Ion thermochemistry of low-volatility compounds in the gas phase. 1. Intrinsic basicities of .alpha.-amino acids

1979 ◽  
Vol 101 (3) ◽  
pp. 686-689 ◽  
Author(s):  
Michael Meot-Ner ◽  
Edward P. Hunter ◽  
Frank H. Field
Keyword(s):  
Amino Acids ◽  
Gas Phase ◽  
Phase 1

Chiral Ions in the Gas Phase. 1. Intramolecular Racemization and Isomerization of O-Protonated (S)-trans-4-Hexen-3-ol

1997 ◽  
Vol 119 (19) ◽  
pp. 4525-4534 ◽  
Author(s):  
Anna Troiani ◽  
Francesco Gasparrini ◽  
Felice Grandinetti ◽  
Maurizio Speranza
Keyword(s):  
Gas Phase ◽  
Phase 1

Vibrational Signature of Charge Solvation vs Salt Bridge Isomers of Sodiated Amino Acids in the Gas Phase

2004 ◽  
Vol 126 (6) ◽  
pp. 1836-1842 ◽  
Author(s):  
Catherine Kapota ◽  
Joël Lemaire ◽  
Philippe Maître ◽  
Gilles Ohanessian
Keyword(s):  
Amino Acids ◽  
Gas Phase ◽  
Salt Bridge ◽  
Charge Solvation

Kinetic Resolution ofd,l-Amino Acids Based on Gas-Phase Dissociation of Copper(II) Complexes

1999 ◽  
Vol 71 (19) ◽  
pp. 4427-4429 ◽  
Author(s):  
W. Andy Tao ◽  
Duxi Zhang ◽  
Feng Wang ◽  
Peter D. Thomas ◽  
R. Graham Cooks
Keyword(s):  
Amino Acids ◽  
Gas Phase ◽  
Kinetic Resolution ◽  
Gas Phase Dissociation

An On-Line Isocratic HPLC System for the Analysis of PTH-Amino Acids on A Gas-Phase Sequencer

Proteins ◽  
1987 ◽  
pp. 383-394
Author(s):  
J. E. Shively ◽  
D. Hawke ◽  
R. M. Kutny ◽  
B. Krieger ◽  
J. L. Glajch
Keyword(s):  
Amino Acids ◽  
Gas Phase ◽  
Hplc System ◽  
On Line ◽  
Isocratic Hplc

An Integrated Approach to Geological Disposal of UK Wastes Containing Carbon-14

2013 ◽  
Author(s):  
Sarah Vines ◽  
David Lever
Keyword(s):  
Radioactive Waste ◽  
Gas Phase ◽  
Alternative Treatment ◽  
Phase 1 ◽  
Project Team ◽  
Waste Stream ◽  
Second Phase ◽  
Geological Disposal ◽  
Carbon 14 ◽  
Design Options

Carbon-14 is a key radionuclide in the assessment of the safety of a geological disposal facility for radioactive waste because of the calculated assessment of the radiological consequences of gaseous carbon-14 bearing species [i]. It may be that such calculations are based on overly conservative assumptions and that better understanding could lead to considerably reduced assessment of the radiological consequences from these wastes. Alternatively, it may be possible to mitigate the impact of these wastes through alternative treatment, packaging or design options. The Radioactive Waste Management Directorate of the UK’s Nuclear Decommissioning Authority (NDA RWMD) has established an integrated project team in which the partners are working together to develop a holistic approach to carbon-14 management in the disposal system [ii]. For a waste stream containing carbon-14 to be an issue: • There must be a significant inventory of carbon-14 in the waste stream; AND • That waste stream has to generate carbon-14 bearing gas; AND • A bulk gas phase has to entrain the carbon-14 bearing gas: AND • These gases must migrate through the engineered barriers in significant quantities; AND • These gases must migrate through the overlying geological environment (either as a distinct gas phase or as dissolved gas); AND • These gases must interact with materials in the biosphere (i.e. plants) in a manner that leads to significant doses and risks to exposed groups or potentially exposed groups. The project team has developed and used this “AND” approach to structure and prioritise the technical work and break the problem down in a manageable way. We have also used it to develop our approach to considering alternative treatment, packaging and design options. For example, it may be possible to pre-treat some wastes to remove some of the inventory or to segregate other wastes so that they are removed from any bulk gas phase which might facilitate migration through the geosphere. Initially, the project team has undertaken a six month programme of work to examine the current understanding of these aspects and has captured this in the Phase 1 report [ii], in a modelling basis spreadsheet and in scoping assessments, which help us better understand the potential significance of carbon-14. Using the current modelling basis, but ignoring any potential benefits from the geosphere in retarding or preventing gas from reaching the surface, the calculated release of carbon-14 is dominated by: corrosion of irradiated reactive metals (in the operational and early post-closure time frame); corrosion of irradiated stainless steel and leaching of irradiated graphite (in the longer term). The Phase 1 work has shown that there is considerable scope for reducing the calculated radiological consequence for these wastes and a roadmap has been developed for a second Phase of work.

Quantum chemical study on the formation of isopropyl cyanide and its linear isomer in the interstellar medium

2020 ◽  
pp. 1-11
Author(s):  
Keshav Kumar Singh ◽  
Poonam Tandon ◽  
Alka Misra ◽  
Shivani ◽  
Manisha Yadav ◽  
...  
Keyword(s):  
Amino Acids ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Dark Cloud ◽  
Water Ice ◽  
Hydrocarbon Radicals

Abstract The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN is especially important since it is the first and only branched molecule in ISM, hence, it could be a precursor of branched amino acids such as leucine, isoleucine, etc. Therefore, both n-PrCN and i-PrCN have significant astrobiological importance. To study the formation of n-PrCN and i-PrCN in ISM, quantum chemical calculations have been performed using density functional theory at the MP2/6-311++G(2d,p)//M062X/6-311+G(2d,p) level. All the proposed reactions have been studied in the gas phase and the interstellar water ice. It is found that reactions of small cyanide with hydrocarbon radicals result in the formation of either large cyanide radicals or ethyl and vinyl cyanide, both of which are very important prebiotic interstellar species. They subsequently react with the radicals CH2 and CH3 to yield n-PrCN and i-PrCN. The proposed reactions are efficient in the hot cores of SgrB2 (N) (where both n-PrCN and i-PrCN were detected) due to either being barrierless or due to the presence of a permeable entrance barrier. However, the formation of n-PrCN and i-PrCN from the ethyl and vinyl cyanide always has an entrance barrier impermeable in the dark cloud; therefore, our proposed pathways are inefficient in the deep regions of molecular clouds. It is also observed that ethyl and vinyl cyanide serve as direct precursors to n-PrCN and i-PrCN and their abundance in ISM is directly related to the abundance of both isomers of propyl cyanide in ISM. In all the cases, reactions in the ice have smaller barriers compared to their gas-phase counterparts.

Electrocyclic reactions of gas-phase 1-methyl- and 3-methylcyclobutene radical cations

1984 ◽  
Vol 106 (20) ◽  
pp. 5780-5786 ◽  
Author(s):  
Chhabil Dass ◽  
Thomas M. Sack ◽  
Michael L. Gross
Keyword(s):  
Gas Phase ◽  
Phase 1 ◽  
Radical Cations ◽  
Electrocyclic Reactions
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