Europäisches Patentamt (19) European Patent Office Office européen des brevets (11) EP 1 094 052 A2 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int. Cl.7: C07C 51/16, C07C 53/16, 25.04.2001 Bulletin 2001/17 C02F 1/461, B01J 19/12, (21) Application number: 00122084.7 B01J 19/08 (22) Date of filing: 11.10.2000 (84) Designated Contracting States: • Sugawa, Etsuko, AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU c/o Canon Kabushiki Kaisha MC NL PT SE Tokyo (JP) Designated Extension States: • Kato, Kinya, AL LT LV MK RO SI c/o Canon Kabushiki Kaisha Tokyo (JP) (30) Priority: 12.10.1999 JP 28977099 • Kawaguchi, Masahiro, c/o Canon Kabushiki Kaisha (71) Applicant: Tokyo (JP) CANON KABUSHIKI KAISHA Tokyo (JP) (74) Representative: Weser, Wolfgang Weser & Kollegen, (72) Inventors: Patentanwälte, • Kuriyama, Akira, Radeckestrasse 43 c/o Canon Kabushiki Kaisha 81245 München (DE) Tokyo (JP) (54) Process for preparing trichloroacetic acid and apparatus for use in such process (57) A process for preparing trichloroacetic acid comprises the step of bringing functional water capable of partial oxidizing tetrachloroethylene under irradiation with light or aerated functional water gas which is pro- duced by aerating the above functional water and has a capability similar to that of the above functional water into contact with tetrachloroethylene under irradiation with light. And an apparatus for preparing trichloroacetic acid comprises a closable container as a means for bringing functional water capable of partial oxidizing tet- rachloroethylene under irradiation with light or aerated functional water gas which is produced by aerating the above functional water and has a capability similar to that of the above functional water into contact with tetra- chloroethylene, and means for irradiating the above contact mixture with light. EP 1 094 052 A2 Printed by Xerox (UK) Business Services 2.16.7 (HRS)/3.6 12EP 1 094 052 A2 Description present invention has been thus achieved. [0007] Tetrachloroethylene used in the present BACKGROUND OF THE INVENTION invention as a raw material was once widely and abun- dantly used in various industries as cleaning solvents Field of the Invention 5for metal parts, semiconductor devices, clothing, etc. and as reactive solvents as well, just like trichloroethyl- [0001] The present invention relates to a process ene. However, since the time of the toxicity of these for preparing trichloroacetic acid from tetrachloroethyl- compounds, such as mutagenicity and carcinogenicity, ene using functional water under irradiation with light to organisms having been pointed out, there have been and an apparatus for use in such process. 10 strong demands that those stored without having been used and those having leaked out in nature be treated. Related Background Art Viewed in this light, and moreover, in terms of trans- forming disused articles into useful ones, the present [0002] Trichloroacetic acid is a useful compound invention is considered to be of great significance. which is not only used as a raw material for pharmaceu- 15 ticals, herbicides, caustics, paint removers and depro- SUMMARY OF THE INVENTION teinizing agents, but also used for extracting ATP and AMP and separating DNA from protein. [0008] The present invention is a process for pre- [0003] There have been known various processes paring trichloroacetic acid comprising the step of bring- for preparing trichloroacetic acid. Such processes 20 ing functional water capable of partial oxidizing include, for example, oxidizing chloral with nitric acid, tetrachloroethylene under irradiation with light or aer- organic percarboxylic acid, hydrogen peroxide, etc.; ated functional water gas which is produced by aerating chlorinating acetic acid, monochloroacetic acid or the above functional water and has a capability similar dichloroacetic acid (Japanese Patent Publication No. to that of the above functional water into contact with tet- 37-4111); hydrolyzing trichloroacetonitrile with hydro- 25 rachloroethylene under irradiation with light. chloric acid (Japanese Patent Publication No. 39-2135); [0009] Further, the present invention is an appara- hydrolyzing trichloroacetyl chloride; and oxidizing chlo- tus for preparing trichloroacetic acid comprising a clos- ral with nitric acid. In particular, Japanese Patent Appli- able container as a means for bringing functional water cation Laid-Open No. 5-178786 discloses a process for capable of partial oxidizing tetrachloroethylene under oxidizing chloral with nitric acid to prepare trichloroace- 30 irradiation with light or aerated functional water gas tic acid in which the NO gas produced is oxidized into which is produced by aerating the above functional NO2 in a reactor and condensed, so as to be