(600bo) Homogeneous Esterification of Isoamyl Alcohol with Salycilic ACID, Kinetic Study

HOMOGENEOUS
ESTERIFICATION OF ISOAMYL ALCOHOL WITH SALYCILIC ACID, KINETIC STUDY

Yurani Jiménez, Yohana Páez, Gerardo
Rodríguez, Alvaro Orjuela.

Grupo de Procesos
Químicos y Bioquímicos, Departamento de Ingeniería Química y Ambiental,
Universidad Nacional de Colombia, Bogotá D.C, Colombia.

Fusel oil is
obtained as by-product of ethanol production from the sugar cane in the final
distillation stage[1]. Its quantity and
composition is defined according to the conditions in the fermentation stage,
being the yield of fusel oil in different sugar mills in Colombia about 0.1 to
0.5 % with respect to the volume of ethanol  produced [2-3]. Fusel oil is a
mixture of several alcohols, mainly C3, C4 and C5, aliphatic alcohols where
amyl alcohols reach 80% [9].  

Currently fusel oil
is mainly used as energetic source, solvent and for coatings production[2, 4]. However, those applications
represent low economic benefit and environmental problems. Taking this into
account there is a potential benefit in implementing alternative processes to
transform fusel oil into high added value products (i.e. esters) such as 
isoamyl esters [4-5] [6], [7-8] which can be used
as fragrances, solvents, plasticizers coating, flavoring, cosmetics and others.

One
of those Isoamyl esters is Isoamyl Salicylate, a colorless liquid with diverse applications
in food, cosmetics and fragrances industries because of its clover-like and
orchids-like odor. This ester is currently produced by BASF in different grades
(FCC, Kosher and natural) with purity greater than 98% and has a global market
around 1000 metric tons annually [1]. Traditional synthesis process in the
flavor industry uses concentrated sulfuric acid as catalyst. However,
this catalyst generates high risks due to the
difficulty of handling, high degree of darkening of the product due
to oxidation, high waste generation and consequently some environmental impacts [4].

In this work, the kinetic study of
the esterification reaction between salycilic acid and isoamyl alcohol using p-toluenesulfonic
acid (PTSA) as catalyst is studied. The esterification reaction was carried out
at temperatures between 368.15 K and 399.15 K, the catalyst loading was varied
between 2 to 4 %, using molar ratio 6:1 to 8:1 (alcohol: acid), reaching
conversion above 80%. Due to the non ideality of the reactive mixture, the
activity coefficients were estimated using UNIFAC DOURMUND group contribution
method. The pseudo homogenous kinetic model was fitted obtaining an error about
9.7%, using the ideal and non ideal pseudo homogeneous model.

Keywords: Esterification, kinetics, pseudo
homogeneous model.

References

1.         Cenicaña. Proceso
de obtención de Etanol. Available
from: http://www.cenicana.org/pop_up/fabrica/diagrama_etanol.php.

2.         Patil,
A.G., S.M. Koolwal, and H.D. Butala, Fusel Oil: Compostition, removal and
potential utilization. International Sugar Journal 2002. 104(1238):
p. 51-58.

3.         ICP,
Soluciones para lo que queda despues del Etanol, in Revista innova.
2010, Ecopetrol.

4.         Güvenç,
A., et al., Enzymatic esterification of isoamyl alcohol obtained from fusel
oil: Optimization by response surface methodolgy. Enzyme and Microbial
Technology, 2007. 40(4): p. 778-785.

5.         Teo,
H.T.R. and B. Saha, Heterogeneous catalysed esterification of acetic acid
with isoamyl alcohol: kinetic studies. Journal of Catalysis, 2004. 228(1):
p. 174-182.

6.         Erdem,
B. and M. Cebe, Kinetics of esterification of propionic acid with n-amyl
alcohol in the presence of cation exchange resins. Korean Journal of
Chemical Engineering, 2006. 23(6): p. 896-901.

7.         Deng,
B., Q. Li, and Z. Hu, A new green technology: Synthesis of Isoamyl Benzoate
catalyzed by titanium sulphate. Journal of Baoji College of Art and Science
(Natutal Science Edition), 2003: p. 30-32.

8.         You,
H., Development of synthesis study on Isoamyl Benzoate. Chemical
Engineer, 2004: p. 35-36,64.