Electro‐Organic Reactions: XXX . Cleavage and Coupling of Some Biomass‐Derived Organic Compounds

Abstract

The oxalate cathodic cleavage reaction has been applied to several biomass‐derived organic substrates. Furfuryl alcohols and hydrofuroin undergo the expected deoxygenation reactions, but butane‐2,3‐diol is only deoxygenated by prior conversion into butane‐2,3‐dimethanesulfonate. The one‐pot cathodic conversion of furfural into hydrofuroin, and thence into 1,2‐difurylethene is described.

Strategies to Control Electrochemical Hydrogenation and Hydrogenolysis of Furfural and Minimize Undesired Side Reactions

“…2-Methylfuran (MF) has significant potential use in the future as a high-energy-density biofuel . Hydrofuroin is produced via dimerization of FF and is another value-added product used for further chemical reactions. , …”

Electroorganic reactions. Part 58. Revisiting the cleavage of oxalate ester radical-anions

“…2,3,4 This is difficult to achieve by direct reduction of alcohols because very negative potentials are required 5 and in any event the hydroxyl anion is a poor leaving group. Derivatives such as tosylates 6 , methanesulfonates 7 , diethylphosphates 8 , and acetates 9 are more easily cleaved by cathodic reduction but only at very negative potentials.…”

“…Conversion of hydroxyl into oxalate esters (R 1 OOC.COOR 2 ) was found greatly to reduce the reduction potential and for benzylic or allylic alcohols and vicinal diols cathodic cleavage, in aprotic solvent, of the R-O function took place. 2,3,4 In these cases electron transfer is to the central dicarbonyl function so the oxalate group acts as both electrophore and leaving group. In practice competing hydrolysis by adventitious water in the basic conditions of electrolysis precluded preparative-scale electrolysis of preformed esters.…”

“…However, in situ formation by transesterification during co-electrolysis of benzylic or allylic alcohols and diethyl oxalate led to † For Part 57 see reference 1 efficient 1F cleavage of hydroxyl in the added alcohol. 3,4 Coulometry, qualitative cyclic voltammetry and product studies were best explained 2 in terms of the initially formed radicalanions cleaved to radical (R ). In this context we report here on the direct observation by cyclic voltammetry of several relevant radical-anions and the measurement of their rates of cleavage and of substituent effects on the same.…”

“…This mixture was refluxed for 12 hours under nitrogen. The precipitate of pyridinium hydrochloride was filtered off and the organic layer washed with sodium bicarbonate (NaHCO 3 ) and then dried over MgSO 4 …”