recycled. water and has the capability similar to that of the above [0004] As industrial processes, chlorinating dichlo- functional water into contact with tetrachloroethylene; roacetic acid which is produced as a by-product in man- and means for irradiating the above contact mixture with ufacturing monochloroacetic acid and oxidizing chloral 35 light. with nitric acid are adopted. [0010] According to the present invention, trichloro- [0005] In the industrial processes as described acetic acid can be prepared by the process in which tet- above, however, the reactions require a high tempera- rachloroethylene, which is one of the causes of ture and take a long period time. In addition, in the proc- groundwater contamination and soil contamination, is ess for oxidizing chloral with nitric acid, a number of 40 brought into contact with aerated functional water gas at processes and a large amount of chemical agents are ordinary room temperature and normal pressure under required for detoxifying a large amount of NO2 and NO irradiation with light, instead of the prior art processes gases produced during the oxidation process. Under such as chlorinating dichloroacetic acid at a high tem- these circumstances, there have been demands for perature for a long period of time and oxidizing chloral developing some other process for preparing trichloro- 45 with nitric acid in which a number of processes and a acetic acid. large amount of chemical agents are required for detoxi- [0006] In light of the existing circumstances as fying a large amount of NO2 and NO gases produced. described above, the present inventors conducted an [0011] In other words, according to the present intensive investigation of the processes and finally invention, trichloroacetic acid, which is used for the found the fact that functional water such as acidic water 50 preparation of pharmaceuticals, chemical agents, etc., obtained by electrolysis of water, which has been can be prepared using the compounds which was once reported to have a bactericidal effect (Japanese Patent contaminants of no utility value as raw materials. Application Laid-Open No. 1-180293) and a cleaning effect on the contaminations on semiconductor wafers BRIEF DESCRIPTION OF THE DRAWINGS (Japanese Patent Application Laid-Open No. 7- 55 051675), decomposes tetrachloroethylene into trichlo- [0012] roacetic acid at ordinary temperature and normal pres- sure in a short time when irradiating it with light. The Figure shows an apparatus for continuously prepar- 2 34EP 1 094 052 A2 ing trichloroacetic acid with aerated functional example, an ion-exchange membrane, a micro-porous water gas, which is for use in the present invention. membrane or the like is suitably used. DETAILED DESCRIPTION OF THE PREFERRED (Functional Water - Mixed Electrolytic Ionized Water) EMBODIMENTS 5 [0018] In addition to the acid electrolytic ionized [0013] As described above, the present invention is water as described above, the mixed electrolytic ionized a process for preparing trichloroacetic acid comprising water which is obtained by mixing acidic water and alka- the step of bringing functional water capable of partial line water obtained near a cathode in the electrolysis to oxidizing tetrachloroethylene under irradiation with light 10 produce the acid electrolytic ionized water, in the ratio of or aerated functional water gas which is produced by 1 : 1 or less and which has the following properties: the aerating the above functional water and has the capabil- hydrogen ion concentration (pH value) ranging from 4.0 ity similar to that of the above functional water into con- to 10, the oxidation-reduction potential ranging from 300 tact with tetrachloroethylene under irradiation with light. mV to 1100 mV when the working electrode is a plati- [0014] Further, the present invention is an appara- 15 num electrode and the reference electrode is a silver - tus for preparing trichloroacetic acid comprising a clos- silver chloride electrode, and the chlorine concentration able container as a means for bringing functional water ranging from 2 mg/L to 100 mg/L has the same synthe- capable of partial oxidizing tetrachloroethylene under sis power as the acid electrolytic ionized water. irradiation with light or aerated functional water gas which is produced by aerating the above functional 20 (Functional Water - Synthesized Functional Water) water and has a capability similar to that of the above functional water into contact with tetrachloroethylene; [0019] The functional water having almost the same and means for irradiating the above contact mixture with tetrachloroethylene-decomposition power as the above- light. described functional water produced by electrolysis can 25 also be prepared not only by electrolysis, but also