JDJCSET | Sigma Xi Poster Competition
Optimizing the green mechanochemical synthesis of 1,3-dimethyl benzimidazolium iodide
Academic Level at Time of Presentation
Senior
Major
Pre-Veterinary Medicine
Minor
n/a
2nd Student Academic Level at Time of Presentation
Junior
2nd Student Major
Chemistry Area
2nd Student Minor
n/a
List all Project Mentors & Advisor(s)
Rachel Allenbaugh, PhD
Presentation Format
Poster Presentation
Abstract/Description
Mechanochemistry involves milling reagents in a ball mill to induce reaction. Typically, mechanochemical reactions only utilize chemicals in a solid state; however, the Allenbaugh research group has recently investigated a synthesis that involves both solid and liquid reactants. Multiple syntheses of 1,3-dimethyl benzimidazolium iodide (HBZM-Me2I) were analyzed to determine the optimal mixing ratio of reactants to maximize yield. The traditional synthesis of HBZM-Me2I requires the use of a pressure tube and large excess of methyl iodide, a highly toxic suspected carcinogen. The newly developed mechanochemical method drastically reduces the amount of methyl iodide required for the reaction; however, due to changes in the physical properties of the reaction mixture over time, the mixture ‘glazes’ the milling balls, preventing reagents from reacting and limiting yields to 33.49% or less. While these yields are lower than the pressure tube method, the reduction in methyl iodide use and the elimination of the safety hazards associated with a pressure tube makes the mechanochemical method a far greener and safer alternative. Additionally, the Allenbaugh group mathematically fits reaction kinetics to models, allowing conversion over time to be predicted. Reaction time is a necessary parameter to understand before greener mechanochemical methods will be widely adopted. Previous research by the group has shown sigmoidal reaction kinetics for several mechanochemical reactions. HBZM-Me2I conversion data was successfully fitted to two sigmoidal reaction models, the Johnson-Mehl-Avarami-Yerofeev-Kolmogrov and Finke-Watzky models.
Spring Scholars Week 2018 Event
Sigma Xi Poster Competition
Optimizing the green mechanochemical synthesis of 1,3-dimethyl benzimidazolium iodide
Mechanochemistry involves milling reagents in a ball mill to induce reaction. Typically, mechanochemical reactions only utilize chemicals in a solid state; however, the Allenbaugh research group has recently investigated a synthesis that involves both solid and liquid reactants. Multiple syntheses of 1,3-dimethyl benzimidazolium iodide (HBZM-Me2I) were analyzed to determine the optimal mixing ratio of reactants to maximize yield. The traditional synthesis of HBZM-Me2I requires the use of a pressure tube and large excess of methyl iodide, a highly toxic suspected carcinogen. The newly developed mechanochemical method drastically reduces the amount of methyl iodide required for the reaction; however, due to changes in the physical properties of the reaction mixture over time, the mixture ‘glazes’ the milling balls, preventing reagents from reacting and limiting yields to 33.49% or less. While these yields are lower than the pressure tube method, the reduction in methyl iodide use and the elimination of the safety hazards associated with a pressure tube makes the mechanochemical method a far greener and safer alternative. Additionally, the Allenbaugh group mathematically fits reaction kinetics to models, allowing conversion over time to be predicted. Reaction time is a necessary parameter to understand before greener mechanochemical methods will be widely adopted. Previous research by the group has shown sigmoidal reaction kinetics for several mechanochemical reactions. HBZM-Me2I conversion data was successfully fitted to two sigmoidal reaction models, the Johnson-Mehl-Avarami-Yerofeev-Kolmogrov and Finke-Watzky models.