JPS6094943A - Production of carbonic acid diester - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high selectivity, by reacting carbon monoxide with a nitrous acid ester in the presence of oxygen in a uniform solution containing a salt of a platinum group element or a complex thereof and an alcohol under a specific partial pressure of the carbon monoxide while feeding the carbon monoxide thereto. CONSTITUTION:Carbon monoxide is reacted with a nitrous acid ester in the presence of oxygen in a uniform solution containing a salt of a platinum group element, e.g. palladium chloride, or a complex thereof, e.g. PdCl2(PhCN)2 (Ph is phenyl), and an alcohol under 0.01-4.5kg/cm<2> partial pressure of the carbon monoxide while feeding a gas containing the carbon monoxide thereto to give a diester of carbonic acid. The selective synthesis of the diester of the carbonic acid can be carried out by the above-mentioned method, and the loss of the carbon monoxide, nitrous acid and alcohol is reduced. The formation of diester of oxalic acid due to the presence of water is remarkably suppressed, and the diester of the carbonic acid of high purity is easily isolated by simple distillation, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing carbonic diester, and more particularly to a method for selectively producing carbonic diester from nitrite and carbon monoxide.

Diester carbonate is useful as a raw material for the synthesis of polycarbonate, urethane, etc., and it is known to be produced by the oxidation reaction of alcohol and carbon monoxide using copper halide, palladium halide, selenium, etc. as a catalyst. .

However, all of these methods have slow reaction rates and require high temperature and high pressure conditions.

As an improved method, nitrite ester and carbon monoxide are
A method has been proposed for producing carbonic acid diester by reacting in a liquid phase using a platinum group metal or its salts as a catalyst under conditions where the partial pressure of carbon oxide is 0.1 to 5 kg/crri' (Unexamined Japanese Patent Publication No. Publication No. 56-1+54145) is
In this invention, a reaction is carried out using a solid catalyst in which palladium metal is substantially supported on a carrier in a suspended state in a reaction solution. It was found that the yield of the target carbonic acid diester was low.

Because a large amount of oxalic acid diester is produced as a by-product, ■ it consumes a large amount of expensive nitrite ester and carbon monoxide; ■ its boiling point is close to that of the target carbonic acid diester, making it difficult to separate the two; ■ oxalic acid. Diesters tend to undergo hydrolysis in the presence of water, and the oxalic acid produced causes corrosion of equipment.

The present inventors aimed to provide a method for producing carbonic acid diester from nitrite ester and carbon oxide, which does not generate by-products and can selectively produce carbonic diester in high yield. As a result of intensive studies, we unexpectedly found that in a homogeneous solution containing salts of platinum group elements or their complexes and alcohol, in the presence of oxygen, under a specific partial pressure of carbon monoxide, while supplying -carbon oxide gas The present invention was achieved by discovering that the objects of the present invention can be achieved by reacting esters.

That is, the gist of the present invention is that in a homogeneous solution containing a salt of a platinum group element or a complex thereof and alcohol, in the presence of oxygen, the partial pressure of -carbon oxide is o, o t kg, it:m
'~4.5k) A method for producing a carbonic acid diester, which comprises reacting with a nitrite ester under 7-2 conditions while supplying a carbon oxide-containing gas.

The nitrite ester used in the present invention has 1 to 16 carbon atoms.
aliphatic, -hydric or polyhydric alcohol-/'% fat'f
R formula 7 is a nitrite ester of cole or haal alkyl alcohol, and examples of these alcohols include methanol, ethanol, n-propanol, isobutanol, n-butanol, isobutanol, secondary butanol, and tertiary butanol. a Butanol, amyl alcohol, hexanol, octatool, decanol, lauryl alcohol,
Cetyl alcohol, etc. +7) Aliphatic polyhydric alcohols, ethylene glycol, glopylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, and other aliphatic polyhydric alcohols, cyclohexanol, cyclododecanol, etc. Examples include aralkyl alcohols such as alicyclic alcohols, benzyl alcohol, and 2-phenylethanol.

Also included are substituted alcohols in which any hydrogen atom of these alcohols is replaced with an alkyl group, an alkoxy group, a halogen atom, or a carboxyl group. These substituted alcohols include methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethylene glycol monoacetate,
β.

