Sulfonation of polyhydroxyaromatics
View Patent ↗The present invention provides improved process for the sulfonation of hydroxyaromatics amenable to direct isolation of the sulfonylated hydroxyaromatics in their free-acid forms. The process allows for the recyclization of sulfuric acid and minimizes waste. The starting materials are from a renewal resource, e.g., biomass, and contain detectable 14 C up to a 14 C content of 0.0000000001% (one part per trillion). The products made include sulfonated catechol, disulfonated pyrogallol and sulfonated protocatechuic acid.
1. A process for preparing a sulfonated hydroxyaromatic compound of formula I:
wherein: X is H or Na; R 1 is SO 3 H, SO 3 Na, CO 2 H, or CO 2 Na; and R 2 is H or OH;
said process comprising: reacting a compound of formula II derived from biomass:
wherein: R 1 is H or CO 2 H; and R 2 is H or OH; with concentrated sulfuric acid at a temperature from room temperature to about 120° C. to form the sulfonated hydroxyaromatic compound of Formula I; and separating the sulfonated hydroxyaromatic compound therefrom based on precipitation of the free acid of the sulfonated hydroxyaromatic compound.
2. The process of claim 1 wherein the reacting step is performed under a N 2 atmosphere.
3. The process of claim 1 wherein the separating step is performed in the presence of a solvent.
4. The process of claim 1 wherein in Formula I R 1 is SO 3 Na and R 2 is H, and the sulfonated hydroxyaromatic compound is sulfonated catechol; and wherein in Formula II R 1 and R 2 are both H, and the compound of Formula II is catechol.
5. The process of claim 1 wherein in Formula I R 1 is SO 3 Na and R 2 is OH, and the sulfonated hydroxyaromatic compound is disulfonated pyrogallol; and wherein in Formula II R 1 is H and R 2 is OH, and the compound of Formula II is pyrogallol.
6. The process of claim 1 wherein in Formula I R 1 is CO 2 Na and R 2 is H, and the sulfonated hydroxyaromatic compound is sulfonated protocatechuic acid; and wherein in Formula II R 1 is CO 2 H and R 2 is H, and the compound of Formula II is protocatechuic acid.
7. The process of claim 1 wherein the compound of Formula II is derived from biomass-derived renewable carbon atoms by fermentation methods.
8. A sulfonated hydroxyaromatic compound of formula I:
wherein: X is H or Na; R 1 is SO 3 H, SO 3 Na, CO 2 H, or CO 2 Na; and R 2 is H or OH;
and wherein all carbon atoms of said sulfonated hydroxyaromatic compound are derived from biomass.
9. The sulfonated hydroxyaromatic compound of claim 8 wherein X is H, R 1 is CO 2 H and R 2 is H, and the sulfonated hydroxyaromatic compound is 3,4-dihydroxy-5-sulfobenzoic acid.
10. A process for preparing a sulfonated hydroxyaromatic compound of formula I:
wherein: X is H or Na; R 1 is SO 3 H, SO 3 Na, CO 2 H, or CO 2 Na; and R 2 is H or OH;
said process comprising:
providing a compound of formula II derived from biomass:
wherein R 1 is H or CO 2 H, and R 2 is H or OH; and
reacting the compound of formula II with concentrated sulfuric acid at a temperature from room temperature to about 120° C. to form the sulfonated hydroxyaromatic compound of Formula I.
11. The process of claim 10 further comprising precipitating a free acid of said sulfonated hydroxyaromatic compound.
12. The process of claim 11 wherein the precipitating step is performed in the presence of a solvent.
13. The process of claim 10 wherein the reacting step is performed under a N 2 atmosphere.
14. The process of claim 10 wherein the sulfonated hydroxyaromatic compound of Formula I is sulfonated catechol; and the compound of Formula II is catechol.
15. The process of claim 10 the sulfonated hydroxyaromatic compound of Formula I is disulfonated pyrogallol; and the compound of Formula II is pyrogallol.
16. The process of claim 10 wherein the sulfonated hydroxyaromatic compound is sulfonated protocatechuic acid; and the compound of Formula II is protocatechuic acid.
17. The process of claim 1 wherein the compound of Formula II contains carbon atoms derived from biomass by fermentation.