Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2000-09-11
2004-08-10
Trinh, Ba K. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C210S762000, C210S763000, C210S808000
Reexamination Certificate
active
06774262
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel method of organic synthesis reaction in supercritical water that makes possible an organic synthesis reaction with high reaction rate under non catalytic conditions without adding high-concentration alkali, in supercritical water or subcritical water of at least 350° C. In more particular, the present invention relates to a method of performing an organic synthesis reaction by utilizing supply of OH
−
from the water under non catalytic conditions in supercritical water or subcritical water of at least 350° C. and a method of increasing the reaction rate of this organic synthesis reaction, and to a method of generating alcohol and carboxylic acid by performing a Cannizzaro reaction under non catalytic conditions, in supercritical water, without adding a basic catalyst and a method of generating alcohol and carboxylic acid from an aldehyde under non catalytic conditions without adding a basic catalyst in the vicinity of the supercritical point.
2. Description of the Related Art
Recently, in the field of organic chemical reactions using a supercritical fluid as reaction medium, in addition to the various advantages in terms of the process, very considerable changes are reported in the reaction rate and selectivity in the vicinity of the critical point of the supercritical fluid (1 to 3: the numbers indicate prior art references, listed in the last, here and hereinbelow) and these have attracted considerable attention. A supercritical fluid has physicochemical properties intermediate those of a liquid and a gas, and the molecular kinetic energy is always dominant over the inter molecular forces. Nevertheless, in the vicinity of the critical point, the formation of order of the system due to inter molecular forces and its dispersal due to the kinetic energy of the molecules are in opposition, so, on the micro level, while some degree of order is maintained (formation of clusters), the molecules of these are in a state of rapid turnover. Consequently, in the vicinity of the critical point, slight changes of temperature or pressure produce large changes of fluid density.
In an organic synthesis reaction whose reaction medium is such a supercritical liquid, in regard to the reaction molecules, it has been discovered that the chemical interactions between different molecular species in the micro-regions surrounding these show specific changes in particular in the vicinity of the critical point (4 to 5), and it may be anticipated that changes of dynamic and static structure will considerably affect the equilibrium and rate of the reaction and the distribution of reaction products.
With this in view, the present inventors are striving to elucidate, on the molecular scale, the relationship between micro reaction fields and the factors that affect reactivity by developing new in situ measurement methods such as high-pressure FT-IR, UV/Vis, and Raman spectroscopy. If these can be put into practice, in addition to clarifying the relationship between reactivity and function of the reaction fields of the supercritical fluid, control of the micro reaction fields formed in the supercritical fluid by macro manipulation of temperature and pressure may be envisaged, and this may lead to the creation of novel chemical reaction processes of high selectivity and high efficiency which can also be applied industrially.
Whilst such application to the reaction fields of supercritical fluids is anticipated, in recent years, chemical reactions in which supercritical carbon dioxide and supercritical water are used to provide reaction fields have attracted attention. It is well known that, whereas carbon dioxide is non polar and its basic properties are scarcely changed in the supercritical condition, on changing to the supercritical condition, water shows completely different properties to water at ordinary temperature. For example, while the dielectric constant of water at ordinary temperature and atmospheric pressure is about 80, in the vicinity of the critical temperature, the dielectric constant of supercritical water is about 3 to 20, so the dielectric constant of water can be controlled continuously and in a wide range by means of temperature and pressure. The possibility therefore exists of dissolving organic substances of low polarity such as aromatic compounds, or various gases, in supercritical water; this is of exceptional value industrially.
Thus, oxidative decomposition reactions of toxic substances by utilizing this characteristic of supercritical water (SCWO) have attracted attention internationally (6). This is because supercritical water easily dissolves many organic substances (for example, chlorinated aromatic compounds) and oxidizing agents such as air or oxygen, making it possible to perform oxidative decomposition (combustion). The present inventors also have succeeded in complete decomposition of polychlorinated biphenyl (PCB) by SCWO, using hydrogen peroxide as oxidizing agent. Furthermore, the possibilities of application of supercritical water as a reaction medium for thermochemical reactions such as synthesis reactions, reduction reactions, thermal cracking reactions or dehydration reactions are very wide, clearly demonstrating its promise as a reaction solvent.
organic synthesis reactions in supercritical fluids have attracted attention, but most of these are chemical reactions employing an organo metallic catalyst in supercritical carbon dioxide (8); examples of organic synthesis reactions in which supercritical water is used as the reaction field are very few. The study of organic synthesis reactions in supercritical water is considered to be very significant on account of the properties of supercritical water that non polar compounds easily dissolve in supercritical water and that the critical temperature thereof is much higher than that of carbon dioxide.
Recent investigations (9, 10) have shown that the strength of the hydrogen bonds of water in the vicinity of the critical point is greatly reduced so that a dimer or monomer structure is produced. Furthermore, investigations (11, 12) by the present inventors of supercritical water or high-temperature, high-pressure aqueous solutions using Raman spectroscopy suggest that the monomer structure is further decomposed by structural instability (dynamic changes) in the vicinity of the critical point, with a strong probability that protons are generated. Generation of protons from the monomer structure of water suggests that OH
−
ions (OH
−
are simultaneously generated. If there are few sites for holding OH
−
within the system, the local concentration of OH
−
will rise, so considerable effects on chemical reactions may be anticipated.
As described above, various studies have previously been carried out centered on the vicinity of the critical point, concerning organic chemical reactions in supercritical fluids (carbon dioxide, water, ethane, or propane and the like) regarding temperature and pressure dependence of reaction rate and selectivity, from the point of view of the effects of physicochemical characteristics of the solvent, and the solvent or solute clustering effect. Furthermore, various studies have been made concerning the feasibility of creating novel chemical reactions including inorganic reactions or developing various chemical reactions in supercritical fluids in the presence of catalyst, or in situ methods of spectroscopic measurement of high-temperature/high-pressure reaction fields in for example supercritical water. If the relationship between chemical reactivity and micro factors in the region of the vicinity of the substrate molecules in a supercritical fluid can be elucidated on the molecular scale, this leads to elucidation of the reactivity and function of reaction fields in the supercritical condition and hence to the creation of reaction processes of high selectivity and high efficiency and can be expected to be of high utility from both the scientific and industrial viewpoints.
Hatakeda Kiyotaka
Ikushima Yutaka
Sato Osamu
Japan as represented by Secretary of Agency of Industrial Scienc
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Oh Taylor V.
Trinh Ba K.
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