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Organic Chemistry

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Separation, Purification and Structural Analysis of Organic Compounds

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A set of qualitative experiments were conducted in an organic chemistry lab.

Experiment 1

Chemist 1 treated cyclohexene with 1% aq. KMnO4. One of the products was a cis-glycol.

Experiment 2

Chemist 2 conducted qualitative tests for some carbonyl compounds. Aldehydes and ketones gave a positive test for the reagent 2, 4-dinitro- phenyl hydrazine. The compound tested for the confirmation was propanone. The product formed as a result of this test involving propanone is shown below.

image\Ch 32 Experiment 2.png

Experiment 3

In Experiment 3, three compounds were tested. These three compounds were treated with concentrated hydrochloric acid in the presence of zinc chloride (ZnCl2). Compound A was ethyl alcohol, Compound B was tert-butyl alcohol, and Compound C was 2-propanol. The reactions were based on unimolecular substitution mechanism.

Experiment 4

In Experiment 4, the chemists synthesized the following compound.

image\Ch 32 Expirement 4.png

In Experiment 2, which of the following IR peaks must have disappeared after the treatment of the compound with the reagent?

A A broad IR band at 3400 cm-1
B A peak at 1700 cm-1
C A peak at 800 cm-1
D All the above peaks will be present for the product formed as a result of the reaction with the reagent
Ans. B According to the passage, propanone is reacted with the reagent to form a product that lacks the carbonyl group. Note that the compound propanone is a ketone and contains a carbonyl group. But after the reaction, the carbonyl group is not present in the product formed. So the peak that disappeared is the carbonyl peak.

Separation, Purification and Structural Analysis of Organic Compounds Flashcard List

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