Journal of Advanced Chemical Engineering

Experimental and Theoretical Study of Co-Solvent Effect in Alkaline Hydrolysis of Diethyl Pathalate Ester

Anil Kumar Singh^* Department of Chemistry, Teerthanker Mahaveer University, Moradabad, India
^*Correspondence: Anil Kumar Singh, Department of Chemistry, Teerthanker Mahaveer University, Moradabad, India, Email:

Received: 27-Jun-2022, Manuscript No. ACE-22-17248; Editor assigned: 29-Jun-2022, Pre QC No. ACE-22-17248(PQ); Reviewed: 13-Jul-2022, QC No. ACE-22-17248; Revised: 12-Sep-2022, Manuscript No. ACE-22-17248(R); Published: 19-Sep-2022, DOI: 10.35248/2090-4568.23.13.306

Introduction

The rate of chemical reaction is change with change of solvent composition of reaction mixture which has great importance in laboratory as well as in chemical industry. Some time it is found that rate is increases by a factor 10⁹ with change of solvent [1]. The solvent affect the reaction rate in two ways. One through static or equilibrium solvent effect and another through dynamic or fractional solvent effect [2-5]. The static solvent effect on reaction rate can be understood in term of Transition state theory. The second method are influence the rate of fast reaction. The solvent effect is also closely related to nature and extent of solvent-solute interaction. Solvent solute interaction are very much complex in mixture of the solvent than pure solvent due to possibility of specific solvation of any of solvent present in the mixture. In this investigation studies of solvent effect in hydrolysis of diethyl phthalate has been reported, which has greater use as solvent for the antimony reduction of aluminum chloride phosphorus, dichloride alkyl complex to form the corresponding alkyl phosphorus dichloride.

Materials and Methods

The reactions kinetics has been studied under second-order conditions. The chemical used are Merck grade or BDH (Annular). Known procedure is followed for purifying the ethanol. The diethyl ester containing in a conical flask has been thermo stated for half an hour. Immediately after then 0.4 ml of phthalate ester was withdrawn quickly and added to organic cosolvent mixture with help of pipette. Again 10 ml of aliquot has been withdrawn and allowed to pour into conical flask in which N/10 HCL solution was already present. Phenolphthalein indicator has been used to titrate the excess of alkali with standard solution. When half of aliquot into the cold 0.1 N HCI solution the stop clock was started. Rest of ester has been estimated after quenching the 10 ml of aliquot in 10 ml of 0.1 N HCl in a fixed interval of time.

Results and Discussion

Solvent effect dependence and rate constant

The rate of hydrolysis of diethyl phthalate has been measured in water ethanol medium by the slope of log k against time (Tables 1 and 2). The plot of logk against reciprocal of time has been found has been found to be linear. The retardation of rate with increase solvent composition may be explain on the basis of the fact that formation of polarized transition state is disfavored with increase proportion of ethanol. This fact is also supported by Hugh and in gold qualitative theory. The rate determines step of hydrolysis of ester is addition of hydroxyl ion to the carbon of carbnoyl group and after which rapid reaction with water is followed. Hence if the activity of hydroxyl ion decreases, the reaction rate must be decreases Tommila, et al. [6,7]. The lower the rate in water ethanol mixture suggested that interaction between water and ethanol increases with increase concentration of free water available for salvation of hydroxyl ion. The curve logk against mole fraction of representing smooth decrease, which implies that salvation of hydroxyl ion is stronger and hence the values of rate constant is decreases (Figure 1).

Figure 1: Plots of log k with mole %.

Table 1: Bimolecular rate constant k x 10² (dm)³/mole/mint.

Table 2: Log k values with different mole%.

Activation Energy (Ec) and rate of reaction

Arrhenius plots (Logk against 1/T) has been used to calculate value of activation Energy (E_c) (Table 3 and Figure 2). Table 4 collects the obtained values of activation energies under different solvent composition. The increase in (E_c) values with increase in solvent composition has been noticeable because it will only happened when there is salvation change take place either in initial level or transition level or both.

Figure 2: Plots of log k with 10³/T.

Table 3: Different logk values as a function of temperature.

Table 4: Iso composition activation energy at different solvent fraction.

The increasing value of (Ec) as a function of solvent composition indicate that there is salvation take place at initial level where as desolation at transition level (Table 5 and Figure 3) [8-12].

Table 5: The values logkD at different D.

Figure 3: Variation of log kd with 10³/t.

Dielectric effect on reaction rate

The another aspect of effect solvent may be also be consider by observing the effect of dielectric constant D on reaction rate.

