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Title: Volatility of the catalytic hydrogenation products of 1,4 bis(phenylethynyl)benzene [The effects of hydrogenation on the volatility of organic hydrogen getters]

Measurements of equilibrium vapor pressures by effusion thermogravimetry and melting points by differential scanning calorimetry reveal that the melting temperature and equilibrium vapor pressures of 1,4-bis(phenylethynyl)benzene (DEB) do not vary monotonically with the hydrogenation extent. Contrary to intuition which suggests increasing volatility with hydrogenation, results indicate decreasing volatility for the first two hydrogenation steps before a non-monotonic upward trend, in which trans-isomers are less volatile. Insights on structural packing and functional groups were obtained from x-ray diffraction and infrared studies to shed light on the observed variation in the volatility of DEB with hydrogenation. Density functional theory calculations were performed to obtain molecular level information and to establish the thermodynamics of DEB hydrogenation reactions. A major factor influencing the observed melting points and volatility of the hydrogenated intermediate species is identified as the local attractive or repulsive carbon-hydrogen (CH) dipole interactions among the getter molecules in their respective crystal structures. As a result, such collective CH dipole interactions can be used to predict the trends in the volatilities of catalytic hydrogenation processes.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. AWE Plc, Aldermaston, Reading (United Kingdom)
Publication Date:
Report Number(s):
LLNL-JRNL-727222
Journal ID: ISSN 0021-9606
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 147; Journal Issue: 19; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; organic hydrogen getters; hydrogenation; equilibrium vapor pressures; meting temperatures; volatility
OSTI Identifier:
1418965
Alternate Identifier(s):
OSTI ID: 1420661