Bridged hydrocarbon ring systems

Bridged Hydrocarbon Ring Systems. These compounds are named by prefixing the parent ring with bicyclo, tncyclo, etc.,orin some complex... 

Fig. 50. Numbering of methylene-bridged non-alternant polyaromatic hydrocarbon ring systems.

Other polynuclear hydrocarbons may include bridged hydrocarbons, spiro hydrocarbons, mixed systems containing alicyclic and aromatic rings, and aliphatic chains, etc. Examples may be found in the CRC Handbook [63, Section C]. Physical properties of selected polynuclear aromatic compounds are given in [49, p. 967]. 

Fused ring systems that have other bridges are usually named by prefixing the name of the bridge to the name of the fused ring system. The names of hydrocarbon bridges are derived from the names of the parent hydrocarbons by replacing the final -ane, -ene, etc., by -ano, -eno, etc. Thus, -CH2- is methano and -CH=CH- is etheno. 

Finally, DcTar has studied the lactonization of hydroxy acids in bridged ring systems, with the aid of hydrocarbon models (DeTar, 1974 a,b). The calculated and experimental rates show a reasonable correlation. 

The Hantzsch-Widman system is well suited for the naming of saturated monocyclic compounds. Bridged ring systems, however, present a special challenge, and here the replacement system is preferred. An example is provided by the framework of the bicyclic hydrocarbon norbornane. Heteroatoms may in principle be substituted for any of the carbons. To illustrate, nitrogen substitution at position 7 would give rise to the name 7-azanorbomane. 

The suffix term indicates the total number of atoms in the bridged-ring system, excluding any substituents. This is expressed as a hydrocarbon of the appropriate number of atoms even if there are heteroatoms in the ring (Table 6.2). In the example above, undecane indicates that the bridged ring contains 11 atoms. 

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