Pinacolone is:A. 2-3-dimethyl-2, 3-butanediolB. 3,3- dimethyl-2butanoneC. 1-phenyl-2-propanoneD. 1,1-diphenyl-1, 2-ethanediol

To solve the question regarding the structure of Pinacolone, let’s first understand what Pinacolone is. Pinacolone is the product of the rearrangement of pinacol and can be classified as a ketone.

Steps to determine the correct answer:

Identify the structure of Pinacolone:

Pinacolone is known chemically as 3,3-dimethyl-2-butanone. Its structure includes a ketone functional group (C=O) located on the second carbon of a four-carbon chain, with two methyl groups attached to the third carbon.
Analyze the answer options:

A. 2,3-dimethyl-2,3-butanediol: This compound contains two alcohol (hydroxyl) groups and is not a ketone.
B. 3,3-dimethyl-2-butanone: This matches the structure of Pinacolone perfectly, as it describes a ketone with two methyl groups on the third carbon.
C. 1-phenyl-2-propanone: This compound has a phenyl group, and its structure is not that of Pinacolone.
D. 1,1-diphenyl-1,2-ethanediol: This is also not a ketone and has alcohol functional groups.
Conclusion:

Given the identification of Pinacolone as 3,3-dimethyl-2-butanone and the analysis of the provided options, the correct answer is B. 3,3-dimethyl-2-butanone.
Summary:
Pinacolone is 3,3-dimethyl-2-butanone, which is a ketone, and therefore the answer is B.