Organic Chemistry Chapters 22 & 23. Organic Chemistry The study of carbon-containing compounds...

Organic Chemistry

Chapters 22 & 23

Organic Chemistry

• The study of carbon-containing compounds and their properties

• Carbon can bond strongly to itself and form long chains or rings of carbon atoms

Carbon Bonding

• Carbon can form 4 bonds (because it has 4 valence electrons… remember those?)

• These bonds can be made with 4 carbon atoms or atoms of different elements

• Carbon can also bond to fewer than 4 other atoms if it forms a double or triple bond– Double bonds share 2 pairs of electrons– Triple bonds share 3 pairs of electrons

Carbon Bonding

Aspartame

Alkanes

• Hydrocarbons are compounds made solely of hydrogen and carbon

• Hydrocarbons with all single carbon-carbon bonds are called saturated, because each carbon is bound to 4 atoms – the maximum number

• Hydrocarbons with multiple carbon-carbon bonds (i.e., double and triple bonds) are unsaturated

Alkanes• Saturated hydrocarbons are called alkanes

• Alkanes in which the carbon atoms form long chains are called normal, straight-chain, or unbranched hydrocarbons

• They are given by the general formulaCH3 – (CH2)m – CH3

Or

CnH2n+2

AlkanesName Condensed

FormulaExtended Formula

Methane CH4 CH4

Ethane C2H6 CH3CH3

Propane C3H8 CH3CH2CH3

n-butane C4H10 CH3CH2CH2CH3

n-pentane C5H12 CH3CH2CH2CH2CH3

n-hexane C6H14 CH3CH2CH2CH2CH2CH3

n-heptane C7H16 CH3CH2CH2CH2CH2CH2CH3

n-octane C8H18 CH3CH2CH2CH2CH2CH2CH2CH3

n-nonane C9H20 CH3CH2CH2CH2CH2CH2CH2CH2CH3

n-decane C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

Alkanes

• Give the extended and condensed molecular formulas for an alkane with fifteen carbon atoms.

Structural Formulas and Isomerism

• Structural isomerism occurs when two molecules have the same atoms, but different bonds (different arrangements)– This occurs in butane and all succeeding alkanes

Naming AlkanesThe Rules

1. Find the longest continuous chain of carbon atoms – this “parent chain” determines the base name of the alkane

2. Number the carbons in the parent chain, starting at the end closest to any branching.

3. Using the appropriate name for each alkyl group (next slide), specify its position on the parent chain with a number.

4. When a given type of alkyl group occurs more than once, attach the appropriate prefix (di- for two, tri- for three, etc) to the alkyl name

5. The alkyl groups are listed in alphabetical order, disregarding any prefix

Naming AlkanesCommon Alkyl Substituents

Alkenes and Alkynes

• Hydrocarbons that contain carbon-carbon double bonds are called alkenes

• Hydrocarbons that contain carbon-carbon triple bonds are called alkynes

Alkenes and AlkynesNaming Rules

1. Select the longest continuous chain of carbon atoms that contains the double or triple bond

2. For an alkene, the root name of the carbon chain is the same as for the alkane, but ends in –ene (alkynes end in –yne)

3. Number the parent chain, starting at the end closest to the double/triple bond. The location of the multiple bond is given by the lowest-numbered carbon atom involved in the bond.

4. Substituents on the parent chain are treated the same way as in naming alkanes.

Aromatic Hydrocarbons

• Aromatic hydrocarbons are compounds that have pleasant odors and contain a benzene ring (ring of 6 carbon atoms)– Examples: wintergreen, cinnamon, vanillin

Naming Aromatic Compounds

• Monosubstituted Benzenes (p. 781)– Use the substituent name as a prefix of benzene– When the benzene ring is used as a substituent, it

is called a phenyl group

• Disubstituted Benzenes (p. 781)– When there is more than one substituent on the

benzene ring, numbers are used to indicate the substituent position

Naming Aromatic Compounds

• Some other helpful terms/prefixes:

– Ortho- (o-) means two adjacent substituents

– Para- (p-) means two substituents directly across the ring from each other

– Meta- (m-) means two substituents with one carbon between them

Functional Groups (slide 17)see also Table 23.1 on p. 799

Alcoholssee also p. 805

• Alcohols are characterized by the presence of the –OH group

• Naming Rules1. Select the longest chain of carbon atoms containing

the –OH group2. Number the chain so that the carbon with the –OH

group gets the lowest possible number3. Obtain the root name from the name of the parent

hydrocarbon chain by replacing the final –e with –ol4. Name any other substituents as usual

Aldehydes and Ketonessee also p. 813

Naming Rules:•Refer back to slide 17 to see the structure of aldehydes and ketones…

•Name an aldehyde with the parent alkane name but replace the –e with –al

•Name a ketone with the parent alkane name but replace the –e with -one

Carboxylic Acids and Esterssee also p. 815

• Again, refer to slide 17 to see the structures of carboxylic acids and esters

• Name carboxylic acids using the parent alkane name and replacing –e with –oic acid.– Examples: methanoic acid, ethanoic acid,

propanoic acid, etc.

Carboxylic Acids and Esters

• Esters are formed from the reaction of a carboxylic acid and an alcohol

• They often have sweet, fruity odors• The name consists of the alkyl name from the alcohol

followed by the acid name, where the –ic is replaced by –ate– Example: the ester made from acetic acid and isopropyl

alcohol is called isopropyl acetate

Polymers

• Polymers are large, usually chainlike molecules that are built from small molecules called monomers.

• Polymers are the basis for synthetic fibers, rubbers and plastics

• Examples: – Polyethylene– Teflon– Polyester

Polymers

• Copolymers – made of different types of monomers

• Homeopolymers – made up of a single type of monomer

• Addition polymerization – monomers simply “add together”

• Condensation polymerization – a small molecule (perhaps water) is formed for each extension of the polymer chain – Ex: NYLON

FOR YOUR KNOWLEDGE ONLY…The rest of the slides will not be tested

Reactions of Alkanes

Combustion Reactions• Same as we have seen before• General formula

CnH2n+2 + O2 CO2 + H2O

Reactions of Alkanes

Substitution reactions• One or more hydrogen atoms of the alkane

is/are replaced (substituted) by different atoms

• Example:CH4 + Cl2 CH3Cl + HCl

Reactions of Alkanes

Dehydrogenation reactions• Hydrogen atoms are removed and the product

is an unsaturated hydrocarbon• Example:

CH3CH3 CH2CH2 + H2

Alkenes and AlkynesReactions of Alkenes

• Addition reactions – new atoms form single bonds to the carbons formerly involved in the double or triple bonds– Hydrogenation reactions – addition reactions

with hydrogen atoms being added to the carbons formerly involved in the double or triple bonds

– Halogenation – addition reactions with halogen atoms being added to the carbons formerly involved in the double or triple bonds.

Halogenation Reaction

Hydrogenation Reaction