Distillation: processes – separatory – Distillation in apparatus or element of specific material
Reexamination Certificate
2000-05-22
2003-04-29
Manoharan, Virginia (Department: 1764)
Distillation: processes, separatory
Distillation in apparatus or element of specific material
C203S091000, C203S092000, C203S095000, C568S753000, C568S764000, C202S267100
Reexamination Certificate
active
06554967
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of refining a dihydroxyaryl compound. More particularly, the present invention relates to a method of refining a dihydroxyaryl compound by using a distillation apparatus.
Among the high purity dihydroxyaryl compounds which can be refined by the method of the present invention, catechol has a chelate-forming property with various types of metal, and thus is useful as an impurity metals-removing agent for a base plate in procedures for producing a base plate of electronic devices.
2. Description of the Related Art
It is known that dihydroxyaryl compounds are refined by distillation to increase the degree of purity of the dihydroxyaryl compounds. In the conventional refining method, the distillation is carried out by using a distillation apparatus comprising an evaporating apparatus, a condenser connected to a top portion of the evaporating apparatus, and a tank for collecting the refined product, connected to the condenser through a conduit, which are formed from a stainless steel, and thus the evaporated and condensed fraction of the dihydroxyaryl compound is brought into contact with the inside surfaces of the condenser, conduit and collecting tank, formed from the stainless steel. In this case, the refined dihydroxyaryl compound is contaminated with impurity metals eluted from the stainless steel surface with which the refined dihydroxyaryl compound comes into contact.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of refining a dihydroxyaryl compound, in which contamination of the refined dihydroxyaryl compound with impurity metals can be decreased and thus the resultant refined dihydroxyaryl compound has a high degree of purity.
The above-mentioned object can be attained by the method of the present invention for refining a dihydroxyaryl compound, which comprises; evaporating a dihydroxyaryl compound in a distillation column; condensing the resultant vapor fraction of the dihydroxyaryl compound in a condenser connected to a top outlet of the distillation column; and collecting the condensed dihydroxyaryl compound fraction into a storage tank through a conduit connected to an outlet of the condenser, wherein the condenser has an inside surface thereof formed from a metal material containing at least 25% by weight of nickel, and the condensed dihydroxyaryl compound fraction comes into contact with the nickel-containing metal material inside surface.
In the refining method of the present invention, at least one member of the conduit and the storage tank has an inside surface formed from a metal material containing at least 25% by weight of nickel.
In the refining method of the present invention, the nickel containing metal material comprises 25% by weight or more of nickel and 75% by weight or less of at least one member selected from the group consisting of chromium, molybdenum, tungsten, iron, silicon, copper and aluminum.
In the refining method of the present invention, the collected dihydroxyaryl compound fraction has a degree of purity of 99.9% or more, as determined by gas chromatographic analysis.
In the refining method of the present invention, the collected dihydroxyaryl compound fraction has a total metal content of 200 ppb or less.
In the refining method of the present invention, the dihydroxyaryl compound is selected from the group consisting of catechol, resorcinol, hydroquinone, 3-methylcatechol, 4-methylcatechol, 2-methylhydroquinone, 2-chlorcatechol and 4-chlorocatechol.
In the refining method of the present invention, the evaporating procedure is carried out at a temperature of the top outlet of the distillation column of 120 to 220° C. under an absolute pressure of 1 to 50 kPa.
In the refining method of the present invention, the nickel-containing metal material inside surface is treated with hot water or water steam before or during the refining procedure.
In the refining method of the present invention, the evaporation procedure is suspended and then the hot water or water steam treatment is applied to the nickel-containing metal material inside surface.
In the refining method of the present invention, the hot water or water steam treatment is applied to the nickel-containing metal material inside surface, while the evaporating procedure for the dihydroxyaryl compound is continued.
In the refining method of the present invention, the hot water treatment is effected at a hot water temperature of 40 to 150° C.
In the refining method of the present invention, the water steam is generated from a mixture of the dihydroxyaryl compound with water in an amount of 0.01 to 1% by weight based on the weight of the dihydroxyaryl compound contained in the distillation column.
The refined dihydroxyaryl compound of the present invention is produced by the method of the present invention and has a degree of purity of 99.9% or more, as determined by gas chromatographic analysis.
The refined dihydroxyaryl compound of the present invention is produced by the method of the present invention and has a total metal content of 200 ppb or less.
The dihydroxyaryl compound of the present invention has a degree of purity of 99.9% or more, as determined by gas chromatographic analysis.
The dihydroxy compound of the present invention has a total metal content of 200 ppb or less.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The refined dihydroxyaryl compound produced by the refining method of the present invention preferably has a restricted total content of impurity metals of 200 ppb or less, more preferably 100 ppb or less, as determined by an induced bond plasma meter and/or a flameless atomic absorption spectrometer. Also, the refined dihydroxyaryl compound prepared by the refining method of the present invention preferably has a degree of purity of 99.9% or more, as determined by gas-chromatography and calculated as an area percentage.
The impurity metals which may be contained in the refined dihydroxyaryl compound include iron, nickel, molybdenum, and chromium.
The dihydroxyaryl compound which is subjected to the refining method of the present invention is in the state of a liquid under the ambient atmospheric conditions and is preferably selected from the group consisting of dihydroxyaryl compounds free from alkyl groups, for example, catechol, resorcinol and hydroquinone; dihydroxy compounds having one or more alkyl groups, for example, 3-methylcatechol, 4-methylcatechol and 2-methylhydroquinone; and dihydroxyaryl compounds further substituted with one or more halogen atoms, for example, 3-chlorocatechol or 4-chlorocatechol, more preferably catechol. There is no limitation to the degree or purity of or the type of impurity metals contained in the dihydroxyaryl compound. Usually, the dihydroxyaryl compound, for example, catechol, having a degree of purity of 99% or more, and containing about 500 ppb of iron, about 100 ppb of nickel, about 150 ppb of chromium and about 50 ppb of molybdenum is subjected to the refining method of the present invention.
The distillation column of the distillation apparatus usable for the refining method of the present invention is not limited to a specific type of distillation column and may be selected from conventional evaporator type distillation columns, packed column type distillation columns, and tray type distillation columns, generally the packed column type distillation columns each having at least a condenser having an inside surface formed from a Ni-containing metal. The packing materials for the packed column type distillation columns are selected from trade-available packing materials, preferably, for example, pall rings made from, for example, stainless alloys or Ni—Mo—Fe alloys, for example, HASTELLOY A, B and C (registered trademark), THROUSER (registered trademark) packings (made from a stainless steel), MELAPACK (registered trademark), MELACARBON (registered trademark, made from a carbon), and MELAJUL (registered trademark, made from a ceramic).
The packing materials are usually packed in two or more theoret
Kawashita Tetsuro
Kofuji Hiroshi
Koga Genji
Tanaka Shuji
Manoharan Virginia
Morgan & Lewis & Bockius, LLP
UBE Industries Ltd.
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