Joint Analysis of Ethyl Formate in the Gas Phase by Electron Diffraction and Microwave and Vibrational Spectroscopy Supplemented by ab Initio Calculations of Force Fields

Peng, Zhihui; Shlykov, Sergey A.; Alsenoy, C. Van; Geise, H. J.; Veken, B. Van der

doi:10.1021/j100025a022

Cited by 22 publications

(51 citation statements)

References 6 publications

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“…The existence of two conformers such as I and II with similar energies is typical for substituted formate esters and has already been found for HC(O)OCH 2 CH 3 24, 25 and HC(O)OCH 2 F. 26 The C2−O4−C5−C6 chain of atoms takes the expected 180°a ngle in I, and the unusual value of 80.3°in II ( Table 1). The corresponding C−O−C−C dihedral angle is 180°and 81.7°( r α 0 -structure) in the corresponding two conformers of HC(O)OCH 2 CH 3 , 25 a A-reduction, I r -representation.…”

Section: ■ Results and Discussionsupporting

confidence: 62%

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Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH₂C≡N), a Compound of Potential Astrochemical Interest

2015

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The rotational spectrum of cyanomethyl formate (HC(O)OCH2C≡N) has been recorded in the 12–123 GHz spectral range. The spectra of two conformers were assigned. The rotamer denoted I has a symmetry plane and two out-of plane hydrogen atoms belonging to the cyanomethyl (CH2CN) moiety. In the conformer called II, the cyanomethyl group is rotated 80.3° out of this plane. Conformer I has an energy that is 1.4(6) kJ/mol lower than the energy of II according to relative intensity measurements. A large number of rotational transitions have been assigned for the ground and vibrationally excited states of the two conformers and accurate spectroscopic constants have been obtained. These constants should predict frequencies of transitions outside the investigated spectral range with a very high degree of precision. It is suggested that cyanomethyl formate is a potential interstellar compound. This suggestion is based on the fact that its congener methyl formate (HC(O)OCH3) exists across a large variety of interstellar environments and the fact that cyanides are very prevalent in the Universe. The experimental work has been augmented by high-level quantum chemical calculations. The CCSD/cc-pVQZ calculations are found to predict structures of the two forms that are very close to the Born–Oppenheimer equilibrium structures. MP2/cc-pVTZ predictions of several vibration–rotation interaction constants were generally found to be rather inaccurate. A gas-phase reaction between methyl formate and the cyanomethyl radical CH2CN to produce a hydrogen atom and cyanomethyl formate was mimicked using MP2/cc-pVTZ calculations. It was found that this reaction is not favored thermodynamically. It is also conjectured that the possible formation of cyanomethyl formate might be catalyzed and take place on interstellar particles.

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Section: ■ Results and Discussionsupporting

confidence: 62%

“…The corresponding C−O−C−C dihedral angle is 180°and 81.7°( r α 0 -structure) in the corresponding two conformers of HC(O)OCH 2 CH 3 , 25 a A-reduction, I r -representation. 22 Spectra listed in Tables S12−S16.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH₂C≡N), a Compound of Potential Astrochemical Interest

2015

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“…The small spheres represent the experimental positions. The larger spheres are the positions obtained from Peng et al[57]. The most noticeable differences are in the carbon atom positions.…”

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confidence: 79%

“…Using the direct structural information obtained in this study, we find the value of this dihedral angle to be 97(3)°. The structure of ethyl formate was also investigated by Peng et al [57] using a combination of gas-phase electron diffraction, the microwave data of Riveros and Wilson, and infrared data with additional input from equilibrium geometries calculated using low-level electronic structure theory. The results from the present study agree with 98.3°ethyl dihedral angle reported by Peng et al Comparisons of the structures obtained here and those obtained by Peng et al are found in Fig.…”

Section: Ethyl Formatementioning

confidence: 99%

A Ka-band chirped-pulse Fourier transform microwave spectrometer

Zaleski

Neill

Muckle

et al. 2012

Journal of Molecular Spectroscopy

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“…The ground state of the gauche conformer is 94 ± 30 K higher in energy (Riveros & Wilson 1967) than that of the trans conformer. The geometry of the conformers was studied by Peng (1995), and is presented in Fig. 1 of Medvedev et al (2009).…”

Section: Introductionmentioning

confidence: 99%

On the chemical ladder of esters

Rivilla

Beltrán

Martı́n-Pintado

et al. 2017

A&A

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Context. In recent years, the detection of organic molecules with increasing complexity and potential biological relevance is opening the possibility to understand the formation of the building blocks of life in the interstellar medium. One of the families of molecules of substantial astrobiological interest are the esters. The simplest ester, methyl formate (CH 3 OCHO), is rather abundant in star-forming regions. The next step in the chemical complexity of esters is ethyl formate, C 2 H 5 OCHO. Despite the increase in sensitivity of current telescopes, the detection of complex molecules with more than ten atoms such as C 2 H 5 OCHO is still a challenge. Only two detections of this species have been reported so far, which strongly limits our understanding of how complex molecules are formed in the interstellar medium. New detections towards additional sources with a wide range of physical conditions are crucial to differentiate between competing chemical models based on dust grain surface and gas-phase chemistry. Aims. We have searched for ethyl formate towards the W51 e2 hot molecular core, one of the most chemically rich sources in the Galaxy and one of the most promising regions to study prebiotic chemistry, especially after the recent discovery of the P−O bond, key in the formation of DNA. Methods. We have analyzed a spectral line survey towards the W51 e2 hot molecular core, which covers 44 GHz in the 1, 2 and 3 mm bands, carried out with the IRAM 30 m telescope. Results. We report the detection of the trans and gauche conformers of ethyl formate. A local thermodynamic equilibrium analysis indicates that the excitation temperature is 78 ± 10 K and that the two conformers have similar source-averaged column densities of (2.0 ± 0.3) × 10 −16 cm −2 and an abundance of ∼10 −8. We compare for the first time the observed molecular abundances of ethyl formate with different competing chemical models based on grain surface and gas-phase chemistry. Conclusions. We propose that grain-surface chemistry may have a dominant role in the formation of ethyl formate (and other complex organic molecules) in hot molecular cores, rather than reactions in the gas phase.

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Joint Analysis of Ethyl Formate in the Gas Phase by Electron Diffraction and Microwave and Vibrational Spectroscopy Supplemented by ab Initio Calculations of Force Fields

Cited by 22 publications

References 6 publications

Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH₂C≡N), a Compound of Potential Astrochemical Interest

Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH₂C≡N), a Compound of Potential Astrochemical Interest

A Ka-band chirped-pulse Fourier transform microwave spectrometer

On the chemical ladder of esters

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Joint Analysis of Ethyl Formate in the Gas Phase by Electron Diffraction and Microwave and Vibrational Spectroscopy Supplemented by ab Initio Calculations of Force Fields

Cited by 22 publications

References 6 publications

Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH2C≡N), a Compound of Potential Astrochemical Interest

Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH2C≡N), a Compound of Potential Astrochemical Interest

A Ka-band chirped-pulse Fourier transform microwave spectrometer

On the chemical ladder of esters

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Product

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Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH₂C≡N), a Compound of Potential Astrochemical Interest

Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH₂C≡N), a Compound of Potential Astrochemical Interest