In 1995, Paul Andrews (formerly Health Canada) and Walter Vetter developed and published a nomenclature code system for toxaphene, namely chlorinated bornanes (P. Andrews, W. Vetter, Chemosphere 31 (1995) 3879-3886). In the meantime, this system has been used by a wide number of colleagues throughout the world, in addition to the so-called "Parlar numbers".


  1. Introduction
  2. download and installation
  3. How to use the nomenclature system
  4. advantages of the AV-code system
I. Introduction
The chloropesticide Toxaphene consists of several hundred components, most of which are chlorinated bornanes.

GC/ECD chromatogramm of toxaphene
Figure: GC/ECD chromatogramm of toxaphene

Chlorinated bornanes exist in a variety of 16640 congeners or 32767 enantiomers (W. Vetter, Chemosphere 26 (1993) 1079-1086). Designing abbreviated codes unequivocally for this huge variety is a challenge. For this reason, the AV-code system was based on the following points:
  1. The chlorobornane numbering follows the rules of the International Union of Pure and Applied Chemistry (IUPAC).
    CTT backbone
    Backbone of bornane with IUPAC carbon numbering
    Note that C9 is located above C2/C3 while C8 is located above C5/C6

  2. The AV-codes start with a letter which classifies the hydrocarbon backbone. To date only chlorinated bornanes are ruled and receive the letter "B" .Letter "C" is reserved for camphenes, "D" for dihydrocamphenes, and "E" for bornenes. The latter applies the idea used for DDE.
  3. Directly after the letter B, a number follows which represents the degree of chlorination, i. e. B8 for octachlorobornanes.
  4. After a hyphen, all isomers are listed according to IUPAC rules which are consecutively numbered starting from 1 to 2626 at max.
    Example: the AV-code of the known chlorinated bornane 2,2,5-endo,6-exo,8,9,10-heptachlorobornane (Toxicant B) is B7-515. A Table with most CTTs known to date is following here.
  5. Another complication arises from the fact that >97% of all chlorinated bornanes are chiral (actually all chlorinated bornanes that are known to date are chiral). This fact has been considered in the AV-code system.
These rules were incorporated in a Windows program developed for this reason.
II. Download and Installation
  1. A new subdirectory "vb" must be installed directly on "c:". Result: c:\vb
    Note: do neither create the subdirectory at any other location (e. g. not at "c:\windows") nor name it in another way. The program will only run under "c:\vb".
  2. Copy all files into the new subdirectory "c:\vb".
  3. start the program from the file manager (explorer; windows explorer) by a double click on the "conger.exe" symbol:

    conger.exe symbol
    Figure 1: conger.exe file and symbol found in "c:\vb" directory

  4. The following surface will open

    Figure 2

    Click here for instructions on "How to use the nomenclature system"
III. How to use the nomenclature system
  1. Find the AV-code for a chlorinated bornane with known structure
    STEP1: Mark boxes at respective positions of Cl substituents on the surface.
    For "2-endo,3-exo,5-endo,6-exo,8,8,9,10,10-nonachlorobornane" you will receive the following picture (Figure 3):

    Figure 3

    STEP2: Press the button "calculate number from structure" to receive the AV-code (Figure 4):

    Figure 4

    Result of step 2: the AV-code (here: B9-1679) will appear in box "Congener number" and the chemical name (2-endo,3-exo,5-endo,6-exo,8,8,9,10,10-nonachlorobornane) will appear in box "IUPAC nomenclature for racemate and enantiomer a".
  2. Find chemical name of enantiomer 2:
    STEP3: From a known AV-code or IUPAC structure (Figure 4, above) simply click on "calculate structure from number" button (Figure 5):

    Figure 5

    Result of step 3: the chemical name of enantiomer b will appear in box "IUPAC nomenclature for enantiomer b"
IV. Advantages of the AV-code system:
  1. All chlorinated bornanes are unequivocally covered with this system
  2. Each chlorinated bornane has its own code
  3. AV-system allows to distinguish the enantiomers of a chlorinated bornane
  4. Structures and codes can be easily double-checked (e. g. in Tables)
  5. New discovered chlorinated bornanes can receive an uniformal AV-code