Decision Point Recognition

In Chapter 4 the decision to ionize or not to ionize the leaving group was part of your ability to predict whether the first step in an El or Sjsjl would proceed. Several other similar decisions are collected in this chapter. The most difficult choice is between a species serving as a nucleophile or as a base (Section 9.5). Other decisions are basically a choice of regiochemistry (Sections 9.3, 9.4, 9.6). One (Section 9.2) is a question of extent of reaction stop or keep going. Another (Section 9.7) is the competition between internal reactions and external ones. The last (Section 9.7) is the competition between nucleophilic trapping and cation rearrangement. 

The most important question that you must continually ask yourself when examining any step in a process that has known and unknown branch points is. What else can happen This may seem to add complexity, but it is the essence of critical thinking. Obvious routes often do not work and therefore lead to frustration and the question, Where did I go wrong The answer is usually, You forgot to watch for alternative routes and proceeded with the first idea that occurred to you.  

Draw out every step of the process and look for alternative routes from each step try to find at least one alternative for each step. For hints check resonance forms, proton transfer, alternative sources and sinks, less likely combinations, and higher-energy species. Specifically look for the more obvious decision points covered in this chapter. 

If you find that you habitually miss a decision point or two, then a good idea would be to make up a checklist of reminders until new habits form. Refer to this checklist whenever you are working a problem. Continue to personalize this checklist by adding reminders to watch for common errors that you find yourself repeating. 

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Performance is said to be at either a skill-based or a rule-based level when tasks are routine in nature. Skill-based performance involves the smooth, automatic flow of actions without conscious decision points. As such, skill-based performance describes the decisions made by highly trained operators performing familiar tasks. Rule-based performance involves the conscious perception of environmental cues, which trigger the application of rules learned on the basis of experience. As such, rule-based performance corresponds closely to recognition-primed decisions (Klein 1989). The... 

Particle shape analysis can be carried out using pattern recognition techniques [11-14] in which input data are categorized into classes. The potential use of these techniques [15] and the use of the decision function in morphological analysis have been introduced. There are two points... 

With the recognition that opposite faces of the cube point to conceptual pairs of the kind emphasized in the magical tradition, we come to the startling conclusion that contemporary science has by no means discarded any of the earlier three traditions. Although the general opinion still holds that the mechanical tradition decisively conquered and dispensed with the organic viewpoint while the magical tradition is not even considered worthy of mention, an analysis of the six concepts demonstrates that the three traditions are very much alive (Benfey 1982). 

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