Surface chemistry of alkyl amines. 2. Methylamine and trimethylamine on W(100), W(100)-(5 x 1)-C, and W(100)-(2 x 1)-O

Journal Article · Wed Sep 17 04:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00279a030· OSTI ID:5344845

Pearlstine, K A; Friend, C M

The adsorption and reaction of mono- and trimethylamine have been investigated on W(100), W(100)-(5 x 1)-C, and W(100)-(2 x 1)-O, using temperature-programmed reaction spectroscopy. Reactivity and selectivity are dependent on the presence of the oxide or carbide overlayers and the degree of substitution of the amine. The activation energy for irreversible C-H bond cleavage in trimethyl- and methylamine was significantly greater on the -(2 x 1)-O and -(5 x 1)-C surfaces compared to W(100). Most notable was the elevated temperature up to where molecular amine desorption is observed on the -(2 x 1)-O: 650 and 600 K for methyl- and trimethylamine, respectively, corresponding to approximate desorption energies of 39 and 35 kcal/mol. The extent of amine substitution also qualitatively alters the product distribution, with CH/sub 4/ produced only from (CH/sub 3/)/sub 3/N and NH/sub 3/ only from (CH/sub 3/)NH/sub 2/ on W(100) and W(100)-(5 x 1)-C> No C-N bond scission products were observed on W(100)-(2 x 1)-O, consistent with the predominance of reversible molecular adsorption without significant decomposition. Possible reaction mechanisms are discussed in terms of competing C-H, N-H, and C-N bond activation.

• Research Organization: Harvard Univ., Cambridge, MA
• DOE Contract Number: FG02-84ER13289
• OSTI ID: 5344845
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:19; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATION ENERGY
ADSORPTION
AMINES
CARBON
CHEMICAL BONDS
CHEMICAL REACTIONS
DATA
ELEMENTS
ENERGY
EXPERIMENTAL DATA
INFORMATION
METALS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
THERMODYNAMICS
TRANSITION ELEMENTS
TUNGSTEN