In this experiment, you collected two crops of crystals and were ...

[notis]

In this experiment, you collected two crops of crystals and were given the option of collecting a third crop. The continued heating of the reaction mixture to collect the third and additional crops could be necessary for one of two reasons. First, not all of the starting material had been oxidized after 30 minutes and therefore a longer reaction time was needed. Second, the reaction was complete after 30 minutes; however, the product had not completely evaporated from the reaction mixture. Propose a simple experimental method that would determine which scenario is correct.

Question 2

Write the structure of the product that would be obtained if potassium dichromate in aqueous acid were used for the oxidation.

Question 3

Explain the relative Rf values for the starting material and the product.

[nanny]

Answer to Question 1

The easiest way to determine if the reaction had gone to completion would be to wash a small sample of the Magtrieve mixture with a volatile solvent such as diethyl ether after 30 minutes and then analyze the mixture by TLC versus authentic samples of the starting material and product. If only the product is present, the oxidation is complete, but not all of the product has evaporated. If both starting material and product are present, then the reaction has not gone to completion, assuming an excess of Magtrieve was used.

Answer to Question 2

The product would be the carboxylic acid, because such aqueous-acidic oxidations of primary alcohols lead to an over-oxidized product.

Answer to Question 3

Although both are polar compounds, the alcohol can act as both a hydrogen bond donor and acceptor. The aldehyde can act only as a hydrogen bond acceptor. Therefore, the alcohol will have stronger interactions with the stationary phase resulting in a smaller Rf value relative to the aldehyde.

[notis]

TY

[nanny]

You're welcome