Group vectors

It is evident that methods analogous to the ones developed here could be applied to molecular properties which, instead of being pseudoscalar, belong to some other representation of the skeleton point group (vector, tensor, etc. properties). To treat such properties, one needs only to induce from a different representation of than the chiral one. 

I Modify Constraint J Redisplay All Qroups I Remove All Oesign Panes Remove All Group Vectors I Remove Displayed Molecules... 

Again the graphical representation used by the interactive design enables us to evaluate the effect of any substitution. Replacing, —Cl by 0=CH—, would result in a compound having reduced vapor pressure, an increased enthalpy of vaporization, and an increased liquid heat capacity. These alterations of physical properties are derived from the relative positions of the group vectors and the locations of the constraints. 

The —CHj— group has a 5p contribution of -.328, and 5 contribution of -.512. The slope of the —CH2— group vector in the interactive design space is. 64. This is very close to the acetic acid-water target line slope of. 49. Adding several —CH2— groups to any of the solvents shown in Table XVIII thus results in an acceptable new solvent. 

The direction of the —CHj— group vector is toward lower 6p and 5 values. This reduces the distribution coefficient with increasing number of — CH 2 — groups. This result is in accordance with experimental observation (Lo et al., 1983). 

The above results can be understood from sterlc considerations. For n even, the meso-group vector is parallel to the extended chain vector. Thus for n = 4, a fully extended aliphatic spacer is just long enough to permit double overlaps at both ends of a dimer without sterlc Interferences of the nltro groups. As n (even) Increases, such... 

These spirocyclic molecules are very attractive building blocks. As well as having a clearly defined 3-dimensional shape, a variety of functional group vectors on the spirocycle are available to interact with a binding pocket (Figure 18.19). In addition, these small molecules mimic monocyclic rings (such as morpholines and piperidines, for example) and the linear azaspiro[3.3]heptanes (Figure 18.20) have shown increased aqueous... 

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