An official website of the United States government
The Prototypical Transition Metal Carbenes, (CO) 5 Cr=CH 2 , (CO) 4 Fe=CH 2 , (CO) 3 Ni=CH 2 , (CO) 5 Mo=CH 2 , (CO) 4 Ru=CH 2 , (CO) 3 Pd=CH 2 , (CO) 5 W=CH 2 , (CO) 4 Os=CH 2 , and (CO) 3 Pt=CH 2 : Challenge to Experiment
- Award ID(s):
- 1661604
- PAR ID:
- 10066113
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry A
- ISSN:
- 1089-5639
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
A series of N-doped porous carbons with different textural properties and N contents was prepared from a mixture of algae and glucose and their capability for the separation of CO 2 /CH 4 , C 2 H 6 /CH 4 , and CO 2 /H 2 binary mixtures under different conditions (bulk pressure, mixture composition, and temperature) were subsequently assessed in great detail. It was observed that the gas (C 2 H 6 , CO 2 , CH 4 , and H 2 ) adsorption capacity at different pressure regions was primarily governed by different adsorbent parameters (N level, narrow micropore volume, and BET specific surface area). More interestingly, it was found that N-doping can selectively enhance the heats of adsorption of C 2 H 6 and CO 2 , while it had a negligible effect on those of CH 4 and H 2 . The adsorption equilibrium selectivities for separating C 2 H 6 /CH 4 , CO 2 /CH 4 , and CO 2 /H 2 gas mixture pairs on the porous carbons were predicted using the ideal adsorbed solution theory (IAST) based on pure-component adsorption isotherms. In particular, sample NAHA-1 exhibited by far the best performance (in terms of gas adsorption capacity and selectivity) reported for porous carbons for the separation of these three binary mixtures. More significantly, NAHA-1 carbon outperforms many of its counterparts ( e.g. MOFs and zeolites), emphasizing the important role of carbonaceous adsorbents in gas purification and separation.more » « less
-
Abstract Carbonyl-bearing complex organic molecules (COMs) in the interstellar medium (ISM) are of significant importance due to their role as potential precursors to biomolecules. Simple aldehydes and ketones like acetaldehyde, acetone, and propanal have been recognized as fundamental molecular building blocks and tracers of chemical processes involved in the formation of distinct COMs in molecular clouds and star-forming regions. Although previous laboratory simulation experiments and modeling established the potential formation pathways of interstellar acetaldehyde and propanal, the underlying formation routes to the simplest ketone—acetone—in the ISM are still elusive. Herein, we performed a systematic study to unravel the synthesis of acetone, its propanal and propylene oxide isomers, as well as the propenol tautomers in interstellar analog ices composed of methane and acetaldehyde along with isotopic-substitution studies to trace the reaction pathways of the reactive intermediates. Chemical processes in the ices were triggered at 5.0 K upon exposure to proxies of Galactic cosmic rays in the form of energetic electrons. The products were detected isomer-selectively via vacuum ultraviolet (VUV) photoionization reflectron time-of-flight mass spectrometry. In our experiments, the branching ratio of acetone (CH3COCH3):propylene oxide (c-CH3CHOCH2):propanal (CH3CH2CHO) was determined to be (4.82 ± 0.05):(2.86 ± 0.13):1. The radical–radical recombination reaction leading to acetone emerged as the dominant channel. The propenols appeared only at a higher radiation dose via keto–enol tautomerization. The current study provides mechanistic information on the fundamental nonequilibrium pathways that may be responsible for the formation of acetone and its (enol) isomers inside the interstellar icy grains.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.jpca.8b05394
