:Glycolaldehyde

Glycolaldehyde as a gas is a simple monomeric structure. As a solid and molten liquid, it exists as a dimer. Collins and George reported the equilibrium of glycolaldehyde in water by using NMR.{{Cite web|url=http://ai4c.com/2019/11/11/prediction-of-isomerization-of-glycolaldehyde-in-aqueous-solution-by-ibm-rxn/|title=Prediction of Isomerization of Glycolaldehyde In Aqueous Solution by IBM RXN – Artificial Intelligence for Chemistry|date=11 November 2019 |language=en-US|access-date=2019-11-19}}{{Cite journal|last1=Collins|first1=G. C. S.|last2=George|first2=W. O.|date=1971|title=Nuclear magnetic resonance spectra of glycolaldehyde|journal=Journal of the Chemical Society B: Physical Organic|pages=1352|doi=10.1039/j29710001352|issn=0045-6470}} In aqueous solution, it exists as a mixture of at least four species, which rapidly interconvert.{{cite journal | last1 = Yaylayan | first1 = Varoujan A. | last2 = Harty-Majors | first2 = Susan | last3 = Ismail | first3 = Ashraf A. | year = 1998 | title = Investigation of the mechanism of dissociation of glycolaldehyde dimer (2,5-dihydroxy-1,4-dioxane) by FTIR spectroscopy | journal = Carbohydrate Research | volume = 309 | pages = 31–38 | doi = 10.1016/S0008-6215(98)00129-3 }}

File:Glyoxaldehyde-in20-D2O.png

In acidic or basic solution, the compound undergoes reversible tautomerization to form 1,2-dihydroxyethene.{{cite journal |title= Study of the kinetics and mechanism of the acid-base-catalyzed enolization of hydroxyacetaldehyde and methoxyacetaldehyde |first1= Michal |last1= Fedoroňko |first2= Peter |last2= Temkovic |first3= Josef |last3= Königstein |first4= Vladimir |last4= Kováčik |first5= Igor |last5= Tvaroška |journal= Carbohydrate Research |volume= 87 |issue= 1 |date= 1 December 1980 |pages= 35–50 |doi= 10.1016/S0008-6215(00)85189-7 }}

It is the only possible diose, a 2-carbon monosaccharide, although a diose is not strictly a saccharide. While not a true sugar, it is the simplest sugar-related molecule.{{cite journal |author=Carroll, P. |author2=Drouin, B. |author3=Widicus Weaver, S. |title=The Submillimeter Spectrum of Glycolaldehyde|journal=Astrophys. J. |volume=723|issue=1 |pages=845–849|year=2010|url=http://chemistry.emory.edu/faculty/widicusweaver/papers/carroll2010.pdf|bibcode = 2010ApJ...723..845C |doi = 10.1088/0004-637X/723/1/845 |s2cid=30104627 }} It is reported to taste sweet.{{Cite book|url=https://books.google.com/books?id=TvnjBwAAQBAJ|title=Taste Chemistry|last=Shallenberger|first=R. S.|date=2012-12-06|publisher=Springer Science & Business Media|isbn=9781461526667|language=en}}

Glycolaldehyde is the second most abundant compound formed when preparing pyrolysis oil (up to 10% by weight).{{cite journal|last=Moha|first=Dinesh|author2=Charles U. Pittman, Jr. |author3=Philip H. Steele|s2cid=49239384|title=Pyrolysis of Wood/Biomass for Bio-oil: A Critical Review|journal=Energy & Fuels|date=10 March 2006 |volume=206|issue=3|pages=848–889|doi=10.1021/ef0502397}}

Glycolaldehyde can be synthesized by the oxidation of ethylene glycol using hydrogen peroxide in the presence of iron(II) sulfate.{{Hans Peter Latscha, Uli Kazmaier und Helmut Alfons Klein : '' Organic Chemistry: Chemistry Basiswissen-II '. Springer, Berlin; 6, vollständig überarbeitete Auflage 2008, {{ISBN|978-3-540-77106-7}}, S. 217}}

It can form by action of ketolase on fructose 1,6-bisphosphate in an alternate glycolysis pathway. This compound is transferred by thiamine pyrophosphate during the pentose phosphate shunt.

In purine catabolism, xanthine is first converted to urate. This is converted to 5-hydroxyisourate, which decarboxylates to allantoin and allantoic acid. After hydrolyzing one urea, this leaves glycolureate. After hydrolyzing the second urea, glycolaldehyde is left. Two glycolaldehydes condense to form erythrose 4-phosphate,{{Citation needed|date=October 2021|reason=reliable source required to show that two glycolaldehyde molecules condense to form erythrose/erythrose 4-phosphate, because this sentence is not part of standard biochemistry textbooks}} which goes to the pentose phosphate shunt again.

