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Diazomethane via the Forster Reaction.

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Explosion Resulting from the Oxidation
of Mesitylene with Nitric Acid
By Dr. H. Wilms and Dr. A. Dorlars
Wissenschaftliches Hauptlaboratorium der Farbenfabriken
Bayer A.-G., Leverkusen (Germany)
The oxidation of mesitylene [I) to 3,5-dimethylbenzoic acid
(111) by boiling with dilute nitric acid has been widely
reported [l]. In order to reduce the reaction time (60 hrs.),
the mesitylene (240 g.), water (1,2 litres) and conc. nitric acid
(690 g.) were to be heated together to 115 "C in a 3-litre
stirring autoclave (300 "C operating temperature, 100 gaugeatm. operating pressure).
Several minutes aftsr reaching 115 "C and 10 gauge-atm. a
powerful explosion took place. The autoclave was torn apart
lengthwise and widely scattered, together with the steel doors
of a safety cover.
Starting materials and the technical installation were in
order. Other alkyl aromatics had previously been frequently
oxidised with nitric acid under more rigorous conditions, and
without particular difficulty, in autoclaves. Furthermore, later
oxidation experiments with mesitylene proceeded smoothly
in a 0.3 litre autoclave at 115OC. Depending on the experimental conditions, predominantly 3,5-dimethylbenzoic
acid, 3-methylisophthalic and or benzene-l,3,5-tricarboxylic
acid (trimesic acid) were obtained. However, if these smaller
reaction mixtures were removed after 2-3 hours and workedup, it was found that the hydrocarbon layer contained up to
30 % a-nitromesitylene (11).
small amounts of phenyldiazomethane) [2]. Simple, unsubstituted diazoalkanes have not been obtained [2,3].
We have found that a variation of this reaction produces
diazomethane from formaldehyde oxime in yields of 70-75 %
(based on NHzCI). A solution of 40-50 mmoles CHZ=NONa
in absolute ether and the exact amount of absolute methanol
is combined with an etheral chloramine solution at 0°C.
Within an hour, NaCl separates, and diazomethane can be
isolated by distillation:
CHz=NONa f NH2CI 3 NaCl
+ CHzNz + HzO
The reaction is also possible with hydroxylamine-0-sulphonic acid. However, the yields in this case suffer from the
introduction of the strong acid; very considerable reductions
in yield (right down to a few per cent) are also observed when
other aliphatic oximes are used.
Received, May 17th. 1962
[Z 283/113 IE]
[l] M . 0. Forster, J. chem. SOC.(London) 107, 260 (1919.
[2] J. Meinwald et al., J. Amer. chem. SOC.81, 4751 (1959).
[3] L. A. Curpino et al., J. Amer. chem. SOC.81, 955 (1959).
[4] E. Bamberger, Ber. dtsch. chem. Ges. 28, 1682 (1895), prepared
diazomethane similarly, but from other components (N,N-dichloromethylamine and hydroxylamine.)
The Intermediate Occurrence of
By Dr. W.Tochtermann
Institut fiir Organische Chemie
der UniversitZtt Heidelberg (Germany)
After allowing an etheral suspension of K-t-butoxide to act on
[l] for many hours, 95 %
of the bromine can be detected as silver bromide in the
aqueous phase following hydrolysis. In the presence of furan
or tetramethylfuran this reaction leads to the Diels-Alder
adducts IIa (67 % yield) and I I b (30 % yield), respectively.
In the presence of tetraphenylcyclopentadienone tetraphenyltribenzotropone (111) (45 % yield) is formed with loss of
carbon monoxide. These facts suggest the intermediate occurrence of 4,5-dehydro-2,3,6,7-dibenzotropone(I) [2].
3,5-Dimethylbenzoic acid (111) is then formed from (II),
probably via the hydroxamic acid [2]. It may be assumed,
therefore, that in the case of the mesitylene reaction at a
temperature a little above 115 "C, as may occur temporarily
with larger amounts of reaction mixture because of the
relatively lower heat radiation from the autoclave, an unexpected side-reaction takes place. Under these conditions,
side-chain nitration proceeds more quickly than the further
reaction to carboxylic acid. a,a',a"-Trinitromesitxlene (IV) is
finally formed, which accounts for the highly shattering
effect of the explosion.
Received, May 17th. 1962 I
Z 281/114 IE]
[I] R . Fitfig, Liebigs Ann. Chem. 141, 144 (1867); H. R. Synder
et al., J. Amer. chem. SOC.63, 3281 (1941); E. Gryskiewicz-Trochimowski et al., Bull. Soc. chim. France 595 (1948).
[2] Houben- WeyZ: Methoden der organischen Chemie. G.Thieme,
Stuttgart 1952, vol. VIII, p. 441.
Diazomethane via the Forster Reaction
By Dr. W. Rundel
Chemisches Institut
der Universitat Tubingen (Germany)
The Forster reaction [l] (action of chloramine on a-oximinoketones with the formation of a-diazoketones) has hitherto
only been applied for the preparation of aryl-substituted
diazoalkanes (e.g. diazofluorene, diphenyldiazomethane,
Angew. Chem. internat. Edit. I Vol. I (1962) I No. 7
IIa: R = H; m.p. 204-206 "C
Ilb: R = CHJ; m.p. 261-262°C
111: m.p. 372-378°C
The constitution of compounds (11) and (111) is based on
analyses, spectral data, and chemical behaviour.
These investigations, which have led to the otherwise difficultly accessible tribenzotropone system [3], are being continued, with a view to the preparation of the benzotropylium
radicals (41, etc.
Received, May 17th. 1962
IZ 280/110 IEI
[*I Dedicated to Prof. Dr. G. Wirtig on the occasion of his 65th.
[ I ] W.Treibs and H.-J. Klinkharnmer, Chem. Ber. 84, 671 (1951).
[2] See G. Wittig,Angew. Chem. internatEdit. 1 (1962),in the press.
[3] M . Stiles and A . J. Libbey, J. org. Chemistry 22, 1243 (1957);
E. D. Bergmunn and J. Klein, ibid. 23, 512 (1958).
[4] G. Wittig, E. Rahn, and W.Tochtermann, Chem. Ber. 95, 431
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reaction, diazomethane, via, forster
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