Furfurylidene acetone monomer

Furfural reacts with ketones to form strong, crosslinked resins of technical interest in the former Soviet Union the U.S. Air Force has also shown some interest (42,43). The so-called furfurylidene acetone monomer, a mixture of 2-furfurylidene methyl ketone [623-15-4] (1 )> bis-(2-furfurylidene) ketone [886-77-1] (14), mesityl oxide, and other oligomers, is obtained by condensation of furfural and acetone under basic conditions (44,45). Treatment of the "monomer" with an acidic catalyst leads initially to polymer of low molecular weight and ultimately to cross-linked, black, insoluble, heat-resistant resin (46). 

The well-known condensation between 2-furaldehyde and acetone in a basic medium yields what is usually called furfurylidene acetone monomer composed of a mixture of 2-furfurylidene methyl ketone, di-2-furfurylidene ketone, mesityl oxide and other oligomers derived from further condensation reactions135. This mixture is then polymerized by the action of an acidic catalyst in the first phase of the reaction a polymer of low molecular weight is produced which on further treatment cross-links to a black insoluble and heat-resistant material136. ... 

Furfural-ketone copolymers have found commercial use, particularly in the Soviet Union, in applications ranging from floor coverings, anti-corrosion coatings, wood adhesives, and binders for carbon/graphite. When an alkaline catalyst is used, furfural is known to react with acetone to form the so-called furfurylidene acetone monomer, a mixture of 2-furfurylidene methylketone (6), bis(2-furfurylidene) ketone (7), mesityl oxide, and other oligomers. 

A plugging material with 2-furaldehyde-acetone monomer and silicone oligomers has been described [1099]. The components for this material are shown in Table 18-1. The 2-furaldehyde-acetone monomer can contain mono-furfurylidene-acetone and difurfurylidene-acetone. The hardener can be iron chloride, benzene-sulfonic acid, hexamethylene diamine, or polyethylene polyamine. The plugging stone has improved strength, elastic-deformation, and anticorrosion and adhesion properties. 

Furanic black resins arising from furfural, furfuryl alcohol and furfurylidene acetone 3a are characterized by highly conjugated structures (6-8) their inhibiting power as radical scavengers was tested and turned out to be extremely nigh even in heterogeneous conditions, e.g. with the resin suspended in a monomer solution. 

Whereas the cationic polymerization of furfurylidene acetone 3a engenders crosslinked structures (25), the use of anionic initiators results in linear structures (26). However, the propagation is preceded by an isomerization of the active species which eliminates the steric hindrance to propagation arising from the 1,2-disubstitution in the monomer structure. A proton shift from the 4- to the 2-position places the negative charge at the extremity of the monomer unit and the incoming monomer can add onto this anion without major restrictions. The polymer structure thus obtained is ... 

Compounds 1, 2, and 3 are among the most relevant monomers or co-monomers for furan-based adhesives, but so also are furfurylidene acetone (5) and its bis-adduct 6. The synthesis of 5 involves the base-catalyzed reaction between 1 and acetone [2] and, in the same context, the use of an excess of 1 leads to the formation of 6 ... 

Other furan monomers which polymerize cationically include 2-furfuryl vinyl ether, 2-vinyl furoate (albeit through a polyalkylation mechanism giving a polyester incorporating the ring into the pol5mer backbone), F and MF as co-monomers in conjunction with substituted styrenes and vinyl ethers, as well as 2-furfurylidene methyl ketone (obtained by the base-catalyzed condensation of F with acetone) and its homologues [4d]. 

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