Absolute Proton Affinity for Acetaldehyde

Autor:	John C. Traeger
Rok vydání:	2007
Předmět:	chemistry.chemical_compound Fragmentation (mass spectrometry) chemistry Ab initio quantum chemistry methods Acetaldehyde Proton affinity Physical chemistry Molecular orbital Appearance energy Photoionization Physical and Theoretical Chemistry Photochemistry Standard enthalpy of formation
Zdroj:	The Journal of Physical Chemistry A. 112:342-346
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp077596y
Popis:	Dissociative photoionization mass spectrometry has been used to measure appearance energies for the 1-hydroxyethyl cation (CH(3)CH=OH(+)) formed from ethanol and 2-propanol. Molecular orbital calculations for these two unimolecular fragmentation reactions suggest that only methyl loss from ionized 2-propanol does not involve excess energy at the threshold. The experimental appearance energy of 10.31 +/- 0.01 eV for this latter process results in a 298 K heat of formation of 593.1 +/- 1.2 kJ mol(-1) for CH(3)CH=OH(+) and a corresponding absolute proton affinity for acetaldehyde of 770.9 +/- 1.3 kJ mol(-1). This value is supported by both high-level ab initio calculations and a proposed upward revision of the absolute isobutene proton affinity to 803.3 +/- 0.9 kJ mol(-1). A 298 K heat of formation of 52.2 +/- 1.9 kJ mol(-1) is derived for the tert-butyl radical.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1a55de229eedd8bb206b2cb1a8f513e5 https://doi.org/10.1021/jp077596y Zobrazit plný text záznamu