Carbon dioxide gas accelerates solventless synthesis

Jessop, Philip G.; Wynne, Dolores C.; DeHaai, Scott; Nakawatase, Denise

doi:10.1039/a909703a

Cited by 43 publications

(19 citation statements)

References 12 publications

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“…The Pt-catalyzed hydrogenation of oleic acid (a solid substrate) at 35 °C is limited by solid-solid mass transfer limitations and reaches a maximum of 90% conversion after 25 h. In contrast, in the presence of 55 bar C0 2 the oleic acid melts at 35°C and the reaction proceeds to 97% conversion after only 1 h (84).…”

Section: Multiphase Catalysismentioning

confidence: 97%

“…Facile hydrogenation of compounds such as vinylnaphthalene with a RhCl(PPh 3 ) 3 catalyst which is a solid at ambient conditions was demonstrated by melting the solid with compressed C0 2 and performing the reaction in the melt phase at 33°C, which is well below the normal melting point of the solid (64). This reaction technique is particularly useful in the case of thermally labile substrates.…”

Section: Homogeneous Catalysismentioning

confidence: 98%

See 1 more Smart Citation

Gas-Expanded Liquids: Fundamentals and Applications

Scurto

Hutchenson

Subramaniam

2009

Gas-Expanded Liquids and Near-Critical Media

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Section: Multiphase Catalysismentioning

confidence: 97%

Section: Homogeneous Catalysismentioning

confidence: 98%

Gas-Expanded Liquids: Fundamentals and Applications

Scurto

Hutchenson

Subramaniam

2009

Gas-Expanded Liquids and Near-Critical Media

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“…Interestingly, the compressed CO 2 atmosphere depresses the melting point of the substrates by dissolution of CO 2 in the substrates. [19] This broadens the range of potential substrates that can be used in the beneficial multiphase oxidation regime, as demonstrated for the oxidation of cyclododecane (22; Table 1, entry 5), which could be oxidized efficiently under liquid/supercritical conditions already at 45 8C, although its regular melting point is higher than the reaction temperature (m.p. 60.4 8C [20] ).…”

Section: Wwwchemeurjorgmentioning

confidence: 98%

Selective Oxidation of Alkanes with Molecular Oxygen and Acetaldehyde in Compressed (Supercritical) Carbon Dioxide as Reaction Medium

Theyssen

Hou

Leitner

2006

Chemistry A European J

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The oxidation of cycloalkanes or alkylarenes with molecular oxygen and acetaldehyde as sacrificial co-reductant occurs efficiently in compressed (supercritical) carbon dioxide (scCO2) under mild multiphase conditions. No catalyst is required and high-pressure ATR-FTIR online measurements show that a radical reaction pathway is heterogeneously initiated by the stainless steel of the reactor walls. For secondary carbon atoms, high ketone to alcohol ratios are observed (3.5-7.9), most probably due to fast consecutive oxidation of alcoholic intermediates. Since C--C scission reactions are detected only to a very small extent, tertiary carbon atoms are transformed into the corresponding alcohols with high selectivity. Detailed analysis of the product distributions and other mechanistic evidence suggest that acetaldehyde acts not only as the sacrificial oxygen acceptor, but also as an efficient H-atom donor for peroxo and oxo radicals and as a crucial reductant for hydroperoxo intermediates. In comparison to other inert gases such as compressed N2 or Ar, the use of carbon dioxide was shown to increase the yields of alkane oxygenates under identical reaction conditions.

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“…The pressure of CO 2 (or any other gas near its critical pressure) causes the melting point of the solid to decrease such that it melts or at least softens. Solventless reactions of solids, which are typically very slow for obvious mass-transfer reasons, can be accelerated by the addition of pressurized CO 2 in this manner, without the pressure being high enough for the CO 2 to act as a compressed gas solvent [99]. The principal disadvantage of this technique is that the melting point depression is usually limited to a 20 or 30 K drop, although for some compounds the melting point depression can be significantly greater.…”

Section: New Trendsmentioning

confidence: 99%