Hydrocarbons fused polycyclic

The nomenclature of these compounds in which at least two highly unsaturated rings are fused together through at least two common C-atoms is based on an extended series of trivial names. The most important of 

Acenaphtho from Acenaphthylene Naphtho from Naphthalene 

Anthra from Anthracene Perylo from Perylene 

Benzo from Benzene Phenanthro from Phenanthrene 

With the exception of benzo, fusion prefixes for monocyclic systems are treated as exemplified for cyclopenta, cyclohepta etc. It should be noted here that for fused polycyclic systems the ending. ..ene always indicates the maximum number of non-cumulative double bonds, that is, a man-cude system  

Listed in order of increasing priority for selection as parent compound 

Asterisk after a compound denotes exception to systematic numbering. 

TABLE 1.2 Fused Polycyclic Hydrocarbons (continued) Listed in order of increasing priority for selection as parent compound 

Examples of retained names and their structures are as follows  

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The names of ortho-fused or ortho- and peri-fused polycyclic hydrocarbons with less than maximum number of non-cumulative double bonds are formed from a prefix dihydro- , tetrahydro- , etc., followed by the name of the corresponding unreduced hydrocarbon. The prefix perhydro- signifies full hydrogenation. When there is a choice... 

Alternate to part of Rule A-23.1)—The names of ort/io-fused polycyclic hydrocarbons which have (a) less than the maximum number of non-cumulative double bonds, (b) at least one terminal unit which is most conveniently named as an unsaturated cycloalkane derivative, and (c) a double bond at the positions where rings are fused together, may be derived by joining the name of the terminal unit to that of the other component by means of a letter o with elision of a terminal e . The abbreviations for fused aromatic systems laid down in Rule A-21.4 are used, and the exceptions of Rule A-23.1 apply. 

Univalent radicals derived from ortho-fused or ortho- and peri-fused polycyclic hydrocarbons with names ending in -ene by removal of a hydrogen atom from an aromatic or alicyclic ring are named in principle by changing the ending -ene of the names of the hydrocarbons to -enyl . 

Bivalent radicals derived from o/7/io-fused or ortho- and pen-fused polycyclic hydrocarbons by removal of a hydrogen atom from each of two different carbon atoms of the ring are named by changing the ending -yl of the univalent radical name to -ylene or -diyl . Multivalent radicals, similarly derived, are named by adding -triyl , -tetrayl , etc., to the name of the ring system. 

Fused Polycyclic Hydrocarbons. The names of polycyclic hydrocarbons containing the maximum number of conjugated double bonds end in -ene. Here the ending does not denote one double bond. Names of hydrocarbons containing five or more fixed benzene rings in a linear arrangement are formed from a numerical prefix (see Table 11.4) followed by -acene. A partial list of the names of polycyclic hydrocarbons is given in Table 1.2. Many names are trivial. 

Unlike the lack of logic in the IUPAC system that results when additional "fused polycyclic hydrocarbons" are named by addending rings to one of these "privileged" 35 reference compounds at specified locations, it is highly desirable that the nomenclature for all ring systems uses the same criteria. This is another virtue of proposed system. Meanwhile a close scrutiny of the molecules depicted in Tables 1 and 2 reveal ... 

In fused polycyclic hydrocarbons as well as in heterocyclic systems, special numbering schemes are adopted (see Section P-25 of Ref. 3). 

Being interested here in the volatile components of coffee aroma, we shall arbitrarily limit the list of the aromatic hydrocarbons to tricyclic structures. The higher fused polycyclic hydrocarbons (fluoranthene [206-44-0], pyrene [129-00-0], chrysene [218-01-9], benz[ ]anthracene (1,2-benzanthracene) [56-55-3], benz[< ]acephenanthrylene (3,4-benzofluoranthene) [205-99-2], benzo[ ]pyrene (3,4-benzopyrene, 3,4-BP) [50-32-8], benzo[e]pyrene (1,2-benzopyrene) [192-97-2], perylene [198-55-0], benzo[g,/i,/]perylene (1,12-benzopyrene) [191-24-2], and dibenz[ ,//]anthracene (1,2,5,6-dibenzanthracene) [53-70-3]) cannot be considered as a part of the aroma. However, as some of these, specially benzo[o pyrene, are known for carcinogenic properties, they have been particularly analyzed in food subject to roasting or smoke-curing. 

The OSHA PEL (8-hour TWA) for coal tar pitch volatiles is 0.2 mg/m (benzene-soluble fraction). OSHA defines coal tar pitch volatiles in 29 CFR 1910.1002 as the fused polycyclic hydrocarbons that volatilize from the distillation residues of coal, petroleum (excluding asphalt),... 

Naphthalene is the parent compound of a series of fused polycyclic hydrocarbons, a few other examples of which are... 

The comparison between these two cases suggests that the spin density wave introduced by an external magnetic site on a conjugated hydrocarbon has a long range spatial extent when the bonds of the conjugated system are weakly contrasted. This is the case in fused polycyclic hydrocarbons. 

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