Method of producing carbonic acid diester

Details Method of producing carbonic acid diester Method of producing carbonic acid diester

1992-05-22

1994-03-08

Lee, Mary C.

Organic compounds -- part of the class 532-570 series

Organic compounds

Carbonate esters

558260, 558277, C07C 6996

Patent

active

052929167

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
The present invention relates to a method of producing a carbonic acid diester.
More particularly, the present invention relates to a process of producing a carbonic acid diester selectively and stably from carbon monoxide and a nitrous acid ester.
the carbonic acid diester is very useful as a starting material of medicines and pesticides, and as an intermediate compound of a polycarbonate and urethane.
2. Background Art
A conventional method of producing a carbonic acid diester by a reaction of phosgene with an alcohol has been practiced for a long time. Nevertheless, this conventional method is disadvantageous in that phosgene has an extremely strong toxicity, and the reaction of phosgene with an alcohol produces hydrochloric acid as a by-product, which corrodes the reaction device. Therefore, there is a strong demand for a new method of producing a carbonic acid diester without using phosgene.
In response to this demand, various attempts have been made to produce a carbonic acid diester from an alcohol and carbon monoxide, (as disclosed in, for example, Japanese Unexamined Patent Publication (JP-A) No. 60-75,447, 63-72,650, and 63-38,010, and PCT-Publication No. WO-87/7601). In those methods, the carbonic acid diester is produced by a catalytic oxygen-oxidizing reaction of carbon monoxide with an alcohol in a liquid phase, in the presence of a catalyst consisting of a copper halide or palladium halide. These methods are disadvantageous in that, in the catalytic oxygen-oxidizing reaction, carbon dioxide is produced as a by-product, and thus the production of the carbonic acid diester is effected with a low selectivity based on the amount of carbon monoxide supplied to the reaction system. Also, the catalytic oxygen-oxidizing reaction produces water (H.sub.2 O) as another by-product, and thus the resultant carbonic acid diester must be isolated from the water by a refining procedure. Also, the above-mentioned methods are further disadvantageous in that the aimed carbonic acid diester must be separated from the catalyst in the reaction system. Accordingly, the above-mentioned methods are not satisfactory for industrial use.
Attempts have been made to eliminate the above-mentioned disadvantages, and as one such attempt, JA-A-60-181,051 discloses a method of producing carbonic acid diester by a catalytic oxidizing reaction of a nitrous acid ester with carbon monoxide, in a gas phase, in the presence of a catalyst composed of a solid platinum group metal or compound thereof carried on a solid carrier and an oxidant in an amount of 10 molar % in terms of O.sub.2, per mole of carbon monoxide present in the reaction mixture.
In this method, however, although an oxidant, for example, oxgen, is added in the above-mentioned specific amount to the carbon monoxide, to inhibit a production of oxalic acid diester as a by-product, a certain amount of a by-product consisting of an oxalic acid diester is undesirably produced, and therefore, the selectivity of the aimed carbonic acid diester is low and the reaction rate is unsatisfactory. Further, the above-mentioned method is disadvantageous in that the proportion of nitrous acid ester in a reaction mixed gas comprising the nitrous acid ester, carbon monoxide, alcohol and oxygen is higher than an explosion (flammable) limit of the mixed gas, and thus this reaction mixed gas is not preferable in view of the safety of the procedure. Accordingly this method is not satisfactory for practical use.
As mentioned above, the conventional method of producing carbonic acid diester from a nitrous acid ester and carbon monoxide is disadvantageous in that the reaction rate of carbon monoxide with nitrous acid ester is unsatisfactorily low and the selectivity of the resultant carbon acid diester is low, and thus the resultant carbon acid diester must be recovered through complicated purifying procedures. Also, this method is further disadvantageous in that the nitrous acid ester must be employed in a higher content than the explosion limit of the reaction

REFERENCES:
patent: 5162563 (1992-11-01), Nishihira

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