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Variable Points of Attachment in Structure Drawing

A Variable Point of Attachment (VPA) lets you draw a query with a substituent on a ring where the attachment point on the ring is one variable. For example, if you are interested in pyridine with chlorine attached at the 1, 2, or 3 positions, draw a VPA.


Select two or more (maximum 20) nodes in a single ring system, along with a node in a substituent fragment. Then click Draw > Variable Points of Attachment. A bond is drawn from the fragment to the center of the ring system. To see the specific attachment points on the ring, click Display > Show VPA.

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