Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1988-09-28
1989-11-28
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C07C 6976
Patent
active
048839027
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method of producing tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxymethyl]-methane [hereinafter sometimes referred to as "compound (I)"], which is in wide use as an antioxidant for polyolefins, among others.
DESCRIPTION OF THE PRIOR ART
It is known that the compound (I) can be produced by subjecting pentaerythritol and a 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid alkyl ester [hereinafter sometimes referred to as "compound (II)"] to ester exchange in the presence of a catalyst such as an alkali metal lower alkoxide, wherein the compound (II) is used in an at least stoichiometric amount relative to pentaerythritol, namely in an amount of at least 4 moles per mole of pentaerythritol (Japanese Patent Publication No. 19083/1967).
As described in the above-cited patent specification, a product in which the hydroxyl groups of pentaerythritol have not been fully substituted, namely a tri-substituted pentaerythritol derivative of the formula ##STR1## [hereinafter sometimes referred to as "byproduct"] is formed as a byproduct and contaminates the product compound (I) when this is produced by the above-mentioned method.
Formation of the impurity (III) as a byproduct naturally leads to decreased yields of the desired compound (I). Furthermore, the present inventors found that the byproduct (III) is difficult to separate from the compound (I) by ordinary recrystallization procedures, hence the purity of the product cannot be improved by conventional methods. Accordingly, it is very desirable from the industrial viewpoint if the formation of the byproduct (III) could be inhibited.
In the above-cited patent specification, it is suggested that the formation of the byproduct (III) might be controlled when the compound (II) is used in an at most 15% excess relative to the stoichiometrically required amount, namely in an amount of at most 4.6 moles per mole of pentaerythritol. Based on this suggestion, the present inventors detailedly investigated the relation possibly existing between the mole ratio of the compound (II) to pentaerythritol and the formation of the byproduct (III) and found that the yield of the byproduct (III) can be suppressed to about 10%, preferably 5% or less on the pentaerythritol basis when the compound (II) is used in an amount of 4.6 moles per mole of pentaerythritol. In that case, the subsequent purification step can give the desired product (I) in a form substantially free from the byproduct (III), but that portion of the relatively expensive compound (II) which remains unreacted necessarily means a loss, which leads to an increase in the cost of manufacturing the desired product.
DISCLOSURE OF THE INVENTION
The present inventors made intensive investigations in an attempt to solve the above problems and provide a method of producing the desired product (I) in a highly pure form and in good yields using the compound (II) and pentaerythritol as the starting materials by without using a excessively large amount of the compound (II), which is expensive, while controling the formation of the byproduct (III) to a minimum level. As a result, they have now completed the present invention.
The present inventors surprisingly found that when the ester exchange reaction between the compound (II) and pentaerythritol is carried out in the presence, in the reaction system, of 0.05-1.5% by weight of bis[2,2,2-tris(hydroxymethyl)ethoxy]methane (hereinafter sometimes referred to as "methylenebispentaerythritol") which is represented by the formula ##STR2## the formation of the byproduct (III) can be made minimal and the desired product (I) can be obtained in good yields.
Thus the invention provides a method of producing tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxymethyl]methane which comprises carrying out the ester exchange reaction between the propionic acid alkyl ester (II) and pentaerythritol in the presence of a basic catalyst and in the presence of bis[2,2,2-tris(hydroxymethyl)ethoxy]methane.
In accordance with the inv
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Gohbayashi Masayoshi
Maruno Makoto
Narita Noritsugu
Killos Paul J.
Yoshitomi Pharmaceutical Industries Ltd.
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