Organic Chemistry MCAT Practice Exam

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Master Organic Chemistry for the MCAT. Use flashcards and multiple choice questions to understand concepts, with each question offering hints and detailed explanations. Prepare effectively for your exam!

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Which of the following compounds is known as a thiol?

Ethyl alcohol
Thiophenol
Acetic acid
Acetone

The correct answer is: Thiophenol

Thiol compounds are characterized by the presence of a thiol group, which is a sulfur-containing functional group denoted by –SH. Thiophenol is specifically an aromatic thiol where the thiol group is directly attached to a phenyl ring. This makes it a classic example of a thiol, distinguishing it from the other options that do not contain an –SH group. Ethyl alcohol, also known as ethanol, has a hydroxyl (–OH) functional group instead of a thiol group, making it an alcohol. Acetic acid contains a carboxylic acid group (–COOH), and acetone is a ketone characterized by a carbonyl group (C=O). None of these functional groups support the definition of a thiol, further emphasizing why thiophenol is the correct choice in this context.