Novel Surfactant Catalyst Under Microwave Irradiation

Transcription

1 Novel Surfactant Catalyst Under Microwave Irradiation Ellis Benjamin a, Shannon Hutson a, Tony James a, Christopher Saito a, James Shelton a, Ebony Love a, Jessica Lack a, Yousef Hijji b, Earl Benjamin a. (a) Department of Chemistry and Physics, Arkansas State University, PO Box 419, State University, AR (b) Department of Chemistry, Morgan State University, 1700 E. Cold Spring Lane, Baltimore, MD Corresponding Author: Ellis Benjamin ABSTRACT: Microwave organic chemistry is a green chemical method that improves reaction conditions and product yields, while reducing solvent amounts and reaction times. Although microwave syntheses can decrease the amount of harmful pollutants, little attention has focus on the search for novel eco-friendly catalysts used in microwave reactions. Surface active agents, also called surfactants, are amphiphilic molecules that have the ability to be both catalytic and biodegradable making them an eco-friendly alternative to harmful catalyst commonly used. Although surfactants have been used as catalysts in conventional reactions, no literature has been cited which uses catalytic surfactants in microwave organic synthesis. INTRODUCTION: Although many microwave syntheses are found throughout the literature, little attention has been paid to finding eco-friendly catalysts that can work under microwave conditions. Catalyst such as ruthenium, zinc chloride, nickel, iron, and activated carbon have been used to catalyze microwave syntheses. 1-3 Often these catalyst are toxic to both environmental and biological systems.8-12 The search for environmentally friendly catalyst has the ability to make microwave chemistry closer to the low cost, high yield, non-toxic technique desired by most organic chemist. One series of molecules that have been overlooked as possible microwave catalyst are surfactants. Surface active agents, also called surfactants, are amphiphilic molecules that contain both a hydrophilic head and hydrophobic tail(s) which are widely used industrial manufacturing processes. Surfactants maintain many beneficial characteristics that can be exploited under microwave conditions. Specifically, surfactants can be easily modified to be catalytic, biodegradable, charged or uncharged, thermally stable, metal chelating, and non-toxic while being able to form micelles or reverse micelles. Although these characteristics theoretically make surfactants eco-friendly catalysts, little to no literature can be found to determine their catalytic properties under microwave

2 irradiation. The ability to use surfactant as novel catalyst is highly desirable for many industries that are current using toxic catalysts. This work used a series of 5 surfactants to determine their catalytic properties. Previous studies for the synthesis of phthalimide using phthalic anhydride with ammonium chloride found that no product was found under microwave conditions. This was attributed to the lack of a catalyst with studies testing times below 30 minutes with no product formation. The addition of the base catalyst N,N-Dimethyl aminopyridine (DMAP) found percent yield in the CEM microwave. A series of 5 surfactants (Cetyl Trimethyl Ammonium Bromide (CTAB), Decanol, Hexanol, Trition X100, and Sodium Dodecyl Sulfate (SDS)) were tested as catalyst in this reaction. Two ionic surfactants CTAB and SDS were chosen. SDS maintains a negative charge and CTAB a positive charge. Three non-ionic surfactants were chosen hexanol, decanol, and TritionX100. Materials and Methods: All chemicals were purchased from Sigma-Aldrich and used without further purification. All syntheses were done in a CEM Discover microwave Percent yields were determined by GCMS (Varian CP 3380 Gas Chromatograph and a Saturn 2000 Mass Spectrometry). Results:

3 Percent of Phthalimide Phthalimide (%) Series of Surfactants Series Supercontrol (No DMAP) Control (DMAP CTAB Decanol Hexanol Triton X100 SDS Surfactants Graph 1. Percent Yield of a Series of Surfactants with a Super and DMAP Control 1.00 Phthalimide Synthesis using CTAB CTAB (Grams) Graph 2. Percent Yield of Phthalimide using CTAB as a Catalyst

4 Phthalimide (%) Percent of Phthalimide using CTAB and DMAP (Cocatalyst) Control CTAB (Grams) Graph 3. Percent Yield of Phthalimide using CTAB and DMAP as Cocatalyst Conclusion: We determined that surfactant can function as catalyst in microwave reactions. General: Phthalimide: MS m/z: 147 (M +) 104, 76, Raner, K. D.; Strauss, C. R.; Trainor, R. W.; Thorn, J. S. A New Microwave Reactor for Batchwise Organic Synthesis. The Journal of Organic Chemistry 1995, 60, Bargiggia, F. C.; Murray, W. V. Cross-Metathesis Assisted by Microwave Irradiation. The Journal of Organic Chemistry 2005, 70, Lou, J.; Hatton, T. A.; Laibinis, P. E. Effective Dielectric Properties of Solvent Mixtures at Microwave Frequencies. Journal of Physical Chemistry A 1997, 101, Santagada, V.; Frecentese, F.; Perissutti, E.; Fiorino, F.; Severino, B.; Cirillo, D.; Terracciano, S.; Caliendo, G. Efficient Microwave Combinatorial Parallel and Nonparallel Synthesis of N-Alkylated Glycine Methyl Esters as Peptide Building Blocks. Journal of Combinatorial Chemistry 2005, 7,

5 5. R. J. Butcher, J. P. Jasinski, E. Benjamin, Y. M. Hijji, E. Benjamin. 5-Hydroxy-4- methyl-4-azatricyclo[ ,6]undec-8-en-3-one. Acta Cryst. 2007, E63, o Yousef M. Hijji and Ellis Benjamin. Efficient Microwave Assisted Syntheses of Unsubstituted Cyclic Imides. Heterocycles. 2006, 68(11), p Data from Aldrich Chemical Company (Commerically available)