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CAN YOU HELP ME TO STUDY HOW TO NAME COMPOUNDS WITH GIVEN STRUCTURE?
Counting the carbon atoms
codeno of carbons
meth1
eth2
prop3
but4
pent5
hex6

Types of carbon-carbon bonds

codemeans
aneonly carbon-carbon single-bonds
enecontains a carbon-carbon double bond

                       yne        contains a carbon-carbon triple bond

Alkyl groups

Compounds like methane, CH4, and ethane, CH3CH3

are members of a family of compounds called alkanes. If you remove a hydrogen atom from one of these you get an alkyl group.

For example:

  • A methyl group is CH3.

  • An ethyl group is CH3CH2.

These groups must, of course, always be attached to something else.

The alkanes

Example 1:  Write the structural formula for 2-methylpentane.

Now draw this carbon skeleton:

Put a methyl group on the number 2 carbon atom

or

Finally,  you have to do is to put in the correct number of hydrogen atoms on each carbon so that each carbon is forming four bonds.

The cycloalkanes

In a cycloalkane the carbon atoms are joined up in a ring - hence cyclo.

Example:  Write the structural formula for cyclohexane.

hexan shows 6 carbons with no carbon-carbon double bonds. cyclo shows that they are in a ring. Drawing the ring and putting in the correct number of hydrogens to satisfy the bonding requirements of the carbons gives:

The alkenes

Example 1:  Write the structural formula for propene.

prop counts 3 carbon atoms in the longest chain. en tells you that there is a carbon-carbon double bond. That means that the carbon skeleton looks like this:

Putting in the hydrogens gives you:

Compounds containing halogens

Example 1:  Write the structural formula for 1,1,1-trichloroethane.

This is a two carbon chain (eth) with no double bonds (an). There are three chlorine atoms all on the first carbon atom.

Alcohols

All alcohols contain an -OH group. This is shown in a name by the ending ol.

Example 1:  Write the structural formula for methanol.

This is a one carbon chain with no carbon-carbon double bond (obviously!). The ol ending shows it's an alcohol and so contains an -OH group.

Aldehydes & Ketones

All aldehydes contain the group:

the structural formula for propanal.

Ketones are shown by the ending one.

propanone.


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