Role of the anion in the alkali halides interaction with d-ribose: a 1H and 13C NMR spectroscopy study

Ortíz, Pedro; Fernández‐Bertrán, J.; Reguera, E.

doi:10.1016/j.saa.2004.07.009

Cited by 26 publications

(26 citation statements)

References 18 publications

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“…The spectrum we obtained ( Figure SI-5) was identical to that published by Ortiz et al [27] In general, four signals can be observed for each carbon, corresponding to the four anomers( although there is some overlap);t he a p and b p forms are more difficult to discriminate than the others. The spectrum we obtained ( Figure SI-5) was identical to that published by Ortiz et al [27] In general, four signals can be observed for each carbon, corresponding to the four anomers( although there is some overlap);t he a p and b p forms are more difficult to discriminate than the others.…”

Section: Nmr Spectroscopysupporting

confidence: 79%

“…The 13 CNMR spectrum of ribose in water solutionh as been reported previously and can be used as ab asis forp eak assignments in other samples. The spectrum we obtained ( Figure SI-5) was identical to that published by Ortiz et al [27] In general, four signals can be observed for each carbon, corresponding to the four anomers( although there is some overlap);t he a p and b p forms are more difficult to discriminate than the others. The C1 peaks are particularly well resolved and can be used to quantify the anomeric ratios;i tc an also be verified thatv ery similarr atios are obtained on the basis of the C4 peaks.…”

Section: Nmr Spectroscopysupporting

confidence: 79%

“…Sr 2 + is ap ossible exception. These conclusions are significantly different from those of Ortiz et al [27] who observedm ore significant peak shifts (a few tenths to 2.0 ppm) for ribose in aqueouss olution when KCl and NaCl were added to the medium;i ts hould be noted, however,t hat these authors used much higher salt concentrations. The 13 CC P-MAS NMR spectra of ribose/SiO 2 ,r ibose-Mg/SiO 2 , ribose-Ca/SiO 2 ,a nd ribose-Zn/SiO 2 are presented in Figure 7 and compared with that of bulk ribose.…”

Section: Nmr Spectroscopycontrasting

confidence: 76%

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Thermal Behavior of d‐Ribose Adsorbed on Silica: Effect of Inorganic Salt Coadsorption and Significance for Prebiotic Chemistry

Akouche

Jaber

Zins

et al. 2016

Chemistry A European J

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Understanding ribose reactivity is a crucial step in the "RNA world" scenario because this molecule is a component of all extant nucleotides that make up RNA. In solution, ribose is unstable and susceptible to thermal destruction. We examined how ribose behaves upon thermal activation when adsorbed on silica, either alone or with the coadsorption of inorganic salts (MgCl , CaCl , SrCl , CuCl , FeCl , FeCl , ZnCl ). A combination of C NMR, in situ IR, and TGA analyses revealed a variety of phenomena. When adsorbed alone, ribose remains stable up to 150 °C, at which point ring opening is observed, together with minor oxidation to a lactone. All the metal salts studied showed specific interactions with ribose after dehydration, resulting in the formation of polydentate metal ion complexes. Anomeric equilibria were affected, generally favoring ribofuranoses. Zn stabilized ribose up to higher temperatures than bare silica (180 to 200 °C). Most other cations had an adverse effect on ribose stability, with ring opening already upon drying at 70 °C. In addition, alkaline earth cations catalyzed the dehydration of ribose to furfural and, to variable degrees, its further decarbonylation to furan. Transition-metal ions with open d-shells took part in redox reactions with ribose, either as reagents or as catalysts. These results allow the likelihood of prebiotic chemistry scenarios to be evaluated, and may also be of interest for the valorization of biomass-derived carbohydrates by heterogeneous catalysis.

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Section: Nmr Spectroscopysupporting

confidence: 79%

Section: Nmr Spectroscopysupporting

confidence: 79%

Section: Nmr Spectroscopycontrasting

confidence: 76%

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Thermal Behavior of d‐Ribose Adsorbed on Silica: Effect of Inorganic Salt Coadsorption and Significance for Prebiotic Chemistry

Akouche

Jaber

Zins

et al. 2016

Chemistry A European J

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“…Overall, the observed change in the ratio of a-pyranose/b-pyranose isomers of xylose in the presence of metal halides is smaller than that reported for isomers of ribose and galactose. [18,19] The larger effect of salts on these latter sugars is attributable to the presence of pyranose conformers containing axial-equatorial-axial (ax.-eq.-ax.) orientations of hydroxyl groups, for which the tri-oxygen core strongly attracts cations.…”

