CN1699328A - Process for preparing dialkyl carbonate - Google Patents
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- CN1699328A CN1699328A CN 200510026042 CN200510026042A CN1699328A CN 1699328 A CN1699328 A CN 1699328A CN 200510026042 CN200510026042 CN 200510026042 CN 200510026042 A CN200510026042 A CN 200510026042A CN 1699328 A CN1699328 A CN 1699328A
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Abstract
The invention discloses a process for preparing dialkyl carbonate comprising the steps of, reacting reactants low molecular weight dialkyl ester carbonate and aliphatic mono ethanol at the presence of catalyst, the reaction temperature being 25-250 deg. C, the reacting time being 0.1-25 hours, the reaction pressure being -0.095-0.5 MPa, then separating with the conventional methods.
Description
Technical Field
The invention relates to a method for preparing dialkyl carbonate, in particular to a method for preparing high molecular weight dialkyl carbonate by using low molecular weight dialkyl carbonate as a raw material.
Background
The dialkyl carbonate is an organic compound with wide application, contains alkoxy and carbonyl in the molecule, has active chemical property, can react with various alcohols, phenols, amines, esters and the like, is an important organic synthesis intermediate and a solvent with excellent performance, is widely applied to the industries of synthetic fibers, synthetic resins, medicines, pesticides and the like, is an electrolyte solvent of a lithium battery, is also an excellent gasoline additive, and has high industrial application value and good market prospect.
There are many kinds of synthesis methods for dialkyl carbonate, mainly including phosgene method, oxidative carbonylation method, ester exchange method, etc. The phosgene method (for example, JP6-41019(1994)) is to eliminate the method in which phosgene is reacted with boiling alcohol to produce chloroformate, and then the chloroformate is reacted with corresponding alcohol to obtain dialkyl carbonate.
Oxidative carbonylation has also been studied, for example, in JP 53121720(1978) using carbon monoxide as a catalyst for the preparation of diethyl carbonate and dibutyl carbonate, selenium and dicycloamidine; punnoose, A.et al (Punnoose, A.; Seehra, M.S.; Dunn, B.C.; et al, Characterisation of CuCl2/PdCl2/activated carbon catalysts for the synthesis of ethylene carbonate. energy and Fuels, 2002, v16, p182-188.) diethyl carbonate was prepared from ethanol and carbon monoxide in a heterogeneous catalyst CuCl2/PdCl 2/AC. However, the oxidative carbonylation method is still imperfect, and has various disadvantages, such as low selectivity, expensive catalyst, and difficult operation control.
In the studies of the transesterification method, JP 09221436(1997) discloses a method for producing a dialkyl carbonate by transesterification of a cyclic carbonate with an aliphatic monoalcohol under base catalysis, which is not preferable because of its low equilibrium conversion and low reaction rate.
US5534649(1996) discloses a process for the preparation of diethyl carbonate by reacting urea, methyl carbamate or ethyl carbamate with ethanol in the presence of a catalyst. However, ammonia is released from the product of the method, the reaction time is long, and the yield of diethyl carbonate is low.
In addition, there are also japanese patent JP 2001247520(2001) for preparing diethyl carbonate by reacting liquid carbon dioxide, dimethyl carbonate and ethanol under the catalysis of lithium bromide and EP 503618(1992) for preparing carbonate by using carbon monoxide and nitrite in the presence of a catalyst, but all have the disadvantages of large toxicity of raw materials and the like.
In contrast, the synthesis of dialkyl carbonate with high molecular weight by transesterification of dialkyl carbonate with low molecular weight, especially dimethyl carbonate as green chemical product, and corresponding aliphatic monoalcohol has become a hot point of international research because of the advantages of non-toxic raw materials, no pollution of three wastes in the production process, etc.
Disclosure of Invention
The technical problem to be solved by the invention is to disclose a method for preparing dialkyl carbonate, so as to overcome the defects in the prior art.
