Planning tree

Figure 10-11 Planning tree. Used in the earliest stages of a project, the planning tree will normally contain many options, indicated by the or gates.

By the time the park was dedicated in 1941, the CCC had constructed water lines, a modem sewage system, telephone lines, picnic areas, maintenance buildings and park residences. Miles of park roads were improved. Cave tour route trails were constmcted and hiking trails on the surface were established. Thousands of acres of former farmland were reclaimed by controlling erosion, planning trees, and removing hundreds of stmctures and miles of fences. 

Exploration activities are potentially damaging to the environment. The cutting down of trees in preparation for an onshore seismic survey may result in severe soil erosion in years to come. Offshore, fragile ecological systems such as reefs can be permanently damaged by spills of crude or mud chemicals. Responsible companies will therefore carry out an Environmental Impact Assessment (EIA) prior to activity planning and draw up contingency plans should an accident occur. In Section 4.0 a more detailed description of health, safety and environmental considerations will be provided. 

A drawback of this approach is that it typically generates enormous and imwieldy synthesis trees which contain a large number of dead-end branches which are not worth further consideration. Furthermore, the chemist is forced to follow a rigid scheme during the planning process, alternating between the application of transforms, the derivation of new precursors, and again the application of further transforms to these precursors. 

Tree diagrams are an excellent checking device to ensure correct balancing of all chemical equations in a plan. 

Experimental protocol is built into the construction of tree diagrams so that intermediates that are isolated are distinguishable from those that are made in situ, and the order of input dots matches the order of addition of reagents used in the synthesis plan. 

As an illustrated example of these ideas presented thus far we show in Scheme 4.8 and Figure 4.14 the conventional synthesis plan for triclosan and its corresponding synthesis tree diagram. 

Figure 4.14 Synthesis tree for triclosan synthesis plan shown in Scheme 4.8. Molecular weights for each species are shown within parentheses.

Figure 4.19 Synthesis tree for nicotine plan 1 (Craig, 1 933).

Figure 4.20 Synthesis tree for nicotine plan 2 (Spath, 1 928).

Figure 4.21 Synthesis tree for nicotine plan 3 (Lebreton, 2001).

Figure 4.22 Synthesis tree for nicotine plan 4 (Chavdarian, 1982).

Figure 4.23 Synthesis tree for nicotine plan 5 (Helmchen, 2005).

Figure 4.26 Synthesis tree for nicotine plan 8 (Jacob, 1 982).

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