Organic Chemistry

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The locations or other groups of atoms attached to the longest chain are identified and numbered by counting from the end of the molecule which keeps the numbering system as low as possible.

Hydrocarbon groups that are attached to the longest continuous chain and named using the parent name and changing the –ane suffix to –yl.

Slide 11

Recall that a molecular formula (A) describes the numbers of different kinds of atoms in a molecule, and a structural formula (B) represents a two-dimensional model of how the atoms are bonded to each other. Each dash represents a bonding pair of electrons.

Slide 12

(A)A straight-chain alkane is identified by the prefix n- for "normal" in the common naming system. (B) A branched-chain alkane isomer is identified by the prefix iso- for "isomer" in the common naming system. In the IUPAC name, isobutane is 2-methylpropane. (Carbon bonds are actually the same length.)

Slide 13

Alkenes and Alkynes

Alkenes are hydrocarbons with at least one double carbon to carbon bond.

To show the presence of the double bond, the –ane suffix from the alkane name is changed to –ene.

The alkenes are unsaturated with respect to hydrogen

This means it does not have the maximum number of hydrogen atoms as it would if it were an alkane (a saturated hydrocarbon).

Slide 14

Ethylene is the gas that ripens fruit, and a ripe fruit emits the gas, which will act on unripe fruit. Thus, a ripe tomato placed in a sealed bag with green tomatoes will help ripen them.

Slide 15

Naming is similar to naming alkanes except:

The longest continuous chain must contain the double bond.

The base name now ends in –ene.

The carbons are numbered so as to keep the number for the double bond as low as possible.

The base name is given a number which identifies the location of the double bond.

An alkyne is a hydrocarbon with at least one carbon to carbon triple bond.

Naming an alkyne is similar to the alkenes, except the base name ends in –yne.

Slide 16

Cycloalkanes and Aromatic Hydrocarbons

Cycloalkanes are alkanes (only carbon to carbon single bonds) which form a ring structure.

An aromatic compound is one that is based on the benzene ring.

A benzene ring that is attached to another compound is given the name phenyl.

Slide 17

(A)The "straight" chain has carbon atoms that are able to rotate freely around their single bonds, sometimes linking up in a closed ring. (B) Ring compounds of the first four cycloalkanes.