Preparation method of high-purity diphenyl carbonate

Abstract

The invention discloses a preparation method of high-purity diphenyl carbonate, which comprises the following steps: under the condition of a catalyst, adding phenol and diethyl carbonate into a reactor to carry out reflux reaction, and after the reaction is finished, carrying out vacuum distillation to obtain diphenyl carbonate, the catalyst is a mixture of tetrabutyl titanate and imidazole; according to the preparation method, the raw materials are specifically selected, so that the prepared product is safe and non-toxic, the preparation method is simple in process, easy to operate and convenient for mass production, in addition, the transesterification can be promoted by specifically limiting the catalyst in the preparation method, the selectivity of the prepared product diphenyl carbonate is further improved, and the yield of the product diphenyl carbonate is increased. The product purity is improved.

Description

Technical Field

[0001] The invention relates to the technical field of diphenyl carbonate preparation, and in particular to a method for preparing high-purity diphenyl carbonate. Background Art

[0002] Diphenyl carbonate (DPC) is a white crystalline solid that is insoluble in water but soluble in organic solvents such as hot ethanol, benzene, ether, carbon tetrachloride, glacial acetic acid, etc. It can be decomposed by hot alkali. It is mainly used as a synthetic raw material for engineering plastics such as polycarbonate and polyparaben, and can also be used as a plasticizer and solvent for nitrocellulose.

[0003] Diphenyl carbonate is an important new type of engineering plastic intermediate. It is pollution-free and low-toxic. It is mainly used in the plastics industry and is often used to synthesize polycarbonate. The main methods for synthesizing diphenyl carbonate are phosgene method, transesterification method and phenol oxidative carbonylation method.

[0004] At present, the preparation method of diphenyl carbonate is generally to synthesize diphenyl carbonate by phenol and dimethyl carbonate in the presence of a catalyst. However, the methanol in the product of this method has certain toxicity, high operating requirements, and the purity of the prepared diphenyl carbonate is low.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a method for preparing high-purity diphenyl carbonate. The product of the preparation method of the present invention is safe and non-toxic, the process is simple, and the selectivity of the prepared diphenyl carbonate is higher through the specific limitation of the catalyst.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] The first aspect of the present invention provides a method for preparing high-purity diphenyl carbonate, the preparation method comprising the following steps:

[0009] Under the condition of a catalyst, phenol and diethyl carbonate are added to a reactor for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate;

[0010] The catalyst is a mixture of tetrabutyl titanate and imidazole.

[0011] Preferably, the molar ratio of phenol to diethyl carbonate is (3-5):1.

[0012] Preferably, the added amount of the catalyst is 4% to 8% of the mass of phenol.

[0013] Preferably, the added amount of the catalyst is 6% of the mass of phenol.

[0014] Preferably, the reflux reaction temperature is 150-170° C., and the reaction time is 18-25 h.

[0015] Preferably, the reflux reaction temperature is 160° C. and the reaction time is 22 h.

[0016] Preferably, the molar ratio of tetrabutyl titanate to imidazole is (5-7):1.

[0017] Preferably, the molar ratio of tetrabutyl titanate to imidazole is 6:1.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least:

[0019] The preparation method of the present invention makes the prepared product safe and non-toxic by the specific selection of raw materials, and the preparation method of the present invention has a simple process, is easy to operate, and is convenient for mass production. In addition, the preparation method of the present invention can promote the ester exchange reaction by the specific limitation of the catalyst, thereby improving the selectivity of the prepared product diphenyl carbonate and improving the purity of the product. DETAILED DESCRIPTION

[0020] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0021] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0022] The embodiment of the present invention provides a method for preparing high-purity diphenyl carbonate, the preparation method comprising the following steps:

[0023] Under the condition of a catalyst, phenol and diethyl carbonate are added to a reactor for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate;

[0024] The catalyst is a mixture of tetrabutyl titanate and imidazole.

[0025] The preparation method of the present invention makes the prepared product safe and non-toxic by the specific selection of raw materials, and the preparation method of the present invention has a simple process, is easy to operate, and is convenient for mass production. In addition, the preparation method of the present invention can promote the ester exchange reaction by the specific limitation of the catalyst, thereby improving the selectivity of the prepared product diphenyl carbonate and improving the purity of the product.

[0026] In one embodiment, the molar ratio of phenol to diethyl carbonate may be (3-5):1, specifically 3:1, 4:1 or 5:1.

[0027] In one embodiment, the added amount of the catalyst may be 4% to 8% of the mass of phenol, specifically 4%, 6% or 8%.

[0028] In one embodiment, the catalyst may be added in an amount of 6% by mass of phenol.

[0029] In one embodiment, the reflux reaction temperature is 150-170° C., and the reaction time is 18-25 hours.

[0030] Furthermore, the reflux reaction temperature is 160° C. and the reaction time is 22 h.

[0031] In one embodiment, the molar ratio of tetrabutyl titanate to imidazole may be (5-7):1.

[0032] Furthermore, the molar ratio of tetrabutyl titanate to imidazole is 6:1.

[0033] The technical solution of the present invention is further described in detail below through specific embodiments.

