1 / 12

MiniQuiz 2 Questions:

MiniQuiz 2 Questions:. a) Write the structure of the radical formed when Br . radical reacts with ethyl benzene. b) Why is there no radical formation in the beta position of ethyl benzene?. Today: Diels-Alder (cont.) Esterification (Exp.5) MiniQuiz. Diels-Alder Reaction.

faolan
Télécharger la présentation

MiniQuiz 2 Questions:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MiniQuiz 2 Questions: a) Write the structure of the radical formed when Br. radical reacts with ethyl benzene. b) Why is there no radical formation in the beta position of ethyl benzene?

  2. Today: • Diels-Alder (cont.) • Esterification (Exp.5) • MiniQuiz

  3. Diels-Alder Reaction The Diels-Alder reaction requires a 1,3-diene and a dienophile. The Diels-Alder reaction involves a 1,4-addition of an alkene to a 1,3-diene in an electrocyclic reaction (a “cycloaddition”). 4 1 D.-A. adduct The 1,3-diene must be in s-cis conformation The dienophile is an alkene; it is most reactive if EWG’s are attached

  4. Diels – Alder Reactions Which of the following dienes would be most reactive? why? 1,3-cyclopentadiene, 1,3-butadiene (see problems on Report Form) Which of the following dienophiles would be more reactive? Ethene or maleic anhydride

  5. Diels – Alder Reactions (Exp.4) Which structural feature is always formed as the result of Diels-Alder reactions?

  6. Diels – Alder Reactions Synthesis of Natural Products D C A B

  7. CH3 CH3 D C CH3 CH3 A B HO Cholesterol

  8. Diels – Alder Reactions Reaction equations for our experiment: Retro Diels Alder:Cracking of dimer Diels Alder: Reaction of 1,3-cyclopentadiene with maleic anhydride Hydrolysis of Diels-Alder product Dimer D.-A. adduct Cis endo • Compare: • Polarity of I versus II • Mp. of I versus II

  9. Diels Alder The H-NMR of the dimer of 1,3-cyclopentadiene (dicyclopentadiene) is quite complex, with many signals. In contrast, the proton NMR of our Diels-Alder product is simple, with few signals; the same is true for its hydrolysis product. How can you explain this?

  10. Exp.5:Methyl Benzoate Synthesis(first step for Exp.6 Grignard) You will heat your reaction under reflux for 1 hour! Do Practice Problems, calculations … • In order to increase the yield of the ester, which of the following would help? • use an excess of methanol • use an excess of conc. sulfuric acid • Calculations …! Why sulfuric acid and not HCl?

  11. Esters and Esterifications • General properties of esters? • Compare the boiling points of carboxylic acids and esters of similar molecular weight and explain. • Examples of esters in biological systems?

  12. Next time: Conclusion of “Esterification” (Exp. 5) Grignard reactions (Exp. 6) MiniQuiz on today’s lab lecture!

More Related