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Ab initio investigations of isopropyl cyanide reaction mechanisms and kinetics of formation on an icy grain model

Published online by Cambridge University Press:  12 October 2020

Boutheïna Kerkeni*
Affiliation:
Institut Supérieur des Arts Multimédia de la Manouba, Université de la Manouba, 2010 la Manouba, Tunisia Faculté des Sciences de Tunis, Département de Physique, (LPMC), Université de Tunis El Manar, 2092 Tunis, Tunisia Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92195 Meudon, France email: boutheina.kerkeni@isamm.uma.tn
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Abstract

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Isopropyl-cyanide (iso-PrCN) was recently observed in Sagittarius B2 with an abundance higher than its straight-chain structure isomer (n-PrCN). Here we study theoretically by means of [UMP2(full)/aug-cc-pVTZ/Amber] a hybrid ab initio/molecular mechanics methodology, the routes leading to its formation on a formaldehyde doped water ice grain model of the interstellar medium. The reaction path and the energetics are calculated, the mechanism is found to be exothermic by ∼ 30 kcal/mol and the barrier is ∼ 70 kcal/mol. We use the CVT/ZCT semiclassical method to predict the kinetics of the reaction path starting from initially adsorbed HCN and CH2CHCH3 molecules colliding from the gas phase over the temperature range [100–500K].

Type
Contributed Papers
Copyright
© International Astronomical Union 2020

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