Ethylene compounds, Carbonates, Indole, Nuclear magnetic resonance, Nucleophilic reactions, Nitroaromatic compounds, Ethylene carbonate, 19F NMR, Ethoxylation, Aromatic nitrogen nucleophiles, Reaction development
Although ethoxylation reactions are commonly used, currently used reagents are hazardous, toxic, and/or explosive. Ethylene carbonate has been put forth as an inexpensive, nontoxic, and “green” potential ethoxylation reagent. Herein we study a base-catalyzed ethyl alcohol transfer from ethylene carbonate to indole. The 19F NMR method was used to quantify the product formation yields. Ethylene carbonate is an effective ethoxylation reagent for indoles. An excess use of ethylene carbonate is needed for the reaction to complete in a reasonable amount of time. There are no significant differences between the use of catalytic amount of different bases/nucleophiles, thus catalytic amounts of Cs 2CO3 and DABCO are further explored. As time increases, more side product forms. When DABCO is used as the catalyst, DMSO is recommended as the solvent for the reaction. When Cs 2CO3 is used as the catalyst, DMF is recommended as the solvent for the reaction. To date, our best reaction condition allows us to collect 67% of desired product. More experiments are needed to explore the optimal reaction condition so that an effective base-catalyzed ethylene carbonate ethoxylation on indole nucleophile can be developed, and eventually a general base-catalyzed ethylene carbonate ethoxylation reaction can be applied on various aromatic nitrogen nucleophile substrates.
Chen, Peishan, "Ethylene carbonate ethoxylation on aromatic nitrogen nucleophiles" (2016). Honors Project, Smith College, Northampton, MA.
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