JPH03200746A - Production of diaryl carbonate - Google Patents

Abstract

PURPOSE:To obtain the title compound in high selectivity and in high yield by using carbonates and hydrogencarbonates of alkali metal or alkaline earth metal and double salts thereof as a catalyst and subjecting an alkylaryl carbonate to disproportionation reaction. CONSTITUTION:An alkylaryl carbonate is subjected to disproportionation reaction in the presence of at least one catalyst (e.g. NaHCO3) selected from carbonates, hydrogencarbonates and organic acid salts of alkali metal or alkaline earth metal and double salts thereof into a diaryl carbonate and a dialkyl carbonate to give the diaryl carbonate in high yield and in high selectivity. Since the catalyst used is in a form of salt, etc., the catalyst is readily separated and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an improvement in a method for producing diaryl carbonate.

More specifically, the present invention relates to a method for producing diaryl carbonates by averaging reaction of alkylaryl carbonates.

(Prior art) It is already known to obtain diphenyl carbonate by averaging alkylphenyl carbonate (Japanese Patent Publication No. 5B-48537).However, this method produces Lewis acid and Lewis acid. A catalyst selected from possible transition metal compounds is used.
IX, , TiX5, UXa, V OX3, V
X5 , Z n Xt , FeX3.5nXa (X
is an acetoxy group, an alkoxy group, or an aryloxy group. ) are listed. Such Lewis acids cause severe corrosion of equipment, and there are problems in implementing them industrially.

Furthermore, a method using a mixture of a Lewis acid and a protonic acid as a catalyst (Japanese Unexamined Patent Publication No. 173016/1983) has been proposed, but this method uses a protonic acid in addition to a Lewis acid, so The problem with this is that not only is it more difficult to declare, but it is also difficult to separate and recover the catalyst.

In addition, methods using organometallic compounds such as organotin compounds and organotitanium compounds as catalysts (JP-A-60169444, JP-A-60-169445, JP-A-1-2
65063), but since these organometallic compounds have a vapor pressure, when the product diaryl carbonate is separated by distillation from the reaction mixture, some of it is removed together with the product. It is also known that catalytic components are distilled out. It is difficult to completely remove catalyst components from diaryl carbonate containing these catalyst components.

Also, Mn2(Co)l. A method using metal carbonyls such as the following as a catalyst has also been proposed (Japanese Unexamined Patent Publication No. 1-265063), but such metal carbonyls also have a vapor pressure and are difficult to separate from the product.

(Problems to be Solved by the Invention) The present invention provides an excellent method for obtaining diaryl carbonate in high yield and high selectivity without the problems that conventional methods have. It was done for that purpose.

(Means for Solving the Problems) As a result of intensive research to solve these problems, the present inventors discovered that lead and lead compounds are excellent catalysts, and filed an application for the patent ( (Japanese Patent Application Laid-open No. 1-93560) discovered yet another type of excellent catalyst,
The present invention has now been completed.

That is, the present invention is: In the presence of at least one catalyst selected from alkali metal or alkaline earth metal carbonates, hydrogen carbonates, organic acid salts, and double salts thereof, an alkylaryl carbonate is diarylized. The present invention provides a method for producing diaryl carbonate, in which carbonate and dialkyl carbonate are averaged.

The production method according to the present invention has the following general formula: represents a certain aryl group) The alkylaryl carbonate used as a raw material in the present invention is a compound shown on the left side of the above formula N).

R is an aliphatic group including various isomers such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclobutyl, cyclohexylmethyl, etc. Alicyclic group; aromatic aliphatic groups such as benzyl and phenethyl are preferred.

Ar is an unsubstituted aromatic group such as phenyl, naphthyl, or pyridyl; a substituted aromatic group represented by the following formula (where R'
is a lower alkyl group, an alkoxy group, an acyl group, a halogen, an aryloxy group, an aromatic group, a nitro group, a cyano group,
represents a W substituent with an aromatic aliphatic group, l is an integer of 1 to 5, m is an integer of 1 to 7, n is an integer of 1 to 4, and l, m, and n are each 1 In the case of the above integers, it is preferable that Ro may be the same or different.

