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Ab initio quantum chemical studies of reactions in astrophysical ices. 4. Reactions in ices involving HCOOH, CH 2 NH, HCN, HNC, NH 3 , and H 2 O
Author(s) -
Woon David E.
Publication year - 2001
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.10082
Subject(s) - chemistry , formamide , methylamine , hydrogen cyanide , formic acid , ammonia , ab initio , yield (engineering) , hydrogen , cyanate , quantum yield , isocyanide , photochemistry , computational chemistry , inorganic chemistry , medicinal chemistry , organic chemistry , thermodynamics , physics , quantum mechanics , fluorescence
Ice‐bound condensed‐phase reactions involving formic acid (HCOOH), methylenimine (CH 2 NH), hydrogen cyanide (HCN), hydrogen isocyanide (HNC), and ammonia (NH 3 ) were investigated in order to characterize possible pathways to larger organic species that are efficient at the cold temperatures prevalent in cometary nuclei and the interstellar medium. Previous laboratory and computational modeling has demonstrated that reactions between some closed‐shell species can be significantly enhanced when they occur within a matrix of water ice. Certain key reactions can occur at temperatures under 100 K, in spite of having gas phase barriers that may be 30 kcal/mol or higher. The present study considered one‐ and two‐step reactions of HCOOH and NH 3 to yield formamide (NH 2 CHO), reactions between CH 2 NH and HCN, HNC, NH 3 , and H 2 O, and the reaction of HCOOH and CH 2 NH to yield glycine (NH 2 CH 2 COOH). The most favorable process identified in this work is production of NH 2 CH(OH) 2 , the intermediate in the two‐step pathway from HCOOH and NH 3 to NH 2 CHO, which is enhanced considerably when it occurs within ice but not to the extent that it is likely to occur unassisted at temperatures below 100 K. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 88: 226–235, 2002