Measurement of inverse secondary isotope effect and photochemistry of vinyl bromide by using gas chromatograph

Abstract

The present studies were composed of three parts; i) deconvolution study of gas chromtographic peaks for mesuring of secondary isotope effects or for analyzing products during photochemical raction, ii) measurement of secondary isotope effects directly by using gas chromatography, iii) photochemistry of vinylbromide. In Part A, a simple and improved procedure to resolve an overlapped asymmetric chromatogram into its component peaks has been proposed. The overlapped asymmetric peak profile was assumed to be a convolution of its component peaks, which were characterized by an exponentially modified Gaussian (EMG). The overlapped EMG function was simplified by using its derivative chromatogram and a new technique for initial guessing was suggested. The simulation study showed that the present techniques were praxtical for implimmenation on microcomputer. This techinques were confirmed its validity by comparing with experimental observations and its recovering abilities were found to be no more than 1.6\% of deviations from true values and 2.2\% in standard deviation throughout the study. In Part B, the inverse secondary isotope effects of Rh(I)-$C_2H_4$ and Rh (I)-$C_2H_3D$ were measured directly using a GC column of dicarbonyl-rhodium (I)-3-trifluoroacetyl-1R-camphorate (RHC) in squalane solution and were also deduced from a reduced partition function using harmonic vibrational frequencies of Rh(I)-$C_2H_4$ and Rh(I)-$C_2H_3D$ complexes. The onserved isotope effects were reasonable agreement with the deduced ones from the reduced partition function. Thermodynamic date of the inverse isotope effect were $\triangle_{D,H}\triangle{H}=469\,\pm\,12\,J\,mol^{-1}$ and $\triangle_{D,H}\triangle{S}=-0,975\,\pm\,0.017\,J\,mol^{-1}\,K^{-1}$, respectively. From the vibrational frequencies assignment of RHC-$C_2H_4$, we have correlated the separation factors in the complexation $GC_s$ with the extent of $C_2H_4$ rehybridization for complexation. In Part C, The photolysis of g...