1154 N otizen
Reaction Product of
Formaldehyd and O-Benzylhydroxylamine:
A Schiff Base?
Johannes R espondek
S q u ib b -V o n H e y d e n G m b H , D o n a u sta u fe rstr. 378, D -8400 R e g en s b u rg 1, F R G
Z . N a tu rfo rs ch . 39b, 1 1 5 4 -1 1 5 5 (1984);
receiv ed J a n u a ry 30, 1984
200 M H z 'H a n d 50 M H z 13C N M R sp e c tra w ere re c o rd e d from th e re ac tio n p ro d u c t o f fo rm ald eh y d 1 a n d O -b en y zlh y d ro x y lam in e 2 for th e p u rp o se of its stru c tu re e lu c id atio n .
Introduction
It is known from the literature [1] that O-ben- zylhydroxylam ine 2 cannot be converted into a M annich-Base. Instead, this amine 2 was supposed to provide Schiff base 3 as in the reaction with 40%
form aldehyd 1.
Experimental Section
The 13C and 'H N M R spectra were m easured on a B ruker WP 200 SY (200 M Hz, FT) in a 1% CDC13 solution at the given tem peratures (22 °C, resp.
40 °C) with tetram ethylsilane as internal standard.
The accuracy of the m easurem ents of 13C chemical shifts was 0.05 ppm.
Results and Discussion
In spite of the fact th at the melting point of the reaction product 3? is with 110—111 °C (recrystal
lized from ethanol) only slightly higher than reported (108.5 — 109.5 °C) [1] and in spite of the correct analysis for ( Q H9N O )*, we had doubt as to the cor
rect structure. The IR spectrum displays no olefin;
only weak absorption bonds of the benzyl ring can be seen. O ur doubt was confirmed by the *H NM R spectrum (com pound 4 in Table I). T he singulett at 3,83 and the absence of olefinic protons indicate that structure 3 cannot be the right one.
These results prom pted us to do further structure elucidations. From the above NM R spectrum of 4 we
S chem e
5
H ,C = 0 + H , N - 0 - C H , - C fiH r --- — --- ► 1 n <7S H ,C = N - 0 - C H , - C KH,:
2 2 2 6 5 no so lve n t 3 N ^ N ' ' 2 6 5
1 2 ' V 3
0 0I
C o m p o u n d T[°C] C -l C-2 C - 3 - C - 8
3 40 6.39 (d , J = 7.5 H z. 1 H ) an d 5.10 (s, 2 H ) 7.30 (s. 5 H ) 7.01 (d , J = 7.5 H z, 1H )
4 22 3.83 (b ro a d s, 2 H ) 4.73 (s, 2 H ) 7.30 (s, 5 H )
T a b le I. 200 M H z 'H -N M R (C D C 13) of c o m p o u n d s 3 and 4.
T able II. 50 M H z 13C N M R (CDC13) o f c o m p o u n d s 3 an d 4.
C o m p o u n d T[°C] C -l C-2 C-3 C-4 C-5 C-6 C - l C-8
3 40 137.21(t) 75.97(t) 137.58(s) 128.31(d) 128.12(d) 127.80(t) 128.12(d) 128.31(d)
4 22 73.71(t) 75.20(t) 137.68(s) 128.64(d) 128.05(d) 127.61(t) 128.05(d) 128.64(d)
0 3 4 0 -5 0 8 7 /8 4 /0 8 0 0 -1 1 5 4 /S 01.00/0
Notizen 1155
suggest a polymerised form of Schiff base 3. This was confirmed by the 13C N M R spectrum which is in ac
cord with a trim erised product of 3: Structure 4 is in accordance with the IR spectrum and the analysis.
Warming the trim erised 4 up to 40 °C one obtains formaldoxim-O-benzylether 3. Olefinic protons of 3 can now be seen at 6.39 and 7.01 ppm. The 13C NM R spectrum of 3 in Table II is in accord with its struc
ture. In contrast to trim eres with carbon substituents [2], the O -substituted trim er 4 could not be mono- merised completely using B F3 O E t2 in m ethylene- chloride at room tem perature.
Conclusion
The above discussed results show that the reaction product of form aldehyd 1 and O-benzylhydroxyl- amine 2 is trim erised 4, which should be warm ed up slightly, if one wants to use the reactivity of Schiff base 3.
I wish to thank Dr. Lindner for recording the N M R spectra and helpful discussions.
[1] H. H ellm ann and K. T eichm an n, C hem . Ber. 89, 1134 [2] T. Kam iya, T. O ku, O. N akaguchi, H . T akeno, and
(1956). M. H ashim oto, Tetrahedron Lett. 1978, 5119.
