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US 4,309,564 AGranted
Methods for preparing eutectic mixtures of p-hydroxybenzoic acid esters
AssigneeMallinckrodt Inc.
InventorsDonald F. Loncrini, John J. Taylor
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AssigneeMallinckrodt Inc.
InventorsDonald F. Loncrini, John J. Taylor
Estimating the term…
Novel methods of forming in situ eutectic mixtures of three or more lower alkyl esters of p-hydroxybenzoic acid are disclosed which avoid the prior art methods of forming the respective esters independently and blending them, for example, by melting. Such eutectic mixtures may be formed in situ by first reacting a p-hydroxybenzoic acid and a lower alkanol in the presence of an esterification catalyst to form a first lower alkyl ester of p-hydroxybenzoic acid, reacting the resulting mixture with two or more lower alkanols under heat to form a mixture of three or more lower alkyl esters of p-hydroxybenzoic acid, quenching the reaction when the ratio of the respective lower alkyl esters of p-hydroxybenzoic acid to each other is such that the mixture thereof is liquid at room temperature and isolating the resulting eutectic mixture. Other methods of preparing such eutectic mixtures in situ are also disclosed.
The method of forming in situ eutectic mixtures of three or more lower alkyl esters of p-hydroxybenzoic acid which comprises reacting p-hydroxybenzoic acid and a lower alkanol in the presence of an esterification catalyst to form a first lower alkyl ester of p-hydroxybenzoic acid, reacting the resulting mixture with two or more lower alkanols under heat to form a mixture of three or more lower alkyl esters of p-hydroxybenzoic acid, quenching the reaction when the ratio of the respective lower alkyl esters of p-hydroxybenzoic acid to each other is such that the mixture thereof is liquid at room temperature and isolating the resulting eutectic mixture.
The method of forming in situ eutectic mixtures of isopropyl p-hydroxybenzoate, isobutyl p-hydroxybenzoate and n-butyl p-hydroxybenzoate in a ratio between approximately 1:1:1 and 4:2:2, respectively, which comprises reacting p-hydroxybenzoic acid and isopropyl alcohol in the presence of an esterification catalyst to form isopropyl p-hydroxybenzoate, reacting the resulting mixture with isobutyl alcohol and n-butyl alcohol under heat, quenching the reaction when the ratio of isopropyl p-hydroxybenzoate to isobutyl p-hydroxybenzoate to n-butyl p-hydroxybenzoate is within the range between approximately 1:1:1 and 4:2:2 and isolating the resulting eutectic mixture.
The method of forming in situ eutectic mixtures of three or more lower alkyl esters of p-hydroxybenzoic acid which comprises reacting p-hydroxybenzoic acid and three or more lower alkanols in the presence of an esterification catalyst to form a mixture of three or more lower alkyl esters of p-hydroxybenzoic acid, quenching the reaction when the ratio of the respective lower alkyl esters of p-hydroxybenzoic acid to each other is such that the mixture thereof is liquid at room temperature and isolating the resulting eutectic mixture.
The method of forming in situ eutectic mixtures of isopropyl p-hydroxybenzoate, isobutyl p-hydroxybenzoate and n-butyl p-hydroxybenzoate in a ratio between approximately 1:1:1 and 4:2:2, respectively, which comprises reacting p-hydroxybenzoic acid, isopropyl alcohol, isobutyl alcohol and n-butyl alcohol in the presence of an esterification catalyst, quenching the reaction when the ratio of isopropyl p-hydroxybenzoate to isobutyl p-hydroxybenzoate to n-butyl p-hydroxybenzoate is within the range between approximately 1:1:1 and 4:2:2 and isolating the resulting eutectic mixture.
The method of forming in situ eutectic mixtures of three or more lower alkyl esters of p-hydroxybenzoic acid which comprises reacting a lower alkyl ester of p-hydroxybenzoic acid with three or more lower alkanols in the presence of an esterification catalyst to form a mixture of three or more lower alkyl esters of p-hydroxybenzoic acid derived from said lower alkanols, quenching the reaction when the ratio of the respective lower alkyl esters of p-hydroxybenzoic acid to each other is such that the mixture thereof is liquid at room temperature and isolating the resulting eutectic mixture.
The method of forming in situ eutectic mixtures of isopropyl p-hydroxybenzoate, isobutyl p-hydroxybenzoate and n-butyl p-hydroxybenzoate in a ratio between approximately 1:1:1 and 4:2:2, respectively, which comprises reacting methyl p-hydroxybenzoate with isopropyl alcohol, isobutyl alcohol and n-butyl alcohol in the presence of an esterification catalyst, quenching the reaction when the ratio of isopropyl p-hydroxybenzoate to isobutyl p-hydroxybenzoate to n-butyl p-hydroxybenzoate is within the range between approximately 1:1:1 and 4:2:2 and isolating the resulting eutectic mixture.
Dependencies are inferred from the claim text.