A novel cyclic formal, 1,3,5,7-tetraoxacyclononane, from the direct reaction of 1,3,5-trioxane and ethylene oxide

Article abstract of DOI:10.1039/a801653d

A new reaction between 1,3,5-trioxane and ethylene oxide has been observed and a novel cyclic formal, which is the reaction product of 1 equiv. of 1,3,5-trioxane and 1 equiv. of ethylene oxide, has been isolated and identified.

Full text of DOI:10.1039/a801653d

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A novel cyclic formal, 1,3,5,7-tetraoxacyclononane, from the direct reaction of
1,3,5-trioxane and ethylene oxide
J. Masamoto,*a† N. Yamasaki,a W. Sakai,a T. Itoh,a N. Tsutsumia and H. Nagaharab
a Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585, Japan
b Asahi Chemical Industry Co., Ltd. Kojimashionasu, Kurashiki 711-8510, Japan
A new reaction between 1,3,5-trioxane and ethylene oxide
has been observed and a novel cyclic formal, which is the
reaction product of 1 equiv. of 1,3,5-trioxane and 1 equiv. of
ethylene oxide, has been isolated and identified.
The reaction concentration profile is shown in Fig. 4. The
profile begins when the initiator (a cyclohexane solution of
BF3·OBu2) is injected into the molten mixture of 1,3,5-trioxane
and ethylene oxide. At first, as the ethylene oxide concentration
(4.5 mol% with respect to 1,3,5-trioxane) decreases, the TOCN
concentration increases proportionally. Later, as the TOCN
Weissermel and co-workers1,2 proposed the reaction of formal-
dehyde with ethylene oxide to form 1,3-dioxolane as the
initiation mechanism of the copolymerization of 1,3,5-trioxane
and ethylene oxide. Collins et al.3 confirmed that ethylene oxide
was converted to 1,3-dioxolane and then from 1,3-dioxolane,
1,3,5-trioxepane was formed. They stated that the direct
reaction of ethylene oxide with 1,3,5-trioxane was impossible
because of the weak basicity of 1,3,5-trioxane. Weissermel and
co-workers1,2 and Collins et al.3 proposed the formation
mechanism of 1,3-dioxolane from ethylene oxide and formal-
dehyde, and for a long time this was thought plausible for the
initiation mechanism of copolymerization of trioxane and
ethylene oxide.
Ha
d 5.05
O
O
O
Hb
Hb
d 4.93
O
Hc
H
1.9762
c
d 3.85
b
H
1.9047
We have performed the direct reaction of ethylene oxide with
1,3,5-trioxane, which was thought impossible for a long time,
and isolated a novel cyclic formal. From this novel cyclic
formal, 1,3,5-trioxepane was formed and then 1,3-dioxolane
was also generated. This reaction identified the precise
initiation mechanism of the copolymerization of 1,3,5-trioxane
and ethylene oxide.
a
H
1.000
Purified 1,3,5-trioxane (30 g) was melted under an N2
atmosphere in a glass vessel immersed in an oil bath and held at
70 °C. Gaseous ethylene oxide (4.5 mol% with respect to
1,3,5-trioxane) was introduced into the molten 1,3,5-trioxane
which was stirred with a magnetic mixer. A cyclohexane
solution of BF3·OBu2 (7 3 1023 mol% with respect to
1,3,5-trioxane) was introduced into the molten mixture of
1,3,5-trioxane and ethylene oxide through the cap of the glass
vessel with a microsyringe. The mixture was stirred using a
magnetic mixer in an oil bath to maintain the reaction
temperature at 70 °C. The reaction mixture was sampled with a
syringe and then poured into PrOH containing a small amount
of KOH. The reaction mixture was analyzed by gas chromatog-
raphy. This showed a 33% yield of the novel compound based
on the initial amount of ethylene oxide.
5
4
d
Fig. 1 1H NMR spectrum of the new compound
d 96.9
Ca
O
O
O
Cb
Cb
d 97.1
O
The novel compound was separated using a micro-distillation
apparatus (bp 180 °C at 1 atm; mp 8.4 °C and bp 95 °C at 25
torr). Its chemical structure was confirmed using 1H NMR, 13
NMR and mass spectral and elemental analysis.
C
Cc
d 70.5
Fig. 1 shows the 1H NMR pattern of the new compound. The
ratio of Ha (proton of formal linkage, d 5.05) to Hb (proton of
formal linkage, d 4.93) and Hc (proton of ether linkage, d 3.85)
is 1:2:2. Fig. 2 shows the 13C NMR pattern of the new
compound, and shows three different types of carbon: Ca
(formal carbon, d 96.9), Cb (formal carbon, d 97.1) and Cc (ether
carbon, d 70.5). Fig. 3 shows the EI mass spectrum of the new
compound, which shows the molecular weight of 134 and
composition formula of C5H10O4, which is in accordance with
the molecular weight and composition formula of 1,3,5,7-tetra-
oxacyclononane (TOCN). The observed elemental analyses are
in accordance with the theoretical values (Found: C, 44.76; H,
7.75. Calc.: C, 44.78; H, 7.50%).
110
100
90
80
70
d
Fig. 2 13C NMR spectrum of the new compound
Chem. Commun., 1998
1809

