The Basics of Organic Chemistry

Structural Diversity A carbon atom can reach an octet of electrons in various ways… It can form 4 single bonds. It can form a double bond and 2 single bonds. If can form 2 double bonds. It can form a triple bond and a single bond. Because of this, carbon is the most versatile element and can make a variety of different compounds.

Isomers Isomers are compounds that have identical composition but different structures. C 2 H 6 O can be either ethanol (CH 3 CH 2 OH) or dimethyl ether (CH 3 OCH 3 ).

Hydrocarbons Hydrocarbons are compounds that contain carbon and hydrogen only and are categorized into several subgroups: Alkanes Alkenes Alkynes Cycloalkanes Aromatic compounds Clearly understand Table 11.1 on page 426 and Table 11.2 on page 427.

Alkanes Alkanes have the general formula C n H 2n+2. So, an alkane with 4 carbons will have 2(4) + 2 hydrogens or 10. C 4 H 10

Check and See Draw structures of the five isomers of hexane. Draw the nine isomers of heptane. (1-7, 2-6, 5-5, 1-4)

Naming Alkanes The names of alkanes end in –ane. Names of alkanes with chains of 1-10 C are given in Table The root of the name of the compound has the root based on the longest C chain in the compound. Sub groups of a hydrocarbon chain are identified by a name and the position of the sub group.

Naming Alkanes The position is indicated by a number that refers to the carbon atom to which it is attached. Names of hydrocarbon sub groups, called alkyl groups, are derived from the name of the hydrocarbon. –CH 3 is a methyl group, --CH 2 CH 3 is an ethyl group. Two or more of the same group in the compound are denoted with prefixes, di, tri etc. When different sub groups are on the same alkane, they are listed in alphabetical order.

Check and See Give the systematic name for… CH 3 CHCH 2 CH 2 CHCH 2 CH 3 CH 3 CH 2 CH 3

Cycloalkanes Cycloalkanes are constructed with tetrahedral carbon atoms joined together to form a ring and have the form C n H 2n. Cyclopentane has a 5-carbon ring and cyclohexane has a 6-carbon ring.

Alkenes and Alkynes Alkenes are hydrocarbons with at least one double bond, C=C. The general formula is C n H 2n. They are named similarly to alkanes except they end in –ene. If there is more than one double bond they are named diene and triene. Alkynes are also very similar except they have a triple bond and have the formula, C n H 2n-2.

Check and See Draw 2-methylpropene. Draw and name the compound C 5 H 10, it is an alkene and it has six isomers.

Aromatics Aromatic compounds are a class of compounds so named because they have significant and usually unpleasant odors. Benzene, toluene and naphthalene are three common aromatic compounds. You should memorize the structure for benzene, C 6 H 6. Ortho-, meta- and para- sub groups off of benzene.

Check and See How many isomers are possible for C 6 H 3 Cl 3 ? Assume all Cl are on different carbons. Draw the structure for p-diaminobenzene. What is its systematic name? Its formula is C 6 H 5 NH 2.

Functional Groups A functional group is an atom or group of atoms attached to a carbon atom in a hydrocarbon. Table 11.6 has a list of all the functional groups. You need to know them.

Alcohols Draw the structure of 1-butanol. Draw structures and name each alcohol from a compound with a 5-C chain and one –OH group. Draw 1,2,3-propanetriol (glycerin).

Ketones and Aldehydes Draw the structural formula for 2-pentanone. Draw propanal and 3-pentanone.

Carboxylic Acids Draw butanoic acid and pentacoic acid.

Check and See Draw propanoic acid and methanol. Draw butanoic acid and 1-butanol. Draw hexanoic acid and ethanol. Name each of the following compounds and its functional group… CH 3 CH 2 CH 2 OH CH 3 COOH

Polymers The word polymer means “many parts”. Polymers are giant molecules made by chemically joining small molecules called monomers. Know the monomers and polymers they make in Table on page 456.

Summary Understand the factors that contribute to the large number of organic compounds and wide array of structures. Recognize and draw structures of isomers. Draw structural formulas and name simple hydrocarbons, including alkanes, alkenes, alkynes and aromatic compounds. Draw and name structures of hydrocarbons with all functional groups. Know what a polymer is and some common monomers that make up common polymers.