(30b) In-Pore Superhigh Pressure Effect On Solid Phase Transition and Organic Crystal Synthesis

The solid nanospaces can offer intensive interaction potential fields for molecules. We clearly showed that the gas-phase disproportionation reaction of (NO)₂ to N₂O and NO₂ above 20 MPa occurs efficiently in the slit-shaped carbon nanospaces.¹ We named the effect of carbon nanospaces a quasi-high-pressure effect. The quasi-high-pressure effect of the slit-shaped nanopore spaces was also evidenced in the electrochemical reduction of CO₂ to CO by Fujishima et al..² A more intensive confinement effect of molecules in carbon nanotube spaces is expected, because the interaction potential depth of a molecule with the cylindrical pore is deeper than the slit-shaped pore. The confinement of CH₄ molecules in the tube spaces of single wall carbon nanohorn (SWCNH) elevates the boiling temperature according to the temperature dependence of the rotational vibration spectra.³

Then the effect of confinement of materials in carbon nanotube spaces should be studied in comparison with the effect of  carbon slit shaped pore spaces.  High resolution transmission electron microscopic observation and synchrotron X-ray diffraction studies showed that the confinement of KI in the tube spaces of SWCNHs below 0.1 MPa induced formation of the high pressure solid phase requesting the compression by more than 1.9 GPa.⁴  The superhigh pressure effect for KI in the slit shaped pores of activated carbon fiber (ACF)s was not so remarkable compared with confinement in the tube spaces of SWCNH. Gubbins et al gave the theoretical possibility for the quasi-pressure reaction for slit-shaped carbon pore.⁴  The systematic researches on the superhigh pressure effect have been desirable.   

Superhigh pressure organic synthesis is one of current subjects in organic chemistry and thereby an epoch making simple route for superhigh pressure synthesis should be invented. We have evidenced that the carbon nanospaces of single wall carbon nanotube and ACF could induce superhigh pressure organic synthetic reaction, producing the bulk amount of the target organic product.  Here we selected superhigh pressure reaction of 1,2-epoxy cyclohexane (ECH) into trans-cyclohexanediol (CHD) which occurs at 303 K above 1 GPa⁵, as the target reaction.

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[2] Yamanoto T, Tryk D A,  Hashimoto K.Fujishima A (2000) J. Electrochem. Soc. 147  3393.

[3]  Urita K, Shiba Y, Fujimori T, Hattori Y, Kanoh H, Ohba T,  Tanaka H,  Yudasaka M,  Iijima S. Moriguchi I, Okino F, Endo M, Kaneko K (2011) J. Amer. Chem. Soc. 133 10344

[4] Long, Y. Palmer, J.C. Coasne, B. Sliwinska-Bartokowiak M. Gubbins K. E., 2012 Microporous Mesoporous Mater. 154, 19

[5]  Kotsuki H, Kataoka M, Nishizawa H (1993)  Tetrahedron Lett. 34  4031.