Reaction Kinetics of Para chlorophenol Table I -Reaction...

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Journal of Scientific & Industri ::ti Resea rch Vol. 60, April 200 I , p. 348 Note Reaction Kinetics of Para chlorophenol Table I - Reaction kineti cs of PCP vs NaOH (by titration) and Sodiumhydroxide M Natarajan, P Nalini , S S Dawn , D Mary and K Balu Department of Chemical Engineerin g. Ala ga ppa College of Tec hn ology. Anna Universit y, Chennai 600025. Rece ived: 03 M ay 2000; accep ted OS Janua ry 200 I: Sodium phenoxide is one of the important raw matcrials uscd in th e manufac ture of clofibratc, a product of mcdicinal va lu c. Rcac ti on between p- ch lorophenol and sodium hydroxidc is carried out at at- mospheric conditions to yield sodium ph cnox id c. It obscrved ex- perimentally th at th e rcac tion is second ordcr and th e rate constant is e. timatcd as 12.51 x 10" Llmol/min . Introduction Clofibrate is a antihyper lipidaemic a ge nt. It is most effecti ve in lowering the concentra ti on of very low density lipoproteins and plasma triglyce ri des. The drug causes inhibition of choleste rol synthes is and increa se d faeca l exc ret io n of sterols. Clofibrate is manufactured from react in g p-chlorophenox y iso- butyr ic ac id (PCPIBA) w hi ch, in turn , is produced from seve ral raw materials. One of the raw materi- als is sod ium phenoxide obtained by reaction of p- chlorophenol (PCP) and so dium hydrox id e. The ki- netics of PCP with NaOH is in vestigated. Reaction Kinetics Equimolar (0. 1M) cone . of PCP and NaOH are prepared and the pro gress of the reac ti on is m ea - sured by collecting a sma ll quantity (I Oml) of reac- tion mixture at frequent intervals and titrating the collected sa mples aga in st hydrochloric acid. The re- sults are reported in Table I. For a seco nd order reaction, the dif ferential form t of rate exp ress ion is: c/xlc/I=K(a-x) * (a-x), ... (I) wherex= amo llnt of P CPNa formed at time "f" and a = initial co ncentration of reacting mixture. Time Volume of HCI Rate consta nt (in mi n) ( inml ) (in Llmol/ min) 0 9 1.5 7.7 0.0 125n60 I 3 6.8 n.0119 82 57 4.5 6 0.0 6 5.5 o.n 117 )\.+5 I 7.5 5 n.o II )\51)\5 9 4.6 0011 X0891 10.5 4.2 0.01209373 12 3.9 0.01210826 1 3.5 3.7 n.n 1178957 15 3.4 0.0 11200.+.+ Average K 0.0120.+715 The integrated form of Eq. (I) is: K =.1/ {II * (a-.I) * I){ . . .. (2) If V is the vo lume of HCL cons umed initiall y " and V is the volume of HCL consu med after time I "I" th e n, v" (X a and V, (X (II-X). Hence V" - V, (XII - (a-x) = x Eg . 2 is rearranged as: K={V" - v,/ / { II " *11, * I J. . (3) . ('+) The estimated K va lu es for diff e rent time periods are presented in Table 1. The rate co nstant is found to be co nstant throug hout the course of react ion and the average va lu e is taken for estima ting K. Th e rate co nstant is 12.51 x IO-' Um ol/min. Results and Discussion R eac tion kin et ics ofp-ch iorophenol w ith sod ium hy dro xide is studi ed at room tempe rat ur e. It is ob- serv ed experimentally that the reactio n is seco nd order and the rate constant is est i mated as: 12 .51 x 1 0- J Um ol/min. Reference Oct ave Levenspeil, Chemical Reaclion Engin eering ( Wil ey East- ern Pri va te Limit ed, New Delhi) 1983.

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Journal of Scientific & Industri ::ti Research Vol. 60, April 200 I , p. 348

Note

Reaction Kinetics of Para chlorophenol Table I - Reaction kineti cs of PCP vs NaOH (by titrati on)

and Sodiumhydroxide

M Natarajan, P Nalini , S S Dawn , D Mary and K Balu Department of Chemical Engineering.

Alagappa College of Technology.

Anna Univers ity, Chennai 600025.

Received: 03 M ay 2000; accepted OS January 200 I:

Sodium phenoxide is one of the important raw matcrials uscd in the manufacture of clofibratc, a product of mcdicinal va luc. Rcacti on between p-chlorophenol and sodium hydroxidc is carried out at at­mospheric conditions to yield sodium phcnox idc. It i ~ obscrved ex­perimentally that the rcaction is second ordcr and the rate constant is

e. timatcd as 12.51 x 10" Llmol/min.

Introduction Clofibrate is a antihyper lipidaemic agent. It is

most effecti ve in lowering the concentrati on of very low density lipoproteins and plasma tri g lyce ri des. The drug causes inhibition of cholestero l synthes is and increased faeca l exc retion of sterols. Clofibrate is manufactured from reacting p-chlorophenoxy iso­butyric ac id (PCPIBA) which, in turn , is produced from several raw materials . One of the raw materi­a ls is sodium phenoxide obtained by reaction of p­chlorophenol (PCP) and sodium hydrox ide. The ki­

netics of PCP with NaOH is in vest igated.

Reaction Kinetics Equimolar (0. 1M) cone. of PCP and NaOH are

prepared and the progress of the reac ti on is mea­sured by collecting a small quantity (I Oml) of reac­tion mixture at frequent intervals and titrating the

collected samples against hyd rochloric acid. The re­sults are reported in Table I .

For a second order reaction , the diffe re nti a l form t

of rate expression is : c/xlc/I=K(a-x) * (a-x), .. . ( I )

wherex= amollnt of PCPNa formed at time "f" and a = initial concentration of reacting mixture.

Time Volume of HCI Rate constant (in mi n) (inml ) ( in Llmol/min)

0 9

1.5 7.7 0.0 125n60 I

3 6.8 n.01198257

4.5 6 0.0 12~'+568

6 5.5 o.n 117)\.+5 I

7.5 5 n.o II )\51)\5

9 4.6 0011 X0891

10.5 4.2 0.01209373

12 3.9 0.01210826

13.5 3.7 n.n 1178957

15 3.4 0.0 11200.+.+

Average K 0.0120.+715

The integrated form of Eq. ( I ) is:

K =.1/ {II * (a-.I) * I){. . .. (2)

If V is the vo lume of HCL consumed initiall y "

and V is the volume of HCL consumed after time I

" I " then,

v" (X a and V, (X (II-X).

Hence V" - V, (XII - (a-x) = x

Eg . 2 is rearranged as:

K={V" - v,/ / { II" *11, * I J.

. (3)

. ('+)

The estimated K va lues for diffe rent time periods are presented in Table 1. The rate constant is fo und to be constant throughout the course of reaction and the average va lue is taken fo r estimating K. The rate constant is 12.51 x IO-'Umol/min .

Results and Discussion Reaction kinetics ofp-ch iorophenol w ith sod ium

hydroxide is studied at room temperature. It is ob­served experimentally that the reaction is second order and the rate constant is esti mated as: 12.51 x 1 0-JUmol/min .

Reference

Octave Levenspeil , Chemical Reaclion Engineering (Wiley East­ern Pri vate Limited, New Delhi ) 1983.