Beginning Organic Chemistry (BOC)
3. Line Drawings.

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Line Drawings

Of the many ways of writing down the structures of simple organic compounds, a line drawing must be the easiest and quickest.

In a line drawing:
all carbon to hydrogen bonds are omitted
all carbon atoms are omitted, their presence being inferred at the joining of two, three, or four lines and at the end of a line
all other atoms are represented by their atomic symbols, including hydrogen attached to elements other than carbon
When adding hydrogens to the drawing, remember that carbon atoms have four bonds. Thus in places without multiple bonds and with no other atom types attached:
at the end of a line three hydrogens are required,
where two lines meet two hydrogens are required,
where three lines meet one hydrogen is required,
where four lines meet no hydrogens are required.

Examples

Formula Line Drawing Model Comments
CH3-CH2-CH3 Three carbons, two at end of lines, one at the junction of the two lines.
CH3-CH2-CH2-CH2-CH3 Similar to above, five carbons
Where three lines meet there is just one hydrogen
Six carbons in a ring, two hydrogens at each carbon. Note from the model that the ring is not flat!
A carbon carbon triple bond shown here. There are no hydrogens on the two carbons of this bond, nor at the carbon bonded to four other carbons.
Where three lines meet there is just one hydrogen, the hydrogen on the oxygen is indicated by its symbol.

More Examples.

There are no formulae or comments with these. Make sure that you can relate the line drawing to the model, especially to the number of carbons and to the number of hydrogens on each carbon.

Date created: 2005 06 10.