I Lab Services 

4.18 LogD 

This module calculates the apparent partition coefficient D for dissociative systems logD values 

at various pH (from 0 to 14). 

The resultant dialog box displays a list of logD values at pH from 0.0 to 14.0 in a single step.  All 

of this data can be printed at once by clicking Print, or you may wish to edit the default report 

page in the ChemSketch and then print it (click Insert to start editing). 

4.18.1 Limitations 

The ACD/LogD algorithm does not calculate the logD values for the following chemical 

structures: 

Structures containing atoms other than C, H, O, S, N, and F in possible chemical 

surroundings or structures containing atoms P, Cl, Br, I, Se, Si, Ge, Pb, Sn, As, and B that 

are not within the chemical surroundings shown below (note that A denotes any atom out 

of C, O, S, N, F, or any group listed below

3

):   

A

A

A

A

A

Cl

A 

B

A

Ge

A

P

A

Se

A

4

A

A

A

A

A

A

A

Se

A  

Br

A 

Sn

A

P

A

A

A

A

A

A

A

I

A 

Pb

A

As

A

A

A

Structures containing atoms in non typical valence states (see the Elements Table in the 

ACD/ChemSketch for information on individual atomic valences); 

Structures containing non covalent (co ordination) bonds; 

Structures containing more than 255 heavy atoms or 10 ionization centers; and 

Structures containing more than 10 exchangeable protons. 

Additionally, the ACD/LogD algorithm does not take into account the specific features of different 

geometric isomers, stereomers, conformers, and isotopes.  The algorithm does not correct its 

prediction for long range non covalent bonding, intra molecular shielding, or inter molecular 

association. 

3

 This group cannot be a part of a cycle unless otherwise stated. 

4

 This fragment can be a part of an aromatic cycle. 

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