O-Cubeâ„¢ Application Note - ThalesNano

RESULTS OF ALKENE OZONOLYSIS
Prof. Kappe’s group at University of Graz converted
different alkenes to the corresponding aldehydes/ketones
[3] (Scheme 1.) by reacting 0.05 M of starting materials
with ozone (concentration of 5%) in the O-Cube reactor
resulting in isolated yields of 72-90%, which were found to
be comparable to the published batch ozonolysis results.
As the two steps of the reaction process were carried
out in the same reactor unit, the only process needed
to obtain the 100 – 215 mg products within the 40 mins
reaction time was the evaporation of solvent. Peroxide
strips were used to make sure there was no ozonide and
ozone remaining in the reaction mixture.
RESULTS OF AMINE GROUP OZONOLYSIS
Adopting the same reaction conditions from the alkene
ozonolysis, an alkyl amine was oxidised to the nitro form.
After ozonolysis the ozonide was quenched to result in the
desired 1-nitrooctane with a 73% yield (117 mg) within 40
mins.
RESULTS OF THIOANISOLE OZONOLYSIS
Oxidation reactions of thioethers often lead to the sulfone
due to the fast oxidation of sulfoxide intermediate.
Under flow conditions, by altering the reactions
conditions (ozone concentration and the nature of
quenching agent), both the sulfoxide and sulfone could
be selectively synthesized in high yield, 84 and 87%
respectively, after a simple work-up procedure. With
the sulfone synthesis, the only method necessary to
obtain the product was the evaporation of solvent after
making sure there was no ozonide and ozone remaining in
the reaction solution. Further data of the two representative
reactions can be found in Scheme 3.
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O-Cube Application Note
1.) MeOH, 25 °C, 1 mL/min, 0.05 M, 3% ozone 90%
2.) NaBH 4 /MeOH, 25 °C, 0.7 mL/min
1.) Me 2 CO, 25 °C, 1 mL/min, 0.05 M, 3% ozone 84%
2.) 5% H 2 O/Me 2 CO, 25 °C, 0.7 mL/min
Scheme 1: Ozonolysis of alkene groups followed by reductive quenching
1.) EtOAc, 25 °C, 1 mL/min, 0.05 M, 10% ozone (3 equ.) 73%
2.) 1.5 M H 2 O 2 /CHCl 3 , 25 °C, 0.5 mL/min
Scheme 2: Ozonolysis of amine groups followed by oxidative quenching
1.) Ozonolysis: MeOH, 25 °C, 1 mL/min, ozone: 1 equ.
Reductive quenching: 0.1 M NaBH 4 /MeOH, 25 °C, 0.7 mL/min
2.) Ozonolysis: MeOH, 25 °C, 0.5 mL/min, ozone: 4 equ.
Oxidative quenching: 5 M H 2 O 2 /MeOH, 10 °C, 0.5 mL/min
Scheme 3: Reaction conditions and results of thioanisole ozonolysis
REFERENCES
[1] (a) Bailey, P. S.; Chem. Rev., 1958, 58, 925-1010; (b) Baley, P. S.; Ozonization in Organic Chemistry, Olefinic
Compounds; 1978; 1; (c) Bailey, P. S.; Ozonation in Organic Chemistry, Academic: San Diego; Chem. Abstr.; 1982, 2;
312-319; (d) Razumovskij, S. D.; Zaikov, G. E.; Ozone and Its reaction with Organic Compounds; Elsevier: Amsterdam; 1984
[2] Pluim, H.; Dyer-Smith, P.; Exner, M.; Chimica Oggi/Chemistry Today; 2011; 29(1); 59-62
[3] Irfan, M.; Glasnov, N. T.; Kappe, O. C.; Organic Letters; 2011; 13(5); 984-987
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