Disproportionation/Combination Ratio for H + sec-C4H9

Article abstract of DOI:10.1039/ft9928800663

The reactions of hydrogen atoms with large excesses of various butene isomers have been investigated at a temperature of 290 +/- 3 K, over a pressure range 4-16 Torr (predominantly argon) in a conventional flow-discharge system with gas-chromatographic analysis of the infinite-time reaction products.Two series of experiments were carried out.In the first, each of but-1-ne, (Z)-but-2-ene and (E)-but-2-ene was separately reacted with hydrogen atoms the only measurements made being the ratio of the yields of the other two butenes which are produced.The products of the three possible dispro portionation reactions of H + sec-C4H9 are in the proportions but-1-ene:(E)-but-2-ene:(Z)-but-2-ene = 43.0:40.8:16.3.In a second series of experiments, (Z)-but-2-ene and (E)-but-2-ene reacted separately with hydrogen atoms with a full analysis of products being made.Values are derived for the disproportionation/combination ratio for H + sec-C4H9 (0.66 +/- 0.08) and for the upper limit to the ratio of the rate constant for unimolecular decomposition to that for bimolecular stabilisation (< 1.2x10^-7 mol cm^-3) for excited C4H10 produced by addition of H to sec-C4H9.The basic analysis procedure used is validated by showing that the flow rate of hydrogen atoms necessary to generate the observed products is, within experimental error, equal to the measured flow rate of hydrogen atoms.

Full text of DOI:10.1039/ft9928800663

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