Branching equations

For a linear plan the pseudo-overall yield as defined above is numerically close to the multiplicative product of the reaction yields. The difference between the two values diminishes as the reaction yields approach 1 as would be expected. However, for complex plans with several converging branches this alternative definition becomes less useful. For the triclosan branch equation (4.16) yields 0.405 (40.5%) for the pseudo-overall yield. 

Simple branching equation (SB) A topological method for describing steric effects which takes into account the order of branching by using as parameters the number of atoms other than H that are bonded to the i-th atoms of the substituent. 

The use of sterlo parameters such as and of methods such as the branching equations to represent sterlo effects on bio-activity Is Justified. Transport parameters are composite they are a function of differences In Intermolecular forces. The function of bulk and area parameters Is to provide the proper mix of Intennol-eoular forces required by a particular mode of bloaotlvlty. In the absence of parabolic or bilinear behavior bloactlv-Ity can be modeled by an equation based on Intermolecular forces and steric effects. 

The difficulty can be avoided by the use of topological methods which represent steric effects as the result of contributions of all atoms other than H in the group Various topological methods have been proposed. The discussion here will be restricted to the branching equations (A 8.o). The simple branching (SB) equation is defined by... 

The results obtained for these abiotic systems support the conclusion that 1/ and the branching equations are effective In modelling sterlc effects on Intermoleou lar complex formation and the Interaction of moleoul es with surfaces. We conclude that the use of these methods to i present sterlc effects occurring In steps 1 and 2 of the bloactlvlty model Is Justifiable. 

The three subsets in hexane at —48°C with constant M that vary in the number of branches at Cl were correlated with the simple branching equation in the form of equation 48 ... 

Little in the way of data sets involving the effect of structural variation on bioactivity is available for compounds of germanium and lead. Some data are available for alkylstannanes37 although the data sets are very limited in both the number of data points and in the extent of variation in the alkyl group structure. The toxicity of trialkylstan-nanes to Botrytis and of dialkylstannanes to B. subtilis (sets BA1 and BA2, Table 7) were modeled using the simple branching equation (equation 4) in the form of equation 85 ... 

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