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complete reaction implies many subreactions, such<br />

as:<br />

(B) (D) and (A) (B).<br />

Reaction Centers<br />

The most important part of a reaction is the part<br />

that actually changes from the reactants to the<br />

products. This part, which probably includes a<br />

number of atoms and bonds, is called the reaction<br />

center. For example, only the bold bond below (and<br />

the two atoms on either side) is part of the reaction<br />

center. The rest of the structure is unchanged from<br />

the reactant to the product:<br />

By default, ChemFinder considers reaction centers<br />

whenever you search for reactions. ChemFinder<br />

assumes that any atoms and bonds that change in<br />

the query must be part of the reaction center of the<br />

target.<br />

For example:<br />

does not hit<br />

O<br />

F Cl F Cl<br />

F<br />

Cl<br />

OH<br />

compound. If you deselect the Reaction query must<br />

hit reaction center preference, this query hits the<br />

target above.<br />

When creating reaction queries, it is important to<br />

consider what sort of information you are really<br />

looking for. Suppose you want to convert n-decanal<br />

to n-decanol:<br />

Are you really interested only in these two<br />

compounds? You might be interested in any<br />

reaction that converts a straight-chain aldehyde to<br />

the alcohol:<br />

H<br />

H<br />

H<br />

O<br />

Since the corresponding n-octanal n-octanol<br />

reaction would probably occur under very similar<br />

conditions, it is a reasonable thing to look at.<br />

Generally, you want to use substructure queries that<br />

include little beyond the reaction center in question<br />

when you are searching for reactions.<br />

O<br />

OH<br />

H<br />

H<br />

H<br />

OH<br />

ChemFinder<br />

O<br />

F Cl F Cl<br />

when the Reaction query must hit reaction center<br />

preference is selected. Even though there is a C-F<br />

bond in the target reactant and a C-Cl bond in the<br />

target product, these bonds do not participate in the<br />

reaction, which really affects another part of the<br />

OH<br />

NOTE: ChemFinder supports several query properties to<br />

allow you to specify exactly how a bond participates in a<br />

reaction center. For more information about these properties,<br />

see “Setting Search Details Preferences” on page 327.<br />

Atom-to-Atom Mapping<br />

The second most important part of reaction<br />

searching is the atom-to-atom map. You can<br />

specify maps in ChemDraw, where they are stored<br />

<strong>ChemOffice</strong> 2005/ChemFinder Searching • 323<br />

Reaction Searches

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