The technical idea of the invention is as follows:
the invention relates to a lowmolecular weight dialkyl carbonate (R) in the presence of a catalyst and at a suitable temperature1-OCOO-R1) And aliphatic monoalcohol (R)2-OH) in a certain molar ratio to obtain dialkyl carbonate (R) with higher molecular weight2-OCOO-R2) Or (and) (R)1-OCOO-R2). The reaction of the low molecular weight dialkyl carbonate with the aliphatic monoalcohol can be represented by the following formula:
namely, under the action of a catalyst, firstly, the low molecular weight dialkyl carbonate (R)1-OCOO-R1) With aliphatic monoalcohols (R)2Reaction with-OH) to form the intermediate asymmetric dialkyl carbonate (R)1-OCOO-R2) And low molecular weight alcohols (R)1-OH) and the intermediate can then be reacted further with an aliphatic monoalcohol to form the symmetrical dialkyl carbonate (R)2-OCOO-R2) And low molecular alcohols. Inverse directionThe reaction (1) is a fast reaction, the reaction (2) is a slow reaction, and the rate of the whole reaction is determined by (2), so that R can be adjusted by controlling the reaction conditions1-OCOO-R2And R2-OCOO-R2The generation ratio of (2).
The method of the invention comprises the following steps:
reacting the reactant dialkyl carbonate with low molecular weight with aliphatic monoalcohol in the presence of a catalyst, wherein the reaction temperature is 25-250 ℃, the reaction time is 0.1-25 hours, and the reaction pressure is-0.095-0.5 Mpa, and then separating by adopting a conventional method, such as rectification, so as toobtain the dialkyl carbonate with higher molecular weight;
the general structural formula of the low molecular weight dialkyl carbonate is as follows:
R1-OCOO-R1wherein:
R1represents an aliphatic alkyl group having carbon atoms of between C1 and C8, preferably an aliphatic alkyl group having carbon atoms of between C1 and C3, and the low molecular weight dialkyl carbonate is most preferably dimethyl carbonate or diethyl carbonate;
the structural general formula of the aliphatic monoalcohol is as follows: r2-OH，R2Represents an aliphatic alkyl group having a carbon number of between 2 and 25, preferably between 2 and 16, such as ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, dodecanol, pentadecanol and the like (including n-, iso-, secondary-, tertiary-equivalent isomers);
the general structural formula of the dialkyl carbonate with higher molecular weight is as follows:
R2-OCOO-R2or/and1-OCOO-R2(ii) a Wherein:
R2represents an aliphatic alkyl group having between C2 and C25 carbon atoms, preferably an aliphatic alkyl group having between C2 and C16 carbon atoms, and R represents2Has a carbon number greater than R1The number of carbon atoms of (a);
the catalyst is selected from alkali metal or alkaline earth metal alcoholate, hydroxide, alkali metal carbonate, alkaline earth metal carbonate, organic tin, organic zinc or alkaline resin, and the like, preferably one of sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium hydroxide, potassium carbonate, sodium carbonate, zinc acetate, dibutyl tin oxide or dibutyl tin dilaurate, and the adding amount of the catalyst is 0.1-10 percent based on the total weight of the raw materials;
the molar ratio of the low molecular weight dialkyl carbonate to the aliphatic monoalcohol is 0.5-10: 1.
According to a preferred technical scheme of the invention, the reaction is carried out in a reaction rectifying tower, and the method comprises the following steps:
adding reactants of low molecular weight dialkyl carbonate, a catalyst and aliphatic monoalcohol into a reaction rectifying tower, starting to perform total reflux, controlling the reflux ratio to be 0.5-20 after the tower top temperature is stable, controlling the tower top temperature to be 60-80 ℃, the tower bottom temperature to be 90-250 ℃, the reaction pressure to be-0.095-0.5 Mpa and the reaction time to be 0.1-25 hours, and collecting a tower bottom product, namely the higher molecular weight dialkyl carbonate.
The reaction rectifying tower is one kind of conventional chemical rectifying apparatus, including plate tower, packed tower, float valve tower, etc. and has synchronous reaction and separation.
