CH EM I STRY & CH EM I CAL TECH N OLOGY Chem. Chem. Technol., 2018, Chemistry Vol. 12, No. 2, pp. 158– 166 A PRELIMINARY INVESTIGATION CONCERNING M ETAL OXIDES AS CATALYSTS FOR ESTERIFICATION OF LAURIC ACID WITH ISOPROPANOL Fernanda Krause 1 , Swami Area M aruyama 1, * , Fernando Wypych 1 https://doi.org/10.23939/chcht12.02.158 Abstract. 1 This paper reports the synthesis of isopropyl laurate while using a mixture of metal oxides as a catalyst. The best conversion value was obtained in the following conditions: 393 K, isopropanol:lauric acid molar ratio is 10:1, composition of the catalyst is 33 % CuO, 33 % Ag 2 O and 33 % Al 2 O 3 , catalyst/lauric acid ratio is 8 % (w/w), and reaction time 2 h. Isolation of the catalysts after esterification showed that the oxides were not converted into other materials. Keywords: metal oxide, isopropyl laurate, esterification, lauric acid, isopropanol. 1. Introduction The development of more efficient methods to synthesize isopropyl laurate has been gaining relevance in the scientific community in the recent years, especially because this compound can be used in the composition of different products, such as pigments, tonners and viscosity adjustors [1, 2]. The high demand for the products cited above, together with the unfavorable thermodynamic factors regarding isopropyl laurate synthesis, justifies its high commercial value (U$ 852.84 per gram) [3]. Despite the high price of this compound, it can be synthesized though a reaction between lauric acid and isopropanol, two low priced and easily obtained compounds. There are several methods to synthesize this ester. The most usually described, according to the literature [4] is the esterification reaction catalyzed by an inorganic acid, generally, sulfuric acid. Although it presents a satisfactory conversion [4, 5] the separation between the products and the catalyst is difficult, since it is a homogeneous catalyst. Furthermore, it leads to a huge problem from the environmental point of view: the generated residues from the catalyst washing process are 1 Department of Chemistry, Federal University of Paraná, PO Box 19032, 81531-980, Curitiba, PR, Brazil * swamimaruyama@yahoo.com.br  Krause F., Maruyama S., Wypych F., 2018 extremely toxic for the environment. They also present high carcinogenic activity in humans [6, 7]. An alternative to the esterification with sulfuric acid is the use of heterogeneous catalysts such as inorganic oxides. Several cases of esterification with inorganic oxides have been reported in the literature [8- 10]. In these cases, not only the catalyst separation is performed in an easy manner (because the catalyst is a solid and immiscible material in the reaction system), but the used oxides are Lewis acids of lower toxicity in relation to sulfuric acid. Therefore, the damage to the environment is greatly reduced [7]. However, with the use of heterogeneous catalysts, more extreme conditions regarding the temperature and reagents are necessary in order to obtain a satisfactory reaction yield. Despite the adversities cited above, the possibility of the catalyst recovery and the decrease of environmental impact make up those disadvantages. In order to perform an organized study about the reaction conditions of an esterification system, it is necessary to use a factorial design – a very useful statistic methodology. The factorial design was successfully used, according to the literature, to study several esterification reactions [11]. While there are several studies that analyzed heterogeneous catalyst in esterification reactions with many acids and organic alcohols, there are no descriptions in the literature that include a ternary mixture of oxides as a catalyst for an esterification system. It is also important to mention that, although many different types of catalysts showed very high catalytic activity in esterification reactions, the synthesis of these highly active compounds uses very expensive reagents, which are very time- consuming and demand specific apparatus that many starting laboratories cannot afford. In this context, it is preferable to use catalysts that are relatively cheap, and without complex stages of synthesis/preparation (such as some metal oxides). Therefore, the objective of this work was to evaluate, through experiments suggested by a factorial design, how a ternary oxide mixture acts in the catalysis of Lviv Polytechnic National University Institutional Repository http://ena.lp.edu.ua