Method for preparation of salts of hydroxy-substituted aromatic compounds
View Patent ↗A method for preparing a metal salt of a hydroxy-substituted aromatic compound is described. The method comprises contacting in an aqueous medium at least one hydroxy-substituted aromatic compound with a base comprising a metal cation to provide a mixture comprising water and a metal salt of said hydroxy-substituted aromatic compound. The aqueous metal salt is then contacted with a substantially water-immiscible solvent at a temperature greater than the boiling point of water at the prevailing pressure to provide a slurry comprising the metal salt of the hydroxy-substituted aromatic compound and a vapor stream comprising the water-immiscible solvent and water. The components of the vapor stream are separated using a vapor handling system comprising a partial reflux condenser to provide a water-rich component and a water immiscible solvent-rich component.
1. A method for preparing a metal salt of a hydroxy-substituted aromatic compound, said method comprising steps (a)-(d):
(a) contacting in an aqueous medium at least one hydroxy-substituted aromatic compound with a base comprising a metal cation to provide a mixture comprising water and a metal salt of said hydroxy-substituted aromatic compound;
(b) contacting the mixture formed in step (a) with a substantially water-immiscible solvent at a temperature greater than the boiling point of water at the prevailing pressure to provide a slurry comprising the metal salt of the hydroxy-substituted aromatic compound and the water immiscible solvent, and a vapor stream comprising the substantially water-immiscible solvent and water;
(c) introducing the vapor stream into a vapor handling system comprising a partial reflux condenser; and
(d) separating the vapor stream to provide a water-rich component and a water immiscible solvent-rich component.
2. The method of claim 1 , wherein the contacting in step (b) is achieved by spraying the mixture formed in step (a) into the substantially water-immiscible solvent.
3. The method of claim 1 , wherein the hydroxy-substituted aromatic compound is selected from the group consisting of monohydroxy-substituted aromatic compounds; dihydroxy-substituted aromatic compounds; trihydroxy-substituted aromatic compounds; tetrahydroxy-substituted aromatic compounds, and mixtures thereof.
4. The method of claim 1 wherein the hydroxy-substituted aromatic compound is at least one dihydroxy-substituted aromatic compound having formula I
wherein R l is independently at each occurrence a halogen, a C 1 -C 30 aliphatic radical, a C 3 -C 30 cycloaliphatic radical, or a C 3 -C 30 aromatic radical, R 2 and R 3 are independently hydrogen, a C 1 -C 30 aliphatic radical, a C 3 -C 30 cycloaliphatic radical, a C 3 -C 30 aromatic radical, or R 2 and R 3 together form a C 3 -C 20 cycloaliphatic radical, and “n” is an integer having a value 0 to 4.
5. The method of claim 1 wherein the hydroxy-substituted aromatic compound is at least one dihydroxy-substituted aromatic compound having formula II
wherein R 4 and R 5 are independently at each occurrence halogen, a C 1 -C 30 aliphatic radical, a C 3 -C 30 cycloaliphatic radical, or a C 3 -C 30 aromatic radical, and “m” is an integer having a value 0 to 4.
6. The method of claim 1 wherein the hydroxy-substituted aromatic compound is selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane (bisphenol-A) and 4,4′-dihydroxybiphenyl.
7. The method of claim 1 wherein said vapor stream comprises vapors of the water-immiscible solvent in an amount corresponding to about 3 kg per kg water vapor to about 50 kg per kg water vapor.
8. The method of claim 1 , wherein water-rich component comprises less than about 50 percent by weight of the water-immiscible solvent.
9. The method of claim 8 , wherein water-rich component comprises less than about 30 percent by weight of the water-immiscible solvent.
10. The method of claim 1 wherein the metal cation is sodium.
11. The method of claim 1 wherein the base and the hydroxy-substituted aromatic compound are present in amounts corresponding to a molar ratio of base to hydroxy-substituted aromatic compound which deviates from ideal stoichiometry by no more than 0.4 mole %.
12. The method of claim 1 wherein the water-immiscible solvent comprises at least one solvent having formula III
wherein R 6 is independently at each occurrence a halogen, a C 1 -C 6 aliphatic radical, or a C 3 -C 12 aromatic radical; and “t” is an integer having a value 1-6.
13. The method of claim 12 wherein the water-immiscible solvent is selected from the group consisting of toluene, xylene, phenetole, anisole, veratrole, diphenylsulfone, chlorobenzene, bromobenzene, ortho-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, and 1,2,4-trichlorobenzene.
14. The method of claim 1 wherein the water-immiscible solvent is selected from the group consisting of toluene, ortho-dichlorobenzene, and mixtures thereof.
15. The method of claim 1 wherein the contacting in step (b) is carried out at a temperature in a range from about 75° C. to about 220° C.
16. The method of claim 1 further comprising filtering said slurry comprising the metal salt of the hydroxy-substituted aromatic compound and the water immiscible solvent to provide a solid alkali metal salt of the hydroxy-substituted aromatic compound.
17. The method of claim 1 wherein the metal salt comprises less than 25% of particles with a diameter of greater than about 200 microns.
18. A method for preparing an alkali metal salt of a hydroxy-substituted aromatic compound of formula IV, said method comprising steps (a)-(d):
(a) contacting in an aqueous medium the hydroxy-substituted aromatic compound of formula IV with a base comprising an alkali metal cation to provide a mixture comprising water and an alkali metal salt of said hydroxy-substituted aromatic compound of formula IV;
(b) contacting the mixture formed in step (a) with a substantially water-immiscible solvent at a temperature greater than the boiling point of water at the prevailing pressure to provide a slurry comprising the alkali metal salt of the hydroxy-substituted aromatic compound of formula IV and the water immiscible solvent, and a vapor stream comprising the substantially water-immiscible solvent and water;
(c) introducing the vapor stream into a vapor handling system comprising a partial reflux condenser; and
(d) separating the vapor stream to provide a water-rich component and a water immiscible solvent-rich component.
19. A method for preparing an alkali metal salt of a hydroxy-substituted aromatic compound of formula V, said method comprising steps (a)-(d):
(a) contacting in an aqueous medium the hydroxy-substituted aromatic compound of formula V with a base comprising an alkali metal cation to provide a mixture comprising water and an alkali metal salt of said hydroxy-substituted aromatic compound of formula V;
(b) contacting the mixture formed in step (a) with a substantially water-immiscible solvent at a temperature greater than the boiling point of water at the prevailing pressure to provide a slurry comprising the alkali metal salt of the hydroxy-substituted aromatic compound of formula V and the water immiscible solvent, and a vapor stream comprising the substantially water-immiscible solvent and water;
(c) introducing the vapor stream into a vapor handling system comprising a partial reflux condenser; and
(d) separating the vapor stream to provide a water-rich component and a water immiscible solvent-rich component.
20. A method for preparing a metal salt of hydroxyl-substituted aromatic compound, said method comprising steps (a)-(d):
(a) contacting in an aqueous medium at least one hydroxyl-substituted aromatic compound with a base comprising a metal cation to provide a mixture comprising water and a metal salt of said hydroxyl-substituted aromatic compound;
(b) contacting the mixture formed in step (a) with a substantially water-immiscible solvent at a temperature greater than the boiling point of water at the prevailing pressure to provide a slurry comprising the metal salt of the hydroxyl-substituted aromatic compound and the water immiscible solvent, and a vapor stream comprising the substantially water-immiscible solvent and water;
(c) introducing the vapor steam into a vapor handling system comprising a partial reflux condenser; and
(d) separating the vapor stream to provide a water-rich component and a water immiscible solvent-rich component;
wherein the process is practiced without a co-solvent.