Glycolaldehyde is an intermediate in the formose reaction. In the formose reaction, two formaldehyde molecules condense to make glycolaldehyde. Glycolaldehyde then is converted to glyceraldehyde, presumably via initial tautomerization.{{cite journal |title= Identification of Glycolaldehyde Enol (HOHC═CHOH) in Interstellar Analogue Ices |first1= N. Fabian |last1= Kleimeier |first2= André K. |last2= Eckhardt |first3= Ralf I. |last3= Kaiser |journal= J. Am. Chem. Soc. |volume= 143 |issue= 34 |pages= 14009–14018 |date= August 18, 2021 |doi= 10.1021/jacs.1c07978 |pmid= 34407613 |s2cid= 237215450 }} The presence of this glycolaldehyde in this reaction demonstrates how it might play an important role in the formation of the chemical building blocks of life. Nucleotides, for example, rely on the formose reaction to attain its sugar unit. Nucleotides are essential for life, because they compose the genetic information and coding for life.

It is often invoked in theories of abiogenesis.{{cite journal|last=Kim|first=H.|author2=Ricardo, A. |author3=Illangkoon, H. I. |author4=Kim, M. J. |author5=Carrigan, M. A. |author6=Frye, F. |author7=Benner, S. A. |title=Synthesis of Carbohydrates in Mineral-Guided Prebiotic Cycles|journal=Journal of the American Chemical Society|year=2011|volume=133|issue=24)|pages=9457–9468|doi=10.1021/ja201769f |pmid=21553892}}{{cite journal|last=Benner|first=S. A.|author2=Kim, H.|author3= Carrigan, M. A.|s2cid=10581856|title=Asphalt, Water, and the Prebiotic Synthesis of Ribose, Ribonucleosides, and RNA|journal=Accounts of Chemical Research|year=2012|volume=45|issue=12|pages=2025–2034|doi=10.1021/ar200332w|pmid=22455515}} In the laboratory, amino acids{{cite journal|last=Pizzarello|first=Sandra|author2=Weber, A. L.|title=Prebiotic amino acids as asymmetric catalysts|journal=Science|year=2004|volume=303|issue=5661|page=1151|doi=10.1126/science.1093057|pmid=14976304|citeseerx=10.1.1.1028.833|s2cid=42199392}} and short dipeptides{{cite journal|last=Weber|first=Arthur L.|author2=Pizzarello, S.|title=The peptide-catalyzed stereospecific synthesis of tetroses: A possible model for prebiotic molecular evolution|journal=Proceedings of the National Academy of Sciences of the USA|year=2006|volume=103|issue=34|pages=12713–12717|doi=10.1073/pnas.0602320103|pmid=16905650|pmc=1568914|bibcode=2006PNAS..10312713W|doi-access=free}} have been shown to catalyze the formation of complex sugars from glycolaldehyde. For example, L-valyl-L-valine was used as a catalyst to form tetroses from glycolaldehyde. Theoretical calculations have additionally shown the feasibility of dipeptide-catalyzed synthesis of pentoses.{{cite journal |last=Cantillo |first=D. |author2=Ávalos, M. |author3=Babiano, R. |author4=Cintas, P. |author5=Jiménez, J. L. |author6=Palacios, J. C. |title=On the Prebiotic Synthesis of D-Sugars Catalyzed by L-Peptides Assessments from First-Principles Calculations|journal=Chemistry: A European Journal|year=2012|volume=18|issue=28 |pages=8795–8799|doi=10.1002/chem.201200466|pmid=22689139 }} This formation showed stereospecific, catalytic synthesis of D-ribose, the only naturally occurring enantiomer of ribose. Since the detection of this organic compound, many theories have been developed related various chemical routes to explain its formation in stellar systems.

File:Formation of Glycolaldehyde in star dust.png]]It was found that UV-irradiation of methanol ices containing CO yielded organic compounds such as glycolaldehyde and methyl formate, the more abundant isomer of glycolaldehyde. The abundances of the products slightly disagree with the observed values found in IRAS 16293-2422, but this can be accounted for by temperature changes. Ethylene Glycol and glycolaldehyde require temperatures above 30 K.{{cite journal|last=Öberg|first=K. I. |author2=Garrod, R. T. |author3=van Dishoeck, E. F. |author4=Linnartz, H.|title=Formation rates of complex organics in UV irradiation CH_3OH-rich ices. I. Experiments |journal=Astronomy and Astrophysics|date=September 2009|volume=504|issue=3|pages=891–913|doi=10.1051/0004-6361/200912559 |bibcode=2009A&A...504..891O|arxiv=0908.1169|s2cid=7746611 }}{{cite journal|title=Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA|author=Jørgensen, J. K.|author2=Favre, C. |author3=Bisschop, S. |author4=Bourke, T. |author5=Dishoeck, E. |author6= Schmalzl, M. |journal=The Astrophysical Journal|version=eprint |year=2012|volume=757|issue=1|pages=L4|doi=10.1088/2041-8205/757/1/L4|arxiv=1208.5498|bibcode=2012ApJ...757L...4J|s2cid=14205612|url=http://www.eso.org/public/archives/releases/sciencepapers/eso1234/eso1234a.pdf}} The general consensus among the astrochemistry research community is in favor of the grain surface reaction hypothesis. However, some scientists believe the reaction occurs within denser and colder parts of the core. The dense core will not allow for irradiation as stated before. This change will completely alter the reaction forming glycolaldehyde.{{cite journal |last=Woods |first=P. M |author2=Kelly, G. |author3=Viti, S. |author4=Slater, B. |author5=Brown, W. A. |author6=Puletti, F. |author7=Burke, D. J. |author8=Raza, Z. |title=Glycolaldehyde Formation via the Dimerisation of the Formyl Radical|journal=The Astrophysical Journal|year=2013|volume=777|issue=50|doi=10.1088/0004-637X/777/2/90 |bibcode=2013ApJ...777...90W |page=90|arxiv=1309.1164|s2cid=13969635 }}

