930-18-7Relevant articles and documents
GC/MS SEPARATION AND IDENTIFICATION OF THE C5H10 ISOMERS. APPLICATION TO THE Hg 6(3P1) PHOTOSENSITIZED REACTIONS OF cis-2-PENTENE, 1-PENTENE AND trans-1,2-DIMETHYLCYCLOPROPANE
Mare, George R. De,Termonia, Marc
, p. 155 - 160 (2007/10/02)
The analysis (separation and identification) of eleven C5H10 isomers is performed using coupled GC/MS with a 70 m glass capillary column containing a 2.5 μm thick film of PS225 as stationary phase.Cryogenic CO2 cooling improves the separations.The total analysis time is less than 12 minutes. - Some mechanistic details on the Hg 6(3P1) (hereafter denoted by Hg*) photosensitization of the title compounds are elucidated.Thus the Hg* photosensitization of cis-2-pentene at 20 Torr yields methylcyclobutane with a quantum yield Φ = O.1, not ethylcyclpropane as was previously thought. (Ethylcyclopropane is formed in trace quantities.) The photostationary state for the Hg* sensitization of the 2-pentenes is confirmed to correspond to the concentration ratio / = 1.00.Trans-1,2-dimethylcyclopropane is a product of the Hg* photosensitization of 1-pentene.The major products of the Hg* photosensitization of trans-1,2-dimethylcyclopropane at 80 Torr are 3-methyl-1-butene, trans- and cis-2-pentene and cis-1,2-dimethylcyclopropane which are all formed with quantum yields near 0.1 and in the ratios 1.04 : 1.07 : 1.00 : 1.45.
Multistep Collisional Deactivation of Chemically Activated Dimethylcyclopropane
Szilagyi, I,Zalotai, L.,Berces, T.,Marta, F.
, p. 3694 - 3700 (2007/10/02)
The decomposition of chemically activated cis- and trans-dimethylcyclopropane formed by the photolysis of ketene (at 334 nm) or diazomethane (at 436 and 366 nm) in the presence of excess cis-butene-2 and small amounts of oxygen was studied.Apparent first-order decomposition rate coefficients for the chemically activated molecules were measured and found to be pressure dependent over the extended pressure range from 0.1 to 40 kPa.The turnup observable at low pressure demonstrates the occurence of multistep deactivation of the chemically activated molecules,while the pressure dependence at high pressure is indicative of a wide initial vibrational energy distribution of cis-dimethylcyclopropane.The theoratical approach used RRKM theory to calculate the energy-dependent decomposition rate coefficients and assumed a stepladder model to describe collisional transition probabilities.The initial energy distributions of cis-dimethylcyclopropane were approximated by shifted Gaussian-type functions.The experimental results could be fit over the entire pressure range investigated with a theoratical model utilizing a collisional deactivation step size of about 14-22 kJ mol-1 and initial energy distributions whose widths increased with increasing energy of chemically activated molecules.It has been concluded that the wide distributions obtained in the diazomethane photolysis systems were mainly due to the dispersion originating from energy partitioning in the photolytic event producing singlet methylene.
