.5C and pH 9.0. Reactions were followed by spectrophotometer at the absorbance 662 nm. To obtain first order rate (K) Result and Discussion The reactions of both Mono phosphate were strongly catalyzed at different concentration of CTABr at which the pseudophases first order rates constant were obtained. In table 1, summarization the effect of cationic micelles of CTABr on the rate constants of OHwith 4-CMPP which is shown in figure 1. The reaction between the observed pseudo first order rate constant (Kand surfactant concentration [D] for a spontaneous phosphorylation of 4- CMPP may be shown in following scheme Where Sw and Sm are substrate in aqueous and micellar pseudophases respectively, K’w and K’m are the related first order rate constant and Ks is binding constant18. The concentration of micellised surfactant, Dn is that of total surfactant concentration less that of monomeric surfactant which is assumed to be given by Critical Micelle Concentration CMC19 provided that equilibrium is maintained between micelle and aqueous K’w + K’m + Ks (Dn – CMC) = (1) 1+ Ks (Dn – CMC) Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(8), 63-67, August (2013) Res. J. Chem. Sci. International Science Congress Association 65 It is assumed that interaction of two or more counter ions with anionic micelles are governed by the ion exchange equilibrium equation (2) KOHBrOH +Br OH+Br (2) Where m and w in parenthes denotes micellar and aqueous pseudophases respectively. Equilibrium or ion exchange constants for OH- and denoted by KOHBr can be given by the eqation(3) [OH] [Br] OHBr = (3) [OH] [Br] By employing the following equation (4) and (5), the first order rate constants K’ and K’ are conveniently converated in to second order rate constants K and K respectively, K’ = K [OH] (4) [OH] K’ = K mOH =Km (5) [Dn] Where mOH is the concentration of reactive ions in micelle. Since mOH is expressed in the molar ratio values of the second order rate constant Km cannot be compared directly with second order rate constants intricate because of different dimensions. They can be converted in to Km, which is the second order rate constant expressed in terms mole of reactant per dm (L) of stern layer. This quantity is estimated to be 140 ml or 0.14 L for [CTABr] Km has been calculated from following equation (6). m = 0.14 Km 2.3x10 mol-1 dm-3 sec-1 (6) The order equation(1) can be written in the following manner as in equation (7) K[OH] +K’ K mOH [Dn] K = (7) 1 + K [Dn] It is assumed that KOHBr and is the fraction of micellar head groups neutralized by counter ions may be treated as independents nature of concentration of counter ions (8) for a mixture of OH – and Br is identical with mOH+ mBr the concentration of OH and OH (in molarities) are expressed in terms of total concentration in solution volume so that [OHand [OH can be equation (8) and (9). [OH = [OH] + mOH [Dn] (8) [Br] = [Br] + [ –mOH] [Dn] (9) Substitution for [OH] [OH] [Br] with [OH] and [Br] in equation (3) leads to equation (10) [OH + KOHBr[BrT [OH [mOH+mOH{ - }- (10) [KOHBr -1] [Dn] [KOHBr-1][Dn] The Selecting values of [KOHBr] and as 10 and 0.75 respectively, mOH has been calculated for reaction at 0.451x10-2mol dm [OH] ion in table (2). For convenience equation (7) may be arrange as (11). K – K’w = Km -K K (11) mOH[ Dn] mOHA graph plotted between K–K’w and - K mOH[Dn] mOH in figure (2) which are linear at different [CTABr] and yield values of Ks, Km, [OH-] summarized in table(3) . From the results present in table (3), it is evident that maximum rate enhancement occur in the region of [CTABr] at which bulk of the substrate incorporated in to the micelles. The aryl part of the substrate dianion is deeply buried in interior of micelles and the phosphate dianions are suitably exposed to nucleophilic attack by [OH] ions which are present lower concentration in the micelles. Besides of this Di- anion of mono phosphate ester are relatively hydrophobic and polarisable anions bind to micelles the specific interaction but coulombic binding in much important in binding of hydrophilic anions. The dianions of mono phosphate ester is polarisable and not very hydrophilic interact with phosphate atom of C-O-P linkage present in zwitterionic forms of mono phosphate ester forming hydrogen bonded cyclic intermediate by entrap of reducing this interaction considerably the coulombic interactions [OH-] ions in cationic micelles was ascribed to a higher surface charge density at cationic as compared with the anionic centre. Table-1 Pseudo fist order rate constants for the reaction of NaOH with BIS 4-CMPP in presence of CTABr at pH-9.0 and 40 ± 0.5C S.N. CTABr x10 - 3 moldm-3Psedo first order constant of bis-4- CMPPX10 sec-1 1. 0.2 4.05 2. 0.4 5.61 3. 0.6 7.21 4. 0.8 8.97 5. 1.0 13.41 6. 1.2 16.12 7. 1.4 19.05 8. 1.6 26.61 9. 1.8 18.06 10. 2.0 0.09 Conclusion The order rate constant (K) increases with increasing surfactant concentration to the maximum value at 1.6x10-3 mol dm3 for bis 4-CMPP.It is evident that maximum rate enhancement occurs in the region of CTABr at which bulk of the substrate in corporate in to the micelles. Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(8), 63-67, August (2013) Res. J. Chem. Sci. International Science Congress Association 66 Table-2 Realation between K - K’w/mOH and –K /mOH of bis-4-CMPP pH- 9.0 and 40±0.5C S.N. 10 5 K sec - 1 -K m s OH (K-K’w). 10 5 10 2 (K – K’w) OH [Dn] 1. 5.55 12.30 2.26 6.14 2. 6.22 13.79 2.93 8.12 3. 8.01 17.76 4.73 13.10 4. 10.12 22.43 6.83 18.93 5. 12.41 27.59 9.11 25.27 6. 16.19 35.89 12.90 35.75 7. 18.96 42.03 15.69 43.48 8. 23.15 51.33 19.86 55.00 Table-3 Ion exchange parameter and second order rate constant for reaction of 4-CMPP with OH in presence of CTABr at pH-9.0 and 40±0.5C OH Br 10 3 10 4 10 3 m s OH 10 3 10 4 10 5 10 5  [OH - T ] [OH - m ] [OH - w ] K s K’ m K’ w K 2 m mol mol mol mol - 1 s - 1 mol - 1 mol - 1 dm - 3 dm - 3 dm - 3 dm - 3 dm - 3 dm - 3 10 20.8 3.61 20.439 0.451 38.61 29.6 3.29 1.792 0.75 logK. 10 sec-CDX10-3 moldm-3Figure-1 Reaction of bis-ester(4-CMPP)with Hydroxyl ions in micellized CTABr at pH-9.0 and 40±0.5C Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(8), 63-67, August (2013) Res. J. Chem. Sci. International Science Congress Association 67 -K’OH -K x10-5 s-1 x10--1 OHFigure-2 Quantitative treatment of micellar effect on the nucleophilicity of bis-4-CMPP References1.Fendler J.H. and Fendler E.J., Catalysis in micellar and macro molecular systems, Academic Press, New York (1975)2.Singh A.P. and Yadav G.C., Proc. Nat. Conf. Current Concept. Scie, Educational Research-T.D.C., JAUNPUR, 41-45 (2011)3.Singh A.P., Verma R.C. and Kushwah R.S., J. of ultra chemistry, 9(1), 23-30 (2012)4.Mortinek K., Yatsiimirski A.V. and Berezin I.V., Micellization Solubilization and micro emulsion, Mittal, K.L., Ed. Plenum Press, New York, 2, 489 (1977)5.Romsted L.S. and Mittal K.L., Ed. 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