Household Ozone Disinfector as An Alternative Ozone Generator for Ozonolysis of Alkenes

Abstract

Ozonolysis is an oxidative cleavage reaction of alkenes with ozone that is indispensable and has found many applications in organic synthesis. However, dedicated laboratory ozone generators are quite expensive equipment and may not be affordable by many laboratories. Recently, lowcost ozone disinfectors have become more common as a household appliance. Herein, we demonstrate the applicability of a household ozone disinfector, which can produce ozone in the order of 10 mmol/h, as alternative equipment for the laboratory scale ozonolysis of alkenes. The ozonolysis of 14 styrene derivatives bearing electron-donating and electron-withdrawing groups on aromatic rings including those with αand β-substituents, as well as 8 natural products containing olefinic moieties were investigated. Ozonolysis of these alkenes at millimole scales proceeded to completion within 30-40 minutes and the carbonyl products were obtained in 68% to quantitative yields. Preparative-scale ozonolysis of 4-methoxystyrene (6.17 g, 46 mmol) was also demonstrated. The reaction proceeded smoothly to yield 4anisaldehyde in 92% yield, which was subsequently converted to p-anisaldehyde dimethyl acetal in 66% yield. This work presents household ozone disinfector as an affordable, compact size, and practical synthetic equipment that does not require extra modification. Thus, the household ozone disinfector offers convenient access to ozonolysis or other reactions involving ozone for low-budget laboratories.

Surfactant-Assisted Ozonolysis of Alkenes in Water: Mitigation of Frothing Using Coolade as a Low-Foaming Surfactant

“…We first began to evaluate a suitable surfactant for the ozonolysis reaction in water using 4-chlorostyrene ( 1 ) as a model substrate, while a household ozone disinfector was employed as an ozone generator (Table ). 4-Chlorostyrene ( 1 ) was suspended in an aqueous solution of an anionic surfactant sodium dodecyl sulfate (SDS; 5 wt %) and vigorously stirred at room temperature for 30 min to obtain an emulsion. When the ozonolysis was carried out, a large amount of foaming occurred immediately after purging the O 3 /O 2 stream, and the foam quickly overfilled the reaction vessel (Figure A, denoted as +++) .…”

“…Safety concern about ozonolysis using the household ozone generator instead of the conventional laboratory ozone generator was previously addressed and those who wish to replicate the experiments should refer to the original reference. 20 4-Chlorobenzaldehyde (1a). Coolade-assisted ozonolysis (Table 2, entry 8): the ozonolysis was performed as described in the general procedure.…”

“…The spectroscopic data of 4-chlorobenzaldehyde (1a) matched those reported in the literature. 20 1 H NMR (500 MHz, CDCl 3 ): δ H 9.99 (s, 1H), 7.83 (d, J = 8.5 Hz, 2H), 7.52 (d, J = 8.4 Hz, 2H). 13 C{ 1 H} NMR (126 MHz, CDCl 3 ): δ C 191.0, 141.0, 134.8, 131.0, 129.5.…”

“…The spectroscopic data of 4-chloroacetophenone (6a) matched those reported in the literature. 20 Coolade-assisted ozonolysis (Table 2, entry 5 f and Table 3, entry 2): the ozonolysis without the reductive workup step was performed as described in the general procedure. 4-Chloro-α-methylstyrene (6) (127 mg, 0.83 mmol) was treated with 2 wt % Coolade solution (1.5 mL, [6] = 0.5 M).…”

“…The spectroscopic data of vanillin (10a) matched those reported in the literature. 20 1 H NMR (500 MHz, CDCl 3 ): δ H 9.83 (d, J = 0.8 Hz, 1H), 7.44−7.41 (m, 2H), 7.04 (dd, J = 8.5, 0.8 Hz, 1H), 6.17 (br, 1H), 3.97 (s, 3H). 13 Control Experiments for the Ozonolysis without the Reductive Workup Step (Scheme 4B).…”