Identification of Alcohols and Phenols

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UNKNOWN: Secondary Alcohol

Discussion:

Several Tests were done on the samples: 1-butanol, 2-butanol, 2-methyl-2-propanol, phenol and an unknown to identify which are alcohols and phenols and differentiate them from one another.

The physical properties test were -done to test the solubility of the samples in water. The alcohols which are 1-butanol, 2-butanol and 2-methyl-2-propanol, and the unknown resulted positive. The phenol however was somehow partly immiscible. This is because it varies significantly from the other alcohols because it possesses an aromatic ring structure that can affect the polarity of the overall molecule. The acidity of a molecule is a chemical property and was tested through the pH paper by pouring drops onto it. As stated in the above table (page 3, Table A.) the resulting pH of the following samples are just examples. From this, the unknown can be suspected either as a phenol, secondary alcohol or a tertiary alcohol.

For the chemical properties test, first that was done was the Iodoform test. No samples responded positive to this test and that is as should be since this test is for alcohols with the part structure –CH3CHOH, and none of the samples have that part structure. Next, was the Lucas test, all the samples tested positive that resulted to cloudiness except for the primary alcohol which is 1-butanol. And that is a positive result because this test is used to distinguish water-soluble primary alcohols from secondary and tertiary alcohols. Next was the Chromic Acid test. Positive test resulted to a dark brown color rather than a blue-green color because it required more time to react and turn to blue-green color. The 1-butanol and 2-butanol along with the unknown tested positive. 2-methyl-2-propanol tested negative since it is a tertiary alcohol and the phenol tested false positive, a phenol does contain a secondary carbon however according to the description of the test, it does not specifically states what happens to a phenol in this test. Last test performed was the Iron (III) chloride test, which is only for phenols and as expected, only the phenol tested positive since it was the only sample that changed color into violet.

Conclusion

The unknown tested positive in Lucas and Chromic acid test and responded similarly like 2-butanol.

From the above data results and observations, it can be concluded that the unknown is a secondary alcohol.

References:

Laboratory Manual

http://www.laney.edu/wp/cheli-fossum/files/2012/01/6-Alcohols-and-Phenols.pdf. Retrieved December 8, 2016