Ozonolysis, methanol as solvent for

Irfan et al. [38] presented a general reaction protocol for ozonolysis reactions on a laboratory scale using the commercially available O-Cube reactor by ThalesNano (www.thalesnano.com). Figure 6.39 depicts a schematic view of the O-Cube reactor setup. The ozonolysis step took place in a cooled reaction loop with an internal volume of 4 ml and an inner diameter of 1 mm. Usually, methanol or acetone was utilized as solvent and temperatures between —20 and 25 °C were applied. The ozonolysis reaction mixtures were quenched immediately in a temperature range of —10 to 25 °C. 

Having served their purpose as masked carbonyl functionalities in the preceding 4 steps of the synthesis, the benzylidene groups in fused terpyridyl 11 are cleaved by ozonolysis in Protocol 7. As shown in Scheme 6.10, the reaction solvent is a mixture of methanol and dichloromethane. Reactant 11 is insoluble in methanol, so dichloromethane is used as a cosolvent to enhance its concentration in the cold (-78°C) reaction mixture. Methanol is a convenient cosolvent for conducting ozonolysis reactions safely because it cleaves ozonides in situ to carbonyl compounds and peroxyhemiacetals or... 

The cleavage reaction, commonly referred to as ozonolysis , is carried out by bubbling ozonized oxygen through a solution of the a ene in various solvents, including methanol, dichloromethane, carbon tetrachloride and ethyl acetate. Other solvents (ethanol, tetrahydrofiiran, acetic acid, or a combination of ethyl acetate and hexane) have also been reported for use in individual reactions.The reaction is usually performed at low temperatures (ateut 0 °C), and, since ozonides are potentially explosive compounds, the intermediates are not isolated. 

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