Process for Preparing Trichloroacetic Acid and Apparatus for Use in Such Process

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 produced 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 tetrachloroethylene 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 tetrachloroethylene, 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 pressure 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 by (Functional Water - Acid Electrolytic Ionized Water) dissolving various reagents in raw water. For example, such functional water can be obtained by dissolving in [0015] The functional water produced by electrolyz- raw water 0.001 to 0.1 N hydrochloric acid, 0.005 to ing water means, for example, water which can be 0.02 N sodium chloride and 0.0001 to 0.01 M sodium obtained near an anode by dissolving an electrolyte 30 hypochlorite. (such as sodium chloride and potassium chloride) in [0020] Further, the functional water having a pH raw water and electrolyzing the water in a water bath value ranging from 4.0 to 10 can also be obtained not with a pair of electrodes and which has the following only by the electrolysis, but also by dissolving various properties: a hydrogen ion concentration (pH value) reagents in raw water. For example, such functional ranging from 1 to 4, an oxidation-reduction potential 35 water can be obtained with hydrochloric acid at a con- ranging from 800 mV to 1500 mV when the working centration of 0.001 to 0.1 N, sodium hydroxide at a con- electrode is a platinum electrode and a reference elec- centration of 0.001 to 0.1 N and sodium hypochlorite at trode is a silver - silver chloride electrode, and a chlorine a concentration of 0.0001 to 0.01 M, or with hypochlorite concentration ranging from 5 mg/L to 150 mg/L. alone, for example with sodium hypochlorite at a con- [0016] When producing functional water having the 40 centration of 0.0001 to 0.01 M, alone. properties described above, the concentration of the [0021] The functional water having a pH value of electrolyte in the raw water is desirably 20 mg/L to 2000 4.0 or less and a chlorine concentration of 2 mg/L can mg/L before electrolysis and the electrolytic current be prepared with hydrochloric acid and hypochlorite. value is desirably 2 A to 20 A. As a means for obtaining Instead of hydrochloric acid as described above, some such functional water, commercially available strong 45 other inorganic acid or organic acid can also be used. acid electrolytic ionized water production equipment (for The inorganic acids applicable include, for example, example, trade name: Oasis Bio Half; manufactured by hydroﬂuoric acid, sulfuric acid, phosphoric acid and Asahi Glass Engineering Co., Ltd., trade name: Strong boric acid. The organic acids applicable include, for Electrolytic Ionized Water Production Equipment Model example, acetic acid, formic acid, malic acid, citric acid FW-200; manufactured by Amano Corporation) can be 50 and oxalic acid. Further, functional water can also be utilized. produced with a weak acidic water producing powdered [0017] In the production of functional water, arrang- agent (for example, N3C3O3NaCl2 commercially availa- ing a diaphragm between a pair of electrodes allows the ble under the trade name of Kinosan 21X; manufacture prevention of acidic water produced near an anode and by Clean Chemical Co., Ltd.). alkaline water produced near a cathode from mixing 55 [0022] The functional water prepared by the above- with each other, thereby acidic water can be obtained described chemical compounding also has the capabil- which ensures more efﬁcient preparation of trichloro- ity of synthesizing trichloroacetic acid when irradiated acetic acid. As the diaphragm as described above, for with light, like the functional water prepared by the elec-