[0034] Example 1

[0035] This embodiment is a method for preparing high-purity diphenyl carbonate, and the preparation method comprises the following steps:

[0036] Under the condition of catalyst, phenol and diethyl carbonate are added into the reactor in a molar ratio of 3:1 for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate, wherein the amount of catalyst added is 8% of the mass of phenol; the reflux reaction temperature is 150°C, and the reaction time is 25h;

[0037] The catalyst is a mixture of tetrabutyl titanate and imidazole, wherein the molar ratio of tetrabutyl titanate to imidazole is 5:1.

[0038] Example 2

[0039] This embodiment is a method for preparing high-purity diphenyl carbonate, and the preparation method comprises the following steps:

[0040] Under the condition of catalyst, phenol and diethyl carbonate are added into the reactor in a molar ratio of 5:1 for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate, wherein the amount of catalyst added is 4% of the mass of phenol; the reflux reaction temperature is 170°C, and the reaction time is 18h;

[0041] The catalyst is a mixture of tetrabutyl titanate and imidazole, wherein the molar ratio of tetrabutyl titanate to imidazole is 7:1.

[0042] Example 3

[0043] This embodiment is a method for preparing high-purity diphenyl carbonate, and the preparation method comprises the following steps:

[0044] Under the condition of catalyst, phenol and diethyl carbonate are added into the reactor in a molar ratio of 4:1 for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate, wherein the amount of catalyst added is 6% of the mass of phenol; the reflux reaction temperature is 160°C, and the reaction time is 22h;

[0045] The catalyst is a mixture of tetrabutyl titanate and imidazole, wherein the molar ratio of tetrabutyl titanate to imidazole is 6:1.

[0046] Comparative Example 1

[0047] This comparative example is a method for preparing high-purity diphenyl carbonate, which comprises the following steps:

[0048] Under the condition of catalyst, phenol and diethyl carbonate are added into the reactor in a molar ratio of 4:1 for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate, wherein the amount of catalyst added is 6% of the mass of phenol; the reflux reaction temperature is 160°C, and the reaction time is 22h;

[0049] The catalyst is tetrabutyl titanate.

[0050] Comparative Example 2

[0051] This comparative example is a method for preparing high-purity diphenyl carbonate, which comprises the following steps:

[0052] Under the condition of catalyst, phenol and diethyl carbonate are added into the reactor in a molar ratio of 4:1 for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate, wherein the amount of catalyst added is 6% of the mass of phenol; the reflux reaction temperature is 160°C, and the reaction time is 22h;

[0053] The catalyst is imidazole.

[0054] Comparative Example 3

[0055] This comparative example is a method for preparing high-purity diphenyl carbonate, which comprises the following steps:

[0056] Under the condition of catalyst, phenol and diethyl carbonate are added into the reactor in a molar ratio of 4:1 for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate, wherein the amount of catalyst added is 6% of the mass of phenol; the reflux reaction temperature is 160°C, and the reaction time is 22h;

[0057] The catalyst is a mixture of tetrabutyl titanate and imidazole, wherein the molar ratio of tetrabutyl titanate to imidazole is 1:1.

[0058] Experimental example

[0059] Diphenyl carbonate was prepared according to the preparation methods of high-purity diphenyl carbonate of Examples 1 to 3 and Comparative Examples 1 to 3 respectively;

[0060] The conversion rate of diethyl carbonate and the selectivity of diphenyl carbonate in the product are determined by chromatographic analysis;

[0061] Table 1

[0062] Group Conversion rate of diethyl carbonate (%) Selectivity (%) Example 1 85.3 90.1 Example 2 86.2 90.8 Example 3 86.7 91.3 Comparative Example 1 62.7 41.1 Comparative Example 2 53.2 58.9 Comparative Example 3 71.7 65.8

[0063] From Table 1, we can see that:

[0064] The technical solution of the present application limits the type of catalyst, so that the diphenyl carbonate prepared by the present application has better selectivity and conversion rate of diethyl carbonate. Specifically, compared with the comparative example, by limiting the type of catalyst (tetrabutyl titanate and imidazole) and the amount used, the generation of diethyl carbonate can be better promoted and its selectivity can be improved. In addition, the preparation method of the present invention is safe and non-toxic, and the preparation method of the present invention has a simple process, is easy to operate, and is convenient for mass production.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for preparing high-purity diphenyl carbonate, characterized in that: The preparation method comprises the following steps: Under the condition of a catalyst, phenol and diethyl carbonate are added to a reactor for reflux reaction, and vacuum distillation is performed after the reaction is completed to obtain diphenyl carbonate; The catalyst is a mixture of tetrabutyl titanate and imidazole.

2. The preparation method according to claim 1, characterized in that: The molar ratio of phenol to diethyl carbonate is (3-5):

1.

3. The preparation method according to claim 1, characterized in that: The added amount of the catalyst is 4% to 8% of the mass of phenol.

4. The preparation method according to claim 1, characterized in that: The added amount of the catalyst is 6% of the mass of phenol.

5. The preparation method according to claim 1, characterized in that: The reflux reaction temperature is 150-170° C., and the reaction time is 18-25 hours.

6. The preparation method according to claim 1, characterized in that: The reflux reaction temperature is 160° C. and the reaction time is 22 h.

7. The preparation method according to claim 1, characterized in that: The molar ratio of tetrabutyl titanate to imidazole is (5-7):

1.

8. The preparation method according to claim 1, characterized in that: The molar ratio of tetrabutyl titanate to imidazole is 6:1.