J. Braz. Chem. Soc., Vol. 17, No. 1, 85-89, 2006. Printed in Brazil - ©2006 Sociedade Brasileira de Química 0103 - 5053 $6.00+0.00 Article * e-mail: flancas@iqsc.usp.br Hydrolysis of Corn Oil Using Subcritical Water Jair Sebastião S. Pinto and Fernando M. Lanças* Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, 13566-590 São Carlos-SP, Brazil Este trabalho apresenta os resultados de um estudo sobre o uso da água subcrítica, como reagente e solvente, para a reação de hidrólise de óleo de milho sem o emprego de ácidos e base entre as temperaturas de 150-280 °C. A hidrólise de óleo de milho leva à formação dos seus respectivos ácidos graxos, com a mesma eficiência dos métodos convencionais. Os ácidos graxos formam um grupo importante de produtos, os quais são usados em diversas aplicações. A identificação e confirmação dos produtos da hidrólise foram feitos por HT-HRGC-FID e HRGC/MS. This work presents the results of a study on the use of subcritical water as both solvent and reactant for the hydrolysis of corn oil without the use of acids or alkalis at temperatures of 150-280 °C. Corn oil hydrolysis leads to the formation of its respective fatty acids with the same efficiency of conventional methods. Fatty acids form an important group of products, which are used in a range of applications. The confirmation and identification of the hydrolysis products was done by HT-HRGC-FID and HRGC/MS. Keywords: subcritical water, hydrolysis, fatty acids, corn oil Introduction The development of methodologies environmentally friend has been one of the principal objectives pursued by researchers of several areas as chemistry, process development and others. Ideally, the absence of organic solvents is a factor of major importance in any process, because they should be recycled, incinerated or submitted to an appropriate unitary operation that does not result in aggression to the environment. Water in the sub or supercritical state presents unusual properties that have been raising a lot of interest as an alternative solvent. 1-4 Many studies have been done exploring the use of water in conditions sub and supercritical to promote organic synthesis reactions, some of those would be alkyl-aromatics oxidation, oxidation of methane in hydrothermal systems, dehydration of alcohol, and organic transformations catalyzed by metals. 1 Another option is the employment of subcritical water as both solvent and reagent for triglycerides hydrolysis. 5 Some studies utilizing pressures higher than 2 MPa and temperature over 250 °C, demonstrate the viability of its use without the need of using either acidic or alkaline catalysts. Hydrolysis of oils is the applied term to the operation in which water reacts with oil to form glycerol and fatty acids. 6 This process is commercially important because the fatty acids are used for soap production, synthetic detergents, greases, cosmetics, and several other products. 7-9 The soap production starting from triglycerides and alkalis is accomplished for more than 2000 years by the Man. 10 where C 3 H 5 (OCOR) 3 represents triglycerides, RCOOH represents any fatty acid and C 3 H 5 (OH) 3 , glycerol. Several authors propose that this reaction is processed in stages, starting from the triglycerides for diglycerides, monoglycerides and glycerol, and to each stage there is liberation of a fatty acid. This reaction is homogeneous of first order in the oily phase. 10 As water and the oil are insoluble at low temperature, the reaction in these conditions is extremely slow. Increasing the temperature the oil solubility in water increases and the speed of the reaction accelerates quickly. An increase of 10 °C in the temperature increases the rate of reaction of a factor 10 from 1.2 to 1.5.