β, β-trifluoroethanol, 2,2,5,5.3-
Examples include pentafluoroethanol.

In place of the nitrite ester, nitric oxide reacts with the alcohol present to give the nitrite ester under the reaction conditions;
Nitrogen oxides such as nitrogen dioxide and dinitrogen trioxide, nitric acid, and nitrous acid can also be used.

The catalyst components that catalyze the reaction between nitrite and carbon monoxide include palladium, platinum, iridium, rhodium,
Salts or complexes of platinum group elements such as ruthenium.

Examples of salts include the above-mentioned halogen atoms of platinum group elements,
nitrates, sulfates, phosphates, acetates, propionates,
Examples include butyrate, acetylacetonate, oxalate, benzoate, and the like. Examples of complexes include alkyl phosphines such as trimethylphosphine, arylphosphines such as triphenylphosphine, alkylarylphosphines such as diethylphenylphosphine, triphenylphosphine, triphenylphosphine, etc. Examples include complexes in which Co, No, ON, halogen atoms, etc. are coordinated.

Specifically, salts of platinum group elements include palladium chloride, palladium bromide, palladium iodide, palladium fluoride, palladium nitrate, palladium sulfate, palladium phosphate, palladium acetate, palladium tetrapionate, and (acetylacetonato)palladium, palladium oxalate, palladium benzoate, platinum chloride, potassium tetrachloroplatinate, potassium hexachloroplatinate, bis(acetylacetonato)platinum, iridium chloride, sodium hexachloroiridate, rhodium chloride, rhodium bromide , rhodium iodide, rhodium nitrate, rhodium sulfate, rhodium acetate, tris(acetylacetonato)rhodium, ruthenium chloride, ruthenium iodide, tris(acetylacetonato)ruthenium, and the like.

As a complex of platinum group elements, PdCr2(PhGN)2
゜PdCl! 2 (PPh3)2. (PdCl(CjO)
). , pa(co)(pph3)3゜pa(pph)
ptcz (pph) pt(co)2(pph3
)2゜34 polished 2 32- Pt (PPh5)4. IrCl! (PPh5),,I
rCl! (00)(PPh3)2゜gxr(co)(p
ph3)3. Ir4(CO), 2Jth(co)2(a
cac).

nhcl! (pph3)3. Rhcz(co)(pph
5)2. (uhcz(co)2〕2゜nnh(co)(
pph,)3. Hph(co)(p(oph)3.]3
゜Hnh(co)(Asph3)3. Rh4(co)1
2. ph6 (co), 6°Rue/2 (PPh3)3.
RuH2(PPh3)4. Ru(Go)5. Ru3(G
o), 2, etc. (here, ph represents a phenyl group, and acac represents acetylacetonate).

The amount of the catalyst component to be used is not particularly limited, and the concentration in the reaction solution is usually within the range of 5 ppm by weight to 0.25 weight percent. This reaction solution refers to the entire catalyst component, alcohol, nitrite ester, and solvent used as necessary.

The alcohol used in the present invention is usually the same alcohol that forms the nitrite ester, but different alcohols can also be used. The appropriate amount of alcohol to be used is 0.1 to 50 times, preferably 0.2 to 30 times, the molar ratio to nitrite; outside this range, the production rate of carbonic acid diester tends to decrease. show.

Although the present invention is carried out in the presence of oxygen, the amount of oxygen used is not particularly limited, and it is usually sufficient that it is present at the same level as the partial pressure of carbon oxide. However, it is desirable to keep the concentration of oxygen below 8% by volume of the total gas in order to stay outside the explosive limits. In addition to pure oxygen, oxygen diluted with an inert gas such as nitrogen, or air may also be used.

The reaction temperature is usually 20-150C1, preferably 40-1
If the temperature is lower than this, the reaction rate will be slow, and if it is higher than this, side reactions will increase.

The reaction pressure may be a pressure at which the nitrite ester and the alcohol maintain a liquid phase at the reaction temperature, and is usually normal pressure to 20 g/i.

