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How to Understand a Skeleton Diagram Pacific College of Oriental Medicine — Winter 2009 Mark Kuebel, L.Ac.; MS Traditional Chinese Medicine; BA Biological Sciences. Typical Skeleton Diagram.
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How to Understand a Skeleton DiagramPacific College of Oriental Medicine — Winter 2009 Mark Kuebel, L.Ac.; MS Traditional Chinese Medicine; BA Biological Sciences
Typical Skeleton Diagram • As a shorthand in organic chemistry, since we are dealing with carbon and hydrogen (hydrocarbons) so frequently, their presence is “understood” or hidden in skeleton diagrams. This simplifies the diagrams, and allows them to be readable. Cholesterol
Typical Skeleton Diagram • A line is a bond. Two lines that converge at an angle form an elbow. • The crux of an an elbow with no element indicated is always a carbon atom. • Carbon always has 4 bonds, always. • If the carbon (at the elbow) is bonded to an oxygen, nitrogen or other element besides hydrogen or carbon, the element will be indicated by a letter. • If the carbon (at the crux of the elbow) is bonded to another elbow, that is a carbon-to-carbon bond. • Count the number of bonds to the carbon at the elbow. If it does NOT add up to 4, the other missing bonds are bonds to hydrogen. The hydrogen and its bond are left out.
H Typical Skeleton Diagram H H C Carbons have 4 bonds, and they are always filled. H and C are hidden to keep down clutter The H bond ( — ) is also hidden H C C H H H H C H Indicates bond is 3-Dleaning behind the main molecular plane C Indicates bond is 3-D leaning in front of the main molecular plane H
Typical Skeleton Diagram • R- Groups • Frequently, for shorthand purposes, an “R-” is placed in a skeleton diagram to indicate that some chemical group is attached to the atoms in question, but it is not important to see or know what that chemical group is. • Occasionally, when looking at a molecule, there will be an R- and an R'- (R-prime) which indicated 2 different R groups.