Process for producing halogenated phenol compounds

Details Process for producing halogenated phenol compounds Process for producing halogenated phenol compounds

2000-08-15

2001-07-24

Richter, Johann (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S774000, C568S775000, C568S709000

Reexamination Certificate

active

06265621

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing halogenated phenol compounds. In particular, the present invention relates to a process for producing halogenated phenol compounds from phenol compounds in the presence of a halide ion (X
−
) and a semiconductor catalyst with a photocatalytic activity under light irradiation conditions.
2. Description of the Prior Art
A halogenated phenol compound is used e.g. as an active ingredient in medicines and agrochemicals or as a synthetic intermediate of such an active ingredient. For example, a phenol compound containing a radioactive halogen atom in the molecule is widely used as a radioactive tracer used for measurement of the in vivo movement or functions of pharmaceutical chemicals etc., or as an active ingredient in diagnostic or therapeutic drug. Specifically, thyroxine containing iodine-125, for example, is used for measurement of thyroid functions; an antihuman colon cancer-derived sugar chain antigen antibody iodinated with iodine-125 is used for diagnosis of the cancer of digestive organs; an antihuman prostate acid phosphatase antibody iodinated with iodine-125 is used for diagnosis of prostate cancer; and human fibrinogen iodinated with iodine-125 is used for detection of thrombus sites.
In general, since a radioactive halogen atom is supplied stably in the state of a halide ion, a method of reacting the halide ion (X
−
) with a phenol compound in the presence of an oxidizing agent such as chloramine T (N-chloro-4-methylbenzenesulfonamide sodium salt), Iodo-Gen™ (1,3,4,6-tetrachloro-3 &agr;, 6 &agr;-diphenylglycoluril), Iodo-beads™ (N-chloro-benzenesulfonamide (sodium salt) derivatized, uniform, nonporous, polystyrene beads) and hydrogen peroxide is used for producing the above-described phenol compound containing a radioactive halogen atom in the molecule.
In the method described above, however, the phenol compound to be halogenated is placed under oxidizing conditions, thus making it difficult to apply said method to those compounds which are unstable under such conditions.
Accordingly, there is a demand for development of a method of halogenation under moderate conditions applicable to those phenol compounds which are unstable under oxidizing conditions.
SUMMARY OF THE INVENTION
Under such circumstances, the present inventors have studied intensively, and have found that a halogenated phenol compound can be produced from a phenol compound in the presence of a halide ion (X
−
) and a semiconductor catalyst with a photocatalytic activity, to reach the present invention.
That is, the present invention provides a process for producing a halogenated phenol compound represented by the general formula [II]:
wherein Q is a monovalent organic residue, and A is, the same or different, a hydrogen atom, halogen atom, —SO
3
H or —SO
3
Na group, or A at the ortho-position relative to Q may be combined with Q to form a divalent organic residue and X is a halogen atom including each isotope thereof, which comprises the step of reacting in a solvent a phenol compound represented by the general formula [I]:
wherein X, Q and A have the same meanings as defined above with a halide ion represented by the general formula X
−
wherein X has the same meanings as defined above, under light irradiation conditions in the presence of a semiconductor catalyst with a photocatalytic activity (this process is referred to hereinafter as the process of the present invention.).
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step.
DETAILED DESCRIPTION OF THE INVENTION
The semiconductor catalyst with a photocatalytic activity to be used in the process of the present invention are semiconductor catalysts which are solid catalysts with the property that electrons in a valence band of the catalysts are excited by light. Most of the catalysts are metal oxides or metal sulfates. Specific examples of them include titanium oxide (TiO
2
), strontium titanate (SrTiO
3
), tungsten oxide (WO
3
), bismuth oxide (Bi
2
O
3
), zirconium oxide (ZrO
2
), stannum oxide (SnO
2
), zinc oxide (ZnO) and zinc sulfide (ZnS). The semiconductor catalyst with a photocatalytic activity may have any form as long as its solid surface can receive light during its use. For example, powder, granule and ones supported on carriers by coating are available. Further, commercial available ones may also be employed.
The amount, in molar ration, of the semiconductor catalyst with a photocatalytic activity is preferably not less than that of the halide ion (X
−
). When the concentration of the halide ion in a solution is low, the amount of the semiconductor catalyst is preferably excessive.
The light to be used in the process of the present invention may be any one which has a wavelengths at which the light can excite electrons of the semiconductor catalyst with a photocatalytic activity. For example, when titanium oxide (TiO
2
), strontium titanate (SrTiO
3
) or tungsten oxide (WO
3
) is used, any light with wavelengths shorter than 388 nm may be applied. A black light, a mercury lamp, a xenon lamp and the like can be employed as a light source. By regulating the intensity of irradiation light, the rate of reaction may be regulated. Further, the wavelength used may be selected in consideration of stability of the phenol compound as the raw material and the halogenated phenol compound as the reaction product
Examples of the halide ion (X
−
) to be used in the process of the present invention include iodide ion (I
−
), bromide ion (Br
−
) and chloride ion (Cl
−
). The halide ion is used in the form of its salt of a metal such as an alkali metal or of a quaternary ammonium such as tetrabutylammonium. Examples of such salts include sodium iodide (NaI), potassium iodide (KI), sodium bromide (NaBr), potassium bromide (KBr), sodium chloride (NaCl), potassium chloride (KCl). Furthermore, the halide ion also includes ions of isotopes of the halogen atoms. The isotopes may be radioactive isotopes. Examples of such isotopes include iodine-123, 125, 128, and 131, bromine-75, 76, 77, 80 and 82, chlorine-36 and 38.
The solvent to be used in the process of the present invention may be any one in which the phenol compound, which is one of the raw materials, can be dissolved with stability and a small amount of a salt of a halide can be dissolved. Examples of the solvent include dipolar aprotic solvents such as acetonitrile, dimethylformamide, dimethyl sulfoxide and the like, as well as mixed solvents thereof with water. When the raw phenol compound is water-soluble, water or a buffer may be used.
The reaction in which the reaction of the process of the present invention is conducted may be any one made of a material through which the light of a desired wavelengths can pass, and borosilicate glass reactor, a sample tube made of polypropylene and the like may be used. The light source is mounted near the reactor, and as needed, is cooled for the purpose of prevention of the temperature rise in the reactor caused by the heat from the light source. The reaction solution is stirred depending upon demand.
Q in the phenol compound of the general formula [I] used in the process of the present invention is a monoval

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