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Diels-Alder Reaction: The Synthesis of an “exo-exo” alkene. Group 1:. Ian. Nick. Jamie. Lauren. History Of the Diels-Alder Reaction. Was first discovered in 1928 by two German chemists, Otto Diels and Kurt Alder
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Diels-Alder Reaction: The Synthesis of an “exo-exo” alkene
Group 1: Ian Nick Jamie Lauren
History Of the Diels-Alder Reaction • Was first discovered in 1928 by two German chemists, Otto Diels and Kurt Alder • Their find was important because its reaction’s chemistry advanced the understanding of organic reactions • Later, this find won them the Nobel Prize.
General Information • Useful in organic synthesis because of the two carbon-carbon bonds it forms in one step • When the diene and dienophile are cyclic, it is possible to form two products with different geometries, called exo- and endo- adducts • Most commonly, this reaction takes place in a closed container at an elevated pressure and temperature because dienes and dienophiles are usually gases.
General Information Continued • The dienophile gets its name because of its ability to react with the diene General Information: Esterification • It gets its name from an ester as the product from the reaction
Real World Uses for the Diels-Alder and Esterification Reactions • The Diels-Alder reaction helps to create more useful products and solvents • An esterification reaction helps to make biodiesel
Materials • Maleic Anhydride Hazards: Harmful if swallowed, inhaled or absorbed through the skin. Corrosive- causes burns. Irritant. Uses- Motor oil additives, hair spray, pharmaceuticals, and artificial sweeteners Molecular Formula: C4H2O3 Molar Mass: 98.058 g/mol Melting Point: 52.8-60°C (226K) Boiling Point: 200°C (475K) Density: 1.314g/cm 3
Materials Continued Hazards: Extremely flammable liquid and vapor. Vapor may cause flash fire. May form explosive peroxides. Harmful if swallowed or inhaled. Causes irritation to skin, eyes, and respiratory tract. Affects central nervous system. Uses- Degreaser • Tetrahydrofuran Molecular Formula: C4H8O Molar Mass: 72.11g/mol Melting Point: -108.4°C (164.75K) Boiling Point: 66°C (339.15K) Density: 0.886 g/cm3 @ 20°C
Materials Continued • Furan Molecular Formula: C4H4O Molar Mass: 68.07 g/mol Density: 0.936 g/mL Melting Point: -85.6°C Boiling Point: 31.4°C Hazards: Extremely flammable. Vapor and air mixtures are explosive. Cough. Sore Throat. Redness to the skin. Furan is used in making adhesives. Ex- Flooring adhesives
Materials Continued • Methanol Hazards: Vapor harmful. May be fatal or cause blindness if swallowed. Harmful if inhaled or absorbed through skin. Cannot me made nonpoisonous. Flammable liquid and vapor. Causes irritation to skin, eyes, and respiratory tract. Affects the central nervous system and liver. Uses- Fuel and the making of other chemicals. Molar Mass: 32.04 g/mol Density: 0.791 g/cm3 Melting Point: -98°C (176K) Boiling Point: 64.6°C (337.8K)
Materials Continued • Hydrochloric Acid Hazards: Corrosive. Liquid and mist cause severe burns to all body tissue. May be fatal if swallowed or inhaled. HCL has many uses such as in the process of making fertilizers and dyes, used in pickling, cleaning of metal products, and is used in the rubber industry. Molar Mass: 36.46 g/mol (HCl) Density: 0.909 g/cm3, 37% solution Melting Point: -114.24°C Boiling Point: -85.06°C
Overall Reactions: Day 2: Day 1:
DAY 1 OBSERVATIONS • Maleic Anhydride (left) was a white crystalline solid packed into large pieces • Solid was broken up into a fine powder. • Exactly 5 grams was added to the 25-mL round bottom flask (w/ stir bar). Image courtesy of global-b2b-network.com
DAY 1 OBSERVATIONS • Tetrahydrofuran (THF) was a clear liquid. • 15-mL THF added to Maleic Anhydride • Result = cloudy liquid • Solution became clear with agitation. Image courtesy of piercenet.com
DAY 1 OBSERVATIONS • Furan was a transparent liquid with a slight yellow tint. • 3.3-mL Furan added to solution. • Result = solution became slightly yellow. Image courtesy of lgl.bayern.de
DAY 1 OBSERVATIONS • Flask was sealed with a septum. • Copper wire was attached to septum to add security. • Flask was allowed to sit undisturbed from 7/18 to 7/23.
DAY 2 OBSERVATIONS • Large semi-transparent white crystals were recovered after washing and filtration w/ THF. • 5.008 g recovered (M.P. 108.1-108.6oC) • Lit. values = 4.7 g (M.P. 116-117oC)
DAY 2 OBSERVATIONS • Product was mixed in 10-mL methanol (clear liquid). • Product did not dissolve completely. • 0.5-mL concentrated HCl was added causing no change.
DAY 2 OBSERVATIONS • Solution was refluxed for 2 hours using a water condenser. • As the solid dissolved, heat had to be increased to maintain reflux. • During course of reflux, solid completely dissolved.
DAY 2 OBSERVATIONS • Following reflux, the solution was cooled to room temperature. • No solid was obtained following filtration and immersion in an ice bath. • Solution was allowed to sit for an additional 48 hours.
DAY 3 OBSERVATIONS • After 48 hours, still no product formation. • Solution was placed in the roto-vac and still no product was formed. • Esterfication reaction failed.
DISCUSSION OF RXN 1 • First reaction was a Diels-Alder reaction of a diene (Furan) and a dienophile (Maleic Anhydride). • Crystal formation indicated a successful reaction. • Yield higher than literature value probably due to slight presence of impurities.
DISCUSSION OF RXN 2 • Second reaction was a Fischer Esterfication reaction of the product from RXN 1 and methanol using concentrated HCl as a catalyst. • No product formation indicated failure of reaction.
RXN 2 Failure • The failure of RXN 2 was most likely due to an under-concentration of HCl. • An under-concentration of HCl would have only partially catalyzed the reaction.
