Ring Shape?

Aromatic hydrocarbons have a ring shape. The aromatic content in oil increases with the increase of the average molecular mass of the fraction. In lower fractions (petrol)there are aromatics with one nucleus and a short side chain, and in higher fractions(gas oils and fuel oils) there are condensed aromatics and aromatics with naphthene rings.

Hi Atonija...This is obviously to do with certain processes/stages in the refinery. The second part it is a bit confusing.

I'm not familiar with 'the short side chain' and also 'napthene ring' so I'm guessing they are stages or sections of the refining process and I've rearraged it accordingly.

I hope I haven't altered your original context.

Aromatic hydrocarbons are ring shaped. The aromatic content of the oil grows with a corresponding increase in the average molecular mass of the fraction.

In the lower fractions there are aromatics with a single nucleus which ('are sent through' or 'belong to') the short side chain (petrol). In the higher fractions there are condensed aromatics and other aromatics which ('are sent to'or 'belong to') the napthene ring (gas oils and fuel oils).

Oops....seems Alan and myself were replying at the same time. I hope his interpretation is the correct one.

Hi, Squeaky, no problem. However this text isn't really related to the processes but the chemical composition of the products from the refinery.

The side chain refers to the difference between benzene and its derivatives, such as toluene or xylene. Benzene is a simple ring compound but toluene has one side chain and xylene has two.

A condensed aromatic or the naphthenes have two benzene rings fused together.

Thank you both, Squeaky and Alan.