Alicyclics and Aromatics

-Carbon chains can form two types of closed loops
-Alicyclics are loops usually made with single bonds
-If the parent chain is a loop standard naming rules apply with one addition: 'cyclo' is added in front of the parent chain

Cyclopentane

-Numbering can start anywhere and go CW or CCW on the loop but side chain numbers must be the lowest possible

-Loops can also be a side chain

-Same rules apply but the side chain is given a cyclo-prefix

Aromatics

-Benzene (C6H6) is a cyclic hydrocarbon with unique bonds between the carbon atoms

-Structurally if can be drawn with alternating double bonds

-Careful analysis shows that all 6-C-C bonds are identical and really represent a 1.5 bond

-This is due to e- resonance

-e- are free to move all around the ring

Aromatic Nomenclature

-A Benzene molecule is given a special diagram to show it's unique bond structure

-Benzene can be a parent chain or a side chain

-As a side chain it is given the name phenyl

-T.H