1070-4272/02/7508-1369 $27.00 C 2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 8, 2002, pp. 1369!1370. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 8, 2002,
Original Russian Text Copyright + 2002 by V. Maslosh, Kotova, O. Maslosh.
Effect of Acetylacetone on the Residual Content
of Formaldehyde in Urea!Formaldehyde Resin
V. Z. Maslosh, V. V. Kotova, and O. V. Maslosh
Institute of Applied Chemistry, Ministry of Education and Science of Ukraine,
Rubezhnoe, Lugansk oblast, Ukraine
Received March 25, 2002
Abstract-The effect of small additions of acetylacetone and ammonia to urea3formaldehyde resin is con-
sidered. The occurring processes, involving the formation of 2,6-dimethyl-3,5-diacetyl-1,4-dihydropyridine
and condensation of this compound and acetylacetone with terminal methylol groups of the resin, are dis-
Stringent environmental requirements are imposed
upon the quality of urea3formaldehyde resins (UFRs),
which are widely used as binders and are produced on
large scale in many countries.
The major drawback of UFRs is their toxicity,
resulting from the presence of free formaldehyde. The
toxicity can be decreased by improving the production
process or introducing special additives that bind free
formaldehyde. Numerous additives have been patented
for this purpose , such as urea, thiourea, mela-
mine, higher aldehydes and ketones, aliphatic amines,
some inorganic compounds, etc. However, the prob-
lem of decreasing the content of free formaldehyde in
UFRs remains topical.
The poor performance of the majority of additives
may be due to the fact that they react with formalde-
hyde relatively slowly and reversibly. Thus, the fol-
lowing requirements to the additives can be formulated
a priori: They should react with formaldehyde fast
and irreversibly in the absence of strong acids, bases,
and oxidants degrading UFRs or causing their prema-
ture curing. Furthermore, the additives and products
of their reactions with formaldehyde should be well
compatible with UFRs.
Despite the fact that the formaldehyde chemistry
has been extensively studied [8, 9], there are only a
few reactions meeting these requirements. One of
them is the reaction of formaldehyde with b-diketones
and ammonia, yielding pyridine derivatives . This
reaction is fast at room temperature, even at very low
concentration of formaldehyde.
In this study, we examined the possibility of using
this reaction to decrease the content of free formal-
dehyde in UFR.
We used a commercial sample of KFMP-15 resin
containing 0.5% free formaldehyde; 99% pure acetyl-
acetone; and 25% aqueous ammonia, pure grade.
A glass beaker was charged with 100 g of the resin,
and 3.36 g of acetylacetone and aqueous ammonia
containing 0.57 g of NH
were added. The mixture
was stirred at room temperature for 30 min, after
which the content of free formaldehyde and the con-
ventional viscosity (VZ-4 viscometer) were deter-
mined. Samples were placed in a hermetically sealed
vessel, and their viscosity and free formaldehyde con-
tent were determiend daily [11, 12].
Experiments were performed with the simplest
b-diketone, acetylacetone. Addition to UFR of a mix-
ture of acetylacetone and ammonia (molar ratio
2 : 1) in amount of about 3 wt % fully eliminates free
formaldehyde. Monitoring of the sample for 9 days
showed that no free formaldehyde appeared in UFR.
In a control sample (without addition of acetylacetone
and ammonia), the content of free formaldehyde
varied within 0.330.7%. After adding acetylacetone
and ammonia, the resin appearance changed: Within
30 min, the resin became orange-yellow, and the color
grew in intensity in the course of 9-day storage at
room temperature. Three days after preparing the
mixture, the characteristic acetylacetone odor disap-