The Gas‐Phase Formation of Methyl Formate in Hot Molecular Cores

Horn, Andrew B.; Møllendal, Harald; Sekiguchi, Osamu; Uggerud, Einar; Roberts, H.; Herbst, Eric; Viggiano, A. A.; Fridgen, Travis D.

doi:10.1086/422137

Cited by 149 publications

(156 citation statements)

References 38 publications

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“…Most of the more complex species predicted to be abundant by the Charnley et al (1995) model remain undetected, although one of these (not expected to be the most abundant one), ethyl formate HCOOC 2 H 5 , has recently been detected in Sgr B2 (Belloche et al 2009). This ice mantle methanol release/gas-phase post-processing model could not produce enough methyl formate when calculations by Horn et al (2004) showed that the reaction CH 3 OH + 2 + H 2 CO was not possible at interstellar temperatures.…”

Section: Dimethyl Ether and Methyl Formate Observations In Other Regionsmentioning

confidence: 99%

“…Because the main problem to form HCOOCH 3 from CH 2 OH + 2 and H 2 CO is an energy barrier, could this obstacle be removed if one considers that the ions are strongly accelerated with respect to neutrals at some places of an MHD shock? A few km s −1 would represent enough kinetic energy to overcome the reaction barrier, which is 128 kJ/mol (15 000 K or 1.2 eV) according to Horn et al (2004). New quantum calculations and/or laboratory work are required to test this hypothesis.…”

Section: How Do These Models Confront Our Orion Dimethyl Ether and Mementioning

confidence: 99%

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CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

Brouillet

Despois

Baudry

et al. 2013

A&A

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Context. Orion-KL is a remarkable, nearby star-forming region where a recent explosive event has generated shocks that could have released complex molecules from the grain mantles. Aims. A comparison of the distribution of the different complex molecules will help in understanding their formation and constraining the chemical models.Methods. We used several data sets from the Plateau de Bure Interferometer to map the dimethyl ether emission with different arcsec spatial resolutions and different energy levels (from E up = 18 to 330 K) to compare with our previous methyl formate maps. Results. Our data show remarkable similarity between the dimethyl ether (CH 3 OCH 3 ) and the methyl formate (HCOOCH 3 ) distributions even on a small scale (1.8 × 0.8 or ∼500 AU). This long suspected similarity, seen from both observational and theoretical arguments, is demonstrated with unprecedented confidence, with a correlation coefficient of maps ∼0.8. Conclusions. A common precursor is the simplest explanation of our correlation. Comparisons with previous laboratory work and chemical models suggest the major role of grain surface chemistry and a recent release, probably with little processing, of mantle molecules by shocks. In this case the CH 3 O radical produced from methanol ice would be the common precursor (whereas ethanol, C 2 H 5 OH, is produced from the radical CH 2 OH). The alternative gas phase scheme, where protonated methanol CH 3 OH + 2 is the common precursor to produce methyl formate and dimethyl ether through reactions with HCOOH and CH 3 OH, is also compatible with our data. Our observations cannot yet definitely allow a choice between the different chemical processes, but the tight correlation between the distributions of HCOOCH 3 and CH 3 OCH 3 strongly contrasts with the different behavior we observe for the distributions of ethanol and formic acid. This provides a very significant constraint on models.

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Section: Dimethyl Ether and Methyl Formate Observations In Other Regionsmentioning

confidence: 99%

Section: How Do These Models Confront Our Orion Dimethyl Ether and Mementioning

confidence: 99%

CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

Brouillet

Despois

Baudry

et al. 2013

A&A

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“…Until a few years ago it was thought that methyl formate could be formed in the gas phase after the sublimation of icy mantles containing H 2 CO and CH 3 OH. Horn and colleagues studied the specific sequence of reactions that was supposed to lead to the synthesis of methyl formate (Horn et al 2004). The results of their theoretical and experimental gas-phase study have conclusively shown that the processes in the gas phase are unable to produce sufficient amounts of methyl formate.…”

