RESEARCH ARTICLE Investigation of the interaction of ethyl acetoacetate with nano alumina particle as Lewis acid in acetonitrile solvent Asadollah FARHADI (✉) 1 , Mohammad Ali TAKASSI 1 and Mandana DAYER 2 The enol form of ethyl acetoacetate (EAA) displays interesting spectroscopic characteristics; this form of ethyl acetylacetate is very important in condensation reaction. In this investigation, we have studied the interactions and the complex formation constants (K f ) with nano alumina (10–20 nm) particle and alumina (mesh 135) compounds as Lewis acids in the acetonitrile solvent using absorption spectroscopy and related calculations. Furthermore, in this study we calculated the thermodynamic parameters of this reaction. The trend of reactivity of the ethyl acetoacetate (EAA) complexes toward the above Lewis acids, based on the solvent as follows: nano alumina compound > alumina compound. Keywords complex formation constant, ethyl acetoace- tate, nano alumina, alumina, thermodynamic 1 Introduction β-diketones are important compounds in chemistry. They are among the most widely used ligands in coordination chemistry [1]. β-diketones are in solutions as keto and enol tautomers. Since the enolic hydrogen is labile, it can be replaced by a metal cation to form a six-member chelate ring. The β-diketonate complexes thus formed have been the topic of hundreds of papers and reviews [1–5], and widely used in a lot of aspects in industry, such as organic electroluminescent technology, luminescent materials, sensors for bioinorganic applications, luminescent labels in bioaffinity assays [1,2], NMR shift reagents [6–8], laser chelates [9,10], extraction agents [11–13], heat stabilizers for polymers, drugs [14,15], chemical and photochemical catalysts [16]. Moreover, they are used in manufacturing supra-conductors [17,18] and gas chromatography [19,20]. A few papers have also appeared in which β-diketones have been shown to act as neutral ligands by establishing a coordinative interaction with the metal cation [21–26]. However, in this paper, we report the thermodynamic studies on the complexes formation constants (K f ) of ethyl acetoacatate with nano alumina particle and alumina com- pounds as Lewis acids in acetonitrile solvents by Scatchard’s Eq. (1) [27] and the evaluation of the effect of the size of the Lewis acids on K f of complexes. (Scheme 1) 2 Experimental 2.1 Materials and apparatus The materials, ethyl acetoacetate (EAA), the solvent and Lewis acids were obtained from Merck, Fluka and Aldrich. All of the scanning UV-Vis spectra were recorded by Cintra 101 spectrophotometer. 2.2 Electronic spectra The electronic spectra of all investigated complexes show an absorption band at 300–200 nm in this solvent in various temperatures. All complexes show an intensive absorption band at 270–220 nm. During the reactions, we could not observe the isobestic point in all solutions. Fig. 1 shows the spectrum of complex EAA with Al 2 O 3 (nano) compound as Lewis acids in acetonitrile as solvent at different temperatures. The other spectrum of EAA complex with the Al 2 O 3 compound as Lewis acid is similar to Fig. 1. All measure- ments for the thermodynamic studies were carried out at maximum wavelength (l max = 242 nm) (Table 1). 3 Results and discussion A solution from each complex with a concentration of about 10 –3 mol/L was prepared. The formation constants and the thermodynamic parameters were measured spectrophotome- trically. The complex formation measurements were carried out using the Lewis acids in acetonitrile solvent at various temperatures (Scheme 1). The formation constants of EAA complexes were calculated by Scatchard’s Eq. (1) in which b 0 and a 0 are the initial concentrations of the acceptor (Lewis acid) and the donor (EAA) respectively; D (l) is the optical density of the solution including the acceptor (Lewis acid) and the donor (EAA). ε AB (l) is the molar extinction coefficients Received July 1, 2011; accepted July 20, 2011 1. Faculty of Science, Petroleum University of Technology, Ahwaz 61981-44471, Iran 2. Department of Chemistry, Science and Research Branch, Islamic Azad University, Khouzestan, Iran E-mail: farhadichem@yahoo.com Front. Chem. China 2011, 6(3): 248–252 DOI 10.1007/s11458-011-0247-4 ©Higher Education Press and Springer-Verlag Berlin Heidelberg 2011