formaldehyde - Sciencemadness Dot Org

REACTIONS WITH AMIKO AXD AM1D0 COMPQCXDS 213
H*
C
/ \
HaNOO—X X—COXHfl
H2C CH£
\ /
N
CONHs
This trirner, which may also be produced by polycondensation, could then
serve as a resin building block.
Modified resins of the urea-formaldehyde type are also obtainable from
the ethers of mono- and dimethylolureas. These intermediate-: are probably
involved when urea and formaldehyde are condensed in alcohol
solutions 51 .
Substituted Ureas. Mono- and disubstituted ureas form methylol and
methylene derivatives with formaldehyde. In general, the property of
forming useful resins disappears when two or more of the urea hydrogen
atoms have been replaced by alkyl or other non-reactive groups.
Einhom 29 w^as unable to obtain the monomethylol derivative of ethylurea
by reacting it with alkaline formaldehyde, succeeding only in isolating
monomethylolmethylene-bis-ethylurea (m.p. i68-170°Ch CsH6XHCOX-
(CH20H)-CH3-NH-COXHC2H5. Under acidic conditions, he obtained
methylene-bis-monoethyhirea (m.p. 115-116°C). Monomethylol derivatives
of both symmetrical and asymmetrical dimethylurea were prepared
by the same investigator, but dimethylol derivatives were not obtained.
Complex methylenetricarbimides, derived from dimethylurea? and formaldehyde,
having the formulas C12H20O&X20, (Ci0Hi6O5N6)a, and :C^HstA-Xe)^
have also been reported 70 . Einhorn 29 was unable to obtain a formaldehyde
derivative of triethylurea under either acidic or alkaline conditions.
The fact that dimethylureas will not give dimethylol derivatives under
alkaline conditions and that triethylurea will not react with formaldehyde
at all, is possible evidence that the tautomeric isourea structure plays a part
in determining the reactivity of these derivatives. The iso-structure of the
monomethylol derivatives of the dimethylureas, as based on this hypothesis,
HO—C
N—CH3
N—cm
[
I
CH5OH
Monomethplol-sditn
ethylurea
H*C--N—
CHS
I f
HO-
-C
!!
El
N
j
CHaOH
Mon omethylol-asdiimethyluTea