3 56EP 1 094 052 A2 trolysis, though there is a difference in the synthesis (Light Source) power between the two, as seen from the examples described later. The raw water herein used include, for [0026] For the light used in the preparation of example, tap water, river water and seawater. These trichloroacetic acid with functional water for irradiating types of water usually have a pH value ranging from 6 to 5purpose, its wavelength is preferably 300 to 500 nm, 8 and a chlorine concentration less than 1 mg/L at the particularly preferably 350 to 450 nm. The intensity of most. It goes without saying that these types of raw the light irradiating various types of functional water or water have neither tetrachloroethylene-decomposition aerated functional water gas and tetrachloroethylene as power nor trichloroacetic acid-synthesis power. a raw material is preferably 10 µW/cm2 to 10 mW/cm2, 10 particularly preferably 50 µW/cm2 to 5 mW/cm2, in (Aerated Functional Water Gas) terms of synthetic efficiency. Specifically, for the light source having the peak at a wavelength of 365 nm, a [0023] The aerated functional water gas means the good enough amount of synthesis progresses with the gas obtained by aerating the above-described acid elec- intensity of several hundreds µW/cm2 (measured at the trolytic ionized water, mixed electrolytic ionized water 15 wave lengths between 300 nm to 400 nm). and synthesized functional water in oxygen gas or a [0027] As a source of the light as described above, gaseous mixture of oxygen gas and an inert gas. The natural light (such as sunlight) or artificial light (mercury gaseous mixture of oxygen gas and an inert gas is not lamp, black light, color fluorescent lamp, etc.) can be limited to a specific one, and even when using air as a used. gaseous mixture, trichloroacetic acid of quality ade- 20 [0028] In order to accelerate the synthesis, light quate for use in the ordinary applications can be irradiation is conducted preferably at the time various obtained. In order to obtain trichloroacetic acid of higher types of functional water or aerated functional water gas purity, oxygen gas should be used solely, or when using and tetrachloroethylene are allowed to come in contact a gaseous mixture of oxygen gas and an inert gas, any with each other. In the embodiments of the present one of the rare gases such as helium, neon and argon 25 invention where functional water is used, it is not neces- should be used as an inert gas. In this case, the higher sary to use ultraviolet light with a wavelength of 250 nm the purity of the oxygen gas used is, the more preferable which affects the human body significantly. the product is. [0029] All the reactions of the various types of func- [0024] The aerated functional water gas contains tional water and aerated functional water gas described chlorine gas, steam and oxygen. The chlorine concen- 30 above progress under irradiation with light. In such reac- tration is preferably 5 to 1000 ppm V, particularly prefer- tions, the functional water produced by, for example, the ably 20 to 500 ppm V. The steam is the moisture mixed electrolysis of the water containing an electrolyte such with the gas when aerating the functional water. Its con- as sodium chloride contains hypochlorous acid or centration does not need to be controlled; rather, it hypochlorous acid ions. And it is considered that these should not be controlled, because, if the temperature of 35 hypochlorous acid or hypochlorous acid ions induce the functional water is raised intentionally to a tempera- chlorine radicals, hydroxyl radicals and superoxide ani- ture higher than room temperature, so as to increase ons with the aid of the light action, leading to accelerat- the steam amount, the purity of the trichloroacetic acid ing the reaction of producing trichloroacetic acid. prepared is lowered due to the moisture condensation [0030] The amount of the hypochlorous acid, which occurring within the tetrachloroethylene reactor. As for 40 is considered to contribute to the production of trichloro- oxygen concentration, not less than 10 % is enough, acetic acid, in the functional water produced near an and it does not need to be raised to a concentration anode by the electrolysis thereof can be obtained based higher than that of air. on the PH value and the chlorine concentration of the functional water. The water obtained by diluting the (Tetrachloroethylene) 45 functional water with deionized water etc. can also be used for the production of trichloroacetic acid. [0025] The tetrachloroethylene used as a raw mate- [0031] A process of preparing trichloroacetic acid rial for trichloroacetic acid may be that prepared solely with functional water will be described below. In the for industrial use. However the tetrachloroethylene may embodiments of the present invention, the process of also be used such that it was once used at factories etc. 50 allowing tetrachloroethylene and functional water or for, for example, cleaning metal parts, semiconductor aerated functional water gas to come in contact with devices, clothing, etc., leaked in nature, contaminated each under light irradiation can be carried out at the river water, underground water and soil, and recovered ordinary room temperature and normal pressure. therefrom afterward by the vacuum suction of soil or the Accordingly there is no need for special facilities and aeration of underground water. The higher the purity of 55 environment. tetrachloroethylene is, the more preferable the product [0032] The processes in which functional water is. itself is allowed to contact with tetrachloroethylene include, for example, directly mixing the above two; and

