Certain Features of the Mechanism of Formation of Furfuryl Oligomers

Features of the Mechanism of Formation of Crosslinked Furfuryl Polymers

“…The reason for the relatively high formation rate of crosslinked polymers from FAOs in a neutral medium and at moderate temperatures must, in our opinion, be sought in a distinctive feature of their chemical structure. This distinctive feature, as we have established [13][14][15], is the partial linking of the furan rings by dimethylene ester bonds, along with methylene bonds.…”

Investigating the Conditions and Mechanism of Formation of Furfuryl-Formaldehyde Oligomers

“…The obtained experimental data, the given reasoning, and the results of earlier experimental research [1,2], in which it was established that dimethylene ether bonds formed during the homopolycondensation of FA do not break down under similar conditions, made it possible to present the structure of FFOs in the following form:…”

“…The results of calculations and the proportions of methylene ether bonds determined on the basis of data of NMR spectra are given in Table 1. According to earlier data [2], the proportion of dimethylene ether bonds in the structure of the FA oligomer is 8.3%. In the case of the heteropolycondensation of FA:FD (the proportion of dimethylene ether bonds during the homopolycondensation of FA was calculated on the basis of the molar quantity of FA entering into homopolycondensation with account taken of the figure 8.3%), as shown by the data in Table 1, with increase in the molar quantity of FD taken for the reaction of heteropolycondensation from 0 to 2 mol per 1 mol FA, the proportion of dimethylene ether bonds linking furan rings increases from 8.3 to 79.2%.…”

“…The second stage -the polycondensation of 2,5-dimethylolfuran between itself and free FA by the following possible schemes: The dimers formed are subsequently condensed into oligomeric products by similar reactions. It must be pointed out that, under similar conditions, FA readily undergoes homopolycondensation [1,2], and consequently, during the heteropolycondensation of FA with FD, it is unnecessary to eliminate the interaction of FA with itself entirely. Here, as shown by data in Table 1, with increase in the molar quantity of FD per mol FA, the proportion of FA taking part in homopolycondensation gradually decreases.…”