Environmental Enlightenment #179
By Ami Adini -
Reissued April 27, 2016

This is a SHORT, LIGHT and SIMPLE newsletter. Its purpose is to rekindle in the initiated terminology they have once learned, and enlighten the uninitiated on terms they may have heard but never known the meaning of.

Petroleum Hydrocarbon Compounds; Series 3

Cyclic has to do with circular or ring-like arrangement.

A cyclic chemical compound is one that its molecules are structured from rings of atoms.

The water molecule is not cyclic.  It has a linear arrangement where two hydrogen atoms hold hands with one oxygen atom, like this:

The sulfur dioxide molecule is another example of linear arrangement where two oxygens are holding hands with one sulfur

In the organic universe of compounds, in the subset class of hydrocarbon compounds, we have the group of petroleum hydrocarbon compounds. There we find a cross-like molecular arrangement of the very basic compound of methane.


We climb up the ladder of complexity to the caterpillar-like molecule of heptane;


and proceed from there to the royal-like multi-name line, like the one below.

As we get more complex; and petroleum with its over 500 different molecules can get quite interesting; we enter the ring-like fellowship of the cyclic compounds.

The simplest ring of the petroleum gang is benzene; six carbons dancing holding hands and hydrogen toddlers holding to each of the dancers.


The rings evolve to intricate bonds; like the case of ethylbenzene where the ethyl kitty is springing out of the benzene ring.


In the universe of organic compounds, a cyclic compound is one in which a series of carbon atoms are connected together to form a loop or ring. Benzene is a well known example.

Hetero means other or different.  A heterocyclic compound would be the case where atoms other than carbon enter into the ring; the molecule is built of a ring of atoms of more than one kind.

The ring-like molecule diagrammed below is heterocyclic; nitrogen entered into the carbon ring.

A heteroatom is an atom other than carbon in the ring of a heterocyclic compound.  In the above ring, the nitrogen is designated that status; the nitrogen is a heteroatom.

Petroleum and petroleum products are very complex mixtures that contain primarily hydrocarbons (compounds containing molecules of carbon and hydrogen atoms), heteroatom compounds (compounds containing molecules of carbon and hydrogen atoms with heteroatoms such as sulfur, nitrogen, or oxygen), and relatively small concentrations of metallic constituents.

The complexity of petroleum and petroleum products increases with carbon number. The heavier the material, the larger the number of possible combinations of atoms.

Acknowledgment: The Association for Environmental Health and Sciences; http://www.aehs.com/publications/catalog/contents/tph.htm

You can find past issues of "Environmental Enlightenment" at www.amiadini.com - A wealth of information about environmental site assessments in the real estate transactions and issues concerning assessment and cleanup of contamination in the subsurface soil and groundwater.

Call me if you've got any questions. There are no obligations.

Ami Adini & Associates, Inc.
Environmental Consultants
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818-824-8102; 818-824-8112 fax

Ami Adini is a mechanical engineer, California Registered Environmental Assessor, Level II, and president of AMI ADINI & ASSOCIATES, INC. (AA&A), an environmental consulting firm specializing in all phases of environmental site assessments, rehabilitation of contaminated sites and upgrading of underground storage tank facilities. AA&A supplies practical solutions to environmental concerns using the highest standards of ethics and integrity while providing its clients with maximum return on their investments.