4 78EP 1 094 052 A2 conducting electrolysis in an electrolytic bath containing ride gas are adsorbed therein, after that, the trap is an aqueous electrolyte with tetrachloroethylene added exhausted. thereto. [0039] Hydrogen chloride is considered to be pro- [0033] Preparing trichloroacetic acid by these proc- duced during the reaction. However, in the batch esses is simple and easy, but on the other hand, there 5method, it is easily volatilized by raising the temperature may be cases where water, electrolyte in functional of the water in a glass bottle which is used in the reac- water, etc. mix with the trichloroacetic acid prepared as tion. In the continuous method, the trichloroacetic acid impurities. Thus, in order to avoid allowing those impuri- produced is easy to separate, since it is cooled at room ties to mix with the trichloroacetic acid prepared, the temperature after discharged from the reaction coil, process is more preferable in which functional water 10 condensed and finally solidified. When intending to itself is not allowed to contact with tetrachloroethylene, heighten the purity of the trichloroacetic acid, the liquid but the functional water gas, which is obtained by aerat- obtained after the reaction should be refined by, for ing the functional water previously prepared or the func- example, the vacuum distillation, the solvent extraction tional water being prepared in the electrolysis with and the adsorption separation. oxygen gas or a gaseous mixture of oxygen gas and an 15 [0040] Now the present invention will be described inert gas, is allowed to contact with tetrachloroethylene. in further detail based on the examples below. [0034] The process of the present invention may be carried out in accordance with any one of the batch (Example 1) Preparation of Batch with Acid Electrolytic method and the continuous method. When adopting the Ionized Water batch method, tetrachloroethylene and functional water 20 or aerated functional water gas may be filled into a glass [0041] First, functional water was prepared with container at a time and irradiated with light. When strong acid functional water production equipment adopting the continuous method, an apparatus, for (trade name: Strong Electrolytic Ionized Water Produc- example, shown in Figure may be used. tion Equipment; manufactured by Amano Corporation, [0035] The aerated functional water gas is supplied 25 Model FW-200). In this case, a diaphragm was by aerating the functional water in a functional water arranged between the anode and the cathode. aerating bath 1 with compressed air. This functional [0042] While changing the electrolyte concentration water aerating bath may also be allowed to serve as an of the water electrolyzed and the electrolysis time using electrolytic bath by providing the bath with electrodes this equipment, the pH values and oxidation-reduction and a diaphragm for separating the electrolysis solution 30 potentials of the acid functional water obtained on the between the electrodes and arranging a bubbler for the side of the anode in this equipment were measured with aeration near the anode. a pH meter (TCX-90i and KP900-2N; manufactured by [0036] Tetrachloroethylene, as the raw material, is Toko Chemical Institute, Co., Ltd.) and a conductivity vaporized by being aerated with oxygen gas or a gase- meter (TCX-90i and KP900-2N; manufactured by Toko ous mixture of oxygen gas and an inert gas, such as air, 35 Chemical Institute, Co., Ltd.), respectively, and the chlo- sent to a bubbler arranged in a tetrachloroethylene rine concentration of the same was measured with chlo- vaporizing bath 2. rine test paper (Advantic Co., Ltd.). [0037] The aerated functional water gas and the [0043] As a result, the pH value, the oxidation- vaporized tetrachloroethylene are mixed with each reduction potential and the chlorine concentration of this other and allowed to pass through a reaction coil 4 40 functional water varied from 1.0 to 4.0, from 800 mV to made of glass tube which goes down in the direction of 1500 mV and from 5 mg/L to 150 mg/L, respectively, gravity while winding around a light irradiating means 3, with the concentration of sodium chloride as the electro- so as to produce trichloroacetic acid. The trichloroacetic lyte (a standard concentration is 1000 mg/L), the elec- acid produced within the reaction coil 4, which is in the trolytic current value and the electrolysis time. Then in liquid state, is pushed by the gas within the glass tube 45 this example, functional water with a pH value of 2.6, an coil due to the heat of the light irradiating means 3 and oxidation-reduction potential of 1000 mV and a residual allowed to drop into a recovery bath 5. In the recovery chlorine concentration of 75 mg/L was prepared as bath, the trichloroacetic acid is cooled, condensed, and functional water used for an experiment of the produc- finally crystallized. tion of trichloroacetic acid. [0038] Although the melting point of trichloroacetic 50 [0044] 2.6 mL of this functional water and 8.2 µL acid is about 57°C, in cases where the calorific power of (about 13 mg) of tetrachloroethylene stock solution the light irradiating means 3 is too low and the trichloro- were put in a 27.5 mL glass vial, and the glass vial was acetic acid is condensed, a heater for heating the reac- sealed with a butyl rubber stopper with Teflon liner. tion coil 4 may be prepared specially or the entire Then this glass vial was installed in a seesaw type stir- reaction apparatus may be heated so as to raise the 55 rer and was irradiated with light, while stirring the mixed temperature within the reaction coil 4 to about 60°C. solution, using a black light fluorescent lamp (trade The gas discharged from the coil is introduced into a name: FL10BLB; manufactured by Toshiba Corporation, trap 6 and the excess chlorine gas and hydrogen chlo- 10 W) installed above the glass vial. The quantity of the

