IR VARIABLE TEMPERATURE SPECTROSCOPY (I). HYDROGEN BONDING IN 1,2,3,4-TETRAHYDRONAPHTALIL HYDROPEROXIDE Cristina Mandravel Ú , Maria Deacu and Ioana Stanculescu The aim of this work was to study the effect of controlled heating on the 1,2,3,4- tetrahydronaphtalil hydroperoxide in tetraline solutions. Using two solvents, CCl4 and tetraline, it was systematically observed the change of IR spectra, carried out at different temperatures. It was determined the activation energy, Ea, of the hydrogen bonding for hydroperoxide of tetraline (HPT). Introduction Hydroperoxydes are, in general, used as initiators in process of polymerisation because of their high reactivity [1]. The type of their decomposition is a very interesting characteristic. Thus, kinetics of the decomposition for hydroperoxide of 1,2,3,4 tetrahydronaphtalene (HPT) was studied in different conditions: in presence of polyoxyethylene complexes with CoCl 2 , of Co (II) and Cu (II) salts, or some acids [2÷4]. In relation with this we are interested in the spectral and theoretical studies of hydrogen bonding of different compound in various matrices [5,6]. The breaking of these bonds in process of heating is a preliminary physical stage to that of decomposition. We use in this study the IR variable temperature spectroscopy as differentiating technique. As is known, the existence of hydrogen bonding affects all the modes of vibrations related with the polar groups X-H.[7] But the effect of temperature on IR spectra of HPT solutions must be the most spectacular. Experimental The IR spectra were obtained using SPECORD IR–71 Carl Zeiss Jena spectrophotometer within the range 4600-650 cm -1 . For this study we used a variable temperature IR-cell and an electrical heating system, made by the same firm, which was calibrated by us to assure a suitable temperature control (to 1°C) in the range of temperature –180 to +250°C /6/. The time necessary to attend the thermal equilibrium was 15-30 minutes to temperature below 70°C and approximately one hour for highest temperatures. IR spectra of HPT solutions were carried out only after stabilization of thermal equilibrium. For one solution on the same spectrogram were registered distinctly the spectra at 3÷4 temperatures at two rates of Ú Faculty of Chemistry, Department of Physical Chemistry, University of Bucharest, 4-12 Regina Elisabeta, Bucharest, Romania