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Context. Analyses of dust cometary grains collected by the Stardust spacecraft have shown the presence of amines and amino acids molecules, and among them glycine (NH2CH2COOH). We show how the glycine molecule could be produced in the protostellar environments before its introduction into comets.

Context. We study carbamic acid [ NH2COOH] and ammonium carbamate [ NH2COO-] [ NH4+] formation in interstellar ice analogs.

Reactivity in astrophysical environments is still poorly understood. In this contribution, we investigate the thermal reactivity of interstellar ice analogs containing acetone ((CH3)2CO), ammonia (NH3), hydrogen cyanide (HCN) and water (H2O) by means of infrared spectroscopy and mass spectrometry techniques, complemented by quantum chemical calculations. We show that no reaction occurs in H2O:HCN:(CH3)2CO ices. Nevertheless, HCN does indeed react with acetone once activated by NH3into CN−to form 2-hydroxy-2-methylpropanenitrile (HOC(CH3)2CN), with a calculated activation energy associated with the rate determining step of about 51 kJ mol−1. This reaction inhibits the formation of 2-aminopropan-2-ol (HOC(CH3)2NH2) from acetone and NH3, even in the presence of water, which is the first step of the Strecker synthesis to form 2-aminoisobutyric acid (NH2C(CH3)2COOH). However, HOC(CH3)2CN formation could be part of an alternative chemical pathway leading to 2-hydroxy-2-methyl-propanoic acid (HOC(CH3)2COOH), which could explain the presence of hydroxy acids in some meteorites.

We use infrared–visible double-resonance overtone excitation to prepare HOCl molecules in single, well-characterized rotational levels of the high OH stretching states &z.italv;_OH = 7 and &z.italv;_OH = 8. This work extends our recent studies on HOCl dissociation dynamics to higher energies above the dissociation threshold on the ground potential energy surface. In spite of a rapid increase of the vibrational coupling with &z.italv;_OH, unimolecular dissociation is still limited by the rate at which energy initially deposited in the OH stretch leaks out into the reaction coordinate. We observe that the increased coupling is not sufficient to put the molecule in the statistical limit, even at the energy of &z.italv;_OH = 8, which is 5000 cm−1 above the dissociation threshold. This implies that a microcanonical ensemble of HOCl molecules prepared even at an energy substantially higher than the dissociation threshold should exhibit non-exponential decay, contrary to the assumptions of statistical theories.

Context.Studing chemical reactivity in astrophysical environments is an important means for improving our understanding of the origin of the organic matter in molecular clouds, in protoplanetary disks, and possibly, as a final destination, in our solar system. Laboratory simulations of the reactivity of ice analogs provide important insight into the reactivity in these environments. Here, we use these experimental simulations to investigate the Strecker synthesis leading to the formation of aminoacetonitrile in astrophysical-like conditions. The aminoacetonitrile is an interesting compound because it was detected in SgrB2, hence could be a precursor of the smallest amino acid molecule, glycine, in astrophysical environments.

Aims.We investigate the purely thermal formation of hexamethylenetetramine (HMT, C6H12N4) in interstellar ice analogs from non-photolysed ice and compare our results with those for the formation from photolysed ice. Methods.We use Fourier transform-infrared spectroscopy to follow residue formation from VUV irradiation of H2CO:NH3ice mixture in different concentration ratios. We also report the warming of the H2CO:NH3:HCOOH ice mixture. Results.We present the characterization of organic residues obtained at 330 K from VUV irradiation of H2CO:NH3ice mixtures. The organic residues contain compounds related to polyoxomethylene (POM, [-CH2-O-]n) and HMT (C6H12N4). We report, for the first time, the formation of HMT from the warming of an interstellar ice analogs, H2CO:NH3:HCOOH, without any energetic processing (i.e. photons or particles). New insights into HMT formation mechanism are proposed. These results strengthen the hypothesis that HMT is present in interstellar grains or in comets, where it may be detected with the COSAC instrument of the Rosetta mission.

Context.The study of the chemical reactivity in interstellar ices in astrophysical environments is an important tool for understanding the origin of the organic matter in molecular clouds, in protoplanetary disks, and possibly, as a final destination, in our solar system. The laboratory simulations of the reactivity in ice analogs provide important information for understanding the reactivity in these environments. Here, we used these experimental simulations to trace some formation pathways of two nitriles, acetonitrile and amino acetonitrile, which are two potential precursors of amino acids in astrophysical environments.

Aims.Aminoalcohol molecules such as alpha-aminoethanol NH2CH(CH3)OH may be aminoacid precursors. We attempt to characterize and detect this kind of molecules which is important to establish a possible link between interstellar molecules and life as we know it on Earth.