5 91EP 1 094 052 A2 0 irradiating light was 0.1 to 0.2 mW/cm2. functional water were used. [0045] After 60-minute light irradiation, the fluores- [0050] After 60-minute light irradiation, the fluorescent lamp was turned off, the gas in the glass vial was cent lamp was turned off and the gas in the glass vial sampled with a gas tight syringe and measured with a was measured. As a result, no tetrachloroethylene was gas chromatography (GC-14B with a Fire Ionized 5detected for both the functional water a and b. Then the Detector; manufactured by Shimadzu Corporation, The liquid in the glass vial was measured, and it was found column used was DB-624 manufactured by J&W). As a that trichloroacetic acid was produced at a concentra- result, no tetrachloroethylene was detected. Then the tion of 4100 mg/L for the mixed functional water a and at liquid in the glass vial was sampled and measured with a concentration of 4200 mg/L for the mixed functional a high pressure liquid chromatography (manufactured 10 water b. by Waters), as a result of which it was found that trichlo- [0051] After tetrachloroethylene was mixed with roacetic acid was produced at a concentration of 4500 each mixed functional water and irradiated with light, it mg/L. was found that trichloroacetic acidic aqueous solution [0046] After tetrachloroethylene was mixed with the was obtained in a yield of 81 % for the mixed functional electrolytic functional water and irradiated with light, it 15 water a and in a yield of 83 % for the mixed functional was found that trichloroacetic acidic aqueous solution water b in 60 minutes. was obtained in a yield of 89 % in 60 minutes. (Example 3) Preparation of Batch with Synthesized (Comparative Example 1) Functional Water 20 [0047] The same experiment as in Example 1 was [0052] First, the pH value, the oxidation-reduction conducted, except that the black light fluorescent lamp potential and the chlorine concentration were measured was not turned on. Sixty minutes after mixing the func- for the aqueous solution prepared to have a hydrochlo- tional water and tetrachloroethylene stock solution, the ric acid concentration of 0.001 to 0.1 N, a sodium chlo- gas in the glass vial was measured, and 56000 ppm V 25 ride concentration of 0.005 to 0.02 N and a sodium of tetrachloroethylene was detected. Then the liquid in hypochlorite concentration of 0.0001 to 0.01M. As a the glass vial was measured, but no trichloroacetic acid result, the pH value varied in the range of 1.0 to 4.0, the was detected. oxidation-reduction potential in the range of 800 mV to [0048] Thus, it was found that, even in cases where 1500 mV and the chlorine concentration in the range of tetrachloroethylene was mixed with the electrolytic func- 30 5 mg/L to 150 mg/L. tional water, if the mixed liquid was not irradiated with [0053] Then in this example, the aqueous solution light, the reaction did not occur and tetrachloroethylene was prepared in a glass vial to have a hydrochloric acid remained as it was. concentration of 0.006 N, a sodium chloride concentration of 0.014 N and a sodium hypochlorite concentration (Example 2) Preparation of Batch with Mixed Electro- 35 of 0.002M, and functional water with a pH value of 2.3, lytic Ionized Water an oxidation-reduction potential of 1180 mV and a residual chlorine concentration of 105 mg/L. The same [0049] Electrolysis was conducted with the same experiment as in Example 1 was conducted, except that electrolytic ionized water production equipment as in this functional water was used. Example 1 using sodium chloride with a concentration 40 [0054] After 60-minute light irradiation, the fluores- of 1000 mg/L as the electrolyte, so as to prepare acid cent lamp was turned off and the gas in the glass vial functional water with a pH value of 2.6, an oxidation- was measured. As a result, no tetrachloroethylene was reduction potential of 1000 mV and a residual chlorine detected. Then the liquid in the glass vial was meas- concentration of 70 mg/L on the anode side and alkaline ured, and it was found that trichloroacetic acid was pro- functional water with a pH value of 11.5, an oxidation- 45 duced at a concentration of 4400 mg/L. reduction potential of 850 mV and a residual chlorine [0055] After tetrachloroethylene was mixed with the concentration of 10 mg/L on the anode side. The acid synthesized functional water and irradiated with light, it functional water and the alkaline functional water were was found that trichloroacetic acidic aqueous solution mixed in the ratio of 1 : 1, so as to prepare mixed func- was obtained in a yield of 87 % in 60 minutes. tional water a with a pH value of 7.1, an oxidation-reduc- 50 tion potential of 400 mV and a residual chlorine (Example 4) Preparation of Batch with Aerated Func- concentration of 42 mg/L. Further, the acid functional tional Water Gas water and the alkaline functional water were mixed in the ratio of 1 : 0.5, so as to prepare mixed functional [0056] First, functional water with a pH value of 2.6, water b with a pH value of 6.5, an oxidation-reduction 55 an oxidation-reduction potential of 1000 mV and a resid- potential of 480 mV and a residual chlorine concentra- ual chlorine concentration of 75 mg/L was prepared, just tion of 47 mg/L. And the same experiment as in Exam- like Example 1. 100 mL of this functional water was aer- ple 1 was conducted, except that these types of ated with compressed air at a flow rate of 10 mL/min