Section: Effects Of Metal Halides On the Distribution Of Xylose Confomentioning

confidence: 99%

The Role of Metal Halides in Enhancing the Dehydration of Xylose to Furfural

Enslow

Bell

2015

ChemCatChem

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The dehydration of xylose yields furfural, a product of considerable value as both a commodity chemical and a platform for producing a variety of fuels. When xylose is dehydrated in aqueous solution in the presence of a Brønsted acid catalyst, humins are formed via complex side processes that ultimately result in a loss in the yield of furfural. Such degradative processes can be minimized via the in situ extraction of furfural into an organic solvent. The partitioning of furfural from water into a given extracting solvent can be enhanced by the addition of salt to the aqueous phase, a process that increases the thermodynamic activity of furfural in water. Although the thermodynamics of using salts to improve liquid–liquid extraction are well studied, their impact on the kinetics of xylose dehydration catalyzed by a Brønsted acid are not. The aim of the present study was to understand how metal halide salts affect the mechanism and kinetics of xylose dehydration in aqueous solution. We found that the rate of xylose consumption is affected by both the nature of the salt cation and anion, increasing in the order no salt

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“…Esta característica de o boro favorecer as formas furanósicas da ribose é única quando comparada com a de outros aniões mais abundantes presentes na principal fonte de água líquida na Terra, os oceanos. 50,51 Com uma abundância na crusta terrestre mais elevada do que a do boro, o silício, 13 como silicato, forma compostos com intermediários do ciclo da formose, promovendo a síntese de monossacáridos de maior dimensão, entre os quais as pentoses (ribose). Apesar deste sistema de catálise não ser específico para a síntese de ribose, é esperado que a produção desta seja promovida relativamente a outras pentoses pois as estruturas silicato-ribose são mais estáveis termodinamicamente.…”

Section: Síntese De Riboseunclassified

Os semimetais na origem e evolução da vida

Aureliano¹,

Nolasco²,

Silva³

et al. 2012

Quím. Nova

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Recebido em 16/9/11; aceito em 2/12/11; publicado na web em 23/1/12 METALLOIDS IN ORIGIN AND EVOLUTION OF LIFE. Metalloids have characteristics between metals and non-metals which give them, in some cases, specific properties. At least two of this chemical elements, boron and silicon, are essential to a significant number of living organisms and since some years ago it has been observed that the same metalloids may be involved in the synthesis and stabilization of some molecules relevant to the origin of life.Keywords: RNA world; boron; silicon. INTRODUÇÃOEmbora se verifique uma tendência para abandonar o conceito de semimetal (metaloide), tanto a União Internacional da Química Pura e Aplicada como a Sociedade Brasileira de Química não os incluem separadamente nas suas tabelas periódicas dos elementos, 1 continuam a publicar-se muitos trabalhos sobre semimetais, dado que têm algumas especificidades com aplicações, por exemplo, no fabrico de semicondutores.2 No grupo dos semimetais (Figura 1) são, geralmente, incluídos os seguintes elementos químicos: boro (grupo 13), silício e germânio (grupo 14), arsénio e antimónio (grupo 15), e telúrio (grupo 16), sendo, por vezes, a designação alargada ao polónio (grupo 16) e ao ástato (grupo 17). Caracterizam-se por terem propriedades físicas e/ou químicas de metais e de não metais. Note-se que o ástato apresenta propriedades dos semimetais, embora pertença ao grupo dos halogéneos.Este artigo teve por objetivo descrever os semimetais com características mais próximas dos não metais e com pelo menos um isótopo estável, que possam ter dado contributos no processo de origem e evolução da vida na Terra. De notar também que atualmente os elementos boro, silício, arsénio e telúrio têm sido identificados como tendo funções ou eventuais desempenhos casuísticos nos seres vivos. Por outro lado, todos os isótopos de polónio e de ástato são radioativos, e por isso não são adequados aos processos metabólicos que ocorrem nos sistemas biológicos, pois originam reações que degradam as biomoléculas, como consequência do seu decaimento radioativo. 3-6 OS SEMIMETAIS E OS SISTEMAS BIOLÓGICOSAntes de se analisar os semimetais na sua associação com estruturas biológicas (ou eventualmente pré-biológicas) é conveniente efetuar algumas considerações acerca das razões gerais para a escolha dos elementos químicos pelos organismos vivos, as quais podem ser generalizadas para as estruturas pré-biológicas. Essas razões são, pelo menos, duas das seguintes: abundância, disponibilidade (que, de maneira simples, está relacionada com possibilidade dos elementos químicos serem solubilizados sem dispêndio elevado de energia) e eficiência funcional [a aptidão para possibilitarem determinadas reações (bio)químicas]. 4,7 Muitos elementos químicos são incorporados nos seres vivos na forma de compostos químicos com alguma complexidade. Todavia, no período de transição entre os sistemas minerológicos e a ocorrência dos primeiros organismos vivos, a escolha dos elementos químicos teve em conta as limitações da quanti...

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Role of the anion in the alkali halides interaction with d-ribose: a 1H and 13C NMR spectroscopy study

Cited by 26 publications

References 18 publications

Thermal Behavior of d‐Ribose Adsorbed on Silica: Effect of Inorganic Salt Coadsorption and Significance for Prebiotic Chemistry

Thermal Behavior of d‐Ribose Adsorbed on Silica: Effect of Inorganic Salt Coadsorption and Significance for Prebiotic Chemistry

The Role of Metal Halides in Enhancing the Dehydration of Xylose to Furfural

Os semimetais na origem e evolução da vida

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