Thermodynamic And Kinetic Studies On The Esterification Of Camphene

Esters are derivatives of carboxylic acids and are widely found in nature.Generally they are produced by the reaction of acid with alcohol,but water is also generated,However,some esters can be obtained by direct addition of olefins and carboxylic acids,which the process has high atomic utilization and reduced difficulty in subsequent separation.For example,the synthesis of cyclopentyl acetate,cyclohexyl acetate,lower fatty acid isobornyl ester and so on.The isobornyl esters are produced by the reaction of camphene with the carboxylic acids,They have fragrant smell,which can be used as a raw material for daily chemicals such as flavors and fragrances,indoor air fresheners,and body powders.In addition,isobornyl esters are good lubricant and solvent,and can also be used as intermediates in the reaction and the synthetic drugs.The literatures on the synthesis of isobrnol ester have been reported,the thermodynamics and kinetics of the camphene esterification reaction have rarely been studied.In this paper,the synthesis of three isobornol esters were studied.The effects of different process parameters on the reaction process were systematically investigated and the conditions were optimized.Corresponding thermodynamic parameters and kinetic parameters were calculated by regression of experimental data.It has certain guiding significance for industrial production.The main contents of this paper are as follows:(1)Synthesis of isobornyl acetateThe synthesis of isobornyl acetate was systematically studied in a stirred tank reactor using NKC-9 resin as a catalyst.The optimized process parameters are as follows:the amount of anhydrous NKC-9 resin is 15%of the mass of the total liquid material,the stirring rate is 400 r min-I,and the molar ratio of the initial content of the camphene to Acetic acid is 1:1.5.The temperature is 308K.Under the optimized reaction conditions,the conversion of camphene reached 92.68%at 50 minutes,and the yield of isobornyl acetate was 88.05%.The non-ideality of the solution was corrected by the UNIFAC group contribution method.The enthalpy change △ArH0 of the reaction was-29.54kJ.mol’1,and the entropy change △rS0 was-54.35J-(mol·K)-1,the Gipps free energy change △rG0 is 13.35 kJ·mol-1,and the equilibrium constant expression is:(?)The kinetic study of the reaction was carried out using a pseudo-homogeneous model.The expression of the kinetic equation is:(?)Where(?)(2)Synthesis of isobornyl propionateIt was found that NKC-9 was used as the catalyst of the reaction have a good effect,and the influencing factors of camphene and propionate reaction were investigated in the stirred tank reactor.The optimized parameters are as follows:The amount of catalyst is 15%of the mass of the total liquid material,the stirring rate is 400 r min-1,and the ratio of the initial content of the camphene to Propionic acid is 1:1.5.The temperature was 313 K and the reaction time was 60 minutes.At this time,the conversion of camphene was 93.88%,and the yield of isobornyl propionate was 89.21%.Thermodynamic parameters are corrected by using the UNIFAC group contribution method.The enthalpy change A,H0 of the reaction was-22.03kJ*mol-1,and the entropy change △rS0 was-27.68J.(mol·K)-1,the Gyps free energy change△rG0 is-13.78 kJ mol-1,and the equilibrium constant expression is:(?)The kinetic study of the reaction was carried out using a pseudo-homogeneous(PH)model.The expression of the kinetic equation is:r=-da cam/dt =M cat(kfαcamαBA-KrαIP)(?)Where(?)(3)Synthesis of isobornyl butyrateThe synthesis of isobomyl butyrate was systematically studied in a stirred tank reactor.The optimized process parameters are:The amount of catalyst is 15%of the mass of the total liquid material,the stirring rate is 400 r·min-1,the molar ratio of the initial content of the camphene to Butyric acid is 1:1.2,and the reaction temperature is 313K,the reaction time is 60 minutes,the conversion rate of camphene is 93.14%,and the yield of Isobornyl butyrate can reach 88.07%.Thermodynamic parameters are corrected by using the UNIFAC group contribution method.The thermodynamic calculation obtained the enthalpy change△rH0 was-17.93kJ·mol-1,and the entropy ArS0 was-9.66J·(mol·K)-1,the Gipps free energy change △rG0 is-15.06 kJ·mol-1,and the equilibrium constant expression is:(?)The kinetic study of the reaction was carried out using a pseudo-homogeneous model.The expression of the kinetic equation is:r=-da cam/dt =M cat(kfαcamαBA-KrαIB)(?)Where(?)...