I Lab Services 

4.17.1 Limitations 

The general ACD/LogP algorithm does not calculate the logP values for the following chemical 

structures: 

Charged structures other than the zwitterionic alpha amino acids and their peptide 

derivatives; 

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

1

): 

A

A

A

A

A

Cl

A 

B

A

Ge

A

P

A

Se

A

2

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 that contain elements in their non typical valence; 

Structures with coordinating bonds; and 

Structures containing more than 255 atoms excluding hydrogen. 

ACD/LogP does not take into account the specific features of different geometric isomers, 

stereoisomers, conformers, isotopes, and structures with non covalent bonds. 

It predicts logP values so that in most cases the reliable experimental measurements lie within 

the calculated 

logP interval.  However, it is still possible that some new chemical structures 

might possess new specific structural features, such as far range non covalent bonding, intra 

molecular shielding, or inter molecular association.  In such cases the discrepancy between a 

newly measured experimental value and the calculated 

 logP interval might occur. 

Plots of chemical structures on the logP scales indicate the changes in other properties only 

when these properties correlate with logP.  Usually, this is only the case for a set of compounds 

with closely related structures. 

For calculation of the partition coefficients of a partially dissociated mixture, we recommend use 

of the LogD Module.  This combines knowledge of the extent of acid base ionization with partition 

coefficient calculations. 

1

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

2

 This fragment can be a part of an aromatic cycle. 

ACD/I Lab via ChemSketch  

User's Guide 

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