JPH03236354A - Production of diaryl carbonate - Google Patents

Abstract

PURPOSE:To obtain the subject compound in high yield and selectivity without causing the problem of the apparatus corrosion, etc., by subjecting an alkyl aryl carbonate to disproportionation reaction in the presence of a catalyst consisting of a specific salt or double salt of an alkali or alkaline-earth metal. CONSTITUTION:The objective compound can be produced by disproportionating an alkyl aryl carbonate into a diaryl carbonate and a dialkyl carbonate in the presence of a catalyst selected from the silicate, borate, phosphate, tungstate, Wolfram-bronze, stannic acid salt and their double salt of an alkali metal or an alkaline-earth metal (preferably Li, Na, Mg or Ca) preferably at 80-300 deg.C. The amount of the catalyst is preferably 0.001-2mol per 1mol of of the raw material. Since the catalyst is a salt, it can be easily separated from the product by distillation.

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 diaryl car by averaging reaction of alkylaryl carbonate (prior art) It is already known to obtain diphenyl carbonate by averaging alkylphenyl carbonate (Japanese Patent Publication No. 58-48537). ), however, this method uses a catalyst selected from Lewis acids and transition metal compounds capable of producing Lewis acids.
j! X,,TiL,UXa,VOX:I,VXs
, ZnXt , and FeX3.5nXn (X is a halogen, an acetoxy group, an alkoxy group, or an aryloxy group). 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 Not only is this problem more serious, 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, M nz (CO) +. A method using a metal carbonyl such as as a catalyst (Japanese Patent Application Laid-open No. 1-265064)
have also been proposed, but such metal carbonyls also have vapor pressure and are difficult to separate from the product.

(Problems to be Solved by the Invention) An object of the present invention is to provide an excellent method for obtaining diaryl carbonate with high yield and high selectivity without the problems that the conventional methods described above have. It was made for the purpose of

(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 provides at least one selected from alkali metal or alkaline earth metal silicates, borates, phosphates, tungstates, tungsten bronzes, stannates, and double salts thereof. A method for producing diaryl carbonate is provided in which alkylaryl carbonate is averaged into diaryl carbonate and dialkyl carbonate in the presence of a seed catalyst.

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

Examples of R include aliphatic groups including various isomers such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclobutyl, cyclohexylmethyl, etc. alicyclic group;
Aroaliphatic 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 (here, Ro
represents a substituent such as a lower alkyl group, an alkoxy group, an acyl group, a halogen, an aryloxy group, an aromatic group, a nitro group, a cyano group, an araliphatic group, and l is an integer of 1 to 5;
m represents an integer of 1 to 7, n represents an integer of 1 to 4, and when l, m, and n are each an integer of 2 or more, Ro may be the same or different. ) etc. are preferred.

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,
For example, methyl, dimethyl, ethyl, t-butyl, 2-
This is the case of a substituted phenyl group having 7 to 15 carbon atoms and having a substituent such as phenyl-2-methylethyl.

The catalyst used in the present invention is selected from alkali metal or alkaline earth metal silicates, borates, phosphates, tungstates, tungsten bronzes, stannates and double salts thereof. at least 1
It consists of seeds.

Examples of such catalysts include lithium orthosilicate (Li2Si03), lithium metasilicate (Li2S
i03), potassium orthosilicate (Li6Siz07)
, Sodium orthosilicate (NanStOa), Sodium rum metasilicate (NazStO:+), Sodium disilicate (NazSizOs), Sodium tetrasilicate (NazSinOl), Potassium orthosilicate (K4)
SiO4), potassium metasilicate (KzSiO,), potassium tetrasilicate (KzSi40J, rubidium orthosilicate (Rb4Si04), rubidium metasilicate (R
b4Si04), cesium orthosilicate (Cs4Si
O4), cesium metasilicate (CszSi(h), magnesium orthosilicate (MgSi03), magnesium metasilicate (MgSi03), magnesium trisilicate (MgSi00s), magnesium tetrasilicate (Mg
), calcium orthosilicate (Ca2Si0
4), Calcium metasilicate (CaSiOz), Strontium orthosilicate (Sr, SiO,), Strontium metasilicate (SrsiO,), Barium orthosilicate (BaBaO1), Barium metasilicate (BaS
tOz), silicates such as potassium metasilicate (BaSizOs); calcium sodium trihydrogen metasilicate (NaCaJSizOq), calcium magnesium orthosilicate (CaMgSiO4), tricalcium magnesium niorthosilicate (Ca, Mg(Si04)2),
Magnesium calcium nimetasilicate (CaMgSi
Double salts of silicic acid such as 206); lithium metaborate (
LiB (h), lithium tetraborate (LizB40t),
Lithium pentaborate (LiB, 0.,), sodium metaborate (NaBOz), sodium tetraborate (NaJ
n07), sodium pentaborate (NaBsOs), sodium hexaborate (NaJhO+o), sodium heborate (Na2B, 101,), sodium diborate (
Na, B, O,), potassium metaborate (KBO□),
Potassium tetraborate (NitBnOl), Potassium pentaborate (KB, 0!+), Potassium hexaborate (KJ60+o
), potassium heborate (KJsO+3), rubidium metaborate (RbBO□), cesium metaborate (C
sBOz), magnesium orthoborate (Mgs (
BO3) z], magnesium diborate (MgzBzO
s), magnesium metaborate (Mg (Box) z
), trimagnesium tetraborate (MgSi03), pentamagnesium tetraborate (MgSi03), calcium borate (CaB40t), strontium tetraborate (SrB40t), barium orthoborate (Ba
s (BO3)2], barium metaborate (Ba(BO3)2], barium metaborate (Ba(BO3)2)
z)z), barium diborate (BaJzOs), barium tetraborate (BaBaO1); borates such as lithium phosphate (LisPOg), sodium phosphate (N
aspoa), potassium phosphate (K3PO4), rubidium phosphate (Rh, PO,), cesium phosphate (C53
PO4), magnesium phosphate (Mgs (PO4)
) z], calcium phosphate (Cas(PO4)z)
, strontium phosphate (Srs(Po4)z :l
, barium phosphate (Ba3(PO4)z), lithium dihydrogen phosphate (LiHzPO4), dilithium hydrogen phosphate (LiJPOa), sodium dihydrogen phosphate (NaHzPOa), disodium hydrogen phosphate (Na
BsOs), potassium dihydrogen phosphate (KH, PO4)
, dipotassium hydrogen phosphate (K, HPO,), rubidium dihydrogen phosphate (RbHzPOn), dirubidyram hydrogen phosphate (RbzHPO4), cesium dihydrogen phosphate (
C3H2PO4), dicesium hydrogen phosphate (C3JPO
i) , magnesium hydrogen phosphate (MgHPO4), magnesium dihydrogen phosphate (Mg(H2POa)z:l
, Calcium hydrogen phosphate (CaHPO4), Calcium dihydrogen phosphate (Ca(HzPO4)z), Strontium hydrogen phosphate (SrHPO4), Strontium dihydrogen phosphate (Sr(IbPO4)z), Barium hydrogen phosphate (BaHPO4) ), barium dihydrogen phosphate (Ba(
HzPO4)! ] Phosphates such as lithium tungstate (LiJO4), sodium tungstate (
Na2WO4), potassium tungstate (KJO4)
, rubidium tungstate (Rb211iO4),
Cesium tungstate (CsJOi), Magnesium tungstate (MgW04), Calcium tungstate (callio4), Strontium tungstate (SrWOa), Barium tungstate (BaW
tungsten bronzes such as lithium tungsten bronzes (LixWOs), sodium tungsten bronzes (NaxWO+), potassium tungsten bronzes (KxWOs), potassium sodium tungsten bronzes (KyNazWO3), where x, y.

