Description

STABLE COMPOSITION OF AROMATIC DIALDEHYDE AND METHOD FOR STABILIZING AROMATIC DIALDEHYDE

Technical Field

[1] The present invention relates to a stable composition comprising aromatic dialdehyde and a method of stabilizing aromatic dialdehyde, and more particularly, to an aromatic dialdehyde composition, which can prevent the oxidation of liquid aromatic dialdehyde, due either to oxygen in the air or to heat, and the consequent deterioration or loss thereof, thus maintaining the purity of aromatic dialdehyde, and to a method of stabilizing aromatic dialdehyde. Background Art

[2] Generally, aromatic aldehydes have a highly reactive aldehyde group, and may thus be used in a wide variety of fields. Especially, terephthaldehyde, having two aldehyde groups at the para position thereof, is receiving attention as a base material for medicines, agricultural chemicals, pigments, liquid crystalline polymers, electrically conductive polymers, and heat-resistant plastics.

[3] However, according to the literature (Ulmann's Encyclopedia Vol. Al pp321-349), liquid aldehyde has been reported to be easily oxidized even at low temperatures in an atmosphere to thus be converted into a corrosive acid or altered into an oligomer. Therefore, when aldehyde is stored, an antioxidant or a stabilizer is added, or alternatively, a storage container may be charged with nitrogen.

[4] US Patent No. 1,736,747 discloses a method of stabilizing aldehyde with respect to oxidation using about 0.25-1.0% of 1,2-diaminoethanol. In addition, Japanese Unexamined Patent Publication No. 7,232,963 discloses a method of stabilizing beta- methyl-thio-propionic aldehyde (MTPA) using 0.1% of pyridine, quinoline, collidine, or rutinine. Further, US Patent No. 2,381,771 discloses the use of quinoline as an antioxidant of synthetic rubber, gasoline, and aldehyde, and furthermore, Soviet Patent No. 568,629 discloses a method of adding 0.25-0.5% of triethanolamine as a stabilizer of formaldehyde.

Disclosure of Invention

Technical Problem

[5] Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a stable aromatic dialdehyde composition, which can prevent the oxidation of liquid aromatic dialdehyde due to oxygen in the air or heat and consequent deterioration thereof.

[6] Another object of the present invention is to provide a method of stabilizing aromatic dialdehyde, which can decrease the alteration of aromatic dialdehyde upon the preparation or storage of aromatic dialdehyde so as to prevent the loss of aromatic dialdehyde and to maintain the purity thereof. Technical Solution

[7] In order to accomplish the above objects, the present invention provides an aromatic dialdehyde composition, comprising aromatic dialdehyde and an additive selected from among hydroquinone and its isomers.

Advantageous Effects

[8] According to the present invention, liquid aromatic dialdehyde can be prevented from oxidation, due either to oxygen in the air or to heat, to thus avoid the deterioration thereof. Further, upon the preparation or storage of aromatic dialdehyde, the alteration of aromatic dialdehyde is decreased, thus preventing the loss of aromatic dialdehyde and maintaining the purity thereof.

[9] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various variations and modifications are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Mode for the Invention

[10] Hereinafter, a detailed description will be given of the present invention.

[11] In the present invention, the aromatic dialdehyde composition and the method of stabilizing aromatic dialdehyde are characterized in that hydroquinone or isomers thereof are used as additives.

[12] The aromatic dialdehyde, used in the present invention, is a compound in which two aldehyde groups are attached to a benzene ring, and examples thereof include o- phthaldehyde, in which the aldehyde groups are attached to the ortho position of the benzene ring, isophthaldehyde, in which the aldehyde groups are attached to the meta position thereof, and terephthaldehyde, in which the aldehyde groups are attached to the para position thereof. Furthermore, particularly useful is an aromatic dialdehyde represented by Formula 1 below:

[13] Formula 1

[14]

[15] Useful as the additive in the present invention, the hydroquinone or its isomers function to prevent the oxidation of aromatic dialdehyde.

[16] The hydroquinone or its isomers comprise one or more selected from the group consisting of hydroquinone, catechol, and resorcinol. Although the phase thereof is not limited, a liquid phase or a solid phase is preferably applied.

[17] The additive is preferably used at a concentration of from 1,000 to 1,500 ppm. In the case where the concentration of the additive falls within the above range, the preventive effect of the additive on the oxidation of the aromatic dialdehyde is highly exhibited.

[18] In addition, the present invention provides a method of stabilizing aromatic dialdehyde, which comprises adding an additive, selected from among hydroquinone and its isomers, to aromatic dialdehyde.

[19] As such, the step of adding the hydroquinone or its isomers may be performed in a sequence determined depending on need. For example, the hydroquinone or its isomers may be added in a step of preparing aromatic dialdehyde, may be added in a step of separating the aromatic dialdehyde in a liquid phase and purifying it, or may be added in a step of storing liquid aromatic dialdehyde after the purification.

[20] As described above, according to the present invention, liquid aromatic dialdehyde can be prevented from oxidizing due to oxygen in the air or heat to thus avoid the deterioration thereof. Further, upon the preparation or storage of aromatic dialdehyde, the alteration of aromatic dialdehyde is decreased, and thus the loss of aromatic dialdehyde can be prevented and the purity thereof can be maintained.

[21] Below, a better understanding of the present invention may be obtained through the following examples, which are set forth to illustrate, but are not to be construed as the limit of the present invention.

[22]

[23] Example 1

[24] 2,000 mg of pure terephthaldehyde (TPAL, Aldrich, 99%) and 20 mg of hydroquinone were added into a beaker, after which the beaker was placed in a silicone oil bath. While the bath was maintained at a temperature of 12O ⁰ C, it was allowed to stand in the air for 5 hours. As a result, some of the TPAL was sublimated, and most

thereof was maintained in a molten state. Thereafter, the molten TPAL was recovered and weighed, and the composition of the molten sample was analyzed using GC and LC. The results are shown in Table 1 below.

[25] [26] Comparative Example 1 [27] The present example was conducted in the same manner as in Example 1, with the exception that hydroquinone was not added.

[28] Table 1

[29] As is apparent from Table 1, in the case of Example 1, in which hydroquinone was used to prevent the oxidation of terephthaldehyde according to the present invention, the production of 4-carboxybenzaldehyde and terephthalic acid, which are oxides of terephthaldehyde, was drastically decreased, compared to Comparative Example 1, without the use of hydroquinone. Thereby, hydroquinone was observed to prevent the oxidation of aromatic dialdehyde. Industrial Applicability

[30] According to the present invention, liquid aromatic dialdehyde can be prevented from oxidizing, due either to oxygen in the air or to heat, to thus avoid the deterioration thereof. Further, when aromatic dialdehyde is prepared or stored, the alteration of

aromatic dialdehyde is decreased, therefore preventing the loss of aromatic dialdehyde and maintaining the purity thereof.

[31] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various variations and modifications are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.