Week 6: Two Student Developed Experiments

Oxidation of Cinnamyl Alcohol using Pyridinium Chlorochromate:

1)      Source(s)

Experiment #14 in Mohrig, J. R. “Modern projects and experiments in organic chemistry: Miniscale and standard taper microscale.” (2003) New York; Basingstoke: W.H. Freeman; Palgrave Macmillan.

2)      Changes to published procedure

○We did not visualize the TLC with p-anisaldehyde.

○We did not pre-mix the PCC, NaOAc, and molecular sieves.

○We stopped the reaction after one hour.

○We used hexane instead of pentane in the column chromatography solvent mixture.

3)      Positive

+This is a reaction we are learning in the lecture section.

+The reactant and product smell nice.
+Column chromatography is an important technique

4)      Neutral

±The lab is very TLC intensive. The TLC solvent system should be optimized to give clear indication of what it happening.

±Could a substitute for ethyl ether in the reaction work-up be used?

±GC chromatogram shows that there is an appreciable amount of unreacted alcohol present.

5)      Negative

6)      Inquiry & Extension ideas.

●Versatile reaction: Many different substrates can be envisioned such as benzyl alcohol, hydrocinnamyl alcohol, or substituted cinnamyl alcohol derivatives.

●Could be explored by leaving out reagents such as NaOAc or molecular sieves. What would be the effect of running the reaction longer or refluxing?

●Could be compared and contrasted with other oxidation methods.


 

Synthesis of a Tertiary Alcohol Using a Pre-Made Grignard Reagent

1)      Source(s)

Michael A. G. Berg and Roy D. Pointer. J. Chem. Educ. 2007, 84, 483.

2)      Changes to published procedure

○We changed the configuration of the reaction vessel. Instead of a three-neck round bottom, we used a single-neck round bottom with a Claisen adapter to accommodate a separatory funnel and condenser.

○We had no special treatment of the Grignard reagent other than measuring it from the bottle with a syringe.
○We had no special treatment of the dried glassware.

○We set the addition time to 30 minutes.

○We gave more specific directions for acidification, extraction with ether, back extraction of ether with sodium bicarbonate, drying, and recrystallization.

3)      Positive

+We are learning this reaction in the lecture section. The acid work-up is especially instructive since this concept comes up a lot in reactions.

+Using a commercially available pre-made Grignard is a great idea.
+The reaction turns pink! Very nice. Is it the Mg(OH)2?

+experience with an air & water sensitive reaction is important.

4)      Neutral

±Is a there a possibility of using an alternative to ethyl ether for the extracions?

±Triphenylmethanol has poor solubility in practically every solvent.

±Triphenylmethanol is difficult to remove from the round bottom.

±Determining if the two-phase aqueous work-up is a little tricky.

±TLC system should be optimized.

5)      Negative

-Grignard solution is unstable. Buy a fresh bottle for each lab period.

6)      Inquiry & Extension ideas.

●Versatile reaction: Many different carbonyl substrates can be envisaged. The JCE article suggests acetophenone and 4-chlorobenzophenone in addition to benzophenone.

●Further modification of the alcohol could be performed.

●Qualitative test to confirm the presence of a tertiary alcohol.

Pink Grignard

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