Furfuryl alcohol self-condensation

In conclusion, the self-condensation of 2-furaldehyde promoted by heat occurs with the formation of di- and trifurylic intermediates. The functionality of the growing chain increases after each oligomerization step until gelation and precipitation of the resin occurs. Thus, the process is non-linear from the onset since the condensation product 4 possesses three sites for further attack, namely the free C-5 position and the two formyl groups. It is interestering to note that while the polycondensation of 2-furfuryl alcohol is essentially linear and cross-linking is due to side reactions, the thermal resinification of 2-furaldehyde is intrinsically non-linear and gel formation occurs at earlier conversions. 

A mixture of the alcohol with formic acid rapidly self-heated, then reacted violently [1], A stirred mixture with cyanoacetic acid exploded violently after application of heat [2], Contact with acids causes self-condensation of the alcohol, which may be explosively violent under unsuitable physical conditions. The general mechanism has been discussed [3], The explosion hazards associated with the use of acidic catalysts to polymerise furfuryl alcohol may be avoided by using as catalyst the condensation product of 1,3-phenylenediamine and l-chloro-2,3-epoxypropane [4], See Nitric acid Alcohols (reference 6)... 

Pyrones.—A one-pot conversion of furfuryl alcohol into 3-hydroxy-2-methyl-4//-4-pyrone (maltol) in 70% yield has been effected by chlorination and heating. Tetraketones [such as (43)] undergo self-condensation, on heating for... 

Thermal properties can also be influenced by a furan ring in the para position of a phenolic ring. A phenolic novolac was prepared by reaction of phenol with methanal using oxalic acid as catalyst, and the furfuryl alcohol was added in a proportion of 0.5 mole furfuryl alcohol per mole phenol. The reaction steps in Scheme 11 show that the condensation of furfuryl alcohol at the para position of the phenolic rings is accompanied by the self-condensation of furfuryl alcohol. 

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