Reaction Between CH2 and HCCN: A Theoretical Approach to Acrylonitrile Formation in the Interstellar Medium

Shivani, .; Misra, Alka; Tandon, Poonam

doi:10.1007/s11084-014-9373-6

Cited by 8 publications

(4 citation statements)

References 56 publications

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“…5). Reaction 3 has been previously studied by Shivani et al (2014) and Shivani and Tandon (2014) where they also observed the reaction to be barrierless with an enthalpy of formation of about −52.89 kcal mol −1 at B3LYP/6-311++G(d,p) and −51.78 kcal mol −1 at MP2/6-311++G(d,p) levels of theory. At the UMP2/6-311+(2d,p)//UM062X/6-311+(2d,p) level of theory, the enthalpy of formation for reaction 3 is calculated to be −176.958 kcal mol −1 .…”

Section: Resultsmentioning

confidence: 91%

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

Singh

Tandon

Misra

et al. 2020

International Journal of Astrobiology

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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.

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Section: Resultsmentioning

confidence: 91%

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

Singh

Tandon

Misra

et al. 2020

International Journal of Astrobiology

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“…On the other hand, the abundances of CH 2 CHCN and CH 3 CH 2 CN were highly affected by the inclusion of the related surface routes even when CH 2 CHCN became over abundant. We found that the formation of CH 2 CHCN via the radical-radical reaction (CH 2 + HCCN) proposed by Shivani et al (2014) is very effective while the hydrogenation of HC 3 N is less efficient. The enhanced abundance of this molecule is probably due to the high abundance of one of its parent molecules.…”

Section: Resultsmentioning

confidence: 92%

“…(1) and the radical-radical reactions (2) and (3) from Garrod et al (2008) and Shivani et al (2014), respectively NH 2 + HCO → NH 2 CHO, and…”

Section: Chemical Modelmentioning

confidence: 99%

Nitrogen bearing species in massive star forming regions

Awad

Shalabiea

2019

Proc. IAU

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Recent observations revealed that there is a difference in the spatial distribution of both nitrogen and oxygen bearing species towards massive star forming regions. These differences can be explained under different temperature regimes in hot cores. In this study, we attempt to model the chemistry of few nitrogen species; namely, vinyl cyanide (CH2CHCN), ethyl cyanide (CH3CH2CN), and formamide (NH2CHO), using gas-grain chemical models. A special attention is given to the role and efficiency of surface chemistry as it is suggested to play one of the main key roles in manufacturing these species.

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“…When increasing the temperature, heavier molecules get ionized and addition-addition reactions take place to form large molecules. Radicals are formed through the photodissociation of simple molecules in grains (Shivani et al 2014;Laas et al 2011). A totally exothermic, barrierless reaction path with good estimation of rate coefficients increases the probability of occurrence.…”

Section: Introductionmentioning

confidence: 99%

Formation of E-cyanomethamine in a nitrile rich environment

Shivani

Misra

Tandon

2017

Res. Astron. Astrophys.

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Recently a new molecule, cyanomethamine, has been detected towards Sagittarius B2(N) (Sgr B2(N)). Studying the formation mechanisms of complex interstellar molecules is difficult. Hence, a theoretical quantum chemical approach for analyzing the reaction mechanism describing the formation of interstellar cyanomethamine through detected interstellar molecules and radicals (NCCN+H) is discussed in the present work. Calculations are performed by using quantum chemical techniques, such as Density Functional Theory (DFT) and Møller-Plesset perturbation (MP2) theory with a 6-311G(d,p) basis set, both in the gas phase and in icy grains. The proposed reaction path (NCCN+H+H) has exothermicity with no barrier which indicates the possibility of cyanomethamine formation in the interstellar medium.

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Reaction Between CH2 and HCCN: A Theoretical Approach to Acrylonitrile Formation in the Interstellar Medium

Cited by 8 publications

References 56 publications

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

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

Nitrogen bearing species in massive star forming regions

Formation of E-cyanomethamine in a nitrile rich environment

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