Section: Introductionmentioning

confidence: 99%

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Modica¹,

Palumbo²

2010

A&A

102

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Context. Methyl formate (HCOOCH 3 ) is a complex organic molecule detected in hot cores and hot corinos. Gas-phase chemistry fails to reproduce its observed abundance, which usually varies between 10 −7 and 10 −9 with respect to H 2 . Aims. Laboratory experiments were performed in order to investigate a solid-state route of methyl formate formation, to obtain an estimate of the amount that can be formed, and to verify whether it can account for the observed abundances. Methods. Several solid samples (16 K) of astrophysical interest were analyzed by infrared spectroscopy in the 4400−400 cm −1 range. The infrared spectral characteristics of frozen methyl formate were studied by deriving their band strength values. The effects produced upon warm-up of the samples were analyzed comparing the spectra taken at different temperatures. In order to study the formation and destruction mechanism of methyl formate in the interstellar ices, a binary mixture of methanol (CH 3 OH) and carbon monoxide (CO) ice and a sample of pure methanol were irradiated at 16 K with 200 keV protons. Methyl formate was identified through its fundamental mode (CH 3 rocking) at about 1160 cm −1 . Results. We present the mid-infrared methyl formate ice spectrum showing both the amorphous (16 K) and the crystalline (110 K) structure. We report novel measurements of the band strength values of the six main methyl formate bands. We prove the formation and the destruction of methyl formate after irradiation of CH 3 OH and a CO:CH 3 OH mixture. Extrapolating our results to the interstellar medium conditions we found that the production timescale of methyl formate agrees well with the evolutionary time of molecular clouds. The comparison with the observational data indicates that the amount of methyl formate formed after irradiation can account for the observed abundances. Conclusions. The present results allow us to suggest that gas phase methyl formate observed in dense molecular clouds is formed in the solid state after cosmic ion irradiation of icy grain mantles containing CO and CH 3 OH and released to the gas phase after desorption of icy mantles.

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“…It has also been detected in low-mass star-forming regions (hot corinos), such as NGC1333-IRAS4B and IRAS 2A (Bottinelli et al 2004(Bottinelli et al , 2007. Its large abundance is difficult to account are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/500/1109 for with a production mechanism based only on gas phase reactions with methanol (Horn et al 2004) and grain chemistry should be involved in methyl formate formation. In 1959 Curl studied the chemical structure and the microwave spectrum of the parent methyl formate and 8 other isotopologues (Curl 1959).…”

Section: Introductionmentioning

confidence: 99%

Rotational spectrum of¹³C₂-methyl formate (HCOO¹³CH₃) and detection of the two¹³C-methyl formate in Orion

Carvajal¹,

Margulès

Tercero

et al. 2009

A&A

116

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Context. Laboratory measurements and analysis of the microwave and millimeter-wave spectra of potential interstellar molecules are a prerequisite for their subsequent identification by radioastronomical techniques. The spectral analysis provides spectroscopic parameters that are used in the assignment procedure of the laboratory spectra, and that also predict the frequencies of transitions not measured in the laboratory with a high degree of precision.Aims. An experimental laboratory study and its theoretical analysis is presented for 13 C 2 -methyl formate (HCOO 13 CH 3 ) allowing a search for this isotopologue in the Orion molecular cloud. The 13 C 1 -methyl formate (H 13 COOCH 3 ) molecule was also searched for in this interstellar cloud, using previously published spectroscopic data. Methods. The experimental spectra of 13 C 2 -methyl formate were recorded in the microwave and sub-mm energy ranges (4-20 GHz, 8-80 GHz, 150-700 GHz). The spectra were analyzed using the Rho-Axis Method (RAM), which takes the CH 3 internal rotation and the coupling between internal rotation and global rotation into account. Results. Twenty-seven spectroscopic constants of 13 C 2 -methyl formate have been obtained from a fit of 936 transitions of the ground torsional state with a standard (unitless) deviation of 1.08. A prediction of line positions and intensities is also produced. This prediction allowed us to identify 230 13 C 2 -methyl formate lines in the Orion interstellar molecular cloud. We refitted all previously published ground state transitions of the 13 C 1 -methyl formate molecule in order to provide a prediction of its ground state spectrum. 234 lines of 13 C 1 -methyl formate were detected in the Orion interstellar cloud using that prediction.

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The Gas‐Phase Formation of Methyl Formate in Hot Molecular Cores

Cited by 149 publications

References 38 publications

CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Rotational spectrum of¹³C₂-methyl formate (HCOO¹³CH₃) and detection of the two¹³C-methyl formate in Orion

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The Gas‐Phase Formation of Methyl Formate in Hot Molecular Cores

Cited by 149 publications

References 38 publications

CH3OCH3in Orion-KL: a striking similarity with HCOOCH3

CH3OCH3in Orion-KL: a striking similarity with HCOOCH3

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Rotational spectrum of13C2-methyl formate (HCOO13CH3) and detection of the two13C-methyl formate in Orion

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Product

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CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

Rotational spectrum of¹³C₂-methyl formate (HCOO¹³CH₃) and detection of the two¹³C-methyl formate in Orion