Further, in R, one or more hydrogens may be substituted with a substituent such as a halogen, a lower alkoxy group, or a cyano group.

Particularly preferred alkylaryl carbonates include:
The alkyl group is a lower aliphatic group having 1 to 4 carbon atoms such as methyl, ethyl, propyl, or butyl, and the aryl group is a phenyl group or a substituent having 1 to 9 carbon atoms, such as methyl, dimethyl, or ethyl. , t-butyl, 2-phenyl-2-methylethyl, and other substituents with a carbon number of 7
-15 substituted phenyl groups.

The catalyst used in the present invention is at least one catalyst selected from alkali metal or alkaline earth metal carbonates, hydrogen carbonates, organic acid salts, and double salts thereof.

Such catalysts include, for example, LitCCh, Na
zCO:+, KzCOs, RbtCOs, C5zC
O,, MgCCh , CaC0,,5rC03, Ba
Carbonates such as COx 'W4; Li HCO2,
Na HCOs, KHCO3, RbHCO+, C5H
CO,, Mg (HCO,)z, Ca (HCO3L
Hydrogen carbonates such as K Na CO3, Ca C
Double salts such as O+-MgCOx, KMgH(COs)t; L 1OAc, Na0Ac, KOAC%Rb0A
c, Cs0Ac, Mg (OAc)z, Ca (OAc
)z, Sr (OAc)z, Ba (OAc)z, HC
OOL t, HCOONa, Mg (OCO),, Na
Aliphatic carboxylate salt such as 0COCOOR@; L 1
OBzSNaOBz, Mg (OBz), Ca (OB
z) Aromatic carboxylic acid salts such as z HNaK (O
Double salts such as CO)t and NaK(OBz)t are used (wherein, AC represents an acetyl group and Bz represents a benzoyl group).

Of course, these compounds may be reacted with organic compounds present in the reaction system, such as alkylaryl carbonates, diaryl carbonates, dialkyl carbonates, and the like.

Particularly preferred catalysts among these are salts or double salts in which the alkali metal or alkaline earth metal is lithium, sodium, magnesium, and/or calcium.

There is no particular restriction on the amount of catalyst used, but it is usually 00ooooot-i for the alkylaryl carbonate.
It is in the range of oo times the mole, preferably 0.001 to 2 times the mole.

The catalyst of the present invention is excellent in providing diaryl carbonate in high yield and high selectivity, and is further capable of producing diaryl carbonates of these alkali metals or alkaline earth metals, hydrogen carbonates, organic acid salts, and complexes thereof. Since the salts are neither Lewis acids nor transition metal compounds capable of producing Lewis acids, they are also characterized by the absence of problems such as corrosion of equipment caused by the use of Lewis acids.

Another major feature of the catalyst of the present invention is that since it is a salt, it can be easily separated from the raw material and the desired product, diaryl carbonate. That is, diaryl carbonate and the like are usually separated from the reaction mixture by distillation, but since the catalyst of the present invention is a salt, it will not be distilled out under such distillation conditions. Therefore, in the method of the present invention, a diaryl carbonate that does not contain even a trace amount of catalyst component can be obtained.

Further, the catalyst of the present invention is usually inexpensive and easily produced by hand, and is very advantageous for industrial implementation.

Since the reaction of the present invention is an equilibrium reaction as shown in formula (1), the reaction is carried out by removing at least one of the product diaryl carbonate or dialkyl carbonate from the reaction system. You can progress better.

Since the reaction of the present invention is usually carried out in a liquid phase or a gas phase, it is preferable to proceed with the reaction while distilling off low-boiling components of the product.The boiling points of the raw materials and products are usually Since the order is diaryl carbonate > alkylaryl carbonate > dialkyl carbonate, or dialkyl carbonate > alkylaryl carbonate > diaryl carbonate, one of the products can be easily distilled off.