The present invention has a carbon oxide partial pressure of 0.01 to 4.5 kg/
It is important to carry out the reaction within a range of cm'.

When this partial pressure is lower, the production rate of diester carbonate is low, and when it is higher, the amount of byproducts such as diester oxalate rapidly increases. The carbon monoxide used does not need to be pure, and carbon monoxide diluted with an inert gas such as nitrogen can also be used.

The reaction type can be either batch type or continuous type, but
- It is important to continuously supply the carbon oxide-containing gas to the reaction system. The reaction time is not particularly limited, but in the case of a batch process, it is 10 minutes to 30 hours, preferably 20 minutes to 20 hours, and in the case of a continuous process, the reaction time is determined by the liquid hourly space velocity of the total amount of nitrite ester and alcohol (LH8V ) is 0.1 to 30
, preferably 0.2 to 15 parts by volume/hour/part by volume of catalyst.

Further, the reaction can be carried out by adding a solvent to the reaction solution, which has the effect of lowering the reaction pressure, especially when low-boiling substances such as methyl nitrite and ethyl nitrite are used as raw materials. Solvents that can be used include ethyl acetate, propyl acetate,
Lower fatty acid esters such as butyl acetate, amyl acetate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, pill butyrate, butyl butyrate, dimethyl oxalate, diethyl oxalate, divinyl oxalate, dibutyl oxalate , aliphatic dicarboxylic acid diesters such as dimethyl succinate, diethyl succinate, and dimethyl adipate; nitriles such as acetonitrile, tetrabionitrile, adiponitrile, and benzonitrile; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; 1,1-jetoxycyclohexanone Ketals such as acetaldehyde dibutyl acetal, aromatic carboxylic acid esters such as methyl benzoate, ethyl benzoate, dimethyl phthalate, ethers such as dioxane, dibutyl ether, hexane, heptane, cyclohexane, benzene,
In addition to hydrocarbons such as toluene and xylene, examples include monochlorbenzene, dichlorobenzene, nitrobenzene, acetophenone, alkyl sulfone, alkyl sulfoxide, and methylene chloride. Any of these solvents can be used, but it is better to avoid solvents that have a boiling point close to that of the target carbonic acid diester, as this will make it difficult to recover the carbonic acid diester.

Adopting the above configuration makes it possible to selectively synthesize carbonic acid diesters. Therefore, the present invention has the following advantages: The coexistence brings about effects such as extremely suppressing the by-product of oxalic acid diester, which gives oxalic acid and causes equipment corrosion, and (2) making it easier to isolate high-purity carbonic acid diester by simple distillation.

Hereinafter, the present invention will be explained in detail using examples.

Example 1 In a 600 d glass reactor equipped with a stirrer and a condenser, 50 n-butyl nitrite and 50 n-butanol were added.
Add 33 cm of palladium chloride and 70 cm of palladium chloride while stirring.
CK was kept heated.

Next, - carbon oxide 71% (volume basis, the same below) oxygen input 6
% and 23% nitrogen at 700 m under normal pressure.
Aeration was performed for 3 hours at a rate of /(STP)/min. Gas chromatographic analysis of the reaction products revealed that 149 mmol of moro-butyl carbonate and 2.3 mmol of moro-butyl dicate were produced, with only trace amounts of other products produced. understood. The selectivity for moro-butyl carbonate was 98.5 mol%.

The experiment was conducted under the same reaction conditions as in Example 1, except that the type and amount of catalyst used were changed as shown in Table 1. The results are shown in Table 1 together with the results of Example 1.

The experiment was conducted under the same reaction conditions as in Example 1, except that a catalyst in which palladium metal was supported on a carrier shown in Table 1 was suspended in the reaction solution. The results are shown in Table 1.

Example 9 An experiment was carried out under the same reaction conditions as in Example 1, except that 197 Da of Toisobis(acetylacetonato)platinum was used as a catalyst. Analysis of the reaction product revealed that 6.
It was found that 37 mmol and 0.19 mmol of di-n-butyl oxalate were produced. The selectivity of moro-butyl carbonate was 97.1 mol %. Example 10 An experiment was carried out under the same reaction conditions as in Example 1, except that 132 cm of rhodium chloride trihydrate was used as a catalyst. Analysis of the reaction products revealed that 2.14 mmol of moro-butyl carbonate and 0.05 mmol of di-n-butyl oxalate were produced.

