Method of synthesizing 2,2,4,4-tetramethyl-1,3-cyclobutadione

A technology of cyclobutanedione and a synthesis method, which is applied in the preparation of carbon-based compounds, chemical instruments and methods, preparation of ketene, etc., can solve the problems of low DMK concentration, affecting the activity and life of a hydrogenation catalyst, and complicated operation procedures.

Inactive Publication Date: 2020-09-29
IND TECH RES INST
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Problems solved by technology

[0003] Existing TMCD synthetic method has following problem: (1) spray and dissolve the DMK in the DMK-containing gas with absorption liquid, its equipment and operating procedure are complicated; 12~20wt%); and (3) TMCD is not isolated and purified, cracking impurities, IBAN, and IBA remain in the solution, and directly entering the hydrogenation system will affect the activity and life of the hydrogenation catalyst

Method used

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  • Method of synthesizing 2,2,4,4-tetramethyl-1,3-cyclobutadione

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Embodiment 1

[0032] Isobutyric anhydride (IBAN, 4.17ml / min) and nitrogen (200ml / min) were mixed in a mixing tank at 150°C to form a mixed gas with an IBAN concentration of 75mol%. The mixed gas is introduced into a preheating reactor at 325°C for preheating, and then introduced into a cracking reactor at 475°C to crack IBAN at a reaction pressure of 110torr. The gas residence time of the above cracking reaction is 0.14 seconds, the total reaction is 1 hour, the conversion rate of IBAN is 62.9%, and the selectivity rate of dimethyl ketene (DMK) is 97.2%. The cracked product (containing unreacted IBAN, main product DMK, and by-product isobutyric acid (IBA)) quickly passes through the condenser and cools down to between 30°C and 40°C to form a gas-liquid mixture. The liquid in the gas-liquid mixture is mainly unreacted IBAN and by-product IBA, while the gas is mainly DMK. The gas-liquid mixture after cooling is carried out gas-liquid separation by separating device, then the gas product impo...

Embodiment 2

[0034] IBAN (4.17 ml / min) and nitrogen (100 ml / min) were mixed in a mixing tank at 150° C. to form a mixed gas with an IBAN concentration of 87 mol%. The mixed gas is introduced into a preheating reactor at 325°C for preheating, and then introduced into a cracking reactor at 475°C to crack IBAN at a reaction pressure of 110torr. The gas residence time of the above cracking reaction is 0.16 seconds, the total reaction is 1 hour, the conversion rate of IBAN is 63.0%, and the selectivity of DMK is 98.3%. The cracked product (containing unreacted IBAN, main product DMK, and by-product IBA) quickly passes through the condenser and cools down to between 30°C and 40°C to form a gas-liquid mixture. The liquid in the gas-liquid mixture is mainly unreacted IBAN and by-product IBA, while the gas is mainly DMK. The gas-liquid mixture after cooling is carried out gas-liquid separation through the separation device, then the gas product is introduced into (bubble) absorption bottle (total ...

Embodiment 3

[0036] IBAN (4.17ml / min) was passed into the mixing tank at 150°C to form a gas with an IBAN concentration of 100mol%. After the gas is introduced into a preheating reactor at 325°C for preheating, it is introduced into a cracking reactor at 475°C to crack IBAN at a reaction pressure of 110torr. The gas residence time of the above cracking reaction is 0.18 seconds, the total reaction is 1 hour, the IBAN conversion rate is 59.4%, and the DMK selectivity rate is 98.4%. The cracked product (containing unreacted IBAN, main product DMK, and by-product IBA) quickly passes through the condenser and cools down to between 30°C and 40°C to form a gas-liquid mixture. The liquid in the gas-liquid mixture is mainly unreacted IBAN and by-product IBA, while the gas is mainly DMK. The gas-liquid mixture after cooling is carried out gas-liquid separation through the separation device, then the gas product is introduced into (bubble) absorption bottle (total 2 bottles) in 0 ℃ IIBB (the first b...

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Abstract

The present disclosure provides a process for synthesizing 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione, comprising the steps of (a) cleaving isobutyric anhydride to form a dimethyl ketene-containinggas; (b) introducing gas containing dimethyl ketene into an ester solvent to dissolve the dimethyl ketene in the ester solvent to form an ester solution containing the dimethyl ketene; and (c) standing the ester solution containing the dimethyl ketene under inert gas, so that the dimethyl ketene is dimerized to form the 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione. The synthetic method of the present invention is a synthetic method of collecting DMK generated by cracking IBAN in a new manner and dimerizing DMK to form TMCD, thereby being capable of basically overcoming various defects in the prior art.

Description

technical field [0001] This disclosure is about the synthesis method of 2,2,4,4-tetramethyl-1,3-cyclobutanedione. Background technique [0002] 2,2,4,4-tetramethyl-1,3-cyclobutanedione (2,2,4,4-Tetramethyl-1,3-cyclobutadione, TMCD) is 2,2,4,4-tetramethyl Base-1,3-cyclobutanediol (2,2,4,4-Tetramethyl-1,3-cyclobutanediol, CBDO) hydrogenation raw material. CBDO is a special diol intermediate with high rigidity, toughness, heat resistance, and hydrolysis resistance, which can increase the glass transition temperature of polyester. TMCD is mainly produced from the dimerization of dimethylketene (DMK), and the preparation methods of DMK mainly include acid chloride method, isobutyric anhydride (Isobutyric anhydride, IBAN) thermal cracking method, and isobutyric acid (Isobutyric acid, IBA) catalyst dehydration method and other three methods. The acid chloride method will produce a large amount of salts during the synthesis of TMCD, and the subsequent treatment procedures are qui...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C49/39C07C45/76C07C49/88C07C45/89
CPCC07C45/76C07C45/89C07C2601/04C07C49/88C07C49/39
Inventor 黄建良黄琼辉
Owner IND TECH RES INST
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