6 11 EP 1 094 052 A2 12 and the aerated functional water gas obtained was put measured at this point was about 100 ppm V. And the in a 125 mL glass vial by the downwards displacement. tetrachloroethylene concentration measured with a gas Then the chlorine concentration in the glass vial was chromatography was 900 ppm V. The aerated functional measured with an indicator tube (Gastec Service, Inc., water gas and the gaseous tetrachloroethylene each No. 8H), and it was found that the concentration was 5 obtained by the aeration were mixed with each other, about 200 ppm V. then allowed to enter the reaction coil 4 from the upper [0057] 8.2 µL (about 13 mg) of tetrachloroethylene end portion thereof, allowed to flow down while being stock solution was put in this glass vial, and the glass subjected to light irradiation over about 30 minutes, and vial was sealed with a butyl rubber stopper with Teflon discharged from the lower end portion of the reaction liner. Then this glass vial was irradiated with light, while 10 coil 4. The liquid matter and solid matter were stored in stirring the solution, using a black light fluorescent lamp, the recovering bath 5 and the gas was discharged just like Example 1. through a trap 6. [0058] After 60-minute light irradiation, the fluores- [0062] When bringing a glass rod with ammonium cent lamp was turned off and the gas in the glass vial attached thereon close to the gas discharged from the was measured; however no tetrachloroethylene was 15 recovering bath 5, white smoke was produced. On the detected. Then water was put in the glass vial, so as to other hand, when bringing a glass rod with ammonium dissolve in the whole water the white crystal attached on attached thereon close to the gas discharged from the its wall surface. The liquid was measured with a high trap 6 which was filled with activated carbon and a pressure liquid chromatography; as a result, it was sodium hydroxide aqueous solution, there occurred no found that trichloroacetic acid was produced in an 20 changes. It is presumed from this fact that hydrogen amount of 13 mg. chloride produced in the reaction coil 4 was not stored in [0059] After tetrachloroethylene was mixed with the the recovering bath 5, but discharged therefrom and aerated functional water gas and irradiated with light, it removed by the adsorption in the trap 6. was found that trichloroacetic acid was obtained in a [0063] In this experiment, the gas discharged form yield of 99 % in 60 minutes. 25 the recovering bath 5 was sampled with a gas tight syringe and measured with a gas chromatography. As a (Example 5) Continuous Production with Aerated Func- result, no tetrachloroethylene was detected. tional Water Gas [0064] All the tetrachloroethylene in the tetrachloroethylene vaporizing bath 2 was vaporized in about 30 [0060] Trichloroacetic acid was produced continu- 30 minutes. After that, compressed air was sent for another ously with an apparatus shown in Figure. First, 1000 30 minutes, then sending compressed air was stopped mg/L of sodium chloride aqueous solution was put in a and the fluorescent lamp was turned off. The white crys- vial for electrolytic water provided for a strong acid elec- tallized matter attached on the bottom portion and the trolytic functional water production equipment (trade wall portion of the recovering bath 5 was washed off and name: Oasis Bio Half; manufactured by Asahi Glass 35 recovered, and then subjected to a high pressure liquid Engineering Co., Ltd.) and started to operate it, so as to chromatography. The measurement showed that 1.5 g produce electrolytic functional water continuously. The of trichloroacetic acid was produced. There were functional water obtained was measured in the same observed no peaks of other products. manner as in Example 1, and it was found that the func- [0065] The results showed that trichloroacetic acid tional water had a pH value of 2.4, an oxidation-reduc- 40 could be produced continuously in the average yield of tion potential of 1000 mV and a residual chlorine 78 % when using the apparatus shown in Figure and concentration of 70 mg/L. This functional water was mixing tetrachloroethylene with functional water and supplied continuously to a functional water aerating irradiating the mixture with light in its reaction coil for 30 bath 1, so as to produce aerated functional water gas. minutes. [0061] Then 2 g of tetrachloroethylene was put in 45 the tetrachloroethylene vaporizing bath 2. The black Claims light fluorescent lamp (trade name: FL10BLB; manufactured by Toshiba Corporation, 10 W), as the light irradi- 1. A process for preparing trichloroacetic acid com- ating means, which had been installed in the middle of prising the step of bringing functional water capable the reaction coil made of the glass tube 20 mm in diam- 50 of partial oxidizing tetrachloroethylene under irradi- eter and 1 m in length, was turned on previously, and ation with light or aerated functional water gas after confirming the temperature of the reaction coil which is produced by aerating the functional water reached 60°C or higher, compressed air was sent to the and has a capability similar to that of the functional functional water aerating bath 1 and the tetrachloroeth- water into contact with tetrachloroethylene under ylene vaporizing bath 2, respectively, at a flow rate of 10 55 irradiation with light. mL/min so as to aerate the functional water and the tetrachloroethylene via the respective bubblers. The chlo- 2. The process for preparing trichloroacetic acid rine concentration of the aerated functional water gas according to claim 1, wherein the aeration is con-

