JDJCSET | Sigma Xi Poster Competition

Title

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

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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.