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PUBLICATIONS
 

Structural Studies of Racemates and Quasiracemates: Chloro,Bromo, and Methyl Adducts of 2-Phenoxypropionic Acid

2008

 

 

Aaron M. Lineberry, Ellis T. Benjamin, Raymond E. Davis, W. Scott Kassel, Kraig A. Wheeler. Structural Studies of Racemates and Quasiracemates: Chloro, Bromo, and Methyl Adducts of 2-Phenoxypropionic Acid. Crystal Growth & Design. 2008, 8(2), 612–619.

Abstract:  Quasiracemic compounds derived from the enantiopure Cl, Br, and CH3 analogues of 2-phenoxypropanoic acid crystallize to give approximate centrosymmetry supramolecular assemblies. Each quasiracemate forms the anticipated heterodimers via O-H· · ·O carboxyl interactions that lead to two distinct packing motifs in space group P21 with Z′ = 2 (Cl/Br and Br/CH3) or 8 (Cl/CH3 and Br/CH3). The Z = 2 quasiracemates are isostructural with (rac)-Cl and (rac)-Br, while the Z' = 8 structures form molecular patterns that resemble the packing preferences of (rac)-CH3. The Br/CH3 quasiracemate was retrieved as concomitant polymorphs.

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The Synthesis of Unsubstituted Cyclic Imides Using Hydroxylamine under Microwave Irradiation.

 

 

2008

 

 

Ellis Benjamin and Yousef Hijji. The Synthesis of Unsubstituted Cyclic Imides Using Hydroxylamine under Microwave Irradiation.  Molecules. 2008, 13, 157-169.

 

Abstract: Unsubstituted cyclic imides were synthesized from a series of cyclic anhydrides, hydroxylamine hydrochloride (NH2OH·HCl), and 4-N,N-dimethylamino-pyridine (DMAP, base catalyst) under microwave irradiation in monomode and multimode microwaves. This novel microwave synthesis produced high yields of the unsubstituted cyclic imides for both the monomode (61 - 81%) and multimode (84 - 97%) microwaves.

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Mathematical Models for Conventional and Microwave Thermal Deactivation of Enterococcus faecalis, Staphylococcus aureus and Escherichia coli.

 

2007

 

Earl Benjamin, Aron  Renzik, Ellis Benjamin, Arthur L. Williams. Mathematical Models for Conventional and Microwave Thermal Deactivation of Enterococcus faecalis, Staphylococcus aureus and Escherichia coli Cell Mol. Biol. 2007, 53(3), 42-48.

 

Abstract: Temperature dependencies of survival fecal coliforms such as Enterococcus faecalis, Staphylococcus aureus and Escherichia coli in water were investigated between 25 - 65 °C. Measured dependencies had "bell" shaped form with maximum bacterial viability at 35 - 45 °C. The rates of growth and decay of bacterial viability depend on specific forms of bacteria. At temperatures of 60 - 65 °C the number of viable bacteria decreased in one hundred times in comparison with the maximum value. Similar "bell" shape forms were found for dependencies between bacterial viability and time of microwave (dielectric) heating of water. The dependencies had maximum value at 1 - 2 min of microwave heating. Then, the number of viable bacteria decreased, and at 4 - 5 min of microwave heating, became insignificantly small. The proposed mathematical models for conventional and microwave heating took into account "growth" and "death" factors of bacteria, and had forms of second degree polynomial functions. The results showed good relationships (with coefficient correlation 0.84 - 0.99) between the proposed mathematical models and experimental data for both conventional and microwave heating.

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Mathematical Model of Manganese Ion Catalyzed Microwave Deactivation of Enterococcus faecalis, Staphylococcus aureus and Escherichia coli.

 

2007

 

Earl Benjamin, Aron  Renzik, Ellis Benjamin, Arthur L. Williams. Mathematical Model of Manganese Ion Catalyzed Microwave Deactivation of Enterococcus faecalis, Staphylococcus aureus, and Escherichia coli Cell Mol. Biol. 2007, 53(3), 49-54.