7 13 EP 1 094 052 A2 14

ducted with oxygen gas or a gaseous mixture of 13. The process for preparing trichloroacetic acid oxygen gas and an inert gas. according to claim 1, wherein the functional water is a hypochlorite aqueous solution. 3. The process for preparing trichloroacetic acid according to claim 1, wherein the gaseous mixture 5 14. The process for preparing trichloroacetic acid of oxygen gas and an inert gas is air. according to claim 13, wherein the hypochlorite is at least any one of sodium hypochlorite and potas- 4. The process for preparing trichloroacetic acid sium hypochlorite. according to claim 1, wherein the aerated functional water gas contains chlorine gas at a concentration 10 15. The process for preparing trichloroacetic acid of 5 to 1000 ppmV. according to claim 1, wherein the functional water further comprises inorganic acid or organic acid. 5. The process for preparing trichloroacetic acid according to claim 4, wherein the aerated functional 16. The process for preparing trichloroacetic acid water gas contains chlorine gas at a concentration 15 according to claim 15, wherein the inorganic acid or of 20 to 500 ppmV. the organic acid is at least one selected from the group consisting of hydrochloric acid, hydroﬂuoric 6. The process for preparing trichloroacetic acid acid, sulfuric acid, phosphoric acid, boric acid, ace- according to claim 1, wherein the aerated functional tic acid, formic acid, malic acid, citric acid and oxalic water gas contains steam. 20 acid.

