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Grignard Puzzle Discussion Pointers

REACTION DIAGRAMS AND MECHANISMS MUST BE INCLUDED IN THIS LAB REPORT!

Pointers for Grignard writeup:

The procedure and characterization this week is routine and should not cause any great difficulty. For this reason, you will be expected to place emphasis on putting together a thorough discussion of the results. Focus on mechanism and the effect of the reaction conditions on the products. It is important to understand the mechanism of formation of each of the products in detail.

Which of the four structures formed under which conditions? You must include the product(s) from both 1:1 and 2:1 reactant ratios (please give proper credit to your lab mate who performed the reaction you did not). Do not forget to interpret the data you used to identify your product. Clearly and concisely explain why each product formed under the reaction conditions and why the other possible products did not. Again, mechanistic detail should be a focus.

Are the products mixtures or are they relatively pure (judge by the relative intensity of spots on a TLC plate and by melting point)? Explain why and use your results to make a qualitative assessment of the relative rates of each of the possible addition reactions.

Provide a detailed mechanism for the formation of all of the possible products. Are there other reaction conditions that might lead to one or more of the products that you did not get? What other reagents might add to chalcone to give these other products (we went over some of these in the Friday lecture)?

One of the four possible structures in your handout is particularly unlikely to form under the reaction conditions (refluxing anhydrous ether). Which one is it, and what is it about the mechanism that makes it particularly unlikely? What change in reaction conditions would you make if you were trying to optimize formation of this product?

REMEMBER TO ALSO CONSULT THE LAB MANUAL FOR FURTHER GUIDELINES ON HOW TO WRITE THIS SECTION!

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