Organic compounds Contain Elements C (Four covalent bonds) H (One covalent bond) Halogen (One covalent bond) O (Two covalent bonds) S (Two covalent bonds) N (Three covalent bonds) P (Three covalent bonds

Structural Formulas Full/Fischer Projection Condensed CH 3 CH 2 CH 2 CH 3

HYDROCARBONS The study of carbon compounds is organic chemistry.. Most organic compounds consist of carbon and hydrogen. Hydrocarbons are compounds with only C and H.

Hydrocarbons: Classes Saturated compounds have only  bonds. Unsaturated compounds have both  and  bonds.

HYDROCARBONS: Physical Properties of Alkanes Since the only intermolecular forces available to alkanes are London dispersion forces, the boiling points increase smoothly as the molar mass increases. Methane to butane are gases at normal pressures. Pentane to decane are liquids at normal pressures. Each carbon in an alkane has 4 single bonds. In this table each member differs by one CH 2 unit. This is called a homologous series.

Alkanes

Alkanes Structures of Alkanes VSEPR theory predicts each C atom is tetrahedral. Therefore, each C atom has sp 3 hybridized orbitals. It is easy to rotate about the C-C bond in alkanes. Structural Isomers Straight chain hydrocarbons have each C atom joined in a continuous chain. In a straight chain hydrocarbon no one C atom may be attached to more than two other C atoms.

Alkanes Structures of Alkanes

Nomenclature of Alkanes Rules for naming compounds are given by the International Union for Pure and Applied Chemistry (IUPAC). Prefix suffix system To name alkanes: –1. Find the longest continous chain and use it as the name of the compound. Identify branches/side groups if any. –2. Number the carbon atoms so that the most branches/side groups have lowest possible numbers. –3.Name and give the location of each substituent/branch/side group.

Alkanes

Name the Following

Alkanes Nomenclature of Alkanes

Name the Following

Alkanes: Structural Isomerism Structural isomers exist when can write more than one structural formula from the same molecular formula

Alkanes Structures of Alkanes VSEPR theory predicts each C atom is tetrahedral. Therefore, each C atom has sp 3 hybridized orbitals. It is easy to rotate about the C-C bond in alkanes. Structural Isomers Straight chain hydrocarbons have each C atom joined in a continuous chain. In a straight chain hydrocarbon no one C atom may be attached to more than two other C atoms.

Alkanes: Structural Isomers of C 4 H 10 Structural isomers have different physical and chemical properties.

Alkanes: Structural Isomers of C 5 H 12

Alkanes Cycloalkanes Alkanes that form rings are called cycloalkanes. Reactions with Alkanes The C-C and C-H bonds are very strong. Therefore, alkanes are very unreactive.

CYCLOALKANES

Alkanes: Reactions The C-C and C-H bonds are very strong. Therefore, alkanes are very unreactive. At room temperature alkanes do not react with acids, bases, or strong oxidizing agents. Alkanes do combust in air (making them good fuels): 2C 2 H 6 (g) + 7O 2 (g)  4CO 2 (g) + 6H 2 O(l)  H = kJ

Unsaturated Hydrocarbons: Alkenes Alkenes contain C, H atoms and single and double bonds. The simplest alkenes are H 2 C=CH 2 (ethene) and CH 3 CH=CH 2 (propene): –their trivial names are ethylene and propylene. Alkenes are named in the same way as alkanes with the suffix -ene replacing the -ane in alkanes. The location of the double bond is indicated by a number.

Unsaturated Hydrocarbons Alkenes

Alkynes Alkynes are hydrocarbons with one or more C  C bond. Therefore, alkynes have one  and two  bonds between two C atoms. Ethyne (acetylene) is a reactive alkyne: HC  CH. When acetylene is burned in the presence of oxygen (oxyacetylene torch) the temperature is about 3200 K. Alkynes are named in the same way as alkenes with the suffix -yne replacing the -ene for alkenes.

Reactions of Alkenes Addition Reactions of Alkenes and Alkynes The most dominant reaction for alkenes and alkynes involves the addition of something to the two atoms which form the double bond: Note that the C-C  bond has been replaced by two C-Br  bonds. A common addition reaction is hydrogenation: CH 3 CH=CHCH 3 + H 2  CH 3 CH 2 CH 2 CH 3

Unsaturated Hydrocarbons Aromatic Hydrocarbons

Unsaturated Hydrocarbons: Aromatic Hydrocarbons Benzene is a planar symmetrical molecule. Benzene is not reactive because of the stability associated with the delocalized  electrons. Most aromatic rings are given common names. Even though they contain  bonds, aromatic hydrocarbons undergo substitution more readily than addition.

Functional Groups: Alcohols and Ethers

Alcohols (R-OH)

Compounds with a Carbonyl Group Carboxylic Acids

Compounds with a Carbonyl Group Esters Some common esters are: benzocaine (in sun burn lotions), ethyl acetate (nail polish remover), vegetable oils, polyester thread, and aspirin. Esters contain -COOR groups: Esters can be prepared by reacting a carboxylic acid with an alcohol and eliminating water:

Compounds with a Carbonyl Group: ESTERS Esters tend to have characteristic odors and are used as food flavorings and scents.

AMINES AND AMIDES Amines are organic bases. Amides are composites of carbonyl and amine functionalities:

SULFIDES Example of Sulfide Disulfides