Organic Chemistry By Kevin Barlan

The Basic Components All organic compounds consist of at least one carbon atom bonded to hydrogen atoms. While there may be other elements present, most are hydrocarbons.

Hydrocarbons Hydrocarbons can be grouped into three classes: alkanes, alkenes, and alkynes. A compound in one of these classes can either be linear or circular. Circular hydrocarbons are grouped into cycloalkanes, cycloalkenes, or cycloalkynes.

Naming Alkanes Alkanes are hydrocarbons with all single bonds. Alkanes are named using the prefixes meth- one eth- two prop- three but- four pent- five etc. The prefix for the number of carbons in the longest chain is attached to the ending –ane.

Example: Name the compound C – H Eth ane C C First, count the number of carbons. There are two carbons in the longest chain, so we use the prefix eth-. Since this is an alkane, we use the ending -ane.

CnH2n+2 The compound is ethane, C2H6. If you are given the name of a simple alkane, you can determine the chemical formula by determining the number of carbons, indicated by the prefix. If there are n carbon atoms in a simple alkane, then the chemical formula is CnH2n+2

Alkyl Groups When a carbon atom in one alkane is attached to a carbon atom in another alkane, it is called an alkyl. H – – C – H H C – H

Naming Alkyl Groups 2-methylbutane You count the number of carbons in the longest chain. You then the count the number of carbons in the alkyl groups. H C – There are four carbons in the longest chain. Therefore, the compound is called And there is one carbon in the alkyl group. C And, the alkyl group is attached to the second carbon in the chain. 2-methylbutane 2 C C C C

Now you try: There are six carbon atoms in the longest chain. C – H And one carbon in the alkyl group. Therefore it is called 3-methylhexane

Multiple Alkyl Groups H H H – – – This would be called 2,4-methylethylhexane H – C – – C – C – H – – – – H H – – H C H H H H H – – – – H – C – – C – C – C – C – H – – – – – H H H H H

Alkenes and Alkynes Alkenes are hydrocarbons with some double bonds. Alkynes have some triple bonds. Alkenes and alkynes are named in the same way as alkanes, except for two things: 1) If there are more than three carbons, you put a number in front signifying where the bond begins 2) You use the suffix –ene or –yne. If there are multiple double or triple bonds, you would use the ending –diene, -triene, etc.

C – H Ethene C – H Ethyne H H – – C H H – – – – – C C C – – H H 1,2-butadiene

General Formulas Simple alkenes are CnH2n Simple alkynes are CnH2n-2

Cycloalkanes, Cycloalkenes, Cycloalkynes H H H H – – H H H – C – C – H – – H – C – C – H H H – – H H H H Cyclobutane

Benzene H – C H H – – – – C C – – C C – – – H – H C – H This is benzene, C6H6 These are two short-hand forms for benzene H – C H H – – – – C C – – C C – – – H – H C – H

Aromatic Hydrocarbons Napthalene Anthracene CH3 Toluene

Alcohols Alcohols are molecules consisting of a hydrocarbon chain and a hydroxide ion. Example: To name alcohols, you replace the e at the end of the hydrocarbon’s name with -ol. This molecule is called methanol, CH3OH. C – H OH

Name the following alcohol: – H OH Since there are two carbons, this is called ethanol, C2H5OH. Guess what? You just gave the chemical formula for beer!

Amines Amines consist of a nitrogen atom bonded to one or more hydrogen atoms and one or more alkyl groups. If you take off one or more of the hydrogen atoms in ammonia and replace each one with an alkyl group, you get an amine.

This is ammonia, NH3. C – H If you replace one hydrogen with, for example, methyl H – H – N – H You would get methylamine, CH3NH2

Ketones Ketones are alkanes where an internal carbon atom is double bonded to an oxygen atom. Propanone (Acetone) H O H – – – – H – C – C – C – H – – H H

Aldehydes Aldehydes have a carbon atom double bonded to an oxygen atom and single bonded to a hydrogen atom. H O – – – – – H C – C H – Ethanal (Acetaldehyde) H

Ethers Ethers consist of an alkyl group bonded to an oxygen atom that is bonded to another alkyl group. H H – – H – C – O – C – H – – Dimethyl ether H H

Haloalkanes Haloalkanes are alkanes bonded to one or more halogens instead of hydrogen atoms. C – H – Cl Chloromethane

Carboxylic Acid Carboxylic acids are alkyls with the end carbon attached by a double bond to an oxygen atom and by a single bond to a hydroxide group. H O – – – H – C – C – OH – H Ethanoic Acid

Ester An ester has the following group in it: Esters have the suffix -oate. O – C =

This is methyl ethanoate, or methyl acetate. – C = H H – H – C H – H H

Amides Amides contain the following group: O = Amides have the suffix -amide. N – C = O

This is ethanamide, or acetamide. – C = O C – H H H