Reaction of Novolac Resin with Aromatic Dinitriles
V. F. Burdukovskii and D. M. Mognonov
Baikal Institute of Nature Management, Siberian Branch, Russian Academy of Sciences, Ulan-Ude, Buryatia, Russia
Received September 3, 2010
Abstract—Cross-linking of Novolac resin with aromatic dinitriles in the presence of aluminum chloride was
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 6, pp. 1064–1066. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.F. Burdukovskii, D.M. Mognonov, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 6, pp. 1044–1046.
Cross-linking of Novolac resin with commonly
used hexamethylenetetramine yields an insoluble
cross-linked three-dimensional product, and the
process is accompanied by the evolution of nitrogen,
which sometimes prevents preparation of high-strength
composite materials. Previously we demonstrated the
possibility of preparing aromatic polyamides by
reactions of bisphenols with dinitriles in the presence
of Lewis acids . Therefore, it was of certain interest
to examine the possibility of cross-linking of Novolac
resin via OH groups with aromatic dinitriles with the
formation of stronger azomethine and intermolecular
hydrogen bonds with the aim to enhance the strength
of materials based on this resin.
Apparently, the conversion will be strongly affected
by the mobility of oligomeric fragments and accessi-
bility of OH groups. In this connection, taking also
into account the implementation simplicity and en-
vironmental safety factors, we performed the process
in a melt. The main relationships of the reaction were
studied using as example the reaction of Novolac resin
The choice of the reactant ratio was governed by
the necessity of involving all the OH groups in the
cross-linking, which can be attained at equimolar ratio
of OH and CN groups. However, actually a slight
excess of the dinitrile was required. The reaction
progress was monitored by IR spectroscopy.
It is known [1, 2] that reactions of such types are
well catalyzed by protic and aprotic acids. Acids are
primarily required for increasing the polarity of the
C≡N bond by coordination of the vacant orbital of the
acid with the lone electron pair of the nitrogen atom.
This coordination considerably enhances the electro-
philicity of the nitrile group.
Figure 1 shows that, without a catalyst, the reaction
does not occur to a noticeable extent, and the presence
of concentrated H
leads only to the resin