Aqueous-phase ozonolysis in the atmosphere is an important process during cloud and fog formation. Water in the atmosphere acts as both a reaction medium and a reductant during the ozonolysis. Inspired by the atmospheric aqueous-phase ozonolysis, we herein report the ozonolysis of alkenes in water assisted by surfactants. Several types of surfactants, including anionic, cationic, and nonionic surfactants, were investigated. Although most surfactants enhanced the solubility of alkenes in water, they also generated excessive foaming during the ozone bubbling, which led to the loss of products. Mitigation of the frothing was accomplished by using Coolade as a nonionic and low-foaming surfactant. Coolade-assisted ozonolysis of alkenes in water provided the desired carbonyl products in good yields and comparable to those achieved in organic solvents. During the ozonolysis reaction, water molecules trapped within the polyethylene glycol region of Coolade were proposed to intercept the Criegee intermediate to provide a hydroxy hydroperoxide intermediate. Decomposition of the hydroxy hydroperoxide led to formation of the carbonyl product without the need for a reductant typically required for the conventional ozonolysis using organic solvents. This study presents Coolade as an effective surfactant to improve the solubility of alkenes while mitigating frothing during the ozonolysis in water.

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.

No abstract

Dodecyl benzenesulfonic acid (DBSA)-mediated thioglycosylation in water provided thioglycosides without open-chain dithioacetal sugars, which are common by-products when performing reactions in organic solvent.