There is an increase in rate is found to increase in D whereas the rate is decreases with decrease in D. The dielectric constant value is obtained by interpolation of akerlof data. Linear relationship is obtained between logk and D-1/2D+1 for dipole dipole interaction Lanndskroner. However for ion dipole linear relation is obtain by plotting Logk and LogD or Logk against 1/D. With help of slope of plots of Log kD against reciprocal of absolute temperature, the iso dielectric values has been calculated with help of slope of different linear line. The depletion in (E_D) with decreasing D, showed that depletion in (E_D) values followed similar trend as (E_c) vales with increasing proportion of solvent composition (Table 6) [13].

Table 6: calculated values of (E_D) at constant D.

Conclusion

The gradual decrease of rate constant is found with increase proportion of solvent composition due to increase concentration of free water available for salvation of hydroxyl ion. The increase of activation energy with increasing composition of solvent indicates desolation in transition state and salvation in initial state. Dielectric value follow similar trend as iso composition activation energy.

REFERENCES

1. Cram DJ, Rickborn B, Kingsbury CA, Haberfield P.  Electrophilic Substitution at Saturated Carbon. XIII. Solvent Control of Rate of Acid-Base Reactions that Involve the Carbon Hydrogen Bond. J Am Chem Soc. 1961:83(17):3678-3687.

   [Crossref][Googlescholar]

2. Roses S, Rafols M, Ortega CJ, Bosch E. Solute solvent and solvent solvent interactions in binary solvent mixtures. Part 1. A comparison of several preferential solvation models for describing ET(30) polarity of bipolar hydrogen bond acceptor-cosolvent mixtures. J Chem Soc Perkin Trans. 1995;2(8):16071615.

   [Googlescholar]

3. Buhvestov U, Rived F, Rafols C, Bosch E, Roses M. Solute solvent and solvent solvent interactions in binary solvent mixtures. Part 7. Comparison of the enhancement of the water structure in alcohol water mixtures measured by solvatochromic indicators. J Phys Org Chem. 1998:11(3):185-192.

   [Crossref][Googlescholar]

4. Herodes K, Leito I, Koppel I, Roses M. Solute solvent and solvent solvent interactions in binary solvent mixtures. Part 8. The E T(30) polarity of binary mixtures of formamides with hydroxylic solvents. J Phys Org Chem. 1999;12:109.

   [Crossref][Googlescholar]

5. Hughes ED, Ingold CK. Mechanism of substitution at a saturated carbon atom. Part IV. A discussion of constitutional and solvent effects on the mechanism, kinetics, velocity, and orientation of substitution. J Chem Soc. 1935;244-255.

   [Googlescholar]

6. Metwally MS. Kinetic study of resin catalysed hydrolysis of ethyl propinoate in aqueous solvent system. J React Kinet Catal Lett. 1992;47(2):319-326.

   [Crossref][Googlescholar]

7. Singh AK. Kinetic and solvent effect and mechanism of hydrolysis of ethyl caprylate ester in aquous organic solvent media. Asian J Chem. 2021;14(6):435-437.

   [Googlescholar]

8. Lallan S, Gupta AK, Sıngh RT, Varma DK, Jha RC. Effect of DMSO on kinetics behaviour of alkaline Catalysed hydrolysis of methyl salicylate.  React Kinet Catal Lett. 1986;5:655-659.

   [Googlescholar][Indexed]

9. Aklof G. Dielectric Constants of Some Organic Solvent Water Mixtures At Various Temperatur. J Am Chem Soc. 1932;54(11):4125–4139.

   [Crossref][Googlescholar][Indexed]

10. Laidler KJ, Landskroener PA. The influence of the solvent on reaction rates. Trans Faraday Soc. 1956;52:200-210.

    [Googlescholar]

11. Wolfod RK. Kinetic of acid hydrolysis of acetal in dimethyl sulfoxide water solvents at 150,250 and 350. J  Phys Chem. 1964;68:3392-3398.

    [Crossref]

12. Bano A, Singh AK. A kinetic study of dipolar protic solvent in alkaline hydrolysis of ethyl nicotinate in water-ethanol media. A solvent effect. J Ultra Chem. 2017;13(6):145-150.

    [Crossref][Googlescholar]

13. Singh AK, Arjuman B. Kinetics and Solvent effect on Aquo dipolar protic organic-solvent system of Hexanoate ester. Asian J Chem. 2019;12(6):341-344.

    [Googlescholar]