formaldehyde - Sciencemadness Dot Org

2S0 FORMALDEH YDE
Reactions I and II are believed to take place rapidly, whereas III is comparatively
slow and is the measured reaction. IV may be slow or fast.
The rate determining process III plus reactions I and II results in the twotenme
consumption of formaldehyde and ammonia.
Although the intermediate trinieihylenetriartiine theoretically postulated
ha.- never been isolated in a pure state, there is good chemical evidence for
its presence. By the action of nitrous acid on the reaction mixture, Griess
and Harrow 43 and Mayer 88 were able to isolate trinitrosotrimethylenetriamine
and dinitrosopentamethyleneterramine as derivatives of reaction
intermediates.
C
H, / \
A / x
/ \ X N—NO
ox—x x—xo I \
! i CH2
\ / ! X—NO
X H5C \ CH*
I \ CH2/
Trinitrosotrimethylenetriamine BiKitt'osopentamcthyleneieiramiiie
The dinitroso- compound, as will be seen, indicates a variation of the predominant
mechanism possibly involving the formation of a dinaethyloltrimethylenetriamine,
which could then react with ammonia to give pentamethylenetetramine.
Hexamethylenetetraniine would be formed by
condensation of this product with one mol of formaldehyde.
The formation of the above-mentioned nitroso-derlvatives was confirmed
by Duden and Scharff 36 - 87 , who also isolated the tribenzoyl derivative of
trmiethylenetriamine by reacting benzoyl chloride with the mixture obtained
by treating a cold solution o£ formaldehyde and ammonium chloride
with caustic alkali. This benzoyl derivative/ (CHSIN-COCGHS^J is a
crystalline product melting at 223 °C. The isolation and identification of
these derivatives were offered by these investigators as basic evidence for
the polycyclic structure.
The equilibrium for the reaction of the ammonium ion and formaldehyde
as indicated below was determined by Baur and Ruet-schi 8 in acid-buffered
solutions of ammonia and formaldehyde:
6CH30 + 4XH* + ?=t (CHaieX* -J- 4H- -f- 6HaO
Values reported for the equilibrium constant | -A. J J:--.- ^ J - ? at various
X