{{main|List of interstellar and circumstellar molecules}}

File:Sugar molecules in the gas surrounding a young Sun-like star.jpg

The different conditions studied indicate how problematic it could be to study chemical systems that are light-years away. The conditions for the formation of glycolaldehyde are still unclear. At this time, the most consistent formation reactions seems to be on the surface of ice in cosmic dust.

Glycolaldehyde has been identified in gas and dust near the center of the Milky Way galaxy,{{cite journal|author=Hollis, J.M., Lovas, F.J., & Jewell, P.R.|title=Interstellar Glycolaldehyde: The First Sugar|journal=The Astrophysical Journal|volume=540|pages=107–110|year=2000|doi=10.1086/312881|bibcode=2000ApJ...540L.107H|issue=2|doi-access=free}} in a star-forming region 26000 light-years from Earth,{{cite journal|title=First detection of glycolaldehyde outside the Galactic Center|author=Beltran, M. T.|author2=Codella, C.|author3=Viti, S.|author4=Neri, R.|author5=Cesaroni, R.|version=eprint arXiv:0811.3821|date=November 2008|url=http://babbage.sissa.it/abs/0811.3821}}{{dead link|date=October 2017 |bot=InternetArchiveBot |fix-attempted=yes }} and around a protostellar binary star, IRAS 16293-2422, 400 light years from Earth.{{cite journal|title=Sugar Found In Space|journal=National Geographic |last=Than |first=Ker |date=August 29, 2012 |url=http://news.nationalgeographic.com/news/2012/08/120829-sugar-space-planets-science-life/ |archive-url=https://web.archive.org/web/20120901013431/http://news.nationalgeographic.com/news/2012/08/120829-sugar-space-planets-science-life |url-status=dead |archive-date=September 1, 2012 |access-date=August 31, 2012 }}{{cite web |author=Staff |title=Sweet! Astronomers spot sugar molecule near star |url=http://apnews.excite.com/article/20120829/DA0V31D80.html |date=August 29, 2012 |publisher=AP News |access-date=August 31, 2012 }} Observation of in-falling glycolaldehyde spectra 60 AU from IRAS 16293-2422 suggests that complex organic molecules may form in stellar systems prior to the formation of planets, eventually arriving on young planets early in their formation.

The interior region of a dust cloud is known to be relatively cold. With temperatures as cold as 4 Kelvin, the gases within the cloud will freeze and fasten themselves to the dust, which provides the reaction conditions conducive for the formation of complex molecules such as glycolaldehyde. When a star has formed from the dust cloud, the temperature within the core will increase. This will cause the molecules on the dust to evaporate and be released. The molecule will emit radio waves that can be detected and analyzed. The Atacama Large Millimeter/submillimeter Array (ALMA) first detected glycolaldehyde. ALMA consists of 66 antennas that can detect the radio waves emitted from cosmic dust.{{cite web|title=Building blocks of life found around young star|url=http://www.news.leiden.edu/news-2012/building-blocks-for-life-found-on-young-star.html|access-date=December 11, 2013}}

On October 23, 2015, researchers at the Paris Observatory announced the discovery of glycolaldehyde and ethyl alcohol on Comet Lovejoy, the first such identification of these substances in a comet.{{Cite journal | doi=10.1126/sciadv.1500863|pmid = 26601319|pmc = 4646833| title=Ethyl alcohol and sugar in comet C/2014 Q2 (Lovejoy)| journal=Science Advances| volume=1| issue=9| pages=e1500863| year=2015| last1=Biver| first1=Nicolas| last2=Bockelée-Morvan| first2=Dominique|author2-link=Dominique Bockelée-Morvan| last3=Moreno| first3=Raphaël| last4=Crovisier| first4=Jacques| last5=Colom| first5=Pierre| last6=Lis| first6=Dariusz C.| last7=Sandqvist| first7=Aage| last8=Boissier| first8=Jérémie| last9=Despois| first9=Didier| last10=Milam| first10=Stefanie N.| arxiv=1511.04999| bibcode=2015SciA....1E0863B}}{{Cite web | url=http://obspm.fr/researchers-find-ethyl.html | title=Researchers find ethyl alcohol and sugar in a comet ! -}}

{{Reflist}}

• {{cite news | title=Cold Sugar in Space Provides Clue to the Molecular Origin of Life | publisher=National Radio Astronomy Observatory | date=September 20, 2004 | url=http://www.nrao.edu/pr/2004/coldsugar/ | access-date=December 20, 2006 }}

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Category:Primary alcohols

Category:Hydroxy aldehydes