Reaction rule

After the definition of a reaction type, a scheme for the evaluation of the given reaction type can follow in the reaction rule. An entire hierarchy of evaluations can be implemented, from no evaluation at all to a full-fledged estimation of reaction kinetics [12 ... 

Inspection of Table 6.1 shows the following rule for electrophobic reactions Rule Gl A reaction exhibits purely electrophobic behaviour ((dr/dO)PA 0) when the kinetics are positive order in the electron donor (D) reactant and negative or zero order in the electron acceptor (A) reactant. 

Eastman, R. H., 158, 166 Eaton, P. F., 460 Eigen, M., 80 Eisenberg, W., 125 Electrocyclic addition, 46 Electrocyclic reaction rules, 339 Electrocyclic reactions, 402,408 4n-examples, 408 (4n + 2)-examples, 410 Electron impact spectroscopy, triplet energy, 220-223 Electronic energy transfer, 267 Electronic integral, 21 Electronic transitions /-a ,16 n -Mr, 16... 

In this model, run on a square grid, each unit can adopt one of N states, 0, 1, 2, 3,..., (N - 1) states other than 0 are "excited states." The neighbors are those cells that share an edge with the target cell (a von Neumann neighborhood). The transition rules can be divided into two types first we have reaction rules ... 

SYNLMA performs a retrosynthetic analysis using a special purpose theorem prover built from LMA components. The compound to be synthesized becomes a theorem to be proved. The reaction rules and starting materials become axioms. The choice of a knowledge representation has been one of our greatest problems. 

Our present reaction rule database is made up of approximately one hundred rules adapted from a microfiche generously sent to us by Gelernter (4). For a given reaction, a rule specifies the reactants (subgoal) and the product(s) (goal), in connection table format and any constraints on their composition (Figure 2a). The rules are identified by chapter and schema numbers. The connection tables are organized as follows ... 

Each goal or subgoal clause is terminated with the predicate Rxnrule whose first argument is a reaction rule identification number. After this number, the predicate uses the function LL (for linked list) to list all the atoms in the connection table. 

Figure 2b. Clause representation of the goal and subgoal in reaction rule Chapter 20, Schema 2.

The success of SYNLMA shows that it is possible to base an expert system on a theorem prover. The advantage of using a theorem prover as deductive component is that it allows us to experiment with a number of different representations for chemical information. The same flexibility makes it easy to add new starting materials and reaction rules from large commercial online databases. 

In Lipmann s original scheme group Y was visualized as adding to a carbon-carbon double bond to initiate the sequence. Isotopic exchange reactions ruled out the possibility that either ADP or P might serve as Y, but it was attractive to think that a bound phosphate ion, e.g., in a phospholipid or coenzyme, could be involved. Y B of Fig. 18-12 would be similar in reactivity to an acyl phosphate or thio-ester. However, whatever the nature of Y B, part of group Y would be left attached to B after the transfer of Y to X. For example, if Y were Y OH... 

We now introduce a general treatment of rate of reaction, which is often called the absolute reaction rule theory, because its purpose is to calculate the rate in terms of molecular quanlilies only. ... 

For an ionic reaction, rule 2 becomes a nucleophile (electrophile) reacts preferentially with the reaction partner having the lowest-lying LUMO (highest-lying HOMO). The validity of this rule is examined on p. 75... 

The efficiency of /-elements in catalysis originates from unconventional electrophilic pathways. In contrast to rf-elements oxidative addition/reductive elimination sequences are not accessible. Instead, substrate adduct formation, ligand exchange and insertion reactions rule the mechanistic scenarios. Therefore, the main emphasis is put on the fine-tuning of the spectator ligand of the precatalyst. 

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