Reductive dimerization of furfural via a continuous process

Abstract

Described herein are methods for the continuous preparation of 1,2-di(furan-2-yl)ethane-1,2-diol from furan-2-carbaldehyde. The methods can proceed chemically or electrochemically. In certain examples, the methods further comprise the application of a static mixer. The present methods produce 1,2-di(furan-2-yl)ethane-1,2-diol in greater yield, purity, chemoselectivity, and stereoselectivity than traditional batch methods.

1 .- 21 . (canceled) 
     
     
         22 . A continuous flow system for preparing 1,2-di(furan-2-yl)ethane-1,2-diol from furan-2-carbaldehyde. 
     
     
         23 . The continuous flow system of  claim 22 , wherein said system comprises:
 a first reactant stream comprising said furan-2-carbaldehyde;   a second reactant stream comprising a catalyst;   a solvent; and   a reactor column comprising a metal.   
     
     
         24 . The continuous flow system of  claim 23 , further comprising a coolant. 
     
     
         25 . The continuous flow system of  claim 23 , wherein said reactor column comprising a metal comprises a static mixer, wherein said metal is deposited on surfaces of said static mixer. 
     
     
         26 . The continuous flow system of  claim 23 , wherein said reactor column comprising a metal comprises a packed bed comprising said metal. 
     
     
         27 . The continuous flow system of  claim 23 , further comprising a column comprising an ion exchange material. 
     
     
         28 .- 40 . (canceled) 
     
     
         41 . An electrochemical continuous flow system for reductively dimerizing furan-2-carbaldehyde to prepare 1,2-di(furan-2-yl)ethane-1,2-diol. 
     
     
         42 . The electrochemical continuous flow system of  claim 41 , wherein said system comprises an electrolytic cell having an anode and a cathode in contact with an electrolytic medium. 
     
     
         43 . The electrochemical continuous flow system of  claim 42 , further comprising a static mixer. 
     
     
         44 . The electrochemical continuous flow system of  claim 43 , wherein said static mixer is said cathode. 
     
     
         45 .- 48 . (canceled) 
     
     
         49 . The continuous flow system of  claim 22 , further comprising stainless steel tubing. 
     
     
         50 . The continuous flow system of  claim 26 , wherein the packed bed comprises porous catalytic particles or beads. 
     
     
         51 . The continuous flow system of  claim 24 , wherein the coolant comprises ethylene or propylene glycol mixtures in water. 
     
     
         52 . The continuous flow system of  claim 24 , wherein the coolant comprises antifreeze. 
     
     
         53 . The continuous flow system of  claim 23 , wherein said metal is selected from the group consisting of Cu, Zn, Mn, Mg, Al, Ni, Pd, Rh, Ru, Co, and Pt. 
     
     
         54 . The continuous flow system of  claim 53 , wherein said metal is Zn. 
     
     
         55 . The continuous flow system of  claim 23 , wherein said solvent is selected from the group consisting of tetrahydrofuran, dichloromethane, toluene, acetonitrile, diethyl ether, methanol, and NN-dimethylformamide. 
     
     
         56 . The continuous flow system of  claim 27 , wherein said ion exchange material is polystyrene sulphonate. 
     
     
         57 . The continuous flow system of  claim 27 , wherein said ion exchange material is crosslinked. 
     
     
         58 . The electrochemical continuous flow system of  claim 42 , further comprising an annular tube reactor containing said electrolytic cell, wherein surfaces of said annular tube reactor are said anode.