7. The process for preparing trichloroacetic acid 17. The process for preparing trichloroacetic acid according to claim 1, wherein the functional water is according to claim 1, wherein the functional water an acidic aqueous solution produced near an has a hydrogen ion concentration (pH value) of 1 to anode by the electrolysis of an aqueous solution 25 4, an oxidation-reduction potential (working elec- containing an electrolyte. trode: platinum electrode, reference electrode: silver - silver chloride electrode) of 800 to 1500 mV, 8. The process for preparing trichloroacetic acid and a chlorine concentration of 5 to 150 mg/L. according to claim 1, wherein the functional water is a mixed aqueous solution of the acidic aqueous 30 18. The process for preparing trichloroacetic acid solution produced near an anode and an alkaline according to claim 1, wherein the functional water aqueous solution produced near a cathode by elec- has a hydrogen ion concentration (pH value) of 4 to trolysis of an aqueous solution containing an elec- 10, an oxidation-reduction potential (working electrolyte. trode: platinum electrode, reference electrode: sil- 35 ver - silver chloride electrode) of 300 to 1100 mV, 9. The process for preparing trichloroacetic acid and a chlorine concentration of 2 to 100 mg/L. according to claim 8, wherein the mixed aqueous solution is obtained by mixing the acidic aqueous 19. The process for preparing trichloroacetic acid solution and the alkaline aqueous solution in a ratio according to claim 1, wherein the light comprises of 1 : 1 or less. 40 light having a wavelength range of 300 to 500 nm.

10. The process for preparing trichloroacetic acid 20. The process for preparing trichloroacetic acid according to claim 7, wherein the electrolysis is according to claim 19, wherein the light has a wave- conducted in an electrolytic bath having a dia- length range of 350 to 450 nm. phragm for avoiding mixing the acidic aqueous 45 solution produced near the anode with the alkaline 21. The process for preparing trichloroacetic acid aqueous solution produced near the cathode pro- according to claim 1, wherein an irradiation dose of vided between the two electrodes. the light is in a range of 10 µW/cm2 to 10 mW/cm2.

11. The process for preparing trichloroacetic acid 50 22. The process for preparing trichloroacetic acid according to claim 10, wherein the diaphragm is an according to claim 21, wherein the irradiation dose ion-exchange membrane or a micro-porous mem- of the light is in a range of 50 µW/cm2 to 5 mW/cm2. brane. 23. The process for preparing trichloroacetic acid 12. The process for preparing trichloroacetic acid 55 according to claim 1, wherein the functional water is according to claim 7, wherein the electrolyte is at the acid electrolytic aqueous solution, the place of least any one of sodium chloride and potassium the functional water coming into contact with tetra- chloride. chloroethylene under light irradiation is near the

8 15 EP 1 094 052 A2 16

anode of the electrolytic bath provided with a pair of tional water gas contains chlorine gas at a concen- electrodes where the acid electrolytic aqueous tration of 5 to 1000 ppmV. solution is produced, and the light irradiation is conducted in such a state in which tetrachloroethylene 33. The apparatus for preparing trichloroacetic acid is allowed to exist near the anode. 5 according to claim 32, wherein the aerated functional water gas contains chlorine gas at a concen- 24. The process for preparing trichloroacetic acid tration of 20 to 500 ppmV. according to claim 1, comprising the steps of: 34. The apparatus for preparing trichloroacetic acid supplying the functional water to produce the 10 according to claim 25, wherein the aerated func- aerated functional water gas by aeration; tional water gas contains steam. mixing the aerated functional water gas with tetrachloroethylene; and 35. The apparatus for preparing trichloroacetic acid recovering the trichloroacetic acid produced. according to claim 25 which comprises an equip- 15 ment for producing functional water, the equipment 25. An apparatus for preparing trichloroacetic acid comprising a pair of electrodes, a power source for comprising: applying a voltage between the electrodes and a container storing an electrolyte aqueous solution a closable container as means for bringing therein, wherein and the functional water is pro- functional water capable of partial oxidizing tet- 20 duced by applying a voltage between the elec- rachloroethylene under irradiation with light or trodes so as to electrolyze the electrolyte aqueous aerated functional water gas which is produced solution. by aerating the functional water and has the capability similar to that of the above functional 36. The apparatus for preparing trichloroacetic acid water into contact with tetrachloroethylene; and 25 according to 35, wherein the functional water is an means for irradiating the contact mixture with acidic aqueous solution produced near the anode light. by electrolysis of an aqueous solution containing an electrolyte. 26. The apparatus for preparing trichloroacetic acid according to claim 25, wherein the light irradiated 30 37. The apparatus for preparing trichloroacetic acid from the light irradiating means comprises light hav- according to 35, wherein the functional water is a ing a wavelength range of 300 to 500 nm. mixed aqueous solution of the acidic aqueous solution produced near the anode and the alkaline 27. The apparatus for preparing trichloroacetic acid aqueous solution produced near the cathode by the according to claim 26, wherein the light irradiated 35 electrolysis of an aqueous solution containing an from the light irradiating means has a wavelength electrolyte. range of 350 to 450 nm. 38. The apparatus for preparing trichloroacetic acid 28. The apparatus for preparing trichloroacetic acid according to claim 37, wherein the mixed aqueous according to claim 25, wherein an irradiation dose 40 solution is obtained by mixing the acidic aqueous of the light is in a range of 10 µW/cm2 to 10 solution and the alkaline aqueous solution in the mW/cm2. ratio of 1 : 1 or less.