The selectivity for moro-butyl carbonate was 97.7 mol%.

Examples 11 to 15 The various nitrite esters shown in Table 2, alcohol 80, and palladium chloride 331n9 were placed in the reactor used in Example 1, and heated and maintained at a predetermined temperature while stirring. . Next, a mixed gas consisting of 9% by volume of carbon oxide, 6% by volume of oxygen, and 85% by volume of nitrogen was added to VC5 under normal pressure.
The reaction was carried out by aerating at a rate of 50 mJ (STP)/min for 2 hours. The reaction products were analyzed and the results are shown in Table 2.

Example 16 The reactor used in Example 1 was charged with 51 liters of ethyl nitrite, 45+R1 of ethanol, 50 of n-butyl acetate, and 421R9 of palladium nitrate, and heated and maintained at 65C without stirring. Next, a mixed gas consisting of 9% by volume of carbon monoxide, 6% by volume of oxygen, 5% by volume of ethyl nitrite, and 80% by volume of nitrogen,
Aeration was carried out at a rate of 3 som (sTp) for 7 minutes under normal pressure for 1 hour. Analysis of the reaction product revealed that diethyl carbonate was 27.5
Mi! It was found that 7 mol and 0.3 mmol of diethyl oxalate were produced. The selectivity of diethyl carbonate was 98.9 mol%.

Example 17 Into the reactor used in Example 1 were placed 25 cm of methanol, 75 cm of propionitrile, and 42 cm of palladium nitrate, and heated and maintained at 6 DC while stirring. K, - carbon oxide 9
% by volume, 6% by volume of oxygen, 10% by volume of methyl nitrite, 5% by volume of nitrogen oxide (NO), and 70% by volume of nitrogen at a rate of 550111 (S T P ') 7 minutes under normal pressure for 1 hour. Ventilated. Analysis of the reaction products revealed that dimethyl carbonate was 29.1 mmol and dimethyl oxalate was 0.
．． It was found that 3 mmol was produced. The selectivity of dimethyl carbonate was 99.0 mol%.

In an autoclave with an internal volume of 200 cm equipped with a condenser, a pressure regulating valve, and a stirrer, 50 cm of n-butanol was added.
5 oml of n-butyl nitrite and 33 da of palladium chloride were added, and the mixture was heated and maintained at 70 CIC while stirring. Next, −
A mixed gas consisting of 71% by volume of carbon oxide, 6% by volume of oxygen, and 23% by volume of nitrogen was passed through the autoclave at a rate of 7 minutes of yooml (SRP) for 1 hour while maintaining the internal pressure of the autoclave at a predetermined pressure. The reaction products were analyzed and the results are shown in Table 3.

Example 21 An experiment was conducted under the same reaction conditions as in Example 1, except that a mixed gas having a composition of 9% by volume of carbon monoxide, 6% by volume of oxygen, and 85% by volume of nitrogen was used.

Analysis of the reaction product revealed that it was 107% moro-butyl carbonate.
0 mmol, di-n-butyl oxalate o, s -: 9
It was found that a mole had formed. The selectivity of moro-butyl carbonate was 99.3 mol%.

Comparative Example 6 Carbon monoxide 0.5% by volume, oxygen 3% by volume, nitrogen 96.5%
An experiment was conducted under the same reaction conditions as in Example 1, except that a mixed gas having a composition of % by volume was used. Analysis of the reaction products revealed that 11.3 mmol of moro-butyl carbonate and o.t mmol of di-n-butyl oxalate were produced.

The selectivity of moro-butyl carbonate was 99.1 mol%.

Claims (1)

[Claims] In a homogeneous solution containing salts of platinum group elements or their complexes and alcohol, in the presence of oxygen, the partial pressure of -carbon oxide is
, a1*g/crl to 4.5ky/country 2. A method for producing a carbonic acid diester, which comprises reacting it with a nitrite ester while supplying a -carbon oxide-containing gas.