BEGIN:VCALENDAR VERSION:2.0 PRODID:-//ZContent.net//ZapCalLib 1.0//EN CALSCALE:GREGORIAN METHOD:PUBLISH BEGIN:VEVENT DTSTART;TZID=Atlantic/Canary:20230518T103000 DTEND;TZID=Atlantic/Canary:20230518T113000 UID:iactalks-1659 X-WR-CALNAME: IAC Talks: Open Astronomy Seminars X-ORIGINAL-URL: /iactalks/Talks/view/1659 CREATED:2023-05-18T10:30:00+01:00 X-WR-CALDESC: IAC Talks upcomming talks SUMMARY:Complex Organic Molecules in the Interstellar Medium DESCRIPTION:Complex Organic Molecules in the Interstellar Medium\nDr. Bouth eïna Kerkeni\n\nMore than 200 species have been detected in the interstel lar medium (ISM), among them many molecules, radicals and ions, conta ining the −C≡N functional group. Both linear and branched  ;isomers of propyl cyanide (PrCN; C 3 H 7 CN) are ubiquitous in interstell ar space. To date, PrCN is one of the most complex molecules found in the interstellar medium. Furthermore, it is the only one observed sp ecies to share the branched atomic backbone of amino acids, some of the bu ilding blocks of life. Radical-radical chemical reactions in gas phas e and on an ice model are examined in detail using density functional theory M062X/6-311++g(d,p) and ab initio methods CCSD(T)-F12//MP2. The re action mechanism involves the following radicals association: CH 3 CHCH 3 +CN, CH 3 +CH3CHCN for iso-PrCN and CH 3 CH 2 +CH 2 CN, CH 3 +CH 2 CH 2 CN, CN+CH 3 CH 2 CH 2 for n-PrCN formation. Rate constants (see Fi gure 1) are also reported for gas phase association reactions. All re action paths are exoergic and barrier-less in the gas phase and on the ice -model, suggesting that the formation of iso-PrCN and n-PrCN is effic ient on the water-ice model adopted.\n Another molecule : acetaldehyd e (CH 3 CHO) is ubiquitous in interstellar space and is important for astrochemistry as it can contribute to the formation of amino acids throu gh reaction with nitrogen containing chemical species. Quantum chemic al and reaction kinetics studies are reported for acetaldehyde format ion from the chemical reaction of C(3 P) with a methanol molecule ads orbed at the eighth position of a cubic water cluster. We present extensiv e quantum chemical calculations by means of CCSD(T)//wB97XD/6-311++G( 2d,p) for total spin S=1 and S=0. The rate limiting step for forming acetaldehyde is the C–O bond breaking in CH 3 OCH to form adsorbedCH 3 and HCO. We find two positions on the reaction path where spin crossing may be possible such that acetaldehyde can form in its singlet spin state.\n1. I. BenChouikha, B. Kerkeni, et al. “Quantum chemical stud y of the reaction paths and kinetics of acetaldehyde formation on a m ethanol-water ice model”, ACS Adv., 12,18994 (2022).2. B. Kerkeni, V Gámez, G. Ouerfelli, M-L. Senent, and N. Feautrier “Understa nding Propyl-cyanide and its isomers Formation: Ab initio Study of th e Spectroscopy and Reaction Mechanisms.”, Mon. Not. Roy. Astron. Soc . https://doi.org/10.48550/arXiv.2301.12297 (2023). END:VEVENT END:VCALENDAR