 

Abstract: Enterococcus faecalis, Staphylococcus aureus and Escherichia coli survival was investigated using microwave irradiation (power 130 W) both in a water control and in the presence of a 1 µM manganese ion solution. Measured survival dependencies had "bell' shape form with maximum bacterial viability between 1 - 2 min of microwave heating. Additional heating revealed bacteria survival decreasing up to 3 min of microwave heating when viability became insignificantly small. The total deactivation time of bacteria in the presence of manganese ions was significantly smaller then that of bacteria irradiated in the microwave without manganese ions present (4 -5 min). One possible explanation for the rapid reduction of bacterial survival during microwave irradiation in the presence of manganese ions is that increasing manganese ion penetration into bacteria along with microwave irradiation related to an increase of kinetic energy of ions, and damaging of bacteria by metal ions. The proposed mathematical model for microwave heating took into account "growth" and "death" factors of bacteria. It assumes that rates of bacterial growth and decay are linear functions of water temperature, and rate of bacterial decay that relates with metal concentration into water is also linear, which influenced the differential equation for the dependence between number of survival bacteria and temperature water. By using proportionality between the time of microwave heating and water temperature we derived the differential equation, between bacterial viability and time of microwave irradiation which was used as mathematical model for microwave heating in the presence of metal ions. This model had forms of second-degree polynomial functions. We received good relationships (with coefficient of correlation 0.92 - 0.99) between proposed mathematical model and experimental data for all bacterial deactivation.

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1-Methoxy-pyrrolidine-2,5-dione

 

2007

 

 

Ray J. Butcher, Yousef M. Hijji, Ellis Benjamin. 1-Methoxy-pyrrolidine-2,5-dione Acta Cryst. 2007, E63, o1502-o1503.

 

Abstract: The title compound, C5H7NO3, was synthesized by microwave methods. The five-membered pyrrolidine-2,5-dione ring is planar. There is extensive C—H...O hydrogen bonding.

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3-Aminocyclopent-2-en-1-one

 

2007

 

 

Ray J. Butcher, Yousef M. Hijji, Ellis Benjamin. 3-Aminocyclopent-2-en-1-one Acta Cryst. 2007, E63, o610–o612.

 

Abstract: The title compound, C5H7NO, was synthesized by the reaction of 1,3-cyclopentanedione with ammonium acetate under microwave conditions in 81% yield. The crystal packing is determined by intermolecular N—H...O and C—H...O hydrogen bonds.

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Efficient Microwave Assisted Syntheses of Unsubstituted Cyclic Imides.

 

2006

 

Yousef M. Hijji, Ellis Benjamin. Efficient Microwave Assisted Syntheses of Unsubstituted Cyclic Imides. Heterocycles 2006, 68(11), p2259-2267.

 

Abstract: A number of cyclic imides were synthesized from cyclic anhydrides using ammonium chloride (NH4Cl), and 4-N,N-dimethylaminopyridine (DMAP) or with ammonium acetate (NH4OAc) under microwave irradiation in both a mono-mode and a conventional microwave. Several substituted succinic anhydrides used as reactants were synthesized efficiently by Diels-Alder reactions of maleic anhydride with 1,3-cyclohexadienes in 63-82% for the mono-mode and 72-92% in the conventional microwave ovens. Cyclic imides were synthesized with yields from 50 – 98%.

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cis-3-Azabicyclo[3.2.0]heptane-2,4-dione

 

2006

 

 

Raymond J. Butcher, Yousef M. Hijji, Ellis Benjamin, cis-3-Azabicyclo[3.2.0]heptane-2,4-dione. Acta Cryst. 2006, E62, o1266-o1268.

 

Abstract: The title compound, C6H7NO2, was synthesized from cis-1,2-cyclobutanedicarboxylic anhydride by reaction with ammonium acetate under microwave conditions. The crystal structure of the compound shows that the cyclobutane ring is planar with angles ranging from 89.64 (12) to 90.37 (12). The cis-3-azabicyclo[3.2.0]heptane-2,4-dione molecules are linked into a chain formation through hydrogen N—H...O=C bonds. Parallel packing is seen between two cyclobutane rings related by inversion symmetry.
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Efficient Synthesis of Enaminones and Cyclic Imides Using Ammonium Acetate Under Microwave Conditions.

 

2005

 

 

 

Yousef Hijji, Ellis Benjamin, Melvin Bolden. Efficient Synthesis of Enaminones and Cyclic Imides Using Ammonium Acetate Under Microwave Conditions. Proceedings of the 39th Annual International Microwave Power Institute 2005, p125-128. Seattle, Washington. (July 2005)

 

Abstract:
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Microwave Assisted Efficient Conversion of Anhydrides to Cyclic Imides and N-Methoxy Imides.

 

2004

 


Yousef M. Hijji, Ellis Benjamin. Microwave Assisted Efficient Conversion of Anhydrides to Cyclic Imides and N-Methoxy Imides. The 5th, 6th, 7th, and 8th International Electronic Conferences on Synthetic Organic Chemistry 2004, p1084-1091. Editor(s): Seijas, Julio A.

 

Abstract:

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