Thermochimica Acta, 80 (1984) 115-122 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands 115 zyxwvutsrqpo THERMilL STUDIES ON 2,6_XYLYLIMINODIACETATO COMPOUNDS OF SOME TRANSITION METAL IONS M. ROMAN-CEBA, J.C. AVILA ROSON and J. SUAREZ-VARELA Department of Generai Chemistry, Faculty of Sciences, University of Granada, Granada (Spain) J.M. SALAS-PEREGRIN * Department of Inorganic Chemistry, Faculty of Sciences, University of Granada, Granada (Spain) (Received 23 April 1984) ABSTRACT Some new 2,6-xylyliminodiacetato compounds of Mn(II), Fe(III), Ni(III), Zn(I1) and Cd(I1) have been prepared in aqueous media. The thermal behaviour of these compounds has been studied by TG, DTG, and DSC techniques. Heats of dehydration have been calculated from the DSC curves. INTRODUCTION The iminodiacetic acids RN(CH,-COOH), are excellent complexing agents for most di- and trivalent cations [l-6]. These compounds are weak acids with “zwitterion” or dual type ion formation causing considerable differences in the dissociation of the acid groups [7]. When partially neutral- ized, these acids readily form chelate compounds with most cations; in these compounds chelate formation occurs through the nitrogen and acid groups zyxwvutsrq [81. An aryl derivative of iminodiacetic acid, the 2,6-xylyliminodiacetic acid, 2,6-H, XIDA (Scheme l), was synthesized by Skubin et al. [9] who de- CH3 / 0 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA CH2 -COO t-) / -N-H I+),\ \ CHz -coon C”a Scheme 1 termined its first dissociation constant (pK= 2.92). Recently, Salinas et al. * To whom correspondence should be addressed. 0040-6031/84/$03.00 0 1984 Elsevier Science Publishers B.V.