Schotten baumann reaction pdf

Acetic anhydride is somewhat weaker than acetyl chloride as a reagent, but is less corrosive and reacts with amines quite readily. It also produces only acetic acid as a byproduct, which is biodegradeable. However, it must be handled with gloves in a hood, as it can cause a deep burn to the skin and lungs. It also has a strongly disagreeable vinegarlike odor.

Results and Discussion The amine as commercially available is not quite pure, so it is converted to the hydrochloride by dissolution in aqueous HCL and treated with charcoal to remove colored impurities. The filtered solution containing the purified amine is then sufficiently pure to use in the acetylation reaction. Adding the acetic anhydride and sodium acetate begins the acetylation reaction.

According to the literature for the acetylation of aniline, this as all that is necessary to complete the reaction, but in our hands, the reaction was not complete after 2 hours. The amide was purified by extraction of the solution with ethyl acetate and evaporation. In this way any of the very soluble starting materials acetic anhydride, aminopyridine and byproducts acetic acid are left in the aqueous waste. Removal of the solvent by rotary evaporation yielded a white solid which was not quite pure by melting point and was found to have a small amount of solvent remaining and a minor impurity which was not identified.

The Schotten-Baumann procedure is very mild and is done in a water solvent which is environmentally friendly. The reagents used are mild and biodegradeable, although acetic anhydride must be handled carefully. Acknowledgements We wish to thank Dr. Richard Kjonaas for helpful discussions regarding the mechanism of the reaction.

We also thank our labmates, Lester Flatt, who helped with using the vacuum pump and Earl Scruggs who helpe with ChemDraw. Experimental Section: General: All solvents and reagents were commercially available and used as received..

Melting points are uncorrected. Thin layer chromatography was performed using manually cut E-Merck silica gel plates with fluorescent indicator and visualized with UV light and stained using ninhydrin. Coupling constants are reported in Hz.

Infrared spectra were recorded on a MIDAC single-beam instrument in percent transmittance mode and are absorptions are reported in wavenumbers. Approximately mg microspatulaful of activated charcoal was added and the solution was vacuum filtered on a Hirsch funnel into a 50 mL Ehrlenmeyer flask, removing most of the color. Acetic anhydride 2. This resulted in slight precipitation of I, which persisted for some time. After 1. At 2 hours, an additional 2 mL of Ac2O was added.

An additional 2 mL of Ac2O was added, and the mixture was allowed to stir overnight at room temperature. The reaction was worked up by saturation of the solution with sodium bicarbonate and extraction with 5 x 10 mL of EtOAc. The combined organic extracts were washed with 50 mL of brine, dried over Na2SO4, and stripped of solvent to afford an off white solid. Yield 1. Mp oC, lit. GC Retention time 7.

References 1. Greene, T. Protective Groups in Organic Chemistry, 3rd Ed. Williamson, K. Organic Experiments 9th Ed. Usually, aqueous NaOH is used as the base catalyst, but pyridine also can be used in this reaction. Related Chapters Aldol condensation. Benzoin Condensation. Beckmann Rearrangement. Cannizzaro Reaction. Clemmensen Reduction. Claisen condensation. Friedel-Crafts alkylation. Friedel Crafts Acylation. Fries Rearrangement. Gattermann-Koch Reaction. Grignard Reagent.

Hell-Volhard-Zelinsky Reaction. Hunsdieker reaction. Hoffmann Bromamide Degradation. Jones reagent. Kolbes Reaction. Knoevenagel Reaction.