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Objectives
• 18.1 Write and interpret structural formulas of linear, branched, and cyclic alkanes, alkenes, and alkynes
• 18.1 Distinguish among isomers of a given hydrocarbon
• 18.1 Infer the relationship between fossil fuels and organic chemicals
Objectives
• 18.2 Compare and contrast the structures of the major classes of substituted hydrocarbons
• 18.2 Summarize properties and uses of each class of substituted hydrocarbons
• 18.3 Identify monomers that form specific polymers; draw structural formulas for polymers made from given monomers.
Objectives
• 18.3 Differentiate between condensation and addition polymerization reactions
• 18.3 Summarize the relationship between structure and properties of polymers
Quiz 1 Organic Chemistry
• Naming of Organic Molecules
– Anes, enes, ynes, cyclic, substituted including halogens and alcohols
• Drawing of Organic Molecules
• Differences and General properties between Alkanes, Alkenes, Alkynes, and Aromatic Organic Molecules
Quiz 2 Organic Chemistry
• Isomers
• Organic Reactions
• Functional Groups (by memory)
• Biological Connection
– Proteins, Carbohydrates, Lipids, Nucleic Acids
Organic Chemistry
• The chemistry of carbon compounds.
• Carbon has the ability to form long chains.
• Without this property, large biomolecules such as proteins, lipids, carbohydrates, and nucleic acids could not form.
Hydrocarbons
• Four basic types:
– Alkanes
– Alkenes
– Alkynes
– Aromatic hydrocarbons
• With many different functional groups
Alkanes
• Only single bonds.
– Able to rotate freely (unlike other groups)
• Saturated hydrocarbons.
– “Saturated” with hydrogens.
• Unreactive (unlike other groups
Alkenes
• Contain at least one carbon–carbon double bond.
• 120 degree angles
• Unsaturated.
– Have fewer than maximum number of hydrogens.
• More reactive than alkane, less than alkyne
Structure of Alkenes
• Unlike alkanes, alkenes cannot rotate freely about the double bond.
– Fixed bond
• Reactive bonds (useful for digestion)
Alkynes
• Contain at least one carbon–carbon triple bond.
• Also unsaturated (more unsaturated)
• More reactive then alkenes
Formulas
• Lewis structures of alkanes look like this.
• Also called structural formulas.
– Skeletal when only carbon and groups drawn
Cycloalkanes
• Carbon can also form ringed structures.
• Five- and six-membered rings are most stable.– Can take on conformation in which angles are very close
to tetrahedral angle.
– Smaller rings are quite strained.
Reactions of Aromatic Compounds
• Electrons are delocalized; this stabilizes aromatic compounds.
– Middle electrons are shared
Structure of Aromatic Compounds
• Two substituents on a benzene ring could have three possible relationships
– O(ortho)-: On adjacent carbons.
– M(meta)-: One carbon between them.
– P(para)-: On opposite sides of ring.
Organic Nomenclature
• Three parts to a compound name:
– Base: Tells how many carbons are in the longest continuous chain.
Organic Nomenclature
• Three parts to a compound name:
– Base: Tells how many carbons are in the longest continuous chain.
– Suffix: Tells what type of compound it is.
Organic Nomenclature
• Three parts to a compound name:
– Base: Tells how many carbons are in the longest continuous chain.
– Suffix: Tells what type of compound it is.
– Prefix: Tells what groups are attached to chain.
To Name a Compound…
1. Find the longest chain in the molecule.
2. Number the chain from the end nearest the first substituent encountered.
3. List the substituents as a prefix along with the number(s) of the carbon(s) to which they are attached.
1. Ending becomes - yl
Nomenclature of Alkynes
• Analogous to naming of alkenes.
• Suffix is -yne rather than –ene.
4-methyl-2-pentyne
Nomenclature of Alkenes• Chain numbered so double bond gets smallest possible
number.
• cis- alkenes have carbons in chain on same side of molecule.
• trans- alkenes have carbons in chain on opposite side of molecule.
Organic Prefixes (Important Slide)
• Meth = 1 Hex = 6
• Eth = 2 Hept = 7
• Prop = 3 Octa = 8
• But = 4 Non =9
• Penta = 5 Dec = 10
To Name a Compound…
If there is more than one type of substituent in the molecule, list them alphabetically.
Quiz 2 Organic Chemistry
• Isomers
• Organic Reactions
• Functional Groups (by memory)
• Biological Connection
– Proteins, Carbohydrates, Nucleic Acids
Note
• For second quiz, you will recognize structures by name and vice versa– A vocabulary if you
will
• Don’t need to know general info about them (except OH/F)
Halogens/Alcohols
• Increase the Boiling Point (alcohols more due to hydrogen bonding)
• Make the molecules polar (if not countered)
• Make the molecules more acidic
Alcohols• Contain one or more hydroxyl groups, —OH
• Named from parent hydrocarbon; suffix changed to -ol and number designates carbon to which hydroxyl is attached.
Carboxylic Acids
• Have hydroxyl group bonded to carbonyl group.
• Tart tasting.
• Carboxylic acids are weak acids. CH3COOH
Esters
• Products of reaction between carboxylic acids and alcohols.
• Found in many fruits and perfumes.
Chirality
• Carbons with four different groups attached to them are handed, or chiral.
• Optical isomers or stereoisomers
• If one stereoisomer is “right-handed,” its enantiomer is “left-handed.”
Chirality
• Many pharmaceuticals are chiral.
• Often only one enantiomer is clinically active.
– Difference between sugars that are not recognized by body and those that are
S-ibuprofen
Amino Acids and Proteins
• Proteins are polymers of -amino acids.
– Amino acids = Have an amine functional group and are acidic
Amino Acids and Proteins
• Hydrogen bonding in peptide chains causes coils and helices in the chain.
• Kinking and folding of the coiled chain gives proteins a characteristic shape.
Amino Acids and Proteins
• Most enzymes are proteins.
• The shape of the active site complements the shape of the substrate on which the enzyme actshence, the “lock-and-key” model.
Carbohydrates
Simple sugars are polyhydroxy aldehydesor ketones.
Are Isomers of one another, differ in location of oxygen
Carbohydrates
• In solution they form cyclic structures.
• These can form chains of sugars that form structural molecules such as starch and cellulose.
Nucleic AcidsTwo of the building blocks of RNA and DNA are sugars (ribose or deoxyribose) and cyclic bases (adenine, guanine, cytosine, and thymine or uracil).
Reactions of Alkenes
• Addition Reactions
• Two atoms (e.g., bromine) add across the double bond.
• Exothermic
Mechanism of Addition Reactions
• Two-step mechanism:
– First step is slow, rate-determining step.
– Second step is fast.
Mechanism of Addition Reactions
In second step, new bond forms between negative bromide ion and positive carbon.
Reactions of Alcohols
• An alcohol in the presence of a large acid (such as Sulfuric) can change into an eneinstead of an ol. (Called dehydration)
• An alcohol in the presence of a small acid (such as Hydrochloric) can change into an alkyl halide (a hydrocarbon with a halogen on it)