The invention adopts dialkyl carbonate with low molecular weight, especially dimethyl carbonate which is a green chemical raw material, to react with aliphatic monoalcohol to synthesize dialkyl carbonate, the raw material is clean and nontoxic, the production process has no three-waste pollution, the effective utilization rate of atoms reaches 100 percent, and the method is a synthesis method of dialkyl carbonate with mild reaction conditions and environmental protection.
The following examples further illustrate the implementation of the present invention, which are provided for better understanding of the present invention and are not intended to limit the present invention.
Detailed Description
Example 1
153.4g of butanol, 135.1g of dimethyl carbonate, 6.0g of potassium carbonate and several grains of zeolite were added to a three-necked flask equipped with a rectifying column and a thermometer, and then a heating reaction was carried out, total reflux was started, the column top temperature was stabilized, the reflux ratio was controlled to 3, and the column top temperature was controlled to 63.5 ℃. After the reaction was rectified for 5 hours, it was analyzed by gas chromatography. The composition of the top solution was 70.2% methanol and 29.8% dimethyl carbonate (mass content unless otherwise specified), and the composition of the bottom solution was 6.73% butanol, 0.16% dimethyl carbonate, 2.11% methylbutyl carbonate and 91.00% dibutyl carbonate.
Example 2
102.3g of butanol, 135.1g of dimethyl carbonate and 5.6g of zinc acetate, otherwise as in example 1. The composition of the solution at the top of the tower is 70.5 percent of methanol and 29.5 percent of dimethyl carbonate; the composition of the solution at the bottom of the tower is 4.65% of butanol, 1.09% of dimethyl carbonate, 15.59% of methyl butyl carbonate and 78.67% of dibutyl carbonate.
Example 3
Using the method of example 1, 260.5g of isooctanol, 122.5g of dimethyl carbonate and 3.8g of sodium methoxide were charged, and the mixture was heated and reacted for 3 hours while controlling the reflux ratio to 2 and the column top temperature to 64 ℃ and analyzed by gas chromatography. The composition of the solution at the top of the tower is 70.2 percent of methanol and 29.8 percent of dimethyl carbonate; the composition of the solution in the bottom of the tower is 17.19% of isooctanol, 11.4% of dimethyl carbonate, 5.75% of methyl isooctyl carbonate and 65.66% of diisooctyl carbonate.
Example 4
354.2g of isooctanol, 122.5g of dimethyl carbonate and 5.2g of sodium methoxide were used, otherwise the same as in example 3. The composition of the solution at the top of the tower is 70.0 percent of methanol and 30.0 percent of dimethyl carbonate; the composition of the tower bottom solution is 19.39% of isooctanol, 9.87% of dimethyl carbonate, 3.25% of methyl octyl carbonate and 67.49% of dioctyl carbonate.
Example 5
Using the method of example 1, 260.2g of ethanol, 167.6g of dimethyl carbonate and 4.5g of sodium ethoxide were added, the reaction was heated for 10 hours with a reflux ratio of 5 and a column top temperature of 63.8 ℃ and analyzed by gas chromatography. The composition of the solution at the top of the tower is 70.3 percent of methanol and 29.7 percent of dimethyl carbonate; the composition of the solution at the bottom of the tower is 47.18 percent of ethanol, 2.95 percent of dimethyl carbonate, 13.67 percent of methyl ethyl carbonate and 36.2 percent of diethyl carbonate.
Example 6
107.1g of ethanol, 135.0g of dimethyl carbonate and 2.6g of sodium ethoxide, the rest being as in example 5. The composition of the solution at the top of the tower is 70.1 percent of methanol and 29.9 percent of dimethyl carbonate; the composition of the solution at the bottom of the tower is 20.37% of ethanol, 7.14% of dimethyl carbonate, 41.27% of methyl ethyl carbonate and 31.22% of diethyl carbonate.
Example 7
460.0g ethanol, 143.3g dimethyl carbonate and 2.4g potassium carbonate, which begin to be total reflux, after the temperature at the top of the tower is stable, the reflux ratio is controlled to be 3.5, the temperature at the top of the tower is 63.5 ℃, the compositions of distillate at the top of the tower are 70.1 percent of methanol and 29.9 percent of dimethyl carbonate; the solution in the bottom of the tower consists of 74.99% of ethanol, 0.06% of dimethyl carbonate, 0.08% of methyl ethyl carbonate and 24.87% of diethyl carbonate.
