Method for producing 3,5-di-tert-butyl-4-hydroxybenzoic acid
View Patent ↗The present invention provides a method for producing 3,5-di-tert-butyl-4-hydroxybenzoic acid comprising: (1) providing 2,6-di-tert-butylphenol which may contain up to 0.5% by weight of 3,3′,5,5′-tetra-tert-butyl-4,4′-dihydroxybiphenyl; (2) reacting a basic alkali metal compound with an excess amount of the 2,6-di-tert-butylphenol, which is in excess of the basic alkali metal compound, to give the alkali metal 2,6-di-tert-butylphenolate; and (3) reacting the alkali metal 2,6-di-tert-butylphenolate obtained in step (2) with carbon dioxide to give 3,5-di-tert-butyl-4-hydroxybenzoic acid. According to the method of the present invention, 3,5-di-tert-butyl-4-hydroxybenzoic acid can be obtained with high and stable yield.
1. A method for producing 3,5-di-tert-butyl-4-hydroxybenzoic acid comprising:
(1) providing 2,6-di-tert-butylphenol which may contain up to 0.5% by weight of 3,3′,5,5′-tetra-tert-butyl-4,4′-dihydroxybiphenyl;
(2) reacting sodium methoxide with an excess amount of the 2,6-di-tert-butylphenol, which is excess of sodium methoxide, to give sodium 2,6-di-tert-butylphenolate; and
(3) reacting the sodium 2,6-di-tert-butylphenolate obtained in step (2) with carbon dioxide to give 3,5-di-tert-butyl-4-hydroxybenzoic acid.
2. The method according to claim 1 , wherein step (1) comprises purifying 2,6-di-tert-butylphenol so that the 3,3′,5,5′-tetra-tert-butyl-4,4′-dihydroxybiphenyl content in 2,6-di-tert-butylphenol is no more than 0.5% by weight.
3. The method according to claim 1 , wherein the 3,3′,5,5′-tetra-tert-butyl-4,4′-dihydroxybiphenyl content in 2,6-di-tert-butylphenol is no more than 0.3% by weight.
4. The method according to claim 2 , wherein 2,6-di-tert-butylphenol is purified so that the 3,3′,5,5′-tetra-tert-butyl-4,4′-dihydroxybiphenyl content in 2,6-di-tert-butylphenol is no more than 0.3% by weight.
5. The method according to claim 1 , wherein in step (2) sodium methoxide and 2,6-di-tert-butylphenol are reacted at a temperature of 80–300° C. and at the same time alcohol, which is generated as byproduct, is distilled away from the reaction.
6. The method according to claim 1 , wherein the starting amount of 2,6-di-tert-butylphenol is 2–30 fold moles to sodium methoxide.
7. The method according to claim 2 , wherein 2,6-di-tert-butylphenol is subjected to distillation under reduced pressure at a temperature of 80–200° C.
8. A method for producing 3,5-di-tert-butyl-4-hydroxybenzoic acid comprising:
(a) reacting sodium methoxide with an excess amount of 2,6-di-tert-butylphenol, which is in excess of sodium methoxide, to give sodium 2,6-di-tert-butylphenolate;
(b) reacting the sodium 2,6-di-tert-butylphenolate obtained in step (a) with carbon dioxide to give 3,5-di-tert-butyl-4-hydroxybenzoic acid;
(c) collecting unreacted 2,6-di-tert-butylphenol from the reaction system after step (b);
(d) purifying 2,6-di-tert-butylphenol collected in step (c) so that the 3,3′,5,5′-tetra-tert-butyl-4,4′-dihydroxybiphenyl content in 2,6-di-tert-butylphenol is no more than 0.5% by weight; and
(e) conducting steps (a)–(d) repeatedly using the 2,6-di-tert-butylphenol purified in step (d) for step (a) of the next cycle.
9. The method according to claim 8 , wherein in step (d) 2,6-di-tert-butylphenol is purified so that the 3,3′,5,5′-tetra-tert-butyl-4,4′-dihydroxybiphenyl content in 2,6-di-tert-butylphenol is no more than 0.3% by weight.
10. The method according to claim 8 , wherein in step (a) sodium methoxide and 2,6-di-tert-butylphenol are reacted at a temperature of 80–300° C. and at the same time alcohol, which is generated as byproduct, is distilled away from the reaction.
11. The method according to claim 8 , wherein the starting amount of 2,6-di-tert-butylphenol is 2–30 fold moles to sodium methoxide.
12. The method according to claim 8 , wherein in step (d) 2,6-di-tert-butylphenol is subjected to distillation under reduced pressure at a temperature of 80–200° C.
13. The method according to claim 8 , wherein the steps (a)–(d) are repeatedly conducted no less than five times.