Multiple Choice
How many chiral centers are present in the structure of ?
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5. Chirality
Chirality
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How many chirality centers are present in a -ketohexose molecule?
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Verified step by step guidance1
Step 1: Understand the structure of a 2-ketohexose. A hexose is a six-carbon sugar, and a 2-ketohexose has a ketone functional group at the second carbon (C-2). The general formula is C6H12O6 with a ketone at C-2.
Step 2: Draw the carbon chain of the 2-ketohexose, labeling carbons from 1 to 6, with the ketone group (=O) at carbon 2. The rest of the carbons (C-3 to C-6) will have hydroxyl (–OH) groups and hydrogens attached.
Step 3: Identify chirality centers by looking for carbons bonded to four different groups. The ketone carbon (C-2) is not chiral because it is double bonded to oxygen and bonded to two carbons, so it has only three different substituents.
Step 4: Examine carbons 3, 4, 5, and 6. Typically, in a 2-ketohexose, carbons 3, 4, and 5 are bonded to –OH, –H, and two different carbon groups, making them chiral centers. Carbon 6 is usually a terminal –CH2OH group and is not chiral.
Step 5: Count the number of chiral centers identified (usually 3 for a 2-ketohexose) and confirm that these are the only stereogenic centers in the molecule.
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