Example 8
Using the method of example 1, 180g of isopropyl alcohol, 102.6g of dimethyl carbonate and 3.0g of potassium carbonate were added, the reaction was heated for 8 hours with the reflux ratio controlled at 4 and the column top temperature controlled at 64 ℃ and analyzed by gas chromatography. The composition of the solution at the top of the tower is 70.5 percent of methanol and 29.5 percent of dimethyl carbonate; the composition of the solution in the bottom of the column was 43.14% of isopropyl alcohol, 2.5% of dimethyl carbonate, 9.93% of methyl isopropyl carbonate and 44.43% of diisopropyl carbonate.
Example 9
327g of isooctanol, 132.2g of diethyl carbonate and 4.6g of potassium hydroxide were charged by the method of example 1, and the mixture was heated and reacted for 8 hours while controlling the reflux ratio to 4 and the overhead temperature to 73.9 ℃ and analyzed by gas chromatography. The top of the tower is 99.8 percent of ethanol, 0.2 percent of diethyl carbonate, and the bottom solution of the tower consists of 23 percent of isooctanol, 2.79 percent of diethyl carbonate, 11.15 percent of ethyl isooctyl carbonate and 63.06 percent of diisooctyl carbonate.
Example 10
In a three-necked flask equipped with a rectifying column and a thermometer, 231.7g of lauryl alcohol, 81g of diethyl carbonate, 4.3g of dibutyltin oxide and several pieces of zeolite were charged. Vacuumizing the top of the rectifying tower to ensure that the reaction pressure is-0.03 Mpa, heating for reaction, starting to perform total reflux, controlling the temperature at the top of the tower to be 64 ℃ after the temperature at the top of the tower is stable, controlling the reflux ratio to be 3, and analyzing by using a gas chromatography after reacting for 6 hours. 99.7 percent of ethanol and 0.3 percent of diethyl carbonate at the tower top; the composition of the solution in the bottom of the tower is 9.7 percent of lauryl alcohol, 3.86 percent of diethyl carbonate, 8.44 percent of ethyl dodecyl carbonate and 78.0 percent of didodecyl carbonate.
Example 11
227.9g of lauryl alcohol, 66.8g of dimethyl carbonate and 4.2g of dibutyltin dilaurate were added by the method of example 10, the reflux ratio was controlled to 4, the reaction pressure was-0.05 MPa, the temperature at the top of the column was 41.2 ℃, and the mixture was heated and reacted for 6 hours, followed by analysis by gas chromatography. The composition of the solution at the top of the tower is 66.3 percent of methanol and 33.7 percent of dimethyl carbonate; the composition of the solution in the bottom of the column is 16.2% of lauryl alcohol, 1.6% of dimethyl carbonate, 8.0% of methyl dodecyl carbonate and 74.0% of didodecyl carbonate.
Example 12
163.4g of ethanol, 138.2g of dimethyl carbonate and 6.0g of potassium carbonate are added into a three-neck flask, the mixture is heated and reacted at the temperature of 120 ℃ for 1 hour, the reaction pressure is increased to 0.3Mpa, then the mixture is separated by rectification, the reflux ratio is controlled to be 5, and the solution at the bottom of the tower consists of 25.4% of ethanol, 0.5% of dimethyl carbonate, 21.6% of methyl ethyl carbonate and 52.5% of diethyl carbonate.
