HYDROCARBON RADICALS AND CARBENES ARE IMPORTANT INTERMEDIATES IN COMBUSTION AND PYROLYSIS OF HYDROCARBON FUELS. DETERMINATION OF THEIR STRUCTURE BY MEASURING THE ROTATIONAL SPECTRA OF 13C AND 2H-SUBSTITUTED ISOTOPOMERS PROVIDES THE FUNDAMENTAL INFORMATION NEEDED FOR THE INTERACTION WITH QUANTUM CHEMISTRY. PETER BOTSCHWINA (UNIVERSITY OF GOTTIGEN) IS CALCULATING AB INITIO THE STRUCTURES AND THE POTENTIALS FOR THE CUMULENE CARBENE H2C4, AND THE HC4 RADICAL. HE WILL BE ABLE TO DERIVE EQUILIBRIUM STRUCTURES FROM THE SUBSTITUTION STRUCTURES WE OBTAIN FROM OUR MEASUREMENTS OF THE ISOTOPICALLY SUBSTITUTED MOLECULES. KNOWLEDGE OF THE BOND LENGTHS AND ANGLES OF THESE REACTIVE MOLECULES OBTAINED FROM THE PROPOSED MEASUREMENTS WILL ALLOW ESTIMATION OF BOND DISSOCIATION ENERGIES AND HEATS OF FORMATION NEEDED BY THOSE MODELING THE KINETICS OF COMBUSTION AND PYROLYSIS. ABSORPTION LINES OF THE LINEAR HYDROCARBON RADICAL C4H ARE VERY STRONG (SIGNAL-TO-NOISE RATIO OF 200) IN OUR MILLIMETER-WAVE SPECTROMETER, SO WE ARE CONFIDENT WE CAN MEASURE THE ROTATIONAL SPECTRA OF 13CCCCH, C13CCH, CC13CCH, AND CCC13CH AND DETERMINE A PRECISE STRUCTURE. WE WILL THEN ATTEMPT TO MEASURE SPECTRA OF 13C-SUBSTITUTED ISOTOPOMERS OF THE CUMULENE CARBENE H2CCC. THE ROTATIONAL SPECTRUM OF H2CCCC IS MORE COMPLEX THAN THAT OF THE LINEAR C4H RADICAL, BECAUSE H2CCCC IS ASYMMETRIC AND MANY MORE CENTRIFUGAL DISTORTION TERMS ARE NEEDED TO DESCRIBE ITS SPECTRUM. THE SIR HAS SUPPLEMENTED PROFESSOR GOTTLIEB'S SUPPLY OF 13C-LABELED ACETYLENE. FOR THIS PROJECT, WE WERE COMPELLED TO IMPROVE THE SYNTHESIS OF ACETYLENE. IN ADDITION, DR. ANDREW COOKSY VISITED TO LEARN HOW TO SYNTHESIZE 13C LABELED ACETYLENE. THESE IMPROVEMENTS PROVIDED THE FOUNDATION FOR THE SYNTHESIS OF [U-13C3]GLYCEROL WHICH IS POTENTIALLY VERY IMPORTANT FOR STRUCTURAL BIOLOGY RESEARCH.
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