why does annomerism occur in the 2nd carbon of ketones?
Answers
Explanation:
Monosaccharides, the simplest carbohydrates, are aldehydes or ketones that have two or more hydroxyl groups; the empirical formula of many is (C-H2O)n, literally a “carbon hydrate.” Monosaccharides are important fuel molecules as well as building blocks for nucleic acids. The smallest monosaccharides, for which n = 3, are dihydroxyacetone and d- and l-glyceraldehyde.
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They are referred to as trioses (tri- for 3). Dihydroxyacetone is called a ketose because it contains a keto group, whereas glyceraldehyde is called an aldose because it contains an aldehyde group. Glyceraldehyde has a single asymmetric carbon and, thus, there are two stereoisomers of this sugar. d-Glyceraldehyde and l-glyceraldehyde are enantiomers, or mirror images of each other. As mentioned in Chapter 3, the prefixes d and l designate the absolute configuration. Monosaccharides and other sugars will often be represented in this book by Fischer projections (Figure 11.1). Recall that, in a Fischer projection of a molecule, atoms joined to an asymmetric carbon atom by horizontal bonds are in front of the plane of the page, and those joined by vertical bonds are behind (see the Appendix in Chapter 1). Fischer projections are useful for depicting carbohydrate structures because they provide clear and simple views of the stereochemistry at each carbon center.