Process for producing aromatic carbonates

Details Process for producing aromatic carbonates Process for producing aromatic carbonates

1999-12-15

2001-07-17

Boykin, Terressa M. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C528S196000, C528S198000

Reexamination Certificate

active

06262210

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to a process for producing aromatic carbonates. More particularly, the present invention is concerned with a process for producing aromatic carbonates, which comprises transesterifying, in the presence of a metal-containing catalyst, a starting material selected from the group consisting of a dialkyl carbonate, an alkyl aryl carbonate and a mixture thereof with a reactant selected from the group consisting of an aromatic monohydroxy compound, an alkyl aryl carbonate and a mixture thereof, characterized in that:
at least one type of catalyst-containing liquid is taken out,
the catalyst-containing liquid being selected from the group consisting of:
a portion of a high boiling point reaction mixture obtained by the above transesterification and containing the desired aromatic carbonate and the metal-containing catalyst, and
a portion of a liquid catalyst fraction obtained by separating the desired aromatic carbonate from the high boiling point reaction mixture,
each portion containing (A) high boiling point substance having a boiling point higher than the boiling point of the produced aromatic carbonate and containing (B) the metal-containing catalyst;
(C) a functional substance capable of reacting with at least one component selected from the group consisting of the high boiling point substance (A) and the metal-containing catalyst (B) is added to the taken-out catalyst-containing liquid, to thereby obtain at least one reaction product selected from the group consisting of an (A)/(C) reaction product and a (B)/(C) reaction product; and
the (B)/(C) reaction product is recycled to the reaction system, while withdrawing the (A)/(C) reaction product.
According to the process of the present invention, disadvantageous phenomena, such as the accumulation of the high boiling point substance (A) in the reaction system which causes the discoloration of an ultimate aromatic polycarbonate (which is produced from an aromatic carbonate), can be prevented without withdrawing the catalyst from the reaction system so that the desired aromatic carbonates having high purity can be produced stably for a prolonged period of time.
2. Prior Art
An aromatic carbonate is useful as a raw material for, e.g., the production of an aromatic polycarbonate (whose utility as engineering plastics has been increasing in recent years) without using poisonous phosgene. With respect to the method for the production of an aromatic carbonate, a method for producing an aromatic carbonate or an aromatic carbonate mixture is known, in which a dialkyl carbonate, an alkyl aryl carbonate or a mixture thereof is used as a starting material and an aromatic monohydroxy compound, an alkyl aryl carbonate or a mixture thereof is used as a reactant, and in which a transesterification reaction is performed between the starting material and the reactant.
However, since this type of transesterification is a reversible reaction in which, moreover, not only is the equilibrium biased toward the original system but the reaction rate is also low, the production of an aromatic carbonate by the above-mentioned method on an industrial scale is accompanied with great difficulties.
To improve the above-mentioned method, several proposals have been made, most of which relate to the development of a catalyst for increasing the reaction rate. As a catalyst for use in the method for producing an alkyl aryl carbonate, a diaryl carbonate or a mixture thereof by reacting a dialkyl carbonate with an aromatic hydroxy compound, there have been proposed various metal-containing catalysts, which include for example, a Lewis acid, such as a transition metal halide, or compounds capable of forming a Lewis acid, [see Unexamined Japanese Patent Application Laid-Open Specification No. 51-105032, Unexamined Japanese Patent Application Laid-Open Specification No. 56-123948 and Unexamined Japanese Patent Application Laid-Open Specification No. 56-123949 (corresponding to West German Patent Application Publication No. 2528412, British Patent No. 1499530 and U.S. Pat. No. 4,182,726)], a tin compound, such as an organotin alkoxide or an organotin oxide [Unexamined Japanese Patent Application Laid-Open Specification No. 54-48733 (corresponding to West German Patent Application Publication No. 2736062), Unexamined Japanese Patent Application Laid-Open Specification No. 54-63023, Unexamined Japanese Patent Application Laid-Open Specification No. 60-169444 (corresponding to U.S. Pat. No. 4,554,110 and West German Patent Application Publication No. 3445552), Unexamined Japanese Patent Application Laid-Open Specification No. 60-169445 (corresponding to U.S. Pat. No. 4,552,704 and West German Patent Application Publication No. 3445555), Unexamined Japanese Patent Application Laid-Open Specification No. 62-277345, and Unexamined Japanese Patent Application Laid-Open Specification No. 1-265063 (corresponding to European Patent Publication No. 338760 and U.S. Pat. No. 5,034,557)], salts and alkoxides of an alkali metal or an alkaline earth metal (Unexamined Japanese Patent Application Laid-Open Specification No. 56-25138), lead compounds (Unexamined Japanese Patent Application Laid- Open Specification No. 57-176932), complexes of a metal, such as copper, iron or zirconium (Unexamined Japanese Patent Application Laid-Open Specification No. 57-183745), titanic acid esters [Unexamined Japanese Patent Application Laid-Open Specification No. 58-185536 (corresponding to U.S. Pat. No. 4,410,464 and West German Patent Application Publication No. 3308921)], a mixture of a Lewis acid and protonic acid [Unexamined Japanese Patent Application Laid-Open Specification No. 60-173016 (corresponding to U.S. Pat. No. 4,609,501 and West German Patent Application Publication No. 3445553)], a compound of Sc, Mo, Mn, Bi, Te or the like [Unexamined Japanese Patent Application Laid-Open Specification No. 1-265064 (corresponding to European Patent Publication No. 0 338 760 A1 and U.S. Pat. No. 5,034,557)], and ferric acetate (Unexamined Japanese Patent Application Laid-Open Specification No. 61-172852).
As a catalyst for use in the method for producing a diaryl carbonate by a same-species intermolecular transesterification, wherein an alkyl aryl carbonate is disproportionated to a dialkyl carbonate and a diaryl carbonate, there have been proposed various catalysts, which include for example, a Lewis acid and a transition metal compound which is capable of forming a Lewis acid [see Unexamined Japanese Patent Application Laid-Open Specification No. 51-75044 (corresponding to West German Patent Application Publication No. 2552907 and U.S. Pat. No. 4,045,464)], a polymeric tin compound [Unexamined Japanese Patent Application Laid-Open Specification No. 60-169444 (corresponding to U.S. Pat. No. 4,554,110 and West German Patent Application Publication No. 3445552)], a compound represented by the formula R—X(=O)OH (wherein X is selected from Sn and Ti, and R is selected from monovalent hydrocarbon residues) [Unexamined Japanese Patent Application Laid-Open Specification No. 60-169445 (corresponding to U.S. Pat. No. 4,552,704 and West German Patent Application Publication No. 3445555)], a mixture of a Lewis acid and protonic acid [Unexamined Japanese Patent Application Laid-Open Specification No. 60-173016 (corresponding to U.S. Pat. No. 4,609,501 and West German Patent Application Publication No. 3445553)], a lead catalyst [Unexamined Japanese Patent Application Laid-Open Specification No. 1-93560 (corresponding to U.S. Pat. No. 5,166,393)], a titanium or zirconium compound (Unexamined Japanese Patent Application Laid-Open Specification No. 1-265062), a tin compound [Unexamined Japanese Patent Application Laid-Open Specification No. 1-265063 (corresponding to U.S. Pat. No. 5,034,557 and European Patent Publication No. 0 338 760)], and a compound of Sc, Mo, Mn, Bi, Te or the like [Unexamined Japanese Pate

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