The chemical conditions on the parent body of the murchison meteorite: Some conclusions based on amino, hydroxy and dicarboxylic acids

Peltzer, Edward T.; Bada, Jeffrey L.; Schlesinger, G.; Miller, Stanley L.

doi:10.1016/0273-1177(84)90546-5

Cited by 247 publications

(203 citation statements)

References 21 publications

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“…On the basis of this evidence, the consensus is that amino acids in meteorites form thanks to a multi-step process (Cronin et al 1995) implying that amino acid precursors (aldehydes, ketones, ammonia, and HCN) were present (or formed) in the protosolar nebula, and later incorporated into the asteroidal parent body. During aqueous alteration on the parent body, Strecker-cyanohydrin synthesis would have taken place to form the α-amino acids (Peltzer et al 1984;Cronin & Chang 1993;Lerner et al 1993). It has been argued that some of the aminoacids that have been found in the meteorites may have been synthesized in the ISM (Pizzarello et al 2006) because of the high level of deuteration (Pizzarello & Huang 2004, which is similar to that found in the ISM (Ceccarelli et al 2007).…”

Section: Introductionmentioning

confidence: 93%

About the detectability of glycine in the interstellar medium

Lattelais

Pauzat

Pilmé

et al. 2011

A&A

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Context. Glycine, the simplest of aminoacids, has been found in several carbonaceous meteorites. It remains unclear, however, wether glycine is formed in the interstellar medium (ISM) and therefore available everywhere in the Universe. For this reason, radioastronomers have searched for many years unsuccessfully to detect glycine in the ISM. Aims. We provide possible guidelines to optimize the return of these searches. Since, for most of the species observed so far in the ISM, the most abundant isomer of a given generic chemical formula is the most stable one (minimum energy principle (MEP)), we assess whether neutral glycine is the best molecule to search for or whether one of its isomers/conformers or ionic, protonated, or zwitterionic derivatives would have a higher probability of being detected. Methods. The question of the relative stability of these different species is addressed by means of quantum density functional theory (DFT) simulations within the hybrid B3LYP formalism. Each fully optimized structure is verified as a stationary point by means of a vibrational analysis. A comprehensive screening of 32 isomers/conformers of the C 2 H 5 O 2 N chemical formula (neutral, negative, and positive ions together with the corresponding protonated species and the possible zwitterionic structures) is carried out. In the sensitive case of the neutral compounds, more accurate relative energies were obtained by means of high level post Hartree-Fock coupled cluster calculations with large basis sets (CCSD(T)/cc-pVQZ). Results. We find that neutral glycine is not the most stable isomer and, therefore, probably not the most abundant one, which might explain why it has escaped detection so far. We find instead that N-methyl carbamic acid and methyl carbamate are the two most stable isomers and, therefore, probably the two most abundant ones. Among the non-neutral forms, we found that glycine is the most stable isomer only if protonated or zwitterionic if present in interstellar ices. Conclusions. Assuming that MEP can be applied to optimize our search for glycine, our conclusion is that this search will remain extremely difficult with the present instruments and we propose searching instead for other examples among the most stable isomers.

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Section: Introductionmentioning

confidence: 93%

About the detectability of glycine in the interstellar medium

Lattelais

Pauzat

Pilmé

et al. 2011

A&A

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“…In turn, amino acids are the building blocks of proteins, considered a key component for the commencement of life. Multiple routes to the formation of glycine (and other simple amino acids) under interstellar conditions have been proposed including via Strecker synthesis (see, e.g., Peltzer et al 1984), UV-irradiated ice mantles (see, e.g., Bernstein et al 2002;Muñoz Caro et al 2002), and gas-phase chemistry (see, e.g, Blagojevic et al 2003).…”

Section: Implications For Astrobiologymentioning

confidence: 99%

Complex organic molecules in protoplanetary disks

Walsh

Millar

Nomura

et al. 2014

A&A

223

356

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Context. Protoplanetary disks are vital objects in star and planet formation, possessing all the material, gas and dust, which may form a planetary system orbiting the new star. Small, simple molecules have traditionally been detected in protoplanetary disks; however, in the ALMA era, we expect the molecular inventory of protoplanetary disks to significantly increase. Aims. We investigate the synthesis of complex organic molecules (COMs) in protoplanetary disks to put constraints on the achievable chemical complexity and to predict species and transitions which may be observable with ALMA. Methods. We have coupled a 2D steady-state physical model of a protoplanetary disk around a typical T Tauri star with a large gas-grain chemical network including COMs. We compare the resulting column densities with those derived from observations and perform ray-tracing calculations to predict line spectra. We compare the synthesised line intensities with current observations and determine those COMs which may be observable in nearby objects. We also compare the predicted grain-surface abundances with those derived from cometary comae observations. Results. We find COMs are efficiently formed in the disk midplane via grain-surface chemical reactions, reaching peak grain-surface fractional abundances ∼10 −6 -10 −4 that of the H nuclei number density. COMs formed on grain surfaces are returned to the gas phase via non-thermal desorption; however, gas-phase species reach lower fractional abundances than their grain-surface equivalents, ∼10 −12 -10 −7 . Including the irradiation of grain mantle material helps build further complexity in the ice through the replenishment of grain-surface radicals which take part in further grain-surface reactions. There is reasonable agreement with several line transitions of H 2 CO observed towards T Tauri star-disk systems. There is poor agreement with HC 3 N lines observed towards LkCa 15 and GO Tau and we discuss possible explanations for these discrepancies. The synthesised line intensities for CH 3 OH are consistent with upper limits determined towards all sources. Our models suggest CH 3 OH should be readily observable in nearby protoplanetary disks with ALMA; however, detection of more complex species may prove challenging, even with ALMA "Full Science" capabilities. Our grain-surface abundances are consistent with those derived from cometary comae observations providing additional evidence for the hypothesis that comets (and other planetesimals) formed via the coagulation of icy grains in the Sun's natal disk.

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“…2 Scheme for the photochemical synthesis of CH 3 CHO, acrolein, and pentaerythritol from UV irradiation of HCHO Murchison meteorite (Pizzarello 2004), apparently the suggested inhibition of HCHO chemistry by HCN and vice versa (Schlesinger and Miller 1973) is not a genuine problem. The ratio of glycolic acid to glycine in Murchison suggests that NH 3 concentrations were fairly high in the parent body (Peltzer et al 1984). These quantities also suggest that the reactions which form HMT and glycolonitrile are not limiting to either purine or sugar synthesis and that slow kinetic effects may be more important than the initial rapid equilibrium obtained.…”

Section: Environmental Limitationsmentioning

confidence: 96%

Facula, Faculae

Wagner¹

2015

Encyclopedia of Astrobiology

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The chemical conditions on the parent body of the murchison meteorite: Some conclusions based on amino, hydroxy and dicarboxylic acids

Cited by 247 publications

References 21 publications

About the detectability of glycine in the interstellar medium

About the detectability of glycine in the interstellar medium

Complex organic molecules in protoplanetary disks

Facula, Faculae

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