Synthesis of novel ionic liquids from lignin-derived compounds
Methods and compositions are provided for synthesizing ionic liquids from lignin derived compounds comprising: contacting a starting material comprising lignin with a depolymerization agent to depolymerize the lignin and form a mixture of aldehyde containing compounds; contacting the mixture of aldehyde containing compounds with an amine under conditions suitable to convert the mixture of aldehyde containing compounds to a mixture of amine containing compounds; and contacting the mixture of amine containing compounds with an acid under conditions suitable to form an ammonium salt, thereby preparing the ionic liquid.
1. A method for preparing an ionic liquid comprising:
contacting a starting material comprising lignin with a depolymerization agent to depolymerize the lignin and form a mixture of aldehyde containing compounds;
contacting the mixture of aldehyde containing compounds with an amine under conditions suitable to convert the mixture of aldehyde containing compounds to a mixture of amine containing compounds; and
contacting the mixture of amine containing compounds with an acid under conditions suitable to form an ammonium salt, thereby preparing the ionic liquid, wherein:
the ionic liquid comprises at least one compound of the following formula:
wherein each of the R groups of the nitrogen is independently selected from the group consisting of H, CH 3 , and CH 2 CH 3 ;
at least two of the R groups of the nitrogen are independently selected from the group consisting of CH 3 , and CH 2 CH 3 ;
R′, R″, and R′″ are independently selected from the group consisting of H, OH, and OCH 3 ;
R 4 is selected from the group consisting of H, OH, and CH 2 OH; and
X comprises an acid anion.
2. The method of claim 1 , wherein the step of contacting the starting material with a depolymerization agent comprises contacting the starting material with one or more compositions selected from the group consisting of an ionic liquid; hydrogen gas; a hydrogen donating agent selected from the group consisting of tetralin, sodium formate and formic acid; a dilute acid; a concentrated acid; a base; a catalyst and an oxidizing agent selected from the group consisting of nitrobenzene, metal oxides, hydrogen peroxide, and oxygen gas; Fenton's reagent; metal organic frameworks of copper or iron; and ammonium hydroxide.
3. The method of claim 2 , wherein the depolymerization agent comprises a lignin-derived ionic liquid.
4. The method of claim 2 , wherein the depolymerization agent comprises an imidazolium ionic liquid.
5. The method of claim 1 , wherein the step of contacting the mixture of aldehyde containing compounds with an amine is performed under reducing conditions.
6. The method of claim 5 , wherein the reducing conditions comprise an amine, a Brønsted acid; and a hydride donating reducing agent.
7. The method of claim 6 , wherein the amine is selected from the group consisting of a cyclic amine, an acyclic amine, a monoamine, and a dialkylamine.
8. The method of claim 6 , wherein the Brønsted acid is selected from the group consisting of formic acid, acetic acid, proprionic acid, and an aromatic carboxylic acid.
9. The method of claim 6 , wherein the reducing agent is selected from the group consisting of sodium triacetoxyborohydride, sodium cyanoborohydride, sodium borohydride-trifluoroacetic acid, hydrogen gas and a catalyst, and polymethylhydrosiloxane (PMHS).
10. The method of claim 1 , wherein the step of contacting the mixture of amine containing compounds with an acid under conditions suitable to form an amine salt comprises a salt metathesis reaction, wherein the conditions of the salt metathesis reaction comprise acid in a polar solvent.
11. The method of claim 10 , wherein the acid is a mineral acid selected from the group consisting of sulfuric and phosphoric acid.
12. The method of claim 1 , wherein the contacting steps are performed in a single reaction vessel.