Issue 20, 2010

Radical routes to interstellar glycolaldehyde. The possibility of stereoselectivity in gas-phase polymerization reactions involving CH2O and ˙CH2OH

Abstract

A previous report that the interstellar molecule glycolaldehyde (HOCH2CHO) can be made from hydroxymethylene (HOCH:) and formaldehyde has been revisited at the CCSD(T)/6-311++G(3df,2p)//MP2/6-311++G(3df,2p) level of theory. This reaction competes with the formation of acetic acid and methylformate, molecules which have also been detected in interstellar clouds. Other possible modes of formation of glycolaldehyde by radical/radical reactions have been shown to be viable theoretically as follows:HO˙ + ˙CH2CHO → HOCH2CHO [ΔGr(298 K) = −303 kJ mol−1]HOCH2˙ + ˙CHO → HOCH2CHO (−259 kJ mol−1)

The species in these two processes are known interstellar molecules. Key radicals ˙CH2CHO and ˙CH2OH in these sequences have been shown to be stable for the microsecond duration of neutralization/reionization experiments in the dual collision cells of a VG ZAB 2HF mass spectrometer. The polymerization reaction HOCH2CH˙OH + nCH2O → HOCH2[CH(OH)]n˙CHOH (n = 1 to 3) has been studied theoretically and shown to be energetically feasible, as is the cyclization reaction of HOCH2[(CH2OH)4]˙CHOH (in the presence of one molecule of water at the reacting centre) to form glucose. The probability of such a reaction sequence is small even if polymerization were to occur in interstellar ice containing a significant concentration of CH2O. The large number of stereoisomers produced by such a reaction sequence makes the formation of a particular sugar, again for example glucose, an inefficient synthesis. The possibility of stereoselectivity occurring during the polymerization was investigated for two diastereoisomers of HOCH2[(CHOH)]2˙CHOH. No significant difference was found in the transition state energies for addition of CH2O to these two diastereoisomers, but a barrier difference of 12 kJ mol−1 was found for the H transfer reactions ˙OCH2[(CHOH)]2CH2OH → HOCH2[(CHOH)2˙CHOH of the two diastereoisomers.

Graphical abstract: Radical routes to interstellar glycolaldehyde. The possibility of stereoselectivity in gas-phase polymerization reactions involving CH2O and ˙CH2OH

Supplementary files

Article information

Article type
Paper
Submitted
14 May 2010
Accepted
24 Jun 2010
First published
16 Aug 2010

Org. Biomol. Chem., 2010,8, 4757-4766

Radical routes to interstellar glycolaldehyde. The possibility of stereoselectivity in gas-phase polymerization reactions involving CH2O and ˙CH2OH

T. Wang and J. H. Bowie, Org. Biomol. Chem., 2010, 8, 4757 DOI: 10.1039/C0OB00125B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements