JPH08283205A - Production of carbonate - Google Patents

Abstract

PURPOSE: To obtain a carbonate useful as a raw material for polycarbonates, without chlorine loss, in high conversion and selectivity in an industrially advantageous way, in such a manner as to facilitate catalyst separation, by reaction between a chloroformic ester and an organic hydroxy compound in the presence of a specific catalyst. CONSTITUTION: This carbonate is obtained by reaction between (B) a chloroformic ester and (C) an organic hydroxy compound such as a compound of formula I [A is a single bond, O, S, a group of formula II (R<2> and R<3> are each a 1-8C alkyl, 5-8C chcloalkyl or 7-8C aralkyl), group of formula III (R<4> -R<7> are each the same as R<2> ), etc.] in the presence of (A) a catalyst, i.e., a metal element belonging to platinum metals or primary transition metal group or its compound (for example, prepared by the following method: a palladium tetramine complex, acetylacetonato complex or high-valence phosphine complex, or tetrachloropalladium acid salt is reduced by hydrogen into the corresponding metal, which is then carried on a carrier such as alumina, silica or active carbon).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for easily producing a carbonate, particularly an asymmetric carbonate, from a chloroformate and an organic hydroxy compound in the presence of a catalyst. Asymmetric carbonates, especially aryl carbonates, are very useful compounds as raw materials for synthesizing aromatic polycarbonates and urethanes.

[0002]

2. Description of the Related Art Conventionally, a reaction for producing a carbonate (carbonic acid ester) from a chloroformic acid ester and an organic hydroxy compound has been carried out in the presence of a base such as sodium hydroxide (for example, JP-A-63-41529). (See the official gazette). However, in this method, a salt (for example, sodium chloride) that cannot be recycled and reused in an equimolar amount with the reacted chloroformate is produced, and if it is considered from the production of the raw chloroformate as shown in the following formula, it is originally Half of the chlorine used is lost in the form of sodium chloride, which significantly reduces the chlorine consumption. There is also a problem that the treatment of the generated sodium chloride becomes complicated.

[0003]

Embedded image (In the formula, R and R'represent an aryl group)

As a method for producing diphenyl carbonate, phenyl chloroformate and phenol are (1) VB.
Method of reacting in the presence of a catalyst selected from metal oxides, (2) IIA metal, IIIB metal, IVB metal, VB metal, lanthanoid metal and actinide metal silicate, (3) tungsten oxide, (4) clay Is known (see US Pat. No. 5,239,105). However,
This method is not sufficiently industrially satisfactory because the activity and selectivity of the catalyst are not sufficiently high.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a method for producing a carbonate (carbonic acid ester) from a chloroformic acid ester and an organic hydroxy compound, which is a salt having high activity and selectivity and which cannot be circulated and reused, such as sodium chloride. It is an object of the present invention to provide a method for producing a carbonate which does not generate, that is, a method for producing a carbonate which has high activity and selectivity and which can reuse chlorine for producing a chloroformate as a raw material.

[0006]

The object of the present invention is to provide an element selected from a platinum group element and a first transition series element in the form of its metal and / or compound to form a chloroformate and an organic hydroxy compound. Is achieved by a method for producing a carbonate.

The present invention will be described in detail below. Examples of the chloroformate include compounds represented by the following formula.

Embedded image (In the formula, R ¹ is a lower alkyl group having 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group, or a cycloalkyl group having a carbon number of 5 to 8 such as a cyclopentyl group and a cyclohexyl group, or (Indicates a C7-8 aralkyl group such as a benzyl group and a phenylethyl group, and a C6-14 aryl group such as a phenyl group, a tolyl group, and a xylyl group)

Specifically, for example, (1) methyl chloroformate, ethyl chloroformate, n- (or i-) propyl chloroformate, n- (or i-, sec-) butyl chloroformate, n- () chloroformate. Or i-) pentyl, n- (or i-) hexyl chloroformate, n- (or i) chloroformate
-) Heptyl, n- (or i-) octyl chloroformate, etc., a lower alkyl ester of chloroformate having a lower alkyl group having 1 to 8 carbon atoms, (2) cyclopentyl chloroformate, cyclohexyl chloroformate, cycloheptyl chloroformate, chloroformate Cycloalkyl ester having a cycloalkyl group having 5 to 8 carbon atoms such as cyclooctyl acid salt, (3) chloroalkyl formate aralkyl ester having an aralkyl group having 7 to 8 carbon atoms such as benzyl chloroformate and phenylethyl chloroformate, And (4) phenyl chloroformate, tolyl chloroformate, xylyl chloroformate, and the like, chloroformic acid aryl esters having an aryl group having 6 to 14 carbon atoms (including various isomers).

Examples of the organic hydroxy compound include aromatic hydroxy compounds represented by the following formula, in which a hydroxy group is directly bonded to an aryl group (Ar).

Embedded image

Specifically, for example, (1) a phenyl group,
(2) Tolyl group, xylyl group, trimethylphenyl group,
Tetramethylphenyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group,
An alkylphenyl group having a C1-8 alkyl group such as a hexylphenyl group, and (3) an aryl group such as a cycloalkylphenyl group having a C5-8 cycloalkyl group such as a cyclopentyl group and a cyclohexyl group. An aromatic hydroxy compound having a hydroxy group directly bonded to (Ar) (however, including various isomers) is used. Among them, an aromatic hydroxy compound having 6 to 10 carbon atoms is preferable, and phenol is particularly preferable. used.

An aromatic dihydroxy compound represented by the following formula can also be preferably used as the aromatic hydroxy compound of the present invention.

[Chemical 4] (In the formula, A is a simple bond, or -O-, -S-, -CO
A divalent group such as-, --CO _2- , --SO--, --SO _2- ,
Or represents an alkylene group or a substituted alkylene group represented by the following formula)

[0012]

Embedded image (In the formula, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are each a hydrogen atom or a lower alkyl group having 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group; Or a cycloalkyl group having 5 to 8 carbon atoms such as cyclopentyl group and cyclohexyl group, or an aralkyl group having 7 to 8 carbon atoms such as benzyl group and phenylethyl group)

The aromatic dihydroxy compound is, for example, (1) a compound in which A such as hydroquinone is a single bond,
(2) 2,2-bis (4-hydroxyphenyl) propane (generic name: bisphenol A), 2,2-bis (4-
Hydroxycyclohexyl) propane (generic name: hydrogenated bisphenol A), bis (4-hydroxyphenyl) methane (generic name: bisphenol F), 1,1-bis (4
-Hydroxyphenyl) cyclohexane (generic name: bisphenol Z), 2,2-bis (4-hydroxy-3,
A such as 5-dimethylphenyl) propane in which A is a group represented by (a) above, (3) bis (4-hydroxyphenyl) sulfone (generic name: bisphenol B), bis (4-hydroxy-3, A in which A is a —SO ₂ — group such as 5-dimethylphenyl) sulfone, (4) bis (4-)
A in which A is a —O— group such as hydroxyphenyl) ether, and (5) A in a bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxybenzophenone is
Examples thereof include a group having a CO- group, and a group having A as an -SO- group such as (6) bis (4-hydroxyphenyl) sulfoxide. Among these aromatic dihydroxy compounds, bisphenols such as general name: bisphenol A, hydrogenated bisphenol A, bisphenol F and bisphenol Z are preferably used.

In the present invention, a metal selected from a platinum group metal element and a first transition series element and / or a compound thereof is used as a catalyst, and a corresponding carbonate (carbonic acid) is formed from the chloroformic acid ester and the alcohol according to the following reaction formula. Ester) is produced.

[Chemical 6]

The platinum group elements include platinum, palladium,
Examples of the element such as rhodium and ruthenium, and the first transition series element include iron, cobalt, copper, nickel and the like. Among these elements, a platinum group element is preferable, and palladium is particularly preferable. preferable.

The elements are used in the form of their metals and / or compounds. As the compound of the element, nitrate,
Inorganic acid salts such as sulfates, phosphates and halides, organic acid salts such as acetates, oxalates and benzoates, tetraammine complexes, hexaammine complexes, acetylacetonato complexes, acetonitrile complexes, phosphine complexes and hydrides. Examples thereof include complexes. Examples of these compounds for palladium are (1) palladium nitrate, palladium sulfate, palladium phosphate, palladium chloride, palladium inorganic salts such as palladium bromide, (2) palladium acetate, palladium oxalate, palladium benzoate. And other organic acid salts of palladium, (3) tetraammine palladium chloride, tetraammine palladium bromide, tetraammine palladium nitrate and other tetraammine complexes, (4) palladium acetylacetonato complex, and (5) dichlorobis (trimethylphosphine)
A high-valence palladium phosphine complex such as palladium, dichlorobis (triethylphosphine) palladium, dichlorobis (triphenylphosphine) palladium, or (6) tetrakis (trimethylphosphine) palladium, tetrakis (triethylphosphine) palladium,
Examples thereof include low valence palladium phosphine complexes such as tetrakis (triphenylphosphine) palladium, and (7) tetrachloropalladates such as lithium tetrachloropalladate, sodium tetrachloropalladate, and ammonium tetrachloropalladate. Is mentioned. When the element is used in the form of a metal,
It is preferable that the above compound is used after being reduced to a metal with a reducing agent such as hydrogen.

Among the metals and compounds of palladium, the inorganic acid salt, organic acid salt, tetraammine complex, acetylacetonato complex, high-valent phosphine complex and tetrachloropalladium acid salt of palladium are reducing agents such as hydrogen. Preferred is a phosphine complex having a low valence or reduced to a metal by the above, but among them, a tetraammine complex, an acetylacetonato complex, a phosphine complex having a high valence and a tetrachloropalladate are converted into a metal by a reducing agent such as hydrogen. The reduced one is most preferable.

At least one or more of the above-mentioned elements are usually used in the form of a metal and / or a compound, which is supported on a carrier such as alumina, silica, silica-alumina, diatomaceous earth, zeolite, activated carbon or the like and used as a catalyst. This catalyst is used in the form of powder, granules or a molded body, but the size thereof is not particularly limited, and usually 20 to 100 μm in the case of powder, 4 to 200 mesh in the case of granular, molded In the case of a body, one having a length of 0.5 to 10 mm is preferably used. The catalyst may be present in the reaction system in either a fixed bed or a fluidized bed, but it is usually a fixed bed.

The method for preparing the catalyst in which the above-mentioned elements are supported on the carrier in the form of a metal compound does not need to be special, and may be any of the commonly used methods such as impregnation method, kneading method, deposition method, It can be prepared by a method of drying and calcining a catalyst precursor obtained by a precipitation method, a dry evaporation method, an ion exchange method or the like. At this time, the drying is 50 to 7 in the air.
At 0 ° C, calcination is usually carried out in air at 150-300 ° C. When the element is supported on the carrier in the form of a metal (zero valence) (excluding the zero valent complex), the catalyst on which the metal compound obtained by drying and firing is supported may be hydrogen or the like. It is usually prepared by reducing with a reducing agent at 300 to 600 ° C. The amount of the above-mentioned element supported on the carrier as its metal and / or compound is usually 0.01 to 20% by weight, preferably 0.05 to 5% by weight, as a metal with respect to the carrier.

The reaction between the chloroformic acid ester and the organic hydroxy compound is carried out in the presence of the above-mentioned catalyst in a gas phase or a liquid phase by a batch type or a continuous type, and the gas phase continuous type is industrially advantageous. In the case of a gas phase continuous reaction, the reaction temperature is usually 0 to 200 ° C., preferably 5 in the reactor filled with the catalyst.
0-180 ℃, reaction pressure 0.1-100kg / cm
² (gauge pressure), preferably 1 to 20 kg / cm ² (gauge pressure) under the condition that the raw material gas containing the chloroformate and the organic hydroxy compound is 500 to 50,000 h.
The reaction is carried out by feeding at a space velocity of r ^-1 , preferably 1000 to 40,000 hr ^-1 . At this time,
The concentration of chloroformate in the raw material gas is usually 0.1
100% by volume, preferably 0.5 to 50% by volume, and the ratio (molar ratio) of organic hydroxy compound to chloroformate (ArOH / ClCOOR ¹ ) is usually 0.1.
-100, preferably 0.5-50. If necessary, the raw material gas can contain an inert gas such as nitrogen gas, and organic hydroxy compounds that cannot be supplied as a gas or a single liquid are acetone, dichloromethane,
It is supplied after being mixed with a low boiling point solvent such as carbon tetrachloride.

In the case of the liquid phase continuous reaction, the reaction is carried out under the same conditions as the gas phase reaction in a reactor in which the catalyst is suspended in an organic hydroxy compound and / or a solvent. The reaction can also be carried out by a batch method in which an organic hydroxy compound and, if necessary, a solvent are put in a reactor and a raw material gas containing chloroformate is supplied to the reactor. As the solvent, dichloromethane, carbon tetrachloride, 1,
A solvent inert to the reaction such as halogenated hydrocarbons such as 2-dichloroethane and chlorobenzene, non-halogenated aromatic hydrocarbons such as benzene, toluene and xylene, and acetone is used.

The carbonate (carbonic acid ester) produced by the reaction as described above is easily separated and purified by distillation or the like. By-product hydrogen chloride can be used for the production of the raw material chloroformate without being particularly separated from the exhaust gas. The alkyl chloroformate as a raw material can also be produced by a reaction with hydrogen chloride, carbon monoxide and a nitrite, for example, by the method described in JP-A-6-306017.

[0023]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. Example 1 A hard glass vapor phase reaction tube (with an outer jacket) having an inner diameter of 10 mm was charged with 1.0 ml of a catalyst (Pd-Al ₂ O ₃ ) in which 1% by weight of 0-valent palladium was supported on alumina. The reaction tube was fixed vertically, and a heating medium was circulated in the outer jacket to control heating so that the temperature in the catalyst layer became 130 ° C. Then, while supplying a mixed gas consisting of 18% by volume of methyl chloroformate and 82% by volume of nitrogen gas,
A mixed solution consisting of 10% by weight of phenol and 90% by weight of acetone was supplied by a metering pump under normal pressure to
The reaction was carried out at 0 ° C. The phenol supply is 5.0
The space velocity of the raw material gas consisting of the mixed gas and the mixed solution was 10,000 hr ⁻¹ in g / hr. The gas discharged from the reaction tube was passed through ice-cold acetone to collect reaction products and the like. The collected liquid obtained was analyzed by gas chromatography to find that methylphenyl carbonate was found to be 2.
It was produced at 76 g / hr. The conversion based on phenol was 35 mol% and the selectivity was 99 mol%. The above catalyst was prepared by impregnating tetraamminepalladium (II) chloride on palladium in an amount of 1% by weight on alumina, followed by drying (70 ° C.) and baking (200 ° C.) in air.
After that, it was prepared by reducing in hydrogen gas at 300 ° C.

Comparative Example 1 The reaction and analysis were carried out in the same manner as in Example 1 except that 0-valent palladium was not supported on alumina (that is, alumina alone was filled). As a result, methylphenyl carbonate was produced at 0.3 g / hr, the conversion rate based on phenol was 4 mol%, and the selectivity was 99%.
It was mol%.

Example 2 Except that the reaction temperature was changed to 180 ° C. in Example 1,
Reaction and analysis were carried out in the same manner as in Example 1. As a result, methyl phenyl carbonate was produced at 3.0 g / hr, the conversion rate based on phenol was 32 mol%, and the selectivity was 8
It was 5 mol%.

Example 3 In Example 1, the mixed solution of phenol and acetone was replaced with a mixed solution of 10% by weight of 2,2-bis (4-hydroxyphenyl) propane (general name: bisphenol A) and 90% by weight of acetone. The reaction and analysis were performed in the same manner as in Example 1 except that bisphenol A was supplied at a supply amount of 6.0 g / hr. As a result, 2,2-bis (4-hydroxyphenyl) propane bis (methyl carbonate)
Was produced at 0.6 g / hr, and 2,2-bis (4-
The conversion based on hydroxyphenyl) propane was 10 mol%, and the selectivity was 85 mol%.

[0027]

Industrial Applicability According to the present invention, a carbonate (carbonic acid ester) is highly converted from a chloroformic acid ester and an organic hydroxy compound in the presence of a small amount of a catalyst without producing a salt that cannot be recycled and reused such as sodium chloride. Can be manufactured with high rate and high selectivity. That is, in the present invention,
Since chlorine can be recovered in the form of hydrogen chloride that can be reused in the production of the raw material chloroformate, the recovered hydrogen chloride is reacted with, for example, carbon monoxide and a nitrite ester to be converted into a chloroformate ( By regenerating it, it is possible to produce carbonate (carbonic acid ester) by significantly increasing the basic unit of chlorine without losing chlorine as sodium chloride as in the conventional case.
Further, unlike the conventional use of a stoichiometric amount of a base such as sodium hydroxide, since the catalyst can be easily separated and reused, an industrially excellent carbonate that uses a small amount of the catalyst. A manufacturing process of (carbonic acid ester) can be provided. INDUSTRIAL APPLICABILITY The present invention is particularly useful because it can easily produce an aryl carbonate useful as a raw material for an aromatic polycarbonate without causing the above problems.

Claims (1)

[Claims] 1. A carbonate characterized by reacting an chloroformic acid ester with an organic hydroxy compound by allowing an element selected from a platinum group element and a first transition series element to exist in the form of its metal and / or compound. Manufacturing method.