Claims (8)
1. A process for preparing a dialkyl carbonate, comprising the steps of: reacting a reactant of low-molecular-weight dialkyl carbonate with aliphatic monoalcohol in the presence of a catalyst, wherein the reaction temperature is 25-250 ℃, the reaction time is 0.1-25 hours, and the reaction pressure is-0.095-0.5 Mpa, and then separating by adopting a conventional method to obtain the higher-molecular-weight dialkyl carbonate;
saidThe general structural formula of the low molecular weight dialkyl carbonate is as follows: r1-OCOO-R1Wherein: r1Represents an aliphatic alkyl group having carbon atoms of between C1 and C8;
the structural general formula of the aliphatic monoalcohol is as follows: r2-OH, wherein: r2Represents an aliphatic alkyl group having carbon atoms of between C2 and C25;
the general structural formula of the dialkyl carbonate with higher molecular weight is as follows:
R2-OCOO-R2or/and R1-OCOO-R2(ii) a Wherein:
R2represents an aliphatic alkyl group having between C2 and C25 carbon atoms, and R2Has a carbon number greater than R1The number of carbon atoms of (a);
the catalyst is selected from alkali metal or alkaline earth metal alcoholate or hydroxide, alkali metal carbonate, alkaline earth metal carbonate, organic tin, organic zinc or alkaline resin.
2. The method of claim 1, wherein R is1Represents an aliphatic alkyl group having carbon atoms of between C1 and C3.
3. The process of claim 2, wherein the low molecular weight dialkyl carbonate is dimethyl carbonate or diethyl carbonate.
4. The method of claim 1, wherein R is2Represents an aliphatic alkyl group having carbon atoms of between C2 and C16.
5. The method of claim 1, wherein the aliphatic mono-alcohol is selected from the group consisting of ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, dodecanol, and pentadecanol.
6. The method of claim 1, wherein the catalyst is added in an amount of 0.1 to 10% based on the total weight of the feedstock.
7. The method according to claim 1, wherein the molar ratio of the low molecular weight dialkyl carbonate to the aliphatic monoalcohol is 0.5-10: 1.
8. The method according to claim 1, characterized in that the reaction is carried out in a reactive distillation column comprising the following steps: adding reactants of low molecular weight dialkyl carbonate, a catalyst and aliphatic monoalcohol into a reaction rectifying tower, starting to perform total reflux, controlling the reflux ratio to be 0.5-20 after the tower top temperature is stable, controlling the tower top temperature to be 60-80 ℃, the tower bottom temperature to be 90-250 ℃, the reaction pressure to be-0.095-0.5 Mpa and the reaction time to be 0.1-25 hours, and collecting a tower bottom product, namely the higher molecular weight dialkyl carbonate.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102676239A (en) * | 2012-05-17 | 2012-09-19 | 北京金骄生物质化工有限公司 | Environment-friendly type liquid fuel and preparation method thereof |
| EP2664608A1 (en) | 2012-05-17 | 2013-11-20 | Beijing Jinjiao Biomass Chemical Industry Co., Ltd | Environment-friendly liquid fuel and production process thereof |
| CN105439856A (en) * | 2015-11-04 | 2016-03-30 | 江西师范大学 | Method for preparing dilauryl carbonate by using oxometallate ionic liquid as catalyst |
| CN105541630A (en) * | 2016-01-24 | 2016-05-04 | 辽宁会福化工有限公司 | Method for preparing ethyl methyl carbonate |
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2005
- 2005-05-20 CN CN 200510026042 patent/CN1699328A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102676239A (en) * | 2012-05-17 | 2012-09-19 | 北京金骄生物质化工有限公司 | Environment-friendly type liquid fuel and preparation method thereof |
| EP2664608A1 (en) | 2012-05-17 | 2013-11-20 | Beijing Jinjiao Biomass Chemical Industry Co., Ltd | Environment-friendly liquid fuel and production process thereof |
| US9045707B2 (en) | 2012-05-17 | 2015-06-02 | Beijing Jinjiao Biomass Chemical Industry Co., Ltd. | Environmental-friendly liquid fuel and production process thereof |
| CN105439856A (en) * | 2015-11-04 | 2016-03-30 | 江西师范大学 | Method for preparing dilauryl carbonate by using oxometallate ionic liquid as catalyst |
| CN105439856B (en) * | 2015-11-04 | 2019-02-19 | 江西师范大学 | Method for preparing dilauryl carbonate by using oxometallate ionic liquid as catalyst |
| CN105541630A (en) * | 2016-01-24 | 2016-05-04 | 辽宁会福化工有限公司 | Method for preparing ethyl methyl carbonate |
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