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O
O
O
O
O
O
+
O
O
–CH2O
×20
O
–CH2O
O
O
O
O
Scheme 1
of the nine-membered ring compound of TOCN compared to
those of the seven- and five-membered ring compounds. In the
case of the cycloalkane, the ring strain energy of the nine-
membered ring compound is 27 kJ mol21 higher compared to
those of the seven- and five-membered ring compounds.4
The newly isolated intermediate, the novel cyclic compound
TOCN, identifies a new direct reaction between 1,3,5-trioxane
and ethylene oxide, as well as the precise initiation mechanism
of the copolymerization of 1,3,5-trioxane and ethylene oxide.
First, ethylene oxide directly reacts with 1,3,5-trioxane to
produce TOCN (Scheme 1). The 1,3,5-trioxepane is then
formed from TOCN, and 1,3-dioxolane is formed from
1,3,5-trioxepane.
60
70
80
90
100
m / z
110
120
130
140
Fig. 3 EI mass spectrum of the new compound
100
50
Using gas chromatography, we observed compounds of
higher molecular weights than TOCN as minor components,
which were presumed to be the addition product of ethylene
oxide and TOCN. Confirmation of this point will be discussed
in the near future.
0
100
200
300
t / s
Fig. 4 Profile of reaction of 1,3,5-trioxane and ethylene oxide: (2) ethylene
oxide, (-) 1,3,5,7-tetraoxacyclononane, (8) 1,3,5-trioxepane, (5) 1,3-di-
oxolane. [EO]0 = 4.5 mol% with respect to 1,3,5-trioxane. t = 0 indicates
the time at which the initiator is injected into the molten mixture of
1,3,5-trioxane and ethylene oxide. Percentage on the vertical axis indicates
the relative molar concentration of ethylene oxide or related compounds to
the initial concentration of ethylene oxide.
Notes and References
† E-mail: masamoto@ipc.kit.ac.jp
1 K. Weissermel, E. Fischer, K. Gutweiler and H. D. Hermann, Kunststoffe,
1964, 54, 410.
2 K. Weissermel, E. Fischer, K. Gutweiler, H. D. Hermann and H.
Cherdron, Angew. Chem., Int. Ed. Engl., 1967, 6, 526.
3 G. L. Collins, R. K. Green, F. M. Beradinelle and W. H. Ray, J. Polym.
Sci., Polym. Chem. Ed., 1981, 19, 1579.
4 P. Kubisa, in Cationic Polymerization: Mechanism, Synthesis, and
Applications, ed. K. Matyjaszewski, Dekker, New York, 1995, pp. 437–
553.
concentration decreases again, the concentration of 1,3,5-triox-
epane increases. Soon after the appearance of 1,3,5-trioxepane,
1,3-dioxolane appeares, and with the decrease in concentration
of 1,3,5-trioxepane, the concentration of 1,3-dioxolane in-
creases.
Although the equilibrium concentration of 1,3,5-trioxepane
and 1,3-dioxolane exist, there is no equilibrium concentration of
TOCN. This might be attributed to the higher ring strain energy
Received in Cambridge, UK, 27th February 1998; 8/01653D
1810
Chem. Commun., 1998