Quantum Chemical Study of the Interaction of the Short-Chain Poly(oxyethylene)s CH3(OCH2CH2)mOCH3(C1EmC1;m= 1 and 2) with a Water Molecule in the Gas Phase and in Solutions

2006 ◽  
Vol 110 (3) ◽  
pp. 1052-1059 ◽  
Author(s):  
Shaheda A. Wahab ◽  
Takanori Harada ◽  
Toshiaki Matsubara ◽  
Misako Aida
Keyword(s):  
Water Molecule ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Short Chain

A quantum-chemical study of dehydration of ortho forms of formaldehyde and formic acid

1986 ◽  
Vol 51 (9) ◽  
pp. 1819-1833 ◽  
Author(s):  
Jaroslav Leška ◽  
Eugen Németh ◽  
Dušan Loos
Keyword(s):  
Oxygen Atom ◽  
Water Molecule ◽  
Formic Acid ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Reaction Paths ◽  
Full Optimization ◽  
Acid Catalyzed

Gas-phase dehydration of methanediol (I) and methanetriol (II) has been studied by the MINDO/3 method with full optimization of the reaction paths. The intramolecular dehydration goes via high barriers (I 257.4, II 193.3 kJ mol-1). The acid-catalyzed dehydration involving protonation at oxygen atom of I goes via a considerably lower barrier (63.3 kJ mol-1), whereas protonation at oxygen atom of II results in practically spontaneous dehydration (0.4 kJ mol-1), which is the reason for the formic acid not being hydrated in water. Deprotonation of the protonated formaldehyde (II) and protonated formic acid (IV) is connected with high barriers (429.1 and 523.0 kJ mol-1, resp.). The deprotonation by a water molecule added to III and IV involves substantially lower barriers (53.9 and 96.3 kJ mol-1, resp.).

An alternative gas-phase electron diffraction and quantum chemical study of nitroethane

2010 ◽  
Vol 978 (1-3) ◽  
pp. 41-47 ◽  
Author(s):  
Igor F. Shishkov ◽  
Victor A. Sipachev ◽  
Piotr I. Dem’yanov ◽  
Olga V. Dorofeeva ◽  
Natalja Vogt ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Gas Phase Electron Diffraction

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.

The infrared absorption intensities of the water molecule: A quantum chemical study

1986 ◽  
Vol 84 (10) ◽  
pp. 5715-5727 ◽  
Author(s):  
David J. Swanton ◽  
George B. Bacskay ◽  
Noel S. Hush
Keyword(s):  
Water Molecule ◽  
Infrared Absorption ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study
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