29. The apparatus for preparing trichloroacetic acid 39. The apparatus for preparing trichloroacetic acid according to claim 28, wherein the irradiation dose 45 according to claim 36, wherein the electrolytic bath of the light is in a range of 50 µW/cm2 to 5 mW/cm2. in which the electrolysis is conducted has a diaphragm for avoiding mixing the acidic aqueous 30. The apparatus for preparing trichloroacetic acid solution produced near the anode with the alkaline according to claim 25, wherein the aeration is con- aqueous solution produced near the cathode pro- ducted with oxygen gas or a gaseous mixture of 50 vided between the two electrodes. oxygen gas and an inert gas. 40. The apparatus for preparing trichloroacetic acid 31. The apparatus for preparing trichloroacetic acid according to claim 39, wherein the diaphragm is an according to claim 30, wherein the gaseous mixture ion-exchange membrane or a micro-porous mem- of oxygen gas and an inert gas is air. 55 brane.

32. The apparatus for preparing trichloroacetic acid 41. The apparatus for preparing trichloroacetic acid according to claim 25, wherein the aerated func- according to claim 35, wherein the electrolyte is at

9 17 EP 1 094 052 A2 18

least any one of sodium chloride and potassium means for supplying tetrachloroethylene; chloride. means for mixing the aerated functional water gas with tetrachloroethylene; 42. The apparatus for preparing trichloroacetic acid means for irradiating the gaseous mixture with according to claim 35, wherein the electrolytic bath 5 light; and also serves as a closable container as means of means for recovering the trichloroacetic acid bringing the functional water into contact with tetra- produced. chloroethylene, the place of the functional water coming in contact with tetrachloroethylene is near the anode where the acidic aqueous solution is pro- 10 duced, means for supplying tetrachloroethylene directly near the anode is provided, and the light irradiating means irradiates near the anode with light. 15 43. The apparatus for preparing trichloroacetic acid according to claim 25, wherein the functional water is a hypochlorite aqueous solution.

44. The apparatus for preparing trichloroacetic acid 20 according to claim 43, wherein the hypochlorite is at least any one of sodium hypochlorite and potassium hypochlorite.

45. The apparatus for preparing trichloroacetic acid 25 according to claim 25, wherein the functional water further comprises inorganic acid or organic acid.

46. The apparatus for preparing trichloroacetic acid according to claim 45, wherein the inorganic acid or 30 the organic acid is at least one selected from the group consisting of hydrochloric acid, hydroﬂuoric acid, sulfuric acid, phosphoric acid, boric acid, acetic acid, formic acid, malic acid, citric acid and oxalic acid. 35

47. The apparatus for preparing trichloroacetic acid according to claim 25, wherein the functional water has a hydrogen ion concentration (pH value) of 1 to 4, an oxidation-reduction potential (working elec- 40 trode: platinum electrode, reference electrode: silver - silver chloride electrode) of 800 to 1500 mV, and a chlorine concentration of 5 to 150 mg/L.

48. The apparatus for preparing trichloroacetic acid 45 according to claim 25, wherein the functional water has a hydrogen ion concentration (pH value) of 4 to 10, an oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver - silver chloride electrode) of 300 to 1100 mV, 50 and a chlorine concentration of 2 to 100 mg/L.

49. The apparatus for preparing trichloroacetic acid according to claim 25, comprising: 55 means for supplying the functional water to produce the aerated functional water gas by aeration;

10 EP 1 094 052 A2