2 are respectively Q < x < 1, O < y < l
, represents a number that satisfies O<z<L O<y+z<1);
Lithium stannate (LizSnOz), sodium stannate (Nazsn03), potassium stannate (KzSn03)
, magnesium orthostannate (MgzSnOa), calcium hexahydroxostannate (Caz (Sn(
Stannates such as OH)6:l), strontium hexahydroxostanate (SrzCSn(OH)b), and hydrates of these compounds are used. 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 0°00001 to 1% relative to the alkylaryl carbonate.
00 times the mole, preferably in the range of 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 furthermore, it is capable of producing diaryl carbonate in high yield and high selectivity. Salts, tungsten bronzes, stannate salts, and their double salts are neutral or basic and are not Lewis acids, so they pose problems such as corrosion of equipment caused by Lewis acids used in the prior art. Another feature is that there is no.

Furthermore, since the catalyst of the present invention is a salt, another major feature is that 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, the method of the present invention results in a diaryl carbonate that does not contain even traces of catalyst components.

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 -C formula (1), the reaction can be carried out by removing at least one of the product diaryl carbonate or dialkyl carbonate from the reaction system. can proceed 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. Since the boiling points of the raw materials and products are usually in the following order: diaryl carbonate > alkylaryl carbonate > dialkyl carbonate, or dialkyl carbonate > alkylaryl carbonate > diaryl carbonate, it is easy to distill off one of the products.

Dialkyl carbonates whose alkyl groups are lower aliphatic groups such as methyl, ethyl, propyl, and butyl have low boiling points and can 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 of introducing inert gases such as nitrogen, argon, helium, carbon dioxide, and lower hydrocarbon gases into the reaction system and entraining them with these gases; A method performed under reduced pressure, a method using these methods in combination, etc. 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 a temperature of 50 to 400°C, preferably 80 to 300°C.The reaction time is also carried out in a range of several minutes to several tens of hours.The reaction pressure is also reduced,
It can be carried out either under normal pressure or under 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 using Examples, but the present invention is not limited to these Examples.

Example 1 76 g (0.5 mol) of methylphenyl carbonate and Na were placed in a 200 m four-loop flask equipped with a stirring device, a reflux condenser, a gas inlet reaching below the liquid level, and a thermometer.
The reaction was carried out by adding 1 g of t'AOa and immersing it in an oil bath at 195°C with stirring while introducing dry nitrogen at a rate of 80 d/min. 90 for the jacket of the reflux condenser
The reaction was carried out for 5 hours by flowing water at ℃ to distill off the by-produced dimethyl carbonate while refluxing and returning the generated diphenyl carbonate to the reactor. As a result, the reaction of methylphenyl carbonate was confirmed. The yield was 80%, and diphenyl carbonate was obtained in a yield of 74% and a selectivity of 93%.

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 NazWO4 or sodium compounds were detected in this diphenyl carbonate.

Examples 2-9 Using various alkali metal or alkaline earth metal silicates, borates, phosphates, tungstates, tungsten bronzes, stannate, and double salts thereof in place of NaJO. The reaction from methylphenyl carbonate (76 g) to diphenyl carbonate was carried out in the same manner as in Example 1 except for this. The reaction results after 5 hours are shown in Table 1. In addition, in these examples,
The catalyst used was 5 mmol.

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 in 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.

Claims (1)

[Claims] In the presence of at least one catalyst selected from alkali metal or alkaline earth metal silicates, borates, phosphates, tungstates, tungsten bronzes, stannates, and double salts thereof A method for producing diaryl carbonate, which comprises averaging alkylaryl carbonate into diaryl carbonate and dialkyl carbonate.