Benson Rules Input

Benson Rule format

The Benson rule format follows the format of Structure Thermodynamic Input with three lines:

The benson structure is given in columns 10-57 of the first line. The second line is the thermodynamic information and the third line is th atomic make-up. The format of the second and third lines are given in Structure Thermodynamic Input.

Benson String

The Benson rule refers to a 'central' atom and its immediate connections. For example, a primary carbon atom on an alkane has a carbon as the central atom and is connected to three hydrogens and the next carbon in the chain. The Benson string reflecting this is:

c-(h)/3-(c)

One can see the c as the central atom. The connection is with:

• three hydrogens: (h)/3
• One carbon: (c)

As can be seen, if the central atom is connected to multiple atoms of the same type, then a slash is used:

• One Atom: no slash
• Two atoms: /2
• Three atoms /3
• Four atoms: /4

In the Benson tables, atoms are given by their lower case abbreviation, for example:

• Carbon: (c)
• Hydrogen: (h)
• Chlorine: (cl)
• Bromine: (br)

A carbon, regardless of whether it is the central atom or a connecting atom, can have several valences. These are denoted by special 'meta atoms':

• Single Bonded Carbon: ( c)
• Double Bonded Carbon: (c/d)
• Triple Bonded Carbon: (c/t)
• Carbon on an aromatic: (c/b)

In the benson tables, there is also special structures that are considered as a single 'meta-atom':

• C=O group: (co)
• S=O group: (so)
• O=S=O group (so2)

Meta Atoms

Meta atoms are not coded in the system, but are defined by structures within the database.

Within the connectivity specification, a meta-atom is used just like a reqular atom. For example, the connectivity of the co of an aldehyde and a ketone is given by these specifications:

Within JThermodynamics, the molecule atoms are subsituted (see structures within the database.) to form the same molecule, but with meta-atoms instead. In the case of co both the carbon and the oxygen in the double bonded connection is substituted with a single co meta-atom.

Original 'Standard' Benson values

The following is the input file for the standard benson values. These correspond to Table 12 of Benson's book.