Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-10-27
2001-10-09
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S384000, C568S403000, C210S762000, C210S763000, C210S908000
Reexamination Certificate
active
06300523
ABSTRACT:
BACKGROUND OF THE INVENTION
Disclosure of the Invention
The present invention relates to a novel method of organic synthesis using supercritical water which allows organic synthesis to be carried out at a high reaction rate under noncatalytic conditions without the addition of high concentrations of acid to the supercritical water, and more particularly, this invention relates to a method for carrying out organic synthesis utilizing proton supply from water under noncatalytic conditions in supercritical water, a method for increasing the reaction rate during such organic synthesis, a method of pinacol rearrangement in which pinacoline is produced by pinacol rearrangement under noncatalytic conditions without the addition of an acid catalyst in supercritical water, and a method of cyclization for producing cyclic compounds from pinacol under noncatalytic conditions without the addition of an acid catalyst around the supercritical point.
Background of the Invention
Dramatic changes in the reaction rate and selectivity around the critical point of supercritical fluids in organic chemical reactions using supercritical fluids as the reaction medium have recently been reported (1 to 3: numbers of references described in the last paragraph of this specification; and so forth on) and have become the focus of considerable attention. Supercritical fluids have physical properties being intermediate between liquids and gases, with molecular motion energy that is always greater than the intermolecular force. Nevertheless, because of conflict between the formation of the system order due to intermolecular force and the scattering of molecules due to kinetic energy thereof, the molecules are violently reversed while the order is preserved (cluster formation) to some extent at the microscopic level. Thus, slight changes in temperature and pressure around the critical point result in significant changes in fluid density.
Examination of the reaction molecules in organic reactions featuring the use of such supercritical fluids as the reaction medium has revealed that the chemical interaction between different species of molecules in minute surrounding areas thereof changes in particular around the critical point (4 and 5). Changes in the dynamic and static structures are assumed to considerably affect the reaction equilibrium and rate, and the product distribution.
The inventors thus developed methods of in situ measurement such as high pressure FT-IR, UV/Vis, and Raman spectroscopy, which have been used to achieve an understanding, at the molecular level, of the relationship between the reaction site at the microscopic level and factors affecting reactivity. This has resulted not only in the elucidation of the relationship between reactivity and the function of supercritical fluids as the reaction site, but has also allowed the microscopic site of reaction formed in supercritical fluids to be controlled by the manipulation of temperature and pressure at the microscopic level, potentially leading to the development of a novel, industrially promising chemical reaction process with high selectivity and high efficiency.
In anticipation of the application of such supercritical fluids in reaction sites, attention has recently focused on chemical reactions in which supercritical water serves as the reaction site as same as supercritical carbon dioxide. Carbon dioxide is nonpolar in a supercritical state and has essentially the same properties, whereas water in a supercritical state is known to have completely different properties than water at normal temperature. For example, permittivity of water at ordinary temperature and atmospheric pressure is about 80, whereas the permittivity of supercritical water is about 3 to 20 around the critical point, allowing the permittivity of water to be continuously controlled within a wide range by temperature and pressure. It is thus possible that organic compounds with low polarity such as aromatic compounds and various gases can be dissolved in supercritical water, which would be extremely valuable for industrial purposes.
The supercritical water oxidation (SCWO) of toxic substances through the exploitation of the properties of supercritical water is thus receiving attention all over the world (6). This is because of the possibility that many toxic organic substances (such as chlorine-containing aromatic compounds), oxidizing agents such as air, oxygen and other might be readily dissolved in supercritical water and they might be decomposed by oxidation (combustion). The inventors have succeeded in the complete decomposition of polychlorinated biphenyl (PCB) by means of SCWO using hydrogen peroxide as oxidating agent (7). Supercritical water has wide-ranging possibilities in applications as reaction media in thermochemical reactions such as dehydration reactions, pyrrolysis, reduction, and synthesis, showing the promise of supercritical water as a reaction solvent.
Although organic synthesis in supercritical fluids has been noted, most examples have been chemical reactions featuring the use of organometal catalysts in supercritical carbon dioxide (8), with very few examples of organic synthesis using supercritical water as the reaction site. The study of organic synthesis in supercritical water is extremely significant because nonpolar compounds can be readily dissolved in supercritical water, with a far higher critical temperature than that of carbon dioxide.
Recent research (9, 10) has revealed that water has extremely weak hydrogen bonding strength around the critical point of water, and has a dimer or monomer structure. Research (11, 12) by the inventors on supercritical water or high-temperature and high pressure aqueous solutions using Raman spectroscopy showed a strong possibility that the structural instability (change of dynamics) around the critical point resulted in the further break down of the monomer structure and production of proton. If there are few site at which protons can be held within the system following the production thereof, the local proton concentration could be increased, which should also affect the chemical reactivity.
As noted above, much research has thus far been undertaken on the temperature and pressure dependency of the reaction rate and selectivity in organic chemical reactions in supercritical fluids (such as carbon dioxide, water, ethane, propane and the like) from the standpoint of the solvent or solute clustering effects or the physicochemical properties of solvents, centering around the critical point. There has also been considerable research on various chemical reactions in supercritical fluids in the presence of catalysts, the development of spectroscopic methods of measurement in high temperature and high pressure reactions in supercritical water, and the possibility of devising a novel chemical reaction comprising such an inorganic reaction. If the relationship between the micro factors in the vicinity of the substrate molecules and the chemical reactivity in supercritical fluids could be elucidated on a molecular scale, the reactivity and function of the reaction site in supercritical states could be elucidated, and a reaction process with higher selectivity and a higher reaction rate could be devised, which could be extremely useful for both scientific and industrial purposes. However, thus far, there have been virtually no reports on achieving a high reaction rate utilizing the supply of protons from water during organic synthesis in supercritical water.
SUMMARY OF THE INVENTION
The present invention is intended to provide a method for producing pinacoline by means of pinacol rearrangement in supercritical water, which affords an extremely high reaction rate without the addition of high concentrations of acid.
The present invention is directed to a method for increasing the reaction rate during organic synthesis by utilizing the supply of protons from water under noncatalytic conditions in supercritical water, a method of pinacol rearrangement comprising the production of pinacoline by pinacol rearrangement unde
Ikushima Yutaka
Sato Osamu
Agency of Industrial Science and Technology
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Padmanabhan Sreeni
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