Dialkyl carbonates whose alkyl groups are lower aliphatic groups such as methyl, ethyl, propyl, and butyl have low boiling points and can therefore be easily distilled off from the reaction system. In this sense, alkylaryl carbonates having lower aliphatic groups are preferably used.

In order to effectively distill off low-boiling components, there are methods that introduce inert gases such as nitrogen, argon, helium, and carbon dioxide, and lower hydrocarbon gases into the reaction system and entrain them with these gases, and methods such as depressurization. The methods described below and methods using these methods in combination are preferably used. In addition, in the case of a seed reactor, it is also a preferable method to perform effective stirring in order to increase the gas-liquid interfacial area and promote surface renewal. It is also a preferable method to use a device with a large liquid interface area.

The reaction of the present invention is usually carried out at 50-400°C, preferably at 8°C.
It is carried out in the range of 0 to 300°C. Further, the reaction time is from several minutes to several tens of hours, and the reaction can be carried out at zero pressure, reduced pressure, normal pressure, or increased pressure.

The method of the present invention can be carried out without a solvent or with a solvent. If a solvent is used, it is also a preferred method to distill off the low-boiling products together with a portion of the solvent. Examples of such solvents include pentane, hexane,
Aliphatic hydrocarbons such as heptane, octane, nonane, decane, undecane, tridecane; benzene, toluene,
Aromatic hydrocarbons such as xylene, ethylbenzene, and styrene; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Halogenated compounds such as methane chloride, methylene chloride, chloroform, carbon tetrachloride, dichloroethane, chlorobenzene, and dichlorobenzene Hydrocarbons; Nitriles such as acetonitrile, propionitrile, and benzonitrile; Ketones such as acetone, methyl ethyl ketone, and acetophenone; and ethers such as diethyl ether, tetrahydrofuran, dioxane, and diphenyl ether, and the like are preferably used.

Furthermore, the method of the present invention can be carried out either batchwise or continuously.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 In a 200 d fourth flask equipped with a stirrer, a reflux condenser, a gas inlet reaching below the liquid level, and a thermometer, 76 g (0.5 mol) of methylphenyl carbonate was added, Na.
The reaction was carried out by adding 31 g of HC and immersing it in an oil bath at 195°C with stirring while introducing dry nitrogen at a rate of 80 m/min. 90″ for the reflux condenser jacket
The reaction was carried out for 4 hours by flowing the water in C, distilling off the by-produced dimethyl carbonate, and refluxing the methylphenyl carbonate and the produced diphenyl carbonate back to the reactor. As a result, the reaction rate of methylphenyl carbonate was was 87%, and diphenyl carbonate was obtained with a yield of 85% and a selectivity of 98%.

This reaction solution was distilled under reduced pressure at a temperature of 190° C. or lower to recover unreacted methylphenyl carbonate, and then diphenyl carbonate was obtained. No NaHcOs or sodium compounds were detected in this diphenyl carbonate.

Examples 2 to 9 The reaction of methylphenyl carbonate (76 g) to diphenyl carbonate was carried out using various alkali metal or alkaline earth metal carbonates, hydrogen carbonates, and organic methods in place of NaHC○. . The reaction results after 2 hours are shown in Table 1. In addition, in these Examples, 5 mmol of the catalyst was used.

Table 1 (Effects of the Invention) The present invention uses specific alkali metal or alkaline earth metal salts or double salts as a catalyst for producing diphenyl carbonate, so diphenyl carbonate can be obtained with high yield and high selectivity. In addition, since this catalyst is in the form of a salt or the like, it can be easily separated and removed.

(1 other person) -30 and

Claims (1)

[Claims] In the presence of at least one catalyst selected from alkali metal or alkaline earth metal carbonates, hydrogen carbonates, organic acid salts, and double salts thereof, alkylaryl carbonate is averaged into diaryl carbonate and dialkyl carbonate